An extract on #frontals
The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts.
The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex. The dopamine system is associated with reward, attention, short-term memory tasks, planning, and motivation. Dopamine tends to limit and select sensory information arriving from the thalamus to the forebrain.
On the lateral surface of the human brain, the central sulcus separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe.
The frontal lobe can be divided into a lateral, polar, orbital (above the orbit; also called basal or ventral), and medial part. Each of these parts consists of a particular gyrus:
Lateral part: lateral part of the superior frontal gyrus, middle frontal gyrus, inferior frontal gyrus.
Polar part: Transverse frontopolar gyri, frontomarginal gyrus.
Orbital part: Lateral orbital gyrus, anterior orbital gyrus, posterior orbital gyrus, medial orbital gyrus, gyrus rectus.
Medial part: Medial part of the superior frontal gyrus, cingulate gyrus.
The gyri are separated by sulci. E.g., the precentral gyrus is in front of the central sulcus, and behind the precentral sulcus. The superior and middle frontal gyri are divided by the superior frontal sulcus. The middle and inferior frontal gyri are divided by the inferior frontal sulcus.
In humans, the frontal lobe reaches full maturity around the late 20s, marking the cognitive maturity associated with adulthood. A small amount of atrophy, however, is normal in the aging persons frontal lobe. Fjell, in 2009, studied atrophy of the brain in people aged 6091 years. The 142 healthy participants were scanned using MRI. Their results were compared to those of 122 participants with Alzheimer's disease. A follow-up one year later showed there to have been a marked volumetric decline in those with Alzheimer's and a much smaller decline (averaging 0.5%) in the healthy group. These findings corroborate those of Coffey, who in 1992 indicated that the frontal lobe decreases in volume approximately 0.5%1% per year.
The frontal lobe plays a large role in voluntary movement. It houses the primary motor cortex which regulates activities like walking.
The function of the frontal lobe involves the ability to project future consequences resulting from current actions, the choice between good and bad actions (or better and best) (also known as conscience), the override and suppression of socially unacceptable responses, and the determination of similarities and differences between things or events.
The frontal lobe also plays an important part in integrating longer non-task based memories stored across the brain. These are often memories associated with emotions derived from input from the brain's limbic system. The frontal lobe modifies those emotions to generally fit socially acceptable norms.
Psychological tests that measure frontal lobe function include finger tapping (as the frontal lobe controls voluntary movement), the Wisconsin Card Sorting Test, and measures of language and numeracy skills.