Cerebral Cortex Medical Neuroscience Dr Wiegand Comparative Anatomy

Cerebral Cortex Medical Neuroscience Dr. Wiegand

Comparative Anatomy human cat rat Human cortical expansion not strictly due to enlarged motor or primary sensory areas

Longitudinal fissure Gyri & sulci Lateral or Sylvian fissure

Landmarks Precentral & postcentral gyri Lateral or Sylvian fissure Central sulcus Parietooccipital sulcus Preoccipital notch

Lobes poles Frontal lobe Parietal lobe operculum Temporal lobe Occipital lobe

Medial Surface Central sulcus Frontal lobe Parietooccipital sulcus Occipital lobe

Frontal lobe • Sup. /mid. /inf. gyri • Precentral gyrus/sulcus • Pars orpercularis, triangularis, orbitalis Parietal Lobe • Post central gyrus • Supramarginal and angular gyri • Superior parietal lobule • Temporal Lobe • Sup. /mid. /inf. gyri • Transverse gyri

• Corpus callosum • Callosal sulcus • Cingulate gyrus/sulcus • Anterior commissure • Superior frontal gyrus • Paracentral lobule • Precuneus • Calcarine sulcus • Lingual gyrus • Fornix • Septum pellucidum

• Gyrus rectus • Olfactory sulcus/tract/bulb • Olfactory stria • Orbital gyri • Occipitotemporal gyrus • Parahippocampal gyrus & uncus • Collateral & rhinal sulci • Ant. /post. perforated substance

Deep Telencephalic Nuclei claustrum

Gray Matter of the Cerebral Cortex ¢ ¢ Archicortex – 3 layers (hippocampus) Neocortex – 6 cellular layers Hippocampal formation = hippocampus + dentate gyrus

Neocortex – 6 cellular layers ¢ I. II. III. IV. V. VI. Molecular layer – mostly neuropil External granular layer – stellate cells External pyramidal layer – small pyramidal cells Internal granular layer – stellate cells Internal pyramidal layer – large pyramidal cells Multiform layer – multiple cell types

I II IV V VI sensory association motor Association & Commissural Thalamocortical afferents Corticofugal efferents Corticothalmic efferents

Brodmann Areas Area 4 = primary motor cortex Areas 3, 1, 2 = primary somatosensory cortex Area 17 = primary visual cortex Areas 41, 42 = primary auditory cortex

White Matter intracortical intercortical projection fibers

Commissural Fibers ¢ Anterior Commissure l ¢ Posterior Commissure l ¢ Preoptic nuclei (vision) Habenular Commissure l ¢ Inf. & mid. temporal gyri, olfactory areas Habenular nuclei (olfaction) Corpus Callosum l l Connects hemispheres Rostrum, genu, body & splenium

Association Fibers ¢ ¢ Short fibers – connect adjacent gyri Long fibers l l l Superior longitudinal fasc. Arcuate fasciculus Inferior longitudinal fasc. Cingulum – septal area, cingulate and parahippocampal gyri Uncinate fasc. – orbital frontal gyri to temporal pole

Projection Fibers

Internal Capsule Organization medial lateral

Cortical Functional Organization Precentral gyrus Similar organization in visual, auditory and somatosensory cortices