The Six Layers of the Cerebral Cortex | Neuroscience 101

The mammalian neocortex exists of 6 layers, here we discuss them.

The cerebral cortex cosists of six layers:
First, the molecular layer which has very little neurons, and consists of glial cells, dendrites and axons.
Second, the external granular layer with small granule cells (pyramidal neurons).
Third, the external pyramidal layer with medium-sized pyramidal neurons. Together layer 2 and 3 are receive interhemispheric input.
Fourth, the internal granular layer, which is the layer that receives sensory input via the thalamus
Fifth, the internal pyramidal layer, which is the main output layer that has outgoing axons to other brain regions and the corticospinal tract. This layer has large pyramidal neurons (Betz cells).
Sixth, the multiform layer, which has a variety of neurons and reciprocal connections to the cortex.

References:
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Olsen, S. R., Bortone, D. S., Adesnik, H., & Scanziani, M. (2012). Gain control by layer six in cortical circuits of vision. Nature, 483(7387), 47–52. https://doi.org/10.1038/nature10835

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Wagstyl, K., Larocque, S., Cucurull, G., Lepage, C., Cohen, J. P., Bludau, S., Palomero-Gallagher, N., Lewis, L. B., Funck, T., Spitzer, H., Dickscheid, T., Fletcher, P. C., Romero, A., Zilles, K., Amunts, K., Bengio, Y., & Evans, A. C. (2020). BigBrain 3D atlas of cortical layers: Cortical and laminar thickness gradients diverge in sensory and motor cortices. PLoS biology, 18(4), e3000678. https://doi.org/10.1371/journal.pbio....

Narrated and produced by: Miles Wischnewski

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