I’m not like you, inside and out

Credit: Dawn of the Planet of the Apes
Screenshot from “Dawn of the Planet of the Apes” (Director: Tim Burton, 2001)

One mistake than many neuroscientists make (myself included) is the implicit assumption that the human brain is a rodent brain scaled-up, plus a few more bits. Here is a remainder that “a rat is not a monkey is not a human”, in the famous words of A. D. (Bud) Craig (2009).

Mohan et al. (2015) analyzed a portion of the brain (Brodmann area 21) obtained from 28 individuals that had to undergo neurosurgery and have it removed for various illnesses. Using some good microscopy, fancy statistics, and 3-D modeling, they reconstructed the shape of individual neurons from that region. The main finding is that 88% of human pyramidal neurons were distinctly different than their mouse or macaque counterparts. Also, they managed to record the electrical activity of these neurons in less than 10 minutes after resection. So it appears that this morphological distinctness of ours results in unique electrical properties of human neurons, which may account for the “distinct cognitive capabilities of humans”, as the authors put it.

Approximate location of Brodmann Area 21, corresponding to gyrus temporalis medium. Credit: Brain template to _DJ_; Area tracing to Neuronicus
Approximate location of Brodmann Area 21, corresponding to gyrus temporalis medium. Credit: Brain template to _DJ_; Area tracing to Neuronicus

Citation: Mohan, H., Verhoog, M. B., Doreswamy, K. K., Eyal, G., Aardse, R., Lodder, B. N., Goriounova, N. A., Asamoah, B., B. Brakspear, A. B. C., Groot, C., van der Sluis, S., Testa-Silva, G., Obermayer, J., Boudewijns, Z. S., Narayanan, R. T., Baayen, J. C., Segev, I., Mansvelder, H. D., de Kock, C. P. (28 August 2015; Epub ahead of print). Dendritic and Axonal Architecture of Individual Pyramidal Neurons across Layers of Adult Human Neocortex. Cerebral Cortex, 1-15. doi: 10.1093/cercor/bhv188. Article + FREE PDF

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