Varieties of neural activity

Here is a characteristic of human cortical dendrites that has not been found in mouse models:

“In contrast to typical all-or-none action potentials, dCaAPs were graded; their amplitudes were maximal for threshold-level stimuli but dampened for stronger stimuli. These dCaAPs enabled the dendrites of individual human neocortical pyramidal neurons to classify linearly nonseparable inputs—a computation conventionally thought to require multilayered networks.”

Albert Gidon1, Timothy Adam Zolnik1, Pawel Fidzinski, Felix Bolduan, Athanasia Papoutsi, Panayiota Poirazi, Martin Holtkamp, Imre Vida, Matthew Evan Larkum (2020) Dendritic action potentials and computation in human layer 2/3 cortical neurons. Science 03 Jan 2020: Vol. 367, Issue 6473, pp. 83-87. DOI: 10.1126/science.aax6239

Like all cells in a multicellular organism, nerve cells display two kinds of observable behavior.

From the cell’s point of view, the behaviors that matter to it are its means of controlling inputs that maintain its material integrity and its metabolic stability within its environment. We may observe consequent control of the stability of its environment; this includes collective control with other cells in its environment.

The behaviors that matter to the multicellular organism are necessarily neither perceived nor controlled as such by the cell, else conflict would arise between the two orders of control, the cellular level and the multicellular level. We as humans do not control variables that are vital to a nerve cell; the nerve cell does not control the rate of firing in its part of a control loop within a human nervous system. (The same principle applies to any hypothetical multi-body order of organisms in which individual humans participate, e.g. Kroeber’s notion of the ‘superorganic’.)

We must bear this distinction in mind as we learn more about the intra- and inter-cellular variables involved in neural activity. It is all relevant, but in different ways.