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 notchnotch fissurefissure Lobes poles Frontal lobe Parietal lobe operculum Temporal lobe Occipital lobe Medial Surface CentralCentral sulcus sulcus 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 claustrum 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 5 White Matter 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.