Prefrontal cortex · Grey Matter

The prefrontal cortex is the front of the frontal lobe, the region that keeps a goal in mind and bends perception, memory and action toward it: it plans, holds information for the next few seconds, weighs options against their consequences and stops actions that do not serve the goal.

Prefrontal cortex. The prefrontal cortex is the front of the frontal lobe, the region that keeps a goal in mind and bends perception, memory and action toward it: it plans, holds information for the next few seconds, weighs options against their consequences and stops actions that do not serve the goal.

It has no single map of a sense or a muscle. Its job is to control other areas, and its connections show it: it receives from every association cortex, from the amygdala and the hypothalamus, and sends back to all of them and to the basal ganglia. Three broad parts recur in the literature. The dorsolateral prefrontal cortex on the outer side handles working memory, rules and planning; the ventromedial prefrontal cortex and orbitofrontal cortex, on the underside and the midline, value options and regulate emotion; the anterior cingulate cortex beside it detects conflict and errors.

It is the slowest part of the brain to mature, still changing into the mid-twenties.

Its damage changes the person more than the senses. Patients with prefrontal lesions can pass intelligence tests and still decide badly in life, lose their social judgement or become apathetic, which is what made the case of Phineas Gage famous.

Thinking about thinking is associated mostly with this region, and the habit of calling it the brain's executive is fair as long as it is remembered that it executes through others.

Questions: What happens to a person when the anterior cingulate cortex is damaged on both sides? The anterior cingulate cortex, with the medial prefrontal cortex around it, supplies the drive to act: it signals that something matters enough to spend effort on. When it is destroyed on both sides, usually by a stroke of both anterior cerebral arteries or a tumour, patients become apathetic, and in severe cases develop akinetic mutism: awake, following people with their eyes, not paralysed, yet neither moving nor speaking unless strongly prompted. Smaller lesions, including those made surgically for chronic pain, reduce the unpleasantness of pain and the reaction to errors more than the ability to act. Does the cerebellum do anything for thinking, or only for movement? Large parts of the cerebellar hemispheres are connected through the thalamus and pons with the prefrontal and parietal cortex, not with the motor areas. In 1998 Schmahmann and Sherman described patients with lesions of the posterior cerebellum who had trouble planning, switching tasks, finding words and judging space, and whose emotions had become blunted or disinhibited, the cerebellar cognitive affective syndrome. One hypothesis is that the cerebellum applies to thoughts the same predictive correction it applies to movements. How does a decision in the prefrontal cortex become a movement of the hand? The frontal lobe works as a gradient from abstract at the front to concrete at the back. The prefrontal cortex holds the goal (pick up the cup), the premotor cortex and supplementary motor area choose and sequence the movements that serve it, and the primary motor cortex on the precentral gyrus issues the commands down the corticospinal tract to the spinal motor neurons. Along the way the basal ganglia release the chosen action and the cerebellum adjusts its force and timing, so the plan arrives at the muscles already corrected.