Frontal Lobes
The frontal lobes have grown larger in humans than in other primates. If you
place the palm of your hands on your forehead and reach back with your fingers,
you are covering your frontal lobes. In this area of your brain, you process the
steady stream of events to find features of importance to you. In particular,
you process other people’s behavior and adjust your own behavior to be
appropriate to whatever is happening right now. You also plan, reason, receive
advice and make decisions just behind your forehead. Tall foreheads are often
recognized as a sign of superior intelligence.
The anatomy of the frontal lobes is complicated and inappropriate names for
the cortical surfaces persist. The impression that a frontal lobe is a discrete
structure is misleading. If you compare all cortical areas with RAM is a
computer, then the expanded frontal lobe RAM in humans allows for the
intergration and storage of information from diverse subcortical processors
combined with output from other cortical areas.
The frontal lobes may be given credit for the net results of increased
working memory for the integration of other brain regions. For example,
Alexander and Brown suggested: “The medial prefrontal cortex (mPFC) and
especially anterior cingulate cortex is central to higher cognitive function and
many clinical disorders... theories of mPFC have treated effects of errors,
conflict, error likelihood, volatility and reward, using findings from
neuroimaging and neurophysiology in humans and monkeys…(our) model suggests a
new view of mPFC, as a region concerned with learning and predicting the likely
outcomes of actions, whether good or bad. Cognitive control at the neural level
is then seen as a result of evaluating the probable and actual outcomes of one's
actions.”
Romine and Reynolds stated:" The multidimensional nature of the frontal lobes
serves to organize and coordinate brain functioning, playing a central and
pervasive role in human cognition. The executive processes implicated in complex
cognition such as novel problem solving, modifying behavior as appropriate in
response to changes in the environment, inhibiting previous responses, and the
implementation of schemas that organize behavior over time are believed to be
mediated by the frontal regions of the brain. Overall, the functioning of the
frontal lobes assists individuals in goal directed and self-regulatory behavior.
Additional theories of frontal lobe functioning have focused on its involvement
in temporal, or time-related domains... frontal lobe damage has been associated
with deficits in memory for the temporal ordering, or sequencing, of events. "
Neurons have been identified in the premotor cortex are active with actions and
also respond to the actions of others. The name "mirror neurons" was given to
these cells and has become popular despite being inappropriate. The most
important form of learning in most animals, especially primates is to copy the
actions of others. The premotor cortex is required for mimetic learning and for
following the movements of others in group activities such walking together,
marching, dancing and singing. (Romine CB ; Reynolds CR. Sequential memory: a
developmental perspective on its relation to frontal lobe functioning.
Neuropsychol Rev. 2004; 14(1):43-64 (ISSN: 1040-7308))
Damage to the frontal lobes leads to deficits in sociability, planning and
judgment. Patients may act inappropriately, lack empathy, have poor judgment and
lack of concern about the negative consequences of careless or bad behavior.
They are easily distracted, perseverate, and are often unable to carry out
planned activities. When both frontal lobes are damaged, patients lose some or
all of the drive states that propel normal humans into a steady series of
activities. Akinetic mutism is the most severe deficit – the patient does not
move or speak spontaneously.
Poor judgment often disables frontal lobe patients. For example,
Gomez-Beldarrain evaluated patients and matched controls with brain damage using
economic decision-making tasks that required them to forecast an economic
outcome using advice from four advisors. Frontal lobe lesion patients were
inconsistent at using advice and their forecasts were poor. Patients with
parietal lobe lesions were good at assessing advice but were slow at doing so;
they were consistent but poor at using advice and their use of advice was
unrelated to their forecasting. All brain damaged patients were overconfident in
their own performance.
