Frontal Lobe

The frontal lobe, the largest of the cerebral lobes, lies rostral to the central sulcus (that is, toward the nose from the sulcus). One important structure in the frontal lobe is the precentral gyrus, which constitutes the primary motor region of the brain. When parts of the gyrus are electrically stimulated in concious patients (under local anesthesia), they produce localized movements on the opposite side of the body that are interpreted by the patients as voluntary. Injury to parts of the precentral gyrus results in paralysis on the contralateral half of the body.

The frontallobes are the part of the brain most remote from sensory input and whose functions are the most difficult to capture. They can be thought of as the executive that controls and directs the operation of brain systems dealing with cognitive function. The deficits seen after frontal lobe damage are described as a “dysexecutive syndrome.”
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Frontal lobe damage can affect people in any of several ways. On the one hand, they may have difficulty initiating a task or a behaviour, in extreme cases being virtually unable to move or speak, but more often they will simply have difficulty in initiating a task. On the other hand, individuals with frontal lobe damage may perservate, being apparently unable to stop a behaviour once it is started. Rather than appearing apathetic and hypoactive, patients may be uninhibited and may appear rude. Such people may also have difficulty in planning and problem solving and may be incapable of creative thinking. Mild cases of this deficit may be determined by a difficulty in solving mental arithmetic problems that are filled with words, even though the patient is capable of remembering the question and performing the required calculation. In such cases it appears that the patient simply cannot select the appropriate cognitive strategy to solve the problem.

A unifying theme in these disorders is the notion of inadequate control of organization of pieces of behaviour that may in themselves be well formed. Patients with frontal lobe damage are easily distracted. Although their deficits may be superficially less dramatic than those associated with posterior lesions, they can have a drastic effect on everyday function. Irritability and personality change are also frequently seen after frontal lobe damage.

In both sexes, the frontal lobe comprises about 38 percent of the hemisphere (ranging from 36 to 43 percent), the temporal lobe 22 percent (ranging from 19 to 24 percent)

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Bed Side Frontal Lobe Testing from Amit Nulkar on Vimeo.