Nonspecific Nuclei. The first group includes the midline (median) and intralaminar nuclei and the medial portion of the ventral anterior nucleus. These nuclei receive ascending input from the mesencephalic reticular…

Above the interventricular foramina, the two halves of the body of the fornix separate to become the (anterior) columns of the fornix. As each column descends, it sinks into the…

The majority of afferent information arises from the glutamatergic projections arising from pyramidal neurons in layer V of the cortex. These projections largely travel ipsilaterally via the extreme capsule. Information…

The hippocampus is a part of the marginal cortex of the parahippocampal gyrus that has been invaginated, or rolled, into the floor of the inferior horn of the lateral ventricle…

Agenesis of the corpus callosum (ACC) is a congenital birth defect characterized by an absence of a corpus callosum. This condition can occur in isolation (with little to no impact…

The limbic forebrain refers to the areas that are functionally and anatomically connected structures that relate to emotion, motivation, and self-preservation. The limbic system is thought to be a major…

Corticocortical Circuits. Local short association fibers, or U fibers, connect adjacent cortical gyri and lie beneath the sixth cortical layer. Neighborhood association fibers traverse longer distances than U fibers, but…

Lesions to cortical association bundles can provide clinical relevance to fiber pathway tracts and cortical origins and destinations. For instance, a patient who develops acute damage to the uncinate fasciculus…

Posterior Medial Surface. The posterior part of the medial surface has two deep sulci. The upper parietooccipital sulcus inclines backward and upward to cut the superior border. The lower calcarine…

Association Pathways. When one cortical area is activated by a stimulus, other areas also respond. This is due to the rapid activity along a large number of precisely organized, reciprocally…