Brain complexity: human specialized neurons (Introduction)

by David Turell , Wednesday, January 04, 2017, 15:15 (2880 days ago) @ David Turell

We don't just have a big brain. Our neurons are different with special membrane capacitance that allows higher speed of response:

http://medicalxpress.com/news/2017-01-unique-electrical-properties-human-nerve.html

"The theoretical study predicted that layer 2/3 pyramidal neurons from the human temporal cortex would have a specific membrane capacitance that is half of the commonly accepted "universal" value for biological membranes (~0.5 µF/cm2 vs. ~1 µF/cm2). Since membrane capacitance affects how quickly a cell can respond to its synaptic inputs, this finding has important implications for the transmission of signals within and between cells. The theoretical prediction regarding the specific membrane capacitance was then validated experimentally by direct measurements of membrane capacitance in human pyramidal neurons.

"'This is the first direct evidence for the unique electrical properties of human neurons," said researcher Guy Eyal, a Ph.D. student at the Hebrew University's Department of Neurobiology. "Our finding shows that low membrane capacitance significantly improves the efficacy of signal processing and the speed of communication within and between cortical neurons in the human neocortex, as compared to rodents."

"The results of this work imply that human cortical neurons are efficient electrical microchips, compensating for the larger brain and large cells in humans, and processing sensory information more effectively," said Prof. Idan Segev from the Department of Neurobiology and the Edmond and Lily Safra Center for Brain Sciences at the Hebrew University. "Indeed, the study shows that already at the level of the individual building blocks of the nervous system (the nerve cells), humans are distinct as compared to rodents. More research should be performed in this direction on non-human primates."

"The researchers suggest the distinctive biophysical membrane properties of human pyramidal neurons are an outcome of evolutionary pressure to compensate for the increase in size and distances in the human brain."

Comment: An other distinct human brain difference in the quality of function, higher speed of reaction times for more efficient brain function. The authors of the study blame 'evolutionary pressure' suggesting this was accomplished stepwise. It is more likely saltation as each new hominin ancestor arrived with a larger brain size and the newer more efficient neurons in place