Question

How does the neocortex work? Explain how it is organized and how information flows through it.

Answer 1

is the top layer of the cerebral hemispheres, 2-4 mm thick, and made up of six layers, labelled I to VI (with VI being the innermost and I being the outermost).

The neocortex is part of the cerebral cortex (along with the archicortex and paleocortex - which are cortical parts of the limbic system).

It is involved in higher functions such as sensory perception, generation of motor commands, spatial reasoning, conscious thought, and in humans, language.

The neocortex consists of grey matter surrounding the deeper white matter of the cerebrum.

While the neocortex is smooth in rats and some other small mammals, it has deep grooves (sulci) and wrinkles (gyri) in primates and several other mammals.

These folds serve to increase the area of the neocortex considerably.

In humans it accounts for about 76% of the brain's volume. This has 6 layers out of which 5 deal with Information processing.

The external granule layer is the second layer of the neo cortex beneath the molecular layer. It receives inputs from other areas of the neocortex.

Layer III is the external pyramidal cell layer. Pyramidal cells make up this layer; they are called "pyramidal" because their somas are triangular shaped.

Function- Receives input from other cortical regions and outputs to other cortical columns.

Layer IV- Located deeper within the neocortex, and composed of granule cells, this layer is thus called the internal granule layer.

Function- Granule cells in this layer receive sensory input and relay it to adjacent neocortex columns. Layer IV is very thick in primary sensory cortex (i.e. the primary visual cortex).

Layer V- Another layer of pyramidal cells makes up the neocortex. The cells in this internal pyramidal cell layer are larger than those in Layer III.

Function- Layer V is involved heavily in making motor movements.

Layer VI- Many different types of cells make up this layer. Its structure isn't very homogenous, so it was called the multiform layer.

Function- Receiving and integrating information from the brainstem and outputs to the thalamus.