Introducing the brain: suppressing extraneous info (Introduction)

by David Turell @, Monday, February 10, 2020, 20:17 (154 days ago) @ David Turell

Too much info stimuli muddies the important information:

"'Right now, your little toe is sending signals up to your brain, as is every square inch of your body," said Adam Cohen, a professor of chemistry and chemical biology, and of physics, "but most of it is not interesting. Your brain has to ignore all that stuff and only pay attention to the very few things that are actually relevant."


"As their optogenetic tool recorded neural signals in live mice, Cohen and his team added stimuli based on the two main types of attention. First, they flicked a mouse's whisker, provoking a "bottom-up" signal that reports new sensory information. Then, they blew a puff of air on the mouse's face, activating a "top-down" signal in which existing knowledge shapes perception of a stimuli. "Think of it like a wake-up call," Cohen explained.


"The team discovered that neurons in layer one maintain a careful balance between excitation and inhibition. If too many neurons are firing at once, they suppress others from firing. "The circuit acts like a novelty detector," Cohen said. Sudden inputs can spark most neurons to fire, but with long-lasting inputs, most of the neurons inhibit each other and cause the circuit to turn almost completely off.


"Based on their data, the team designed a mathematical model of the circuit, which suggested an intriguing connection to a century-old theory about attention. The so-called Yerkes-Dodson law proposes that a little stress can help increase performance, but it declines when stress increases too much. "Everyone who's ever taken a test knows this," Cohen said. His model showed that layer one neurons behaved in a similar way: A little top-down activation wakes them up so they are more responsive to sensory inputs, but too much activation makes the circuit freeze and ignore incoming information."

Comment: An obviously needed control system, designed to avoid confusing overstimulation.

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