The prefrontal areas project into the secondary motor cortices, which include the premotor cortex and the supplemental motor area. The regions of the frontal lobe that remain are the regions of the cortex that produce movement. These are primarily in the anterior part of the frontal lobe. One way to define the prefrontal area is any region of the frontal lobe that does not elicit movement when electrically stimulated. In generating motor responses, the executive functions of the prefrontal cortex will need to initiate actual movements.
Also, there is new evidence that though his life changed dramatically, he was able to become a functioning stagecoach driver, suggesting that the brain has the ability to recover even from major trauma such as this. However, the accounts suggest that some aspects of his personality did change. Many of the accounts of his change may have been inflated in the retelling, and some behavior was likely attributable to alcohol used as a pain medication. Whereas he was a hardworking, amiable man before the accident, he turned into an irritable, temperamental, and lazy man after the accident. Friends described him as no longer acting like himself. He survived the accident, but according to second-hand accounts, his personality changed drastically. He was a railroad worker who had a metal spike impale his prefrontal cortex ( ). A famous case of damage to the prefrontal cortex is that of Phineas Gage, dating back to 1848. The functions of the prefrontal cortex are integral to the personality of an individual, because it is largely responsible for what a person intends to do and how they accomplish those plans. The prefrontal lobe is responsible for aspects of attention, such as inhibiting distracting thoughts and actions so that a person can focus on a goal and direct behavior toward achieving that goal. These higher cognitive processes include working memory, which has been called a “mental scratch pad,” that can help organize and represent information that is not in the immediate environment. The most anterior regions of the frontal lobe-the prefrontal areas-are important for executive functions, which are those cognitive functions that lead to goal-directed behaviors. Whereas the sensory cortical areas are located in the occipital, temporal, and parietal lobes, motor functions are largely controlled by the frontal lobe. The completion of cortical processing through the primary, associative, and integrative sensory areas initiates a similar progression of motor processing, usually in different cortical areas. These levels of processing can lead to the incorporation of sensory perceptions into memory, but more importantly, they lead to a response. In the cerebral cortex, the initial processing of sensory perception progresses to associative processing and then integration in multimodal areas of cortex. Let’s start with sensory stimuli that have been registered through receptor cells and the information relayed to the CNS along ascending pathways. However, the muscles that are responsible for the basic process of breathing are also utilized for speech, which is entirely voluntary.
One example is the ability of our breathing to switch to unconscious control while we are focused on another task.
However, some aspects of the somatic system use voluntary muscles without conscious control. The term “voluntary” suggests that there is a conscious decision to make a movement. Somatic senses inform the nervous system about the external environment, but the response to that is through voluntary muscle movement. The defining characteristic of the somatic nervous system is that it controls skeletal muscles. Describe several reflex arcs and their functional roles.Explain the initiation of movement from the neurological connections.Compare different descending pathways, both by structure and function.Describe the pathway of descending motor commands from the cortex to the skeletal muscles.List the components of the basic processing stream for the motor system.By the end of this section, you will be able to:
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