Speaker
Description
“Nothing in Biology Makes Sense Except in the Light of Evolution.” Theodosius Dobzhansky
My talk will shine this light onto some specializations in neurons and neuronal networks. The starting point is the distributed nature of information transfer and encoding. In a mammal’s brain, a given input is relayed to hundreds or thousands of neurons, which then collectively transmit it further up the chain. A fundamental requirement in this population encoding is for the individual neuron’s response to occur precisely timed. Precise to the millisecond in a mouse cortex, reportedly even more precise in a human. Using mutations in mice, our earlier work demonstrated that this timing precision relies on scaffold proteins (AnkG, betaIV-spectrin) anchoring NaV and KV channels to the axon initial segment. Interestingly, these anchoring sequences appeared at the branching off of vertebrates and jawed fish, respectively. We now present preliminary data from extant species representing this transition: the lancelet and the lamprey, indicating that indeed spike timing precision improved in parallel with the encephalization burst and the appearance of jaws.
So is this precision further increased in primates? We report data from different mammalian species, including four primate species, that support a different view. Overall, the precision is comparable across species; however, different cell types within the same species exhibit very different response properties. The diversity appears to be larger in marmoset and humans as compared to mice, however that might be partially explained by selection criteria. We currently compile more data on early chordates and primates.
