femme Neuroscience Notes

Some Topics

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.”

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.