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…
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…
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…
Temporal Lobe. The temporal lobe is divided by superior and inferior temporal sulci into superior, middle, and inferior temporal gyri. The sulci run backward and slightly upward, in the same…
SUPEROLATERAL SURFACE On the superolateral surface, two sulci, the lateral and the central, can be easily identified. The lateral (sylvian) sulcus has a short stem between the orbital surface of…
After a normal pregnancy and delivery, early development is apparently normal through age 6 months; however, retrospectively, subtle deviant patterns occur, including deceleration of acquired head growth. Developmental progress stalls…
CLINICAL PRESENTATION The most severe of these disorders, autistic disorder, is characterized by markedly abnormal development in communication and social interaction and a markedly restricted range of activity and interests….
Because the primary deficit in developmental dyslexia is in reading and writing, the abnormality is usually not identified until the first few years of grade school, the time when children…
Defective Proliferation. A decrease in neuronal number may lead to microcephaly (microencephaly vera), whereas an increase may result in megalencephaly. Prenatal influences, including familial factors, are paramount in each abnormality….
