Cerebral Cortex
Medical Neuroscience Dr. Wiegand
Comparative Anatomy
human cat rat
HumanHuman corticalcortical expansionexpansion notnot strictlystrictly duedue toto enlargedenlarged motormotor oror primaryprimary sensorysensory areasareas
LongitudinalLongitudinal fissure fissure
GyriGyri & & sulcisulci LateralLateral or or SylvianSylvian fissurefissure
1 Landmarks
Central sulcus Precentral & Central sulcus postcentral Parieto-Parieto- gyri occipitaloccipital sulcussulcus
LateralLateral or or SylvianSylvian PreoccipitalPreoccipital notch notch fissurefissure
Lobes
poles
Frontal lobe Parietal lobe
Temporal lobe Occipital lobe
Medial Surface
CentralCentral sulcussulcus
Parieto-Parieto- occipital Frontal occipital Parietal sulcus lobe sulcus lobe Occipital lobe
2 Parietal Lobe •Post central gyrus •Supramarginal and angular gyri •Superior parietal Frontal lobe lobule •Sup./mid./inf. gyri •Precentral gyrus/sulcus •Pars orpercularis, triangularis, orbitalis
•Temporal Lobe • Sup./mid./inf. gyri •Transverse gyri
•Corpus callosum •Callosal sulcus •Cingulate gyrus/sulcus •Anterior commissure •Superior frontal gyrus •Paracentral lobule •Precuneus •Cuneus •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
3 Deep Telencephalic Nuclei
Gray Matter of the Cerebral Cortex
| Archicortex – 3 layers (hippocampus) | Neocortex – 6 cellular layers
Hippocampal formation = hippocampus + dentate gyrus
4 Neocortex
| Neocortex – 6 cellular layers I. Molecular layer – mostly neuropil II. External granular layer – stellate cells III. External pyramidal layer – small pyramidal cells IV. Internal granular layer – stellate cells V. Internal pyramidal layer – large pyramidal cells VI. Multiform layer – multiple cell types
sensory association motor I II Association & Commissural III Thalamocortical afferents
IV Corticofugal efferents V Corticothalmic VI 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
intracortical
intercortical
projection fibers
Commissural Fibers
| Anterior Commissure z Inf. & mid. temporal gyri, olfactory areas | Posterior Commissure z Preoptic nuclei (vision) | Habenular Commissure z Habenular nuclei (olfaction) | Corpus Callosum z Connects hemispheres z Rostrum, genu, body & splenium
Commissural Fibers
| Anterior Commissure z Inf. & mid. temporal gyri, olfactory areas | Posterior Commissure z Preoptic nuclei (vision) | Habenular Commissure z Habenular nuclei (olfaction) | Corpus Callosum z Connects hemispheres z Rostrum, genu, body & splenium
6 Association Fibers
| Short fibers – connect adjacent gyri | Long fibers z Superior longitudinal fasc. z Arcuate fasciculus z Inferior longitudinal fasc. z Cingulum – septal area, cingulate and parahippocampal gyri z Uncinate fasc. – orbital frontal gyri to temporal pole
Projection Fibers
Internal Capsule Organization
medial lateral
7 Cortical Functional Organization
Precentral gyrus
Similar organization in visual, auditory and somatosensory cortices
8