ENCYCLOPEDIA
BRITANNICA:
The gray matter of the cerebral cortex usually
is divided into four lobes, roughly defined by major surface folds; sometimes
the limbic system, or limbic lobe, is considered to be a fifth lobe.
The frontal lobe contains control
centers for motor activity and speech, the parietal for somatic senses (touch
and position), and the temporal for auditory reception and memory. The
occipital lobe at the back of the brain holds the brain’s major
visual-reception area.
The frontal lobe is concerned with many
of the components of intelligence (foresight, planning, and comprehension),
with mood, with motor activity on the opposite side of the body, and (in the
case of the dominant hemisphere) with speech production.
Frontal lobe damage can affect people in any of several ways, and the
results are at once subtle and drastic. On the one hand, they may have
difficulty initiating behaviour, in extreme cases being virtually unable to
move or speak but more often simply having difficulty in getting started on a
task. On the other, they may perseverate, being apparently unable to step a
behaviour once started. Rather than appearing apathetic and hypoactive, they
are uninhibited, rude, and boorish. Such people may also have difficulty in
planning and problem solving and may be incapable of creative thinking.
Irritability and personality change are also
frequently seen after frontal lobe damage.
