Neuroanatomy Lab 6: Neocortex

Front 1

How many cell layers are in the Cerebral Neocortex?

Back 1

Six:

1. Molecular,
2. External Granular,
3. External Pyramidal,
4. Internal Granular,
5. Internal Pyramidal, and
6. Multiform layers.

Front 2

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 2

Layer I, the Molecular layer.

It contains relatively few neurons (those being interneurons), mostly consists of interconnecting axons and dendrites.

Front 3

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 3

Layer II, the External Granular Layer.

It contains many small neurons, with both pyramidal and granular cells.

Front 4

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 4

Layer III, the External Pyramidal Layer.

It consists mainly of small to medium-sized pyramidal cells.

Front 5

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 5

Layer IV, the Internal Granular Layer.

It consists of a large number of Stellate ("star-shaped") neurons, also called Granule Cells.

Front 6

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 6

Layer V, the Internal Pyramidal Layer.

It consists of medium to large-sized Pyramidal Cells.

Front 7

Which Neocortex layer is indicated by the green bracket?

What cells are found there?

Back 7

Layer VI, the Multiform Layer.

It contains neurons with a variety of shapes, including Fusiform and Pyramidal Cells.

Front 8

Is this (golgi-stained) Cortex Homotypical or Heterotypical?

If Heterotypical, is it Granular or Agranular?

Back 8

It is Homotypical. You can make out the six different layers

Hint 8

(although I have a hard time figuring out which is which...)

Front 9

What is the distinguishing feature of a Heterotypical Agranular Cortex?

Back 9

Agranular Cortices are typically Primary Motor Cortex. They can be distinguished by the Giant Pyramidal Cells of Betz, in Layer V, which can be up to 100 microns across, and are much bigger than all other neurons.

Front 10

How can you identify Heterotypical Granular Cortex from the Primary Visual Cortex?

Back 10

The Visual Cortex is the only cortex with the Stria Gennari (shown in iron hematoxylin, which stains axons blue).

The Stria arrises from the Optic Radiations off of the Lateral Geniculate Body of the Thalamus.

Hint 10

The Stria is named for Francesco Gennari, an Italian medical student and keener.

Front 11

Is this Cortex Homotypical or Heterotypical?

If Heterotypical, is it Granular or Agranular?

Back 11

This is an Agranular Heterotypical Cortex. You can tell it's a primary motor cortex by the presence of Giant Pyramidal Cells of Betz, indicated.

Front 12

Is this Cortex Homotypical or Heterotypical?

If Heterotypical, is it Granular or Agranular?

Back 12

It is Homotypical, i.e. all 6 layers are ("more or less") readily distinguishable.

Starting with the Molecular Layer most superficially, try to count all six layers by changes in the density of the cell bodies.
Layers 2 and 4, the Granular layers, have more densely packed cell bodies. Go back to the question slide and examine the layers within the red bracket until you're comfortable identifying all six layers.