There is no more brilliant or complicated yet efficient system in the universe. Weighing between two and four pounds and consisting of millions of neurons the human brain produces our every thought, behavior, and emotion. The human brain is comprised of nearly 60% fat and demands about 25% of the body’s blood, glucose, and oxygen. The brain has a conscious thinking system known as the Cortex and an older, more primitive and procedural system known as the subcortex. Two hemispheres (left and right) are connected by a corpus collosum and represent regions of behavioral specialization such as language and spatial function.
The human brain is responsible for all behavior and we really do not understand how the brain works. However, behavioral and cognitive functions can be organized into five distinct domains to include (1) attention and concentration; (2) memory; (3) visuospatial skill; (4) language; and (5) executive function.
The brain has the ability to focus and to process a stimulus on both a superficial and more deep level. The allocation of mental energy to process information is referred to as attention and concentration. The more deeply one attends to a particular stimulus the better the information will be encoded, understood, and retained. Some suggest attention is primarily related to the frontal systems of the brain. However, attention is perhaps better considered a general brain function with multiple inputs from diverse regions. The brain stem is needed for basic arousal and ability to engage the cortex. Sensory systems across the cortex are then engaged and indeed the frontal system that may help to integrate and analyze the stimulus all are critical parts of attention.
The brain has the ability to encode and retain new information thereby permitting memory. Regardless of the type of stimuli the brain can process the information and remember it. It is thought the hippocampus, a structure that lies in the medial section of each temporal lobe (just under each temple) helps to encode information and transition new information into a long term or secondary storage area in the cortex. Without the hippocampus, the brain cannot encode and rapid forgetting of new material occurs. The memory system of the brain has the ability to recall information after delay and to retrieve information from long ago such as childhood experiences. As we get older our ability to spontaneously recall information erodes somewhat. Cueing and prompting helps the older brain recall normally. Diseases such as Alzheimer’s damages the hippocampus and results in a progressive loss of memory ability. Chronic stress has also been found to negatively affect memory and potentially induce damage to the hippocampus.
The brain has the ability to appreciate one’s position in space and to also understand other objects and their relationship in space. This skill is thought to be related to the function of the parietal lobe near the posterior of the cortex. Spatial skill becomes important as we navigate in the world, with driving, and with simple walks around the block. Sometimes we might get lost in an environment such as a parking garage that represents a type of spatial disorientation. The brain has the capacity to affix landmarks and cues to new environments to help us with spatial orientation. Alzheimer’s also affects the spatial skill of the brain often leading to a person getting lost and eventually requiring locked doors to prevent walking away.
Language is a primary and fundamental function of the brain. We use language so often to communicate and to survive that it is thought to be a “dominant” function related to the “dominant hemisphere”. In most persons this is the left hemisphere. Language is complex and includes expression, repetition, and comprehension. Language also involves “prosody” or the pitch and inflexion of the words. We use language when we listen, read, write, and sign. Our entire western civilization, if not the entire world, depends heavily on the use of language. A stroke of the dominant hemisphere can be damaging to the language system and cause significant problems for the victim.
Our brain has a type of maestro or CEO that we believe sits in the front part of the Cortex and helps to execute behavior. The executive system helps to organize, plan, structure, implement, inhibit and abstract. It is not a region that contributes to general intelligence, but it serves to provide a general choreography of behavior for the entire brain. Personality is thought to reside in the front part of the brain and damage to the executive system can result in depression or manic like symptoms. Many of the psychiatric illnesses are thought to be related to structural or chemical alterations in the frontal lobe. The frontal lobe is the youngest and largest region of the Cortex.