Information

If a specific neuron is present in my brain, will it be present in another person's brain?

If a specific neuron is present in my brain, will it be present in another person's brain?

For example if I have a neuron cell that fires when I say the letter 'A' and is located at a specific place in my brain, will another person have that cell at the exact same place and will it fire when he/she says 'A'?


No, unless you are a C. elegans (or have a similarly simple nervous system), and even then maybe not quite.

Wild-type C. elegans has exactly 302 neurons and they are the same neurons in different members of the species. However, even then, learning can change their nervous system so that it isn't exactly identical in two individuals.

Mammals including humans, however, have brains that are much more shaped by experience and learning. Only the general structure is the same, and even that differs somewhat. It has even been shown that different parts of the brain can be different sizes in individuals with different occupations (see Maguire et al., 2000, for example).


Maguire, E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D., Ashburner, J., Frackowiak, R. S., & Frith, C. D. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences, 97(8), 4398-4403.

White, J. G., Southgate, E., Thomson, J. N., & Brenner, S. (1986). The structure of the nervous system of the nematode Caenorhabditis elegans. Philos Trans R Soc Lond B Biol Sci, 314(1165), 1-340.


Neurotransmitters, Neurons, Hormones, and Depression

Biological causes of clinical depression continue to be studied extensively. Great progress has been made in the understanding of brain function, the influence of neurotransmitters and hormones, and other biological processes, as well as how they may relate to the development of depression.

Brain Function in Depression
The brain is the "command center" of the human body. It controls the basic functions of our bodies, our movements, and our thoughts and emotions. Researchers studying clinical depression tend to look at several aspects of brain function including the structures of the limbic system and the function of neurotransmitters within neurons.

Limbic System
Those who research clinical depression have been interested in a particular part of the brain called the limbic system. This is the area of the brain that regulates activities such as emotions, physical and sexual drives, and the stress response. There are various structures of the limbic system that are of particular importance. The hypothalamus is a small structure located at the base of the brain. It is responsible for many basic functions such as body temperature, sleep, appetite, sexual drive, stress reaction, and the regulation of other activities. The hypothalamus also controls the function of the pituitary gland which in turn regulates key hormones. Other structures within the limbic system that are associated with emotional reaction are the amygdala and hippocampus. The activities of the limbic are so important and complex that disturbances in any part of it, including how neurotransmitters function, could affect your mood and behavior.

Neurotransmitters and Neurons
To understand what happens in the brain when a person becomes clinically depressed as well as how antidepressant medications work, it is first important to learn a bit about the function of neurons and neurotransmitters. Within the brain, there are special chemicals called neurotransmitters that carry out many very important functions. Essentially, they help transfer messages throughout structures of the brain's nerve cells. These nerve cells, called neurons, are organized to control specialized activities. We each have somewhere between 10-100 billion neurons within our brains. Whenever we do anything, react, feel emotions, think, our neurons transmit messages in the form of electrical impulses from one cell to another. These electrical impulses travel across the neurons at an amazing rate of speed- less than 1/5,000 of a second. Because they move so quickly, our brains can react instantaneously to stimuli such as pain.

A neuron is made up of a cell body, an axon, and numerous branching dendrites. Chemical messages pass through the brain by traveling through these neuronal structures. First, it begins as an electrical impulse that is picked up by one of the dendrites of the neuron. Next, the impulse moves through the cell body then travels down the axon. When it reaches the axon the electrical impulse is changed to a chemical impulse. These chemical impulses, or neurotransmitters, released by the axon have the duty of carrying messages from one neuron to another. When the message is picked up by the dendrite of a neighboring neuron, it is changed back in to an electrical impulse and process begins again. Neurons do not actually touch one another. Instead, the chemical messenger passes from one neuron to another through a small narrow gap, called a synapse, which separates the neurons.

Neurotransmitters travel from neuron to neuron in an orderly fashion. They are specifically shaped so that after they pass from a neuron into the synapse, they can be received onto certain sites, called receptors, on a neighboring neuron. Neurotransmitters can fit a number of different receptors, but receptor sites can only receive specific types of neurotransmitters. Upon landing at the receptor site of neuron, the chemical message of the neurotransmitter may either be changed into an electrical impulse and continue on its way through the next neuron, or it may stop where it is. In either case the neurotransmitter releases from the receptor site and floats back into the synapse. It is then removed from the synapse in one of two ways. The neurotransmitter may be broken down by a chemical called monoamine oxidase, or it may be taken back in by the neuron that originally released it. The latter case is called reuptake.

Of the 30 or so neurotransmitters that have been identified, researchers have discovered associations between clinical depression and the function of three primary ones: serotonin, norepinephrine, and dopamine. These three neurotransmitters function within structures of the brain that regulate emotions, reactions to stress, and the physical drives of sleep, appetite, and sexuality. Structures that have received a great deal of attention from depression researchers include the limbic system and hypothalamus.

Theories about how neurotransmitters may be related to a person's mood have been based upon the effects that antidepressant medications can have on relieving depression in some people. It is believed that these medications are effective because they regulate the amount of specific neurotransmitters in the brain. However, the role that neurotransmitters play in the development or treatment of clinical depression is not completely clear. For instance, it has been shown that many people who are depressed have low levels of the neurotransmitter norepinephrine. The use of some antidepressants can increase the level of norepinephrine in the brain, and subsequently relieve depressive symptoms. One the other hand, it has also been shown that some other people who are depressed have high levels of norepinephrine. This same scenario may be true for other neurotransmitters. Another reason that the effects of neurotransmitters are not clear-cut has to do with the fact that antidepressant medications do not work for everyone. If there were a direct causal link between the level of a neurotransmitter in the brain and depression, then we would expect a much higher rate of success with medication. Further, although antidepressant medications can change the level of a neurotransmitter in the brain immediately, it normally takes a few weeks for a person with depression to feel better. What is seems to boil down to is that there appears to be a strong relationship between neurotransmitter levels in the brain and clinical depression, and that antidepressant medications work for a great many people, but we are not absolutely certain of the actual relationship between neurotransmitters and depression.

The reason we do not know more about the effects of neurotransmitters has to do with that fact that they are so difficult to study. Neurotransmitters are present in very small quantities, they are only available in certain locations within the brain, and they disappear very quickly once they are used. Because they are removed so fast, they cannot be measure directly. Researchers can only measure what is left over after their use in the brain. The substances that remain are called metabolites and they can be found in blood, urine, and cerebrospinal fluid. By measuring these metabolites, researchers can gain an understanding of the effects of changes in neurotransmitters in the brain.

It is unknown whether changes in levels of neurotransmitters cause the development of depression or depression causes changes in neurotransmitters. It may happen both ways. Researchers believe that our behavior can affect our brain chemistry, and that brain chemistry can affect behavior. For instance, if a person experiences numerous stressors or traumas this may cause his or her brain chemistry to be affected, leading to clinical depression. On the other hand, that same person may learn how to change depressed thoughts and behavior and cope with stressful events. Doing this may also change brain chemistry and relieve depression.

Hormones and the Endocrine System
Another area of research in determining the causes of clinical depression is focused on the endocrine system. This system works with the brain to control numerous activities within the body. The endocrine system is made up of small glands within the body, which create hormones and release them into the blood. The hormones that are released into the body by the glands regulate processes such as reaction to stress and sexual development. It has been found that a great number of people who are depressed have abnormal levels of some hormones in their blood despite having healthy glands. It is believed that such hormonal irregularities may be related to some depressive symptoms such as problems with appetite and sleeping since they play a part in these activities. Further clues to the role of the endocrine system has to do with the fact that those who have particular endocrine disorders sometimes develop depression, and some individuals who are depressed develop endocrine problems despite having healthy glands.

The endocrine system usually keeps the hormonal levels from becoming excessive through an intricate process of feedback, much like a thermostat in a home. Hormonal levels in the body are constantly monitored. When a specific hormone rises to particular level the gland stops producing and releasing the hormone. When an individual is depressed this feedback process may not function as it should.

Problems with hormone levels may be intertwined with the changes in brain chemistry that are seen in clinical depression. The endocrine system is connected with the brain at the hypothalamus which controls many bodily activities such as sleep, appetite, and sexual drive. The hypothalamus also regulates the pituitary gland that, in turn, controls the hormonal secretion of other glands. The hypothalamus uses some of the neurotransmitters that have been associated with depression as it manages the endocrine system. These neurotransmitters, serotonin, norepinephrine, and dopamine all have a role in the management of hormone function.

The development of clinical depression may be a symptom of a disorder present within organs that produce hormones. Such conditions include thyroid disorders, Cushing's syndrome, and Addison's disease.

Cortisol
Of those individuals who are clinically depressed, about one-half will have an excess of a hormone in their blood called cortisol. Cortisol is secreted by the adrenal glands. Located near the kidneys, the adrenal glands assist us in our reactions to stressful events. Cortisol may continue to be secreted even though a person already has high levels in his or her blood. This hormone is believed to be related to clinical depression since the high levels usually reduce to a normal level once the depression disappears.

The hypothalamus may be the culprit when it comes to excessive levels of cortisol in the blood. It is responsible for starting the process that leads to the secretion of cortisol by the adrenal glands. The hypothalamus first manufactures corticotrophic-releasing hormone (CRH). The pituitary gland is then stimulated into releasing adrenocorticotrophic hormone (ACTH). This hormone then makes the adrenal glands secret cortisol in the blood. When the endocrine system is functioning properly, the hypothalamus monitors the level of cortisol that is in the blood. When the level rises, the hypothalamus slows down its influence on the pituitary gland in production of CRH. When cortisol levels become reduced, the hypothalamus causes the pituitary gland to produce more CRH. In a person who is depressed, the hypothalamus may continuously influence the pituitary to produce CRH without regard to the amount of cortisol that is in the blood.


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Anatomy of the Thalamus

The thalamus has two ends, the anterior and posterior poles, and four surfaces: medial, lateral, superior, and inferior. Nuclei in a given pole or surface regulate specific functions or processing of sensory information and maintain particular connections with parts of the nervous and limbic system.

Understanding the anatomy of the thalamus will help you in comprehending the specific regulatory mechanisms of this structure.

Medial Surface

The medial surface of the thalamus comprises the upper portion of the lateral wall of the third ventricle of the brain and is lined by ependyma (remember that ependyma is the layer of ependymal cells that create cerebrospinal fluid, CSF). The medial surface serves to connect the two thalami by an interthalamic adhesion.

On its inferior (bottom) portion, it is connected to the hypothalamus by a hypothalamic sulcus, which extends from the upper part of the cerebral aqueduct (another cerebral ventricle) to the interventricular foramen (tract through which CSF flows).

A bundle of fibers called the stria medullaris thalami are located near the junction of medial and superior (upper) surfaces.

Lateral Surface

The lateral surface of the thalamus is covered by a layer of myelinated fibers called the external medullary lamina which separates the lateral surface from the reticular nuclei.

Superior Surface

This surface of the thalamus is coated by white matter (remember white and gray matter: white matter contains nerve fibers, axons, that extend from their individual neurons.

They are covered in myelin sheaths. Gray matter, on the other hand, is composed of the neuronal cell bodies and unmyelinated axons). This white matter is called the stratum zonale. (Note that the stratum zonale is also composed of gray matter, however, the surface is what makes up the white matter.)

The medial (inner, toward the center of the body) region of the superior surface is separated from the fornix by the choroid fissure (an attachment site for the choroid plexus, the structure which contains ependymal cells).

The superior surface of the thalamus also forms part of the floor of the lateral ventricles.

The lateral region of the superior surface of the thalamus contains the stria terminalis, a structure that plays a role in the regulation of emotions and behaviors related to stress. Another layer of white matter called the external medullary lamina divides the lateral region of the superior surface from the reticular nucleus.

Inferior Surface

The inferior surface of the thalamus is connected to the anterior portion of the hypothalamus and the posterior portion of the subthalamus. The subthalamus is what separates the thalamus from the tegmentum of the midbrain.

Anterior Pole

The anterior pole of the thalamus constitutes the posterior boundary of the interventricular foramen.

Posterior Pole

Also known as the pulvinar, the posterior pole of the thalamus extends past the third ventricle and over the superior colliculus (a small elevation on each side of the posterior region of the midbrain). Reticular nuclei are located laterally to the primary mass of nuclei here.

Nuclei of the midline are connected to either the ependyma of the lateral walls of the third ventricle or are adjacent to the interthalamic adhesion.


How Many Brain Cells Does a Child Have

A baby is born with roughly 86 billion neurons 𔁯​ , almost all the neurons the human brain will ever have 𔁰​ .

Although a newborn has about the same number of neurons as an adult, it has only 25% of its adult brain volume.

That&rsquos because infant&rsquos neurons are connected by only some 50 trillion neural connections, called synapses, whereas a grownup has about 500 trillion of them 𔁱​ .

This network of synaptic connections will ultimately determine how a child thinks and acts.

What Is Synaptic Pruning in Early Brain Development

Synaptic pruning is the process in which unused neurons and neural connections are eliminated to increase efficiency in neuronal transmissions.

The network of synapses grows rapidly during the first year and continues to do so during toddlerhood.

By age 3, the synaptic connections have grown to 1000 trillion.

But not all of the synapses will remain as the child&rsquos brain grows.

Life experience will activate certain neurons, create new neural connections among them and strengthen existing connections, called myelination.

Unused connections will eventually be eliminated. This is called synaptic pruning 𔁲​ .

Synaptic pruning is the process in which unused neurons and neural connections are eliminated to increase efficiency in neuronal transmissions.

Building massive connections, creating and strengthening them through life experiences and pruning unused ones is a remarkable characteristic of human brains.

This experience-based plasticity allows babies to adapt flexibly to any environment they&rsquore born into without the constraint of too many hardwired neural connections 𔁳​ .

For more help on calming tantrums, check out this step-by-step guide

The Use It Or Lose It Brain Sculpting Property

The benefits of developing a baby&rsquos brain this way are enormous, but so are the costs and the risks 𔁴​ .

First, children require a lot of care, i.e. life experiences, before they can be independent.

Second, what parents do or don&rsquot do during the formative years can have a profound impact on the child&rsquos mental health and life.

Here&rsquos a synaptic pruning example. Let&rsquos say a parent consistently shows a toddler love and care, then the &ldquolove-and-care connections&rdquo will develop or strengthen over time. But if the parent constantly punishes or is harsh to the child, then the &ldquopunitive-and-harsh connections&rdquo will be stronger instead. And because the love-and-care experience is missing, those corresponding brain cells will wither and eventually be removed from the child&rsquos brain circuits. As a result, the child grows up lacking the love-and-care understanding that is essential to create healthy, meaningful relationships in his future life 𔁵​ .

Why The Early Years Matter in Baby Brain Development

Early years of life is a period of unique sensitivity during which experience bestows enduring effects 𔁶​ .

Although this experience-based brain plasticity is present throughout one&rsquos life, a child&rsquos brain is a lot more plastic than a mature one.

Brain cell pruning also occurs most rapidly during a child&rsquos preschool years.

The density of these connections during adulthood will reduce to half of that in a toddler at age two.

This is why nurturing and positive parenting are so important.

Things can go seriously wrong for children deprived of basic social and emotional nurturing.

Critical Periods and Sensitive Periods in the Developing Brain

Within early childhood, there are also windows of time when different regions of the developing brain become relatively more sensitive to life experiences.

These periods of time are called critical periods or sensitive periods.

During a critical period, synaptic connections in those brain regions are more plastic and malleable. Connections are formed or strengthened given the appropriate childhood experiences. After the critical period has passed, the synapses become stabilized and a lot less plastic.

For example, a young child can learn a new language and attain proficiency more easily before puberty. So the sensitive period for language skills mastery is from birth to before puberty.

Another example is emotional regulation. Emotional self-regulation forms the foundation of the brain architecture. It&rsquos a person&rsquos ability to monitor and regulate emotions.

Emotion regulation is not a skill we&rsquore born with. Yet it&rsquos an essential skill in a child&rsquos healthy development 𔁷​ .

The sensitive period of learning this crucial life skill is before a child turns two. Critical or sensitive period is another reason why early life experiences matter so much.


Brain Lesions (Lesions on the Brain)

The brain is responsible for regulation the functions of the body, from the unconscious (controlling blood pressure, heart rate and respiratory rate) to the conscious acts like walking and talking. Add the intellectual processes of thought and the brain is a busy part of the human body.

The brain has many parts. The cerebrum consists of two hemispheres which are responsible for movement, sensation, thought, judgment, problem solving, and emotion. The brain stem sits beneath the cerebrum and connects it to the spinal cord. The brain stem houses the structures that are responsible for the unconscious regulation of the body such as wakefulness, heart and lung function, hunger, temperature control, and swallowing. The cerebellum is located beneath and behind the cerebrum and is responsible for posture, balance, and coordination.

While the brainstem is important in maintaining body function, the cerebrum allows body motion and most importantly, is responsible for all the things that make humans special, like thinking and emotion. There are four lobes in each hemisphere: frontal, parietal, temporal, and occipital.

  1. Frontal lobe is the area responsible for personality and movement. The pre-frontal portion is perhaps the most evolved part of the brain and specifically allows judgment, planning and organization, problem solving, and critical thinking. This is the area that gives us the ability to feel emotion and have empathy. Finally, this is where impulse control resides.
  2. Parietal lobes are where sensation is processed and interpreted. Aside from touch, pressure and pain, there is also the concept of spatial cognition, where the brain recognizes where the body is in relationship to the area around it.
  3. Temporal lobes are where the functions of memory, speech, and hearing are located.
  4. Occipital lobes are where vision is located.

Brain cells use glucose almost exclusively for their energy needs and unlike other organs in the body, the brain cannot store glucose for future use. If blood sugar levels fall, brain function can be immediately compromised.

The brain gets its blood supply through four major arteries, the right and left carotids and the right and left vertebral arteries. They join together at the base of the brain at the Circle of Willis. Smaller blood vessels then branch out to provide oxygen and glucose rich blood to all regions of the brain.

Brain Cell Anatomy

The brain is composed of billions of cells that use chemicals and electricity to communicate between themselves and the rest of the body. There are two major types of cells, neurons and glial cells there are subtypes of these cells.

Neurons

  • Neurons are the cells that process and transmit information in the brain. Each cell has two connectors, the axon and dendrite. The axon of one neuron connects with the dendrite of another at junction or synapse. Special chemicals called neurotransmitters help transfer the electrical impulse across the synapse so that one neuron can excite another.

Glial cells

  • Glial cells are located between neurons and help support their activity.
  • Microglial cells are part of the immune system within brain tissue helping clear dead cells and other debris.
  • Astrocytes help clear neurotransmitter chemicals so that the synapse can be ready to react to the next signal that might arrive.
  • Oligodendrocytes produce and maintain the myelin sheath that coats and insulates the axon making electrical conduction more efficient.
  • Ependymal cells produce CSF (cerebrospinal fluid) which is located within the ventricles of the brain and in the subarachnoid space that surrounds the brain and spinal cord. Aside from allowing the brain to float in the skull, CSF acts as a cushion against trauma and also helps wash away some of the metabolic waster protects that are produced with brain function.

Benign Brain Tumor Symptoms & Signs

Symptoms (signs) of benign brain tumors often are not specific. The following is a list of symptoms that, alone or combined, can be caused by benign brain tumors unfortunately, these symptoms can occur in many other diseases:

  • vision problems
  • hearing problems
  • balance problems
  • changes in mental ability (for example, concentration, memory, speech)
  • seizures, muscle jerking
  • change in sense of smell
  • nausea/vomiting
  • facial paralysis
  • headaches
  • numbness in extremities

What are brain lesions?

A brain lesion describes damage or destruction to any part of the brain. It may be due to trauma or any other disease that can cause inflammation, malfunction, or destruction of a brain cells or brain tissue. A lesion may be localized to one part of the brain or they may be widespread. The initial damage may be so small as to not produce any initial symptoms, but progresses over time to cause obvious physical and mental changes.

A brain lesion may affect the neuron directly or one of the glial cells thereby indirectly affecting neuron functions.

What causes brain lesions?

  • Trauma is the most widely recognized cause of an acute brain injury. Bleeding or swelling within the skull can directly damage brain cells or the pressure that can build within the skull can compress the brain and compromise its ability to function. Trauma can also damage the brain on a microscopic level. Shear injuries describe damage to the synapse connections between brain cells decreasing their ability to communicate with each other. Recent reports have linked concussions to the gradual destruction of brain cells that can affect personality and thinking.
  • Inflammation within brain tissue can affect function. This inflammation may be due to infections that cause meningitis and encephalitis. Other infections may cause discrete changes within the brain tissue. Neurocysticercosis, for example, is the most common cause of epilepsy in the developing world the parasite causes small calcifications that are scattered throughout the brain. Infections may also form abscesses within the brain that can lead to symptoms.
  • Inflammatory and autoimmune diseases that may affect brain function include sarcoidosis, amyloidosis, inflammatory bowel disease and rheumatoid arthritis. Some of the brain damage may be caused by inflammation to the blood vessels in the brain, which causes strokes.
  • Certain diseases affect only specific cells within the brain. For example, the symptoms of multiple sclerosis are caused by damage to the glial cells that manufacture and maintain the myelin sheath that insulates axons. Without this normal nerve covering, electrical transmission is compromised and symptoms may occur. Alzheimer's disease and other dementias occur when neuron cells are affected and die prematurely.
  • Stroke or cerebral infarction (cerebral=brain + infarction=loss of blood supply) describes the condition where blood supply to part of the brain is lost and the brain stops functioning. There are numerous reasons for blood supply to decrease. There may be gradual narrowing of an artery to part of the brain, blockage may occur should debris from a diseased carotid artery break loose, or a clot may travel or embolize from the heart.
  • Bleeding may occur from a cerebral aneurysm or arteriovenous malformation or because of uncontrolled hypertension (high blood pressure).
  • Tumors that originate from brain cells or those that metastasize from other organs can affect brain function in two ways. The tumor can destroy brain cells so that their function is lost, or the tumor can take up space and cause pressure and swelling that affects brain cell function. This may occur with benign or cancerous tumors. Common tumors that arise from the brain include meningiomas, adenomas, and gliomas.
  • Pituitary adenomas are common benign tumors that grow in the sella tursica, where the pituitary gland sits and near where the optic nerves travel from the eyes to the occiput in the back of the brain. As the tumor grows it can push on the optic nerve and cause visual changes and blindness.
  • Glioblastoma multiforme, a malignant tumor is the most common type of astrocytoma that arises from astrocytes and is a glioma. Victims of this tumor include Senator Ted Kennedy, George Gershwin, and Ethel Merman.
  • Cerebral palsy describes the condition where a developing infant's brain is deprived of oxygen and fails to develop normally. This may occur in the uterus before birth or may be due to an injury or illness that happens within the first couple of years of life. Often it is an infection or bleeding that is the cause, though many times the reason for cerebral palsy is never found.

QUESTION

What are the types of brain lesions?

There are many types of brain lesions. The brain can be affected by a host of potential injuries that can decrease its function. The type of lesion depends upon the type of insult that the brain receives.

Aging: Some lesions occur as a result of aging with loss of brain cells as they naturally age and die. If enough cells die, atrophy can occur and brain function decreases. This may present with symptoms of loss of memory, poor judgment, loss of insight and general loss of mental agility.

Genetic: Lesions related to a person's genetic makeup, such as people with neurofibromatosis.

Vascular: Loss of brain cells also occurs with stroke. With ischemic strokes (CVA) blood supply to an area of the brain is lost, brain cells die and the part of the body they control loses its function.

Bleeding: Strokes can also be hemorrhagic, where bleeding occurs in part of the brain, again damaging brain cells and causing loss of function. Uncontrolled high blood pressure, AV malformations, and brain aneurysms are some causes of bleeding in the brain.

Trauma: Bleeding in the brain may be caused by trauma and a blow to the head. Bleeding may occur within brain tissue or in the spaces surrounding the brain. Epidural and subdural hematomas describe blood clots that form in the spaces between the meninges or tissues that line the brain and spinal cord. As the clot expands, pressure increases within the skull and compresses the brain.

Acceleration/deceleration injury: Sometimes trauma can affect the brain with no evidence of bleeding on CT scan. Acceleration deceleration injuries can cause significant damage to brain tissue and connections causing microscopic swelling. Shaken baby syndrome is a good example of acceleration/deceleration type injury, where the brain bounces against the inner lining of the skull.

Infection and inflammation: Infectious agents resulting in diseases such as meningitis, brain abscesses or encephalitis

Tumors: Tumors are types of brain lesions and may be benign (meningiomas are the most common) or malignant like glioblastoma multiforme. Tumors in the brain may also be metastatic, spreading from cancers that arise primarily from another organ. Symptoms occur depending upon the location and size of the tumor.

Immune: Immunologic causes may also affect the brain, for example diseases like multiple sclerosis.

Plaques: Some investigators suggest that abnormal deposits of material that form plaques may be a type of disease that causes damage and eventual brain cell death in diseases like Alzheimer's disease.

Toxins: Toxins may affect brain function and may be produced within the body or may be ingested. The most common ingested poison is alcohol, though other chemicals can adversely affect the brain. Individuals can develop encephalopathy due to a variety of chemicals and substances that build up in the blood stream. Ammonia levels rise in patients with liver failure while patients with kidney failure can become uremic.

Multiple types: The type of lesion depends upon its cause and symptoms depend upon its location and amount of brain irritation or damage that has occurred. Some brain lesions types may occur from more than one cause, such as Alzheimer's disease that may be related to plaque formation, brain cell death, and possibly genetics. Research is ongoing and is likely to provide better insights into these various brain lesion types.


What Multiple Sclerosis Looks Like in Your Brain

Multiple sclerosis (MS) is a disease of the central nervous system that causes damage to your brain, spinal cord, and optic nerves. It’s characterized by lesions, or areas of tissue damage that occur when your immune system behaves abnormally and attacks these areas.

While many symptoms of MS throughout the body can be caused by lesions in either the brain or the spinal cord, cognitive symptoms of MS — those related to your memory, language, and problem solving — are believed to be caused only by lesions in the brain.

Brain lesions are a hallmark of MS, but they’re not the only way MS can affect your brain function. MS can also contribute to brain atrophy, or shrinkage, over time — a process that occurs in all people as they age, but typically happens much more quickly in people with MS. Brain atrophy, in particular, can contribute to cognitive symptoms of MS.


Forging new paths

We continue to have the ability to learn new activities, skills or languages even into old age. This retained ability requires the brain to have a mechanism available to remember so that knowledge is retained over time for future recall. This is another example of neuroplasticity and is most likely to involve structural and biochemical changes at the level of the synapse.

Reinforcement or repetitive activities will eventually lead the adult brain to remember the new activity. By the same mechanism, the enriched and stimulating environment offered to the damaged brain will eventually lead to recovery. So if the brain is so plastic, why doesn’t everyone who has a stroke recover full function? The answer is that it depends on your age (younger brains have a better chance of recovery), the size of the area damaged and, more importantly, the treatments offered during rehabilitation.


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11 Comments
Friday, July 25, 2014 4:57:48 AM | posted by Thomas Welter
Friday, July 25, 2014 4:53:51 AM | posted by Thomas Welter
Thursday, July 24, 2014 2:11:49 AM | posted by Bryce Thompson
Thursday, July 24, 2014 2:02:54 AM | posted by Bryce Thompson
Saturday, June 14, 2014 3:49:45 PM | posted by Paul w. horn, PhD
Saturday, June 14, 2014 3:44:55 PM | posted by Paul w. horn, PhD
Thursday, May 8, 2014 4:29:33 PM | posted by Theodore A. Hoppe

In a word, "epigenetics"
There is an old saying that if you only have a hammer every problem looks like a nail. These is what happens with therapy.
Obviously, twin studies have revealed that issues like sexual orientation and schizophrenia can effect one twin and not the other. So these issues have nothing, except perhaps a genetic pre-disposition, to do with brain developing as Brizendine you have us believe.

See Tim Specter's book, "Identically Different."
http://www.theguardian.com/books/2012/aug/08/identically-different-genes-spector-review

Wednesday, February 12, 2014 9:26:54 AM | posted by Alida Vismara
Wednesday, February 12, 2014 9:25:58 AM | posted by Alida Vismara
Wednesday, February 12, 2014 9:25:10 AM | posted by Alida Vismara
Monday, November 11, 2013 7:25:24 PM | posted by J. Fischer

I am sorry, but the issue is much more complex than male straight vs male homosexual because there are a good percentage of male homosexuals who also have a feminine orientation and or identify with females. So it isn't just either male straight or male homosexual hard wiring issue at puberty. There are more components invovled if we utilize your analysis, ie: 1) male straight, 2) male homosexual, 3) male homosexual with feminine orientation, 4) male homosexual with female identification. Also, if you say these are choices (like ordering a steak vs chicken at a restaurant), which I don't believe, then why wouldn't a psychologist be permitted to discuss those choices with this indidivual in therapy, just as he would discuss choices that a depressive or anxious person, or ADHD person or other would need to discuss in a thereapeutic relationship? Why is that treated with such disdain today and new laws and rules are being set up not to allow these discussions, but other disorders are not apart of such distorted rules of the game.

And why do you assume that homosexuality is a choice someone makes at puberty. All reality and science shows that you don't have that choice, it is made for you in the hardwiring of the brain. The real question is normality. Is Gay the new "Normal" to individuals in our industry? I am curious why Homosexuality with and without feminine orientation, which does not promote procreation of life in any way, is now considered "normal", but ADHD is still a disorder? Obviously ADHD is a problem with the hardwiring in the brain just like homosexuality is, but our industry considers ADHD still a disorder, but an even more detremental disorder in the hardwiring of the brain toward an attraction to the same sex is now not considered an abnormality? Talk about disorder bias. This makes no sense even on a very banal level. We are not discussing or assessing a "good" or "bad" or a "fault" behavioral message to the disorder, but it isn't any less a disorder then any of the other "hardwire" brain problems and disorders listed in DSM-IV or V. So are we allowing and supporting the creation of a "newter" gender that is socially acceptable but scientifically abnormal, or are we inhibiting and down-right stopping our ability to help those with problems in the hardwiring of their brains?


Boundaries, Anatomy, Position, and Structure of the Occipital Brain Lobe

The boundaries of the occipital lobe include the edges of the parietal and temporal lobe. The occipital lobe contains the primary visual cortex and associative visual areas (1).

The occipital lobe occupies the posterior parts of the hemispheres. On the convex surface of the hemisphere, the occipital lobe has no sharp boundaries separating it from the parietal and temporal lobes.

The exception is the upper part of the parietal-occipital groove, which, located on the inner surface of the hemisphere, separates the parietal lobe from the occipital lobe. The furrows and edges of the upper canopy of the occipital lobe are unstable and have a variable structure.

On the inner surface of the occipital lobe, there is a groove of spores, which separates the wedge (triangular norm of the occipital lobe) from the lingual gyrus and the occipital-temporal gyrus (1).

In the occipital lobe of the cerebral cortex is, the following fields are positioned:

  • Area 17 - Gray matter buildup in a visual analyzer. This field is the primary zone. It is made up of 300 million nerve cells.
  • Area 18 - It is also a nuclear set of visual analyzers. This field performs the function of perceived writing and is a more complex secondary area.
  • Area 19 – This field is involved in evaluating the value of what we see.
  • Area 39 - This brain part does not completely belong to the occipital region. This area is located at the border between the parietal, temporal, and occipital lobes. Its functions include integrating visual, auditory, and general sensitivity of information (1).

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Neurotransmitters, Neurons, Hormones, and Depression

Biological causes of clinical depression continue to be studied extensively. Great progress has been made in the understanding of brain function, the influence of neurotransmitters and hormones, and other biological processes, as well as how they may relate to the development of depression.

Brain Function in Depression
The brain is the "command center" of the human body. It controls the basic functions of our bodies, our movements, and our thoughts and emotions. Researchers studying clinical depression tend to look at several aspects of brain function including the structures of the limbic system and the function of neurotransmitters within neurons.

Limbic System
Those who research clinical depression have been interested in a particular part of the brain called the limbic system. This is the area of the brain that regulates activities such as emotions, physical and sexual drives, and the stress response. There are various structures of the limbic system that are of particular importance. The hypothalamus is a small structure located at the base of the brain. It is responsible for many basic functions such as body temperature, sleep, appetite, sexual drive, stress reaction, and the regulation of other activities. The hypothalamus also controls the function of the pituitary gland which in turn regulates key hormones. Other structures within the limbic system that are associated with emotional reaction are the amygdala and hippocampus. The activities of the limbic are so important and complex that disturbances in any part of it, including how neurotransmitters function, could affect your mood and behavior.

Neurotransmitters and Neurons
To understand what happens in the brain when a person becomes clinically depressed as well as how antidepressant medications work, it is first important to learn a bit about the function of neurons and neurotransmitters. Within the brain, there are special chemicals called neurotransmitters that carry out many very important functions. Essentially, they help transfer messages throughout structures of the brain's nerve cells. These nerve cells, called neurons, are organized to control specialized activities. We each have somewhere between 10-100 billion neurons within our brains. Whenever we do anything, react, feel emotions, think, our neurons transmit messages in the form of electrical impulses from one cell to another. These electrical impulses travel across the neurons at an amazing rate of speed- less than 1/5,000 of a second. Because they move so quickly, our brains can react instantaneously to stimuli such as pain.

A neuron is made up of a cell body, an axon, and numerous branching dendrites. Chemical messages pass through the brain by traveling through these neuronal structures. First, it begins as an electrical impulse that is picked up by one of the dendrites of the neuron. Next, the impulse moves through the cell body then travels down the axon. When it reaches the axon the electrical impulse is changed to a chemical impulse. These chemical impulses, or neurotransmitters, released by the axon have the duty of carrying messages from one neuron to another. When the message is picked up by the dendrite of a neighboring neuron, it is changed back in to an electrical impulse and process begins again. Neurons do not actually touch one another. Instead, the chemical messenger passes from one neuron to another through a small narrow gap, called a synapse, which separates the neurons.

Neurotransmitters travel from neuron to neuron in an orderly fashion. They are specifically shaped so that after they pass from a neuron into the synapse, they can be received onto certain sites, called receptors, on a neighboring neuron. Neurotransmitters can fit a number of different receptors, but receptor sites can only receive specific types of neurotransmitters. Upon landing at the receptor site of neuron, the chemical message of the neurotransmitter may either be changed into an electrical impulse and continue on its way through the next neuron, or it may stop where it is. In either case the neurotransmitter releases from the receptor site and floats back into the synapse. It is then removed from the synapse in one of two ways. The neurotransmitter may be broken down by a chemical called monoamine oxidase, or it may be taken back in by the neuron that originally released it. The latter case is called reuptake.

Of the 30 or so neurotransmitters that have been identified, researchers have discovered associations between clinical depression and the function of three primary ones: serotonin, norepinephrine, and dopamine. These three neurotransmitters function within structures of the brain that regulate emotions, reactions to stress, and the physical drives of sleep, appetite, and sexuality. Structures that have received a great deal of attention from depression researchers include the limbic system and hypothalamus.

Theories about how neurotransmitters may be related to a person's mood have been based upon the effects that antidepressant medications can have on relieving depression in some people. It is believed that these medications are effective because they regulate the amount of specific neurotransmitters in the brain. However, the role that neurotransmitters play in the development or treatment of clinical depression is not completely clear. For instance, it has been shown that many people who are depressed have low levels of the neurotransmitter norepinephrine. The use of some antidepressants can increase the level of norepinephrine in the brain, and subsequently relieve depressive symptoms. One the other hand, it has also been shown that some other people who are depressed have high levels of norepinephrine. This same scenario may be true for other neurotransmitters. Another reason that the effects of neurotransmitters are not clear-cut has to do with the fact that antidepressant medications do not work for everyone. If there were a direct causal link between the level of a neurotransmitter in the brain and depression, then we would expect a much higher rate of success with medication. Further, although antidepressant medications can change the level of a neurotransmitter in the brain immediately, it normally takes a few weeks for a person with depression to feel better. What is seems to boil down to is that there appears to be a strong relationship between neurotransmitter levels in the brain and clinical depression, and that antidepressant medications work for a great many people, but we are not absolutely certain of the actual relationship between neurotransmitters and depression.

The reason we do not know more about the effects of neurotransmitters has to do with that fact that they are so difficult to study. Neurotransmitters are present in very small quantities, they are only available in certain locations within the brain, and they disappear very quickly once they are used. Because they are removed so fast, they cannot be measure directly. Researchers can only measure what is left over after their use in the brain. The substances that remain are called metabolites and they can be found in blood, urine, and cerebrospinal fluid. By measuring these metabolites, researchers can gain an understanding of the effects of changes in neurotransmitters in the brain.

It is unknown whether changes in levels of neurotransmitters cause the development of depression or depression causes changes in neurotransmitters. It may happen both ways. Researchers believe that our behavior can affect our brain chemistry, and that brain chemistry can affect behavior. For instance, if a person experiences numerous stressors or traumas this may cause his or her brain chemistry to be affected, leading to clinical depression. On the other hand, that same person may learn how to change depressed thoughts and behavior and cope with stressful events. Doing this may also change brain chemistry and relieve depression.

Hormones and the Endocrine System
Another area of research in determining the causes of clinical depression is focused on the endocrine system. This system works with the brain to control numerous activities within the body. The endocrine system is made up of small glands within the body, which create hormones and release them into the blood. The hormones that are released into the body by the glands regulate processes such as reaction to stress and sexual development. It has been found that a great number of people who are depressed have abnormal levels of some hormones in their blood despite having healthy glands. It is believed that such hormonal irregularities may be related to some depressive symptoms such as problems with appetite and sleeping since they play a part in these activities. Further clues to the role of the endocrine system has to do with the fact that those who have particular endocrine disorders sometimes develop depression, and some individuals who are depressed develop endocrine problems despite having healthy glands.

The endocrine system usually keeps the hormonal levels from becoming excessive through an intricate process of feedback, much like a thermostat in a home. Hormonal levels in the body are constantly monitored. When a specific hormone rises to particular level the gland stops producing and releasing the hormone. When an individual is depressed this feedback process may not function as it should.

Problems with hormone levels may be intertwined with the changes in brain chemistry that are seen in clinical depression. The endocrine system is connected with the brain at the hypothalamus which controls many bodily activities such as sleep, appetite, and sexual drive. The hypothalamus also regulates the pituitary gland that, in turn, controls the hormonal secretion of other glands. The hypothalamus uses some of the neurotransmitters that have been associated with depression as it manages the endocrine system. These neurotransmitters, serotonin, norepinephrine, and dopamine all have a role in the management of hormone function.

The development of clinical depression may be a symptom of a disorder present within organs that produce hormones. Such conditions include thyroid disorders, Cushing's syndrome, and Addison's disease.

Cortisol
Of those individuals who are clinically depressed, about one-half will have an excess of a hormone in their blood called cortisol. Cortisol is secreted by the adrenal glands. Located near the kidneys, the adrenal glands assist us in our reactions to stressful events. Cortisol may continue to be secreted even though a person already has high levels in his or her blood. This hormone is believed to be related to clinical depression since the high levels usually reduce to a normal level once the depression disappears.

The hypothalamus may be the culprit when it comes to excessive levels of cortisol in the blood. It is responsible for starting the process that leads to the secretion of cortisol by the adrenal glands. The hypothalamus first manufactures corticotrophic-releasing hormone (CRH). The pituitary gland is then stimulated into releasing adrenocorticotrophic hormone (ACTH). This hormone then makes the adrenal glands secret cortisol in the blood. When the endocrine system is functioning properly, the hypothalamus monitors the level of cortisol that is in the blood. When the level rises, the hypothalamus slows down its influence on the pituitary gland in production of CRH. When cortisol levels become reduced, the hypothalamus causes the pituitary gland to produce more CRH. In a person who is depressed, the hypothalamus may continuously influence the pituitary to produce CRH without regard to the amount of cortisol that is in the blood.


Brain Lesions (Lesions on the Brain)

The brain is responsible for regulation the functions of the body, from the unconscious (controlling blood pressure, heart rate and respiratory rate) to the conscious acts like walking and talking. Add the intellectual processes of thought and the brain is a busy part of the human body.

The brain has many parts. The cerebrum consists of two hemispheres which are responsible for movement, sensation, thought, judgment, problem solving, and emotion. The brain stem sits beneath the cerebrum and connects it to the spinal cord. The brain stem houses the structures that are responsible for the unconscious regulation of the body such as wakefulness, heart and lung function, hunger, temperature control, and swallowing. The cerebellum is located beneath and behind the cerebrum and is responsible for posture, balance, and coordination.

While the brainstem is important in maintaining body function, the cerebrum allows body motion and most importantly, is responsible for all the things that make humans special, like thinking and emotion. There are four lobes in each hemisphere: frontal, parietal, temporal, and occipital.

  1. Frontal lobe is the area responsible for personality and movement. The pre-frontal portion is perhaps the most evolved part of the brain and specifically allows judgment, planning and organization, problem solving, and critical thinking. This is the area that gives us the ability to feel emotion and have empathy. Finally, this is where impulse control resides.
  2. Parietal lobes are where sensation is processed and interpreted. Aside from touch, pressure and pain, there is also the concept of spatial cognition, where the brain recognizes where the body is in relationship to the area around it.
  3. Temporal lobes are where the functions of memory, speech, and hearing are located.
  4. Occipital lobes are where vision is located.

Brain cells use glucose almost exclusively for their energy needs and unlike other organs in the body, the brain cannot store glucose for future use. If blood sugar levels fall, brain function can be immediately compromised.

The brain gets its blood supply through four major arteries, the right and left carotids and the right and left vertebral arteries. They join together at the base of the brain at the Circle of Willis. Smaller blood vessels then branch out to provide oxygen and glucose rich blood to all regions of the brain.

Brain Cell Anatomy

The brain is composed of billions of cells that use chemicals and electricity to communicate between themselves and the rest of the body. There are two major types of cells, neurons and glial cells there are subtypes of these cells.

Neurons

  • Neurons are the cells that process and transmit information in the brain. Each cell has two connectors, the axon and dendrite. The axon of one neuron connects with the dendrite of another at junction or synapse. Special chemicals called neurotransmitters help transfer the electrical impulse across the synapse so that one neuron can excite another.

Glial cells

  • Glial cells are located between neurons and help support their activity.
  • Microglial cells are part of the immune system within brain tissue helping clear dead cells and other debris.
  • Astrocytes help clear neurotransmitter chemicals so that the synapse can be ready to react to the next signal that might arrive.
  • Oligodendrocytes produce and maintain the myelin sheath that coats and insulates the axon making electrical conduction more efficient.
  • Ependymal cells produce CSF (cerebrospinal fluid) which is located within the ventricles of the brain and in the subarachnoid space that surrounds the brain and spinal cord. Aside from allowing the brain to float in the skull, CSF acts as a cushion against trauma and also helps wash away some of the metabolic waster protects that are produced with brain function.

Benign Brain Tumor Symptoms & Signs

Symptoms (signs) of benign brain tumors often are not specific. The following is a list of symptoms that, alone or combined, can be caused by benign brain tumors unfortunately, these symptoms can occur in many other diseases:

  • vision problems
  • hearing problems
  • balance problems
  • changes in mental ability (for example, concentration, memory, speech)
  • seizures, muscle jerking
  • change in sense of smell
  • nausea/vomiting
  • facial paralysis
  • headaches
  • numbness in extremities

What are brain lesions?

A brain lesion describes damage or destruction to any part of the brain. It may be due to trauma or any other disease that can cause inflammation, malfunction, or destruction of a brain cells or brain tissue. A lesion may be localized to one part of the brain or they may be widespread. The initial damage may be so small as to not produce any initial symptoms, but progresses over time to cause obvious physical and mental changes.

A brain lesion may affect the neuron directly or one of the glial cells thereby indirectly affecting neuron functions.

What causes brain lesions?

  • Trauma is the most widely recognized cause of an acute brain injury. Bleeding or swelling within the skull can directly damage brain cells or the pressure that can build within the skull can compress the brain and compromise its ability to function. Trauma can also damage the brain on a microscopic level. Shear injuries describe damage to the synapse connections between brain cells decreasing their ability to communicate with each other. Recent reports have linked concussions to the gradual destruction of brain cells that can affect personality and thinking.
  • Inflammation within brain tissue can affect function. This inflammation may be due to infections that cause meningitis and encephalitis. Other infections may cause discrete changes within the brain tissue. Neurocysticercosis, for example, is the most common cause of epilepsy in the developing world the parasite causes small calcifications that are scattered throughout the brain. Infections may also form abscesses within the brain that can lead to symptoms.
  • Inflammatory and autoimmune diseases that may affect brain function include sarcoidosis, amyloidosis, inflammatory bowel disease and rheumatoid arthritis. Some of the brain damage may be caused by inflammation to the blood vessels in the brain, which causes strokes.
  • Certain diseases affect only specific cells within the brain. For example, the symptoms of multiple sclerosis are caused by damage to the glial cells that manufacture and maintain the myelin sheath that insulates axons. Without this normal nerve covering, electrical transmission is compromised and symptoms may occur. Alzheimer's disease and other dementias occur when neuron cells are affected and die prematurely.
  • Stroke or cerebral infarction (cerebral=brain + infarction=loss of blood supply) describes the condition where blood supply to part of the brain is lost and the brain stops functioning. There are numerous reasons for blood supply to decrease. There may be gradual narrowing of an artery to part of the brain, blockage may occur should debris from a diseased carotid artery break loose, or a clot may travel or embolize from the heart.
  • Bleeding may occur from a cerebral aneurysm or arteriovenous malformation or because of uncontrolled hypertension (high blood pressure).
  • Tumors that originate from brain cells or those that metastasize from other organs can affect brain function in two ways. The tumor can destroy brain cells so that their function is lost, or the tumor can take up space and cause pressure and swelling that affects brain cell function. This may occur with benign or cancerous tumors. Common tumors that arise from the brain include meningiomas, adenomas, and gliomas.
  • Pituitary adenomas are common benign tumors that grow in the sella tursica, where the pituitary gland sits and near where the optic nerves travel from the eyes to the occiput in the back of the brain. As the tumor grows it can push on the optic nerve and cause visual changes and blindness.
  • Glioblastoma multiforme, a malignant tumor is the most common type of astrocytoma that arises from astrocytes and is a glioma. Victims of this tumor include Senator Ted Kennedy, George Gershwin, and Ethel Merman.
  • Cerebral palsy describes the condition where a developing infant's brain is deprived of oxygen and fails to develop normally. This may occur in the uterus before birth or may be due to an injury or illness that happens within the first couple of years of life. Often it is an infection or bleeding that is the cause, though many times the reason for cerebral palsy is never found.

QUESTION

What are the types of brain lesions?

There are many types of brain lesions. The brain can be affected by a host of potential injuries that can decrease its function. The type of lesion depends upon the type of insult that the brain receives.

Aging: Some lesions occur as a result of aging with loss of brain cells as they naturally age and die. If enough cells die, atrophy can occur and brain function decreases. This may present with symptoms of loss of memory, poor judgment, loss of insight and general loss of mental agility.

Genetic: Lesions related to a person's genetic makeup, such as people with neurofibromatosis.

Vascular: Loss of brain cells also occurs with stroke. With ischemic strokes (CVA) blood supply to an area of the brain is lost, brain cells die and the part of the body they control loses its function.

Bleeding: Strokes can also be hemorrhagic, where bleeding occurs in part of the brain, again damaging brain cells and causing loss of function. Uncontrolled high blood pressure, AV malformations, and brain aneurysms are some causes of bleeding in the brain.

Trauma: Bleeding in the brain may be caused by trauma and a blow to the head. Bleeding may occur within brain tissue or in the spaces surrounding the brain. Epidural and subdural hematomas describe blood clots that form in the spaces between the meninges or tissues that line the brain and spinal cord. As the clot expands, pressure increases within the skull and compresses the brain.

Acceleration/deceleration injury: Sometimes trauma can affect the brain with no evidence of bleeding on CT scan. Acceleration deceleration injuries can cause significant damage to brain tissue and connections causing microscopic swelling. Shaken baby syndrome is a good example of acceleration/deceleration type injury, where the brain bounces against the inner lining of the skull.

Infection and inflammation: Infectious agents resulting in diseases such as meningitis, brain abscesses or encephalitis

Tumors: Tumors are types of brain lesions and may be benign (meningiomas are the most common) or malignant like glioblastoma multiforme. Tumors in the brain may also be metastatic, spreading from cancers that arise primarily from another organ. Symptoms occur depending upon the location and size of the tumor.

Immune: Immunologic causes may also affect the brain, for example diseases like multiple sclerosis.

Plaques: Some investigators suggest that abnormal deposits of material that form plaques may be a type of disease that causes damage and eventual brain cell death in diseases like Alzheimer's disease.

Toxins: Toxins may affect brain function and may be produced within the body or may be ingested. The most common ingested poison is alcohol, though other chemicals can adversely affect the brain. Individuals can develop encephalopathy due to a variety of chemicals and substances that build up in the blood stream. Ammonia levels rise in patients with liver failure while patients with kidney failure can become uremic.

Multiple types: The type of lesion depends upon its cause and symptoms depend upon its location and amount of brain irritation or damage that has occurred. Some brain lesions types may occur from more than one cause, such as Alzheimer's disease that may be related to plaque formation, brain cell death, and possibly genetics. Research is ongoing and is likely to provide better insights into these various brain lesion types.


How Many Brain Cells Does a Child Have

A baby is born with roughly 86 billion neurons 𔁯​ , almost all the neurons the human brain will ever have 𔁰​ .

Although a newborn has about the same number of neurons as an adult, it has only 25% of its adult brain volume.

That&rsquos because infant&rsquos neurons are connected by only some 50 trillion neural connections, called synapses, whereas a grownup has about 500 trillion of them 𔁱​ .

This network of synaptic connections will ultimately determine how a child thinks and acts.

What Is Synaptic Pruning in Early Brain Development

Synaptic pruning is the process in which unused neurons and neural connections are eliminated to increase efficiency in neuronal transmissions.

The network of synapses grows rapidly during the first year and continues to do so during toddlerhood.

By age 3, the synaptic connections have grown to 1000 trillion.

But not all of the synapses will remain as the child&rsquos brain grows.

Life experience will activate certain neurons, create new neural connections among them and strengthen existing connections, called myelination.

Unused connections will eventually be eliminated. This is called synaptic pruning 𔁲​ .

Synaptic pruning is the process in which unused neurons and neural connections are eliminated to increase efficiency in neuronal transmissions.

Building massive connections, creating and strengthening them through life experiences and pruning unused ones is a remarkable characteristic of human brains.

This experience-based plasticity allows babies to adapt flexibly to any environment they&rsquore born into without the constraint of too many hardwired neural connections 𔁳​ .

For more help on calming tantrums, check out this step-by-step guide

The Use It Or Lose It Brain Sculpting Property

The benefits of developing a baby&rsquos brain this way are enormous, but so are the costs and the risks 𔁴​ .

First, children require a lot of care, i.e. life experiences, before they can be independent.

Second, what parents do or don&rsquot do during the formative years can have a profound impact on the child&rsquos mental health and life.

Here&rsquos a synaptic pruning example. Let&rsquos say a parent consistently shows a toddler love and care, then the &ldquolove-and-care connections&rdquo will develop or strengthen over time. But if the parent constantly punishes or is harsh to the child, then the &ldquopunitive-and-harsh connections&rdquo will be stronger instead. And because the love-and-care experience is missing, those corresponding brain cells will wither and eventually be removed from the child&rsquos brain circuits. As a result, the child grows up lacking the love-and-care understanding that is essential to create healthy, meaningful relationships in his future life 𔁵​ .

Why The Early Years Matter in Baby Brain Development

Early years of life is a period of unique sensitivity during which experience bestows enduring effects 𔁶​ .

Although this experience-based brain plasticity is present throughout one&rsquos life, a child&rsquos brain is a lot more plastic than a mature one.

Brain cell pruning also occurs most rapidly during a child&rsquos preschool years.

The density of these connections during adulthood will reduce to half of that in a toddler at age two.

This is why nurturing and positive parenting are so important.

Things can go seriously wrong for children deprived of basic social and emotional nurturing.

Critical Periods and Sensitive Periods in the Developing Brain

Within early childhood, there are also windows of time when different regions of the developing brain become relatively more sensitive to life experiences.

These periods of time are called critical periods or sensitive periods.

During a critical period, synaptic connections in those brain regions are more plastic and malleable. Connections are formed or strengthened given the appropriate childhood experiences. After the critical period has passed, the synapses become stabilized and a lot less plastic.

For example, a young child can learn a new language and attain proficiency more easily before puberty. So the sensitive period for language skills mastery is from birth to before puberty.

Another example is emotional regulation. Emotional self-regulation forms the foundation of the brain architecture. It&rsquos a person&rsquos ability to monitor and regulate emotions.

Emotion regulation is not a skill we&rsquore born with. Yet it&rsquos an essential skill in a child&rsquos healthy development 𔁷​ .

The sensitive period of learning this crucial life skill is before a child turns two. Critical or sensitive period is another reason why early life experiences matter so much.


Anatomy of the Thalamus

The thalamus has two ends, the anterior and posterior poles, and four surfaces: medial, lateral, superior, and inferior. Nuclei in a given pole or surface regulate specific functions or processing of sensory information and maintain particular connections with parts of the nervous and limbic system.

Understanding the anatomy of the thalamus will help you in comprehending the specific regulatory mechanisms of this structure.

Medial Surface

The medial surface of the thalamus comprises the upper portion of the lateral wall of the third ventricle of the brain and is lined by ependyma (remember that ependyma is the layer of ependymal cells that create cerebrospinal fluid, CSF). The medial surface serves to connect the two thalami by an interthalamic adhesion.

On its inferior (bottom) portion, it is connected to the hypothalamus by a hypothalamic sulcus, which extends from the upper part of the cerebral aqueduct (another cerebral ventricle) to the interventricular foramen (tract through which CSF flows).

A bundle of fibers called the stria medullaris thalami are located near the junction of medial and superior (upper) surfaces.

Lateral Surface

The lateral surface of the thalamus is covered by a layer of myelinated fibers called the external medullary lamina which separates the lateral surface from the reticular nuclei.

Superior Surface

This surface of the thalamus is coated by white matter (remember white and gray matter: white matter contains nerve fibers, axons, that extend from their individual neurons.

They are covered in myelin sheaths. Gray matter, on the other hand, is composed of the neuronal cell bodies and unmyelinated axons). This white matter is called the stratum zonale. (Note that the stratum zonale is also composed of gray matter, however, the surface is what makes up the white matter.)

The medial (inner, toward the center of the body) region of the superior surface is separated from the fornix by the choroid fissure (an attachment site for the choroid plexus, the structure which contains ependymal cells).

The superior surface of the thalamus also forms part of the floor of the lateral ventricles.

The lateral region of the superior surface of the thalamus contains the stria terminalis, a structure that plays a role in the regulation of emotions and behaviors related to stress. Another layer of white matter called the external medullary lamina divides the lateral region of the superior surface from the reticular nucleus.

Inferior Surface

The inferior surface of the thalamus is connected to the anterior portion of the hypothalamus and the posterior portion of the subthalamus. The subthalamus is what separates the thalamus from the tegmentum of the midbrain.

Anterior Pole

The anterior pole of the thalamus constitutes the posterior boundary of the interventricular foramen.

Posterior Pole

Also known as the pulvinar, the posterior pole of the thalamus extends past the third ventricle and over the superior colliculus (a small elevation on each side of the posterior region of the midbrain). Reticular nuclei are located laterally to the primary mass of nuclei here.

Nuclei of the midline are connected to either the ependyma of the lateral walls of the third ventricle or are adjacent to the interthalamic adhesion.


Boundaries, Anatomy, Position, and Structure of the Occipital Brain Lobe

The boundaries of the occipital lobe include the edges of the parietal and temporal lobe. The occipital lobe contains the primary visual cortex and associative visual areas (1).

The occipital lobe occupies the posterior parts of the hemispheres. On the convex surface of the hemisphere, the occipital lobe has no sharp boundaries separating it from the parietal and temporal lobes.

The exception is the upper part of the parietal-occipital groove, which, located on the inner surface of the hemisphere, separates the parietal lobe from the occipital lobe. The furrows and edges of the upper canopy of the occipital lobe are unstable and have a variable structure.

On the inner surface of the occipital lobe, there is a groove of spores, which separates the wedge (triangular norm of the occipital lobe) from the lingual gyrus and the occipital-temporal gyrus (1).

In the occipital lobe of the cerebral cortex is, the following fields are positioned:

  • Area 17 - Gray matter buildup in a visual analyzer. This field is the primary zone. It is made up of 300 million nerve cells.
  • Area 18 - It is also a nuclear set of visual analyzers. This field performs the function of perceived writing and is a more complex secondary area.
  • Area 19 – This field is involved in evaluating the value of what we see.
  • Area 39 - This brain part does not completely belong to the occipital region. This area is located at the border between the parietal, temporal, and occipital lobes. Its functions include integrating visual, auditory, and general sensitivity of information (1).

What Multiple Sclerosis Looks Like in Your Brain

Multiple sclerosis (MS) is a disease of the central nervous system that causes damage to your brain, spinal cord, and optic nerves. It’s characterized by lesions, or areas of tissue damage that occur when your immune system behaves abnormally and attacks these areas.

While many symptoms of MS throughout the body can be caused by lesions in either the brain or the spinal cord, cognitive symptoms of MS — those related to your memory, language, and problem solving — are believed to be caused only by lesions in the brain.

Brain lesions are a hallmark of MS, but they’re not the only way MS can affect your brain function. MS can also contribute to brain atrophy, or shrinkage, over time — a process that occurs in all people as they age, but typically happens much more quickly in people with MS. Brain atrophy, in particular, can contribute to cognitive symptoms of MS.


Forging new paths

We continue to have the ability to learn new activities, skills or languages even into old age. This retained ability requires the brain to have a mechanism available to remember so that knowledge is retained over time for future recall. This is another example of neuroplasticity and is most likely to involve structural and biochemical changes at the level of the synapse.

Reinforcement or repetitive activities will eventually lead the adult brain to remember the new activity. By the same mechanism, the enriched and stimulating environment offered to the damaged brain will eventually lead to recovery. So if the brain is so plastic, why doesn’t everyone who has a stroke recover full function? The answer is that it depends on your age (younger brains have a better chance of recovery), the size of the area damaged and, more importantly, the treatments offered during rehabilitation.


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11 Comments
Friday, July 25, 2014 4:57:48 AM | posted by Thomas Welter
Friday, July 25, 2014 4:53:51 AM | posted by Thomas Welter
Thursday, July 24, 2014 2:11:49 AM | posted by Bryce Thompson
Thursday, July 24, 2014 2:02:54 AM | posted by Bryce Thompson
Saturday, June 14, 2014 3:49:45 PM | posted by Paul w. horn, PhD
Saturday, June 14, 2014 3:44:55 PM | posted by Paul w. horn, PhD
Thursday, May 8, 2014 4:29:33 PM | posted by Theodore A. Hoppe

In a word, "epigenetics"
There is an old saying that if you only have a hammer every problem looks like a nail. These is what happens with therapy.
Obviously, twin studies have revealed that issues like sexual orientation and schizophrenia can effect one twin and not the other. So these issues have nothing, except perhaps a genetic pre-disposition, to do with brain developing as Brizendine you have us believe.

See Tim Specter's book, "Identically Different."
http://www.theguardian.com/books/2012/aug/08/identically-different-genes-spector-review

Wednesday, February 12, 2014 9:26:54 AM | posted by Alida Vismara
Wednesday, February 12, 2014 9:25:58 AM | posted by Alida Vismara
Wednesday, February 12, 2014 9:25:10 AM | posted by Alida Vismara
Monday, November 11, 2013 7:25:24 PM | posted by J. Fischer

I am sorry, but the issue is much more complex than male straight vs male homosexual because there are a good percentage of male homosexuals who also have a feminine orientation and or identify with females. So it isn't just either male straight or male homosexual hard wiring issue at puberty. There are more components invovled if we utilize your analysis, ie: 1) male straight, 2) male homosexual, 3) male homosexual with feminine orientation, 4) male homosexual with female identification. Also, if you say these are choices (like ordering a steak vs chicken at a restaurant), which I don't believe, then why wouldn't a psychologist be permitted to discuss those choices with this indidivual in therapy, just as he would discuss choices that a depressive or anxious person, or ADHD person or other would need to discuss in a thereapeutic relationship? Why is that treated with such disdain today and new laws and rules are being set up not to allow these discussions, but other disorders are not apart of such distorted rules of the game.

And why do you assume that homosexuality is a choice someone makes at puberty. All reality and science shows that you don't have that choice, it is made for you in the hardwiring of the brain. The real question is normality. Is Gay the new "Normal" to individuals in our industry? I am curious why Homosexuality with and without feminine orientation, which does not promote procreation of life in any way, is now considered "normal", but ADHD is still a disorder? Obviously ADHD is a problem with the hardwiring in the brain just like homosexuality is, but our industry considers ADHD still a disorder, but an even more detremental disorder in the hardwiring of the brain toward an attraction to the same sex is now not considered an abnormality? Talk about disorder bias. This makes no sense even on a very banal level. We are not discussing or assessing a "good" or "bad" or a "fault" behavioral message to the disorder, but it isn't any less a disorder then any of the other "hardwire" brain problems and disorders listed in DSM-IV or V. So are we allowing and supporting the creation of a "newter" gender that is socially acceptable but scientifically abnormal, or are we inhibiting and down-right stopping our ability to help those with problems in the hardwiring of their brains?