Cerebral Cortex

Figure 19a: Anterior Commissure | Basal Ganglia | Central Fissure | Cerebral Cortex | Corpus Callosum | Hippocampus | Lateral Fissure | Lateral Ventricles | Longitudinal Fissure | Temporal Lobes
Figure 19b: Cerebellum | Frontal Lobe | Longitudinal Fissure | Medulla | Olfactory Bulbs | Optic Nerves | Spinal Cord | Temporal Lobe

Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test: 19a | 19b
Part 3: Multiple-Choice Self-Test

Return to main tutorial page

The Cerebral Cortex ("cerebral bark") is the most advanced or developed regions of the forebrain and consists of a layer of grey matter covering the cerebral hemispheres. In humans this cortical layer is highly convoluted or furrowed. These convolutions serve to increase the area of processing in the cortex of phylogenetically evolved species. This increase in size of the cerebral cortex provides additional resources for a more complex processing of the world. Some furrows are very large and deep. These are called fissures. Small, shallow ones are called sulci. These indentations of the cortical surface form the convolutions called gyri. The cerebral cortex is divided into four main regions found on either side of the brain called the frontal lobe, temporal lobe, parietal lobe, and the occipital lobe. Fissures and sulci form some of the boundaries between the cerebral lobes.

Approximately 90% of the human cerebral cortex is classified neocortex, or that which has "recently" evolved (phylogenetically newest). The neocortex is composed of three kinds of areas called the primary sensory cortex, primary motor cortex, and the association cortex. Sensory events for a single sense modality are processed in each primary sensory area. For example, there are primary sensory areas for vision, audition (hearing), and somatosensation (touch). Motor function is controlled exclusively within the primary motor cortex. Association cortex is distinguished from the primary cortical areas by the convergence of information from multiple sensory and/or motor areas of the cortex. The more highly evolved, human cerebral cortex is distinguished primarily from the less evolved cerebral cortex of other animals by the increased area of association cortex provided for the multi-modal processing of the world.

All areas of the neocortex are composed of six layers, numbered consecutively beginning with the layer at the surface. There are two primary cell types in the cortex, pyramidal cells and stellate cells. Pyramidal cells are large cells with pyramidal-shaped cell bodies, an apical dendrite (emerging from the top), and a long axon. Stellate cells are small in size and star-shaped with many short dendrites and a short axon. The stellate cells communicate between neurons in close proximity. Many long dendrites and axons travel in paths perpendicular to the brain's surface. This vertical arrangement and flow of information is the basis for the columnar organization of the cerebral cortex. Experiments reveal that these vertical columns form mini circuits that perform unique functions.