OUR SENSES

You don’t need a brain to sense what’s going on around you—though it helps.

Consciousness may be reserved for creatures with more brainpower than paramecia possess, but there are still at least 100 million microbial species that can process sensory information about their environments. “So why all the fuss about brains?” asks genomics researcher DeSalle (co-author: Welcome to the Microbiome, 2015, etc.), curator of the American Museum of Natural History. It’s a good question, one answer to which is that information about how we sense is most often the product of neuroscientific research. Such research tells us, for instance, that in the resting state, our brains trundle along at about 70 millivolts, while when they’re agitated, they go up by 40 millivolts or so, a matter of “action potential” that has bearing on how the nervous, sensory, and motor systems interact. Given that there are 6,393 synapses connecting the 279 cells of the nematode nervous system, our own electronic wiring scheme begins to look impossibly complex. There, again, neuroscience has mapped out how sensory information arrives in the human brain and how it travels along neural pathways depending on what kind it is—if visual, for instance, along “nerve cells coming from the eye [that] are bundled into rather large neural structures, the optic nerves.” There are no end of possibilities for going haywire, but amazingly, we get it right most of the time. DeSalle’s text is written at a high level of scientific sophistication, requiring scientific literacy to follow the argument. Even so, he is light-handed enough to use Spinal Tap guitarist Nigel Tufnel’s this-amp-goes-to-11 shtick to explain “crossmodality,” and he peppers his text with nice bits of learned trivia, such as the different color perception systems of monkeys and human artists, the lack of balance in tree sloths, and the like.

An animated introduction to the neuroscience of sensory perception with broad appeal to artists, musicians, and other consumers and generators of brainpower.