Anatomy
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 particular gyri:
- Lateral part: Precentral gyrus, 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 only after the 20s, marking the cognitive maturity associated with adulthood. A small amount of atrophy, however, is normal in the aging person’s frontal lobe. Fjell, in 2009, studied atrophy of the brain in people aged 60–91 years. The 142 healthy participants were scanned using MRI (magnetic resonance imaging). Their results were compared to those of 122 participants with Alzheimer’s disease. The participants returned one year later, and the researchers noted that although volumetric decline was clearly evident in large amounts in the AD participants, it was also evident in small quantities in the healthy individuals. A decline in frontal lobe volume of approximately .5% over that year seemed to be average. These findings corroborate those of Coffey, who in 1992 indicated that the frontal lobe decreases in volume approximately .55%-1% per year.
Dr. Arthur Toga, a UCLA professor of neurology, found increased myelin in the frontal lobe white matter of young adults compared to that of teens. A typical onset of schizophrenia in early adult years correlates with poorly myelinated and thus inefficient connections between cells in the fore-brain.
Read more about this topic: Frontal Lobe
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—Ralph Waldo Emerson (1803–1882)