HumanBrain

From Simreal

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Cerebral Cortex

The cerebral cortex makes up 70% to 85% of your brain, (depending on how you do your accounting). It is the wrinkled outer layer of your brain, (cerebrum), and it wraps around the rest of the brain.

The cerebral cortex is where you plan for your future, solve problems, and learn from your experiences. Part of learning from experience, of course, involves anticipating rewards and punishments-- (essentially predicting the future).

Like the brain itself, the cerebral cortex is divided into several named areas.

Frontal Lobe

The frontal lobe of the cerebral cortex is located at your forehead--at the very front of the brain. This lobe is complex enough that the very front-most part has its own name, the prefrontal cortex.

The prefrontal cortex is involved with your ability to pay attention and to stick with a task. Related to this, it manages your impulse control. The prefrontal cortex has a bunch of high-level functions as well, such as managing your judgment, problem solving, and critical thinking skills. This is where your forward thinking comes into play, as well as some of your ability to learn from experience. It is also the seat of your working memory. The prefrontal cortex is your conscience, sitting on your shoulder monitoring your actions and maintaining your empathy.

The rest of the frontal lobe picks up where the prefrontal cortex leaves off, working on your advanced planning behavior, judgments, and consciousness itself. Working with your limbic system, the frontal lobe helps moderate your emotional responses. In its role as memory, it assigns meanings to words and manages word associations, as well as driving your ability to use language.

Problems stemming from frontal lobe damage include paralysis, an inability to plan or execute sequences or complex movements, and a loss of spontaneity and flexibility in your thoughts and interactions with others. You can find yourself stuck on a single thought or repeating one motion, or you could be unable to focus on a task at all. Frontal lobe damage can cast your emotions adrift, opening you up to odd mood changes and variations in social behavior and personality. Of course, you will also see difficulties in problem solving and language.

Parietal Lobe

Moving back from your forehead, you find the parietal lobe at the top, (near the back/top,) of your head.

This lobe manages your visual attention, (that is, what you rest your eyes on), as well as your perception of touch. Probably because of the association with touch, the parietal lobe is involved in your ability to handle objects, or to make the movements you intend to make. The parietal lobe integrates a number of your different senses into a coherent, single concept--a gathering place for inputs.

Problems with the parietal lobe can lead to an inability to focus on more than one object at a time. You may also have a problem naming objects or finding words for writing and reading. An unhappy parietal lobe can lead to problems performing mathematics, drawing objects, or even telling left from right. Parietal lobe damage can lead to a lack of awareness of your body's parts or even the space around you.

Occipital Lobes

Behind the parietal lobe, at the very back of your head, lie your occipital lobes. This part of your brain is, simply, in charge of your vision.

Problems in the occipital lobes can lead to many difficulties in visual processing including blank areas in your visual field and difficulty locating objects in the environment. You can have problems identifying colors, recognizing printed words, identifying objects, or recognizing motion. A damaged occipital lobe can lead to hallucinations and odd visual illusions.

Temporal Lobes

Moving laterally a bit, we find your temporal lobes at, well, your temples (which, if you don't know, are at the sides of your head above your ears). You have two temporal lobes each with somewhat different functions, the dominant lobe, (which is the left lobe for you dexterous people, and the right lobe for sinister folks,) and the other one (submissive lobe? Nah).

Your dominant temporal lobe is specialized for understanding and generating language, with related functions for word retrieval and auditory learning, as well as other visual and auditory processing tasks. It is involved in both intermediate and long-term memory, and supports complex structured memories. Interestingly enough, the dominant temporal lobe is important to your emotional stability.

Problems with your dominant temporal lobe can lead to aggression and dark or violent thoughts and an over-sensitivity to perceived slights (that whole emotional stability thing). You can also get word-related problems and relevant difficulties in reading, problems with auditory processing, and difficulty identifying spoken words. Of course, since this lobe is involved in memory you can also end up with long and short-term memory failures as well as problems categorizing objects.

The other, non-dominant, temporal lobe does some of your stereotyped "right-brain" activities, such as recognizing facial expressions and getting the emotion from vocal intonations. This lobe is also a key player in recognizing and reproducing rhythms and music. Like many parts of the brain, it also has a hand in visual learning.

Problems in the non-dominant temporal lobe can lead to difficulties recognizing faces and decoding the intonation and meaning in words, which, predictably enough, leads to problems with your basic social skills. Of course, scientists will ultimately discover that white-boy dancing has its roots in deficiencies of the temporal lobe.

In general, problems in the temporal lobes can lead to all kinds of memory problems, amnesia, and mysterious headaches. Tweaky temporal lobes can create fear and anxiety, unusual sensory perceptions and distortions, and feelings of deja vu or confusion. Interestingly enough, religious or moral preoccupation and reveries can be traced to temporal lobe problems.

Basal Ganglia

You will find both the basal ganglia ("basement structures") and the limbic system lurking underneath the cerebral cortex and surrounding the brain stem. The basal ganglia are tied fairly closely to the cerebral cortex, (often via the thalamus).

These structures manage your moment-by-moment movements, fine-tuning your motor behavior and suppressing unwanted motions. They also integrate your sense of touch with your movements, a necessary feedback loop. Parts of the basal ganglia set your anxiety level as well as your current pleasure (and ecstasy) level -- needless to say, it plays a role in motivation.

Problems in the basal ganglia can induce anxiety, nervousness, or panic attacks. You may also get fine motor problems, tremors, Tourette's Syndrome (where movement sequences are not properly suppressed), headaches, and low (or excess) motivation.

Limbic System

The limbic system is a set of structures arranged like a donut around the top of your brain stem. This system consists of many named parts including the amygdala, corpus callosum, fornix, hippocampus, mammillary body, olfactory bulb, supracallosal gyrus, and thalamus. Some of the areas in the limbic system are explored here.

Deep Limbic

Deep in the heart of the limbic system are some patches of neurons that set your emotional tone, provide emotional coloring for the events around you, and act as a storage house for memories of particularly strong emotions. These emotions and memories of emotion are an important part of how you decide what is important. The deep limbic system also processes smell, with smell and emotion being closely linked. Other bits work on your motivation, appetite, and sleep patterns.

If your deep limbic system isn't working correctly you can have problems with moodiness and irritability, with increased negative thinking and negative emotions. You may also have decreased motivation, low appetite, or sleep problems. All of this comes with a social toll to be paid, as well.

Hippocampus

"Seahorse" from the Greek, the hippocampus is named after its curled shape. An interesting and important structure, the hippocampus plays a large role in transferring memories from short term to long-term memory. In conjunction with the thalamus, the hippocampus also holds spatial memories.

Amygdala

Like the hippocampus, the amygdala is named after its shape, ("almond"). This speck of your brain is in charge of your emotions, though it plays a role in other non-emotional memories as well.

Thalamus

The thalamus is a blob near the center of your brain. As mentioned above, it works with the hippocampus to store spatial memory. The thalamus also plays a role, with the amygdala, in storing emotional memories.

Hypothalamus

The hypothalamus is a small section deep inside the brain, beneath the thalamus, that secretes the chemicals that guide the regulation of various important equilibriums. It is important to the balance of water in your body, as well as the metabolism of fat and sugar. The hypothalamus works to regulate your body temperature and your various hormones. It is said that it manages your four 'F's -- fighting, fleeing, feeding, and reproduction.

Cingulate Gyrus

The cingulated ("ringlike") gyrus is a structure just above the corpus callosum, which in turn is a thick band of fibers between your brain's halves. The cingulated gyrus has the important task of shifting your attention. This structure gives you your cognitive flexibility and adaptability, as well as your ability to cooperate with others.

A healthy cingulate gyrus is necessary to avoid obsession with your worries, hurts, thoughts, and behaviors. Problems in the cingulated gyrus can lead to uncooperative and inflexible behaviors (including, interesting enough, road rage), addiction problems, and obsessive compulsions.

Cerebellum

This is the little brain, sitting off of your spinal cord at the base of your skull. The cerebellum processes information coming in from your muscles, joints, and tendons, including your sense of balance. It modulates your fine motor activity and keeps your voluntary motions under control. Procedural, or "how," memories, such as how to ride a bicycle or hit a tennis ball, are stored in the cerebellum, tucked down and away from your awareness.

Problems in the cerebellum can lead to difficulty coordinating various fine or rapid movements, including reaching and walking. You can end up with tremors, dizziness, and slurred speech.

Brain Stem

Reaching down to the depths of the brain, we find the brain stem leading to the spinal cord. The brain stem consists of three named parts; the medulla oblongata, the pons, and the midbrain. Together, they, in cooperation with higher systems, manage many automatic and semi-automatic functions such as your breathing, heart rate, swallowing, balance, sweating, blood pressure, digestion, and body temperature. The brain stem is the gateway to your body. In addition to its basic regulatory tasks, it manages some of your reflexes, such as the startle response to loud sounds or rapid motion.

Damage to the brain stem can cause severe problems such as difficulty in breathing, swallowing, and balancing. Brain stem damage can lead to dizziness, nausea, and insomnia, as well as difficulty in organizing your perceptions of the environment.

==Spinal Cord

The spinal cord is a continuation of the lower part of your brain, carrying down to the nerves that communicate with the rest of you. The spinal cord is an important part of your voluntary movements and tactile input, as well as your balance and equilibrium. Many low-level motor reflexives are managed at the spinal cord.