255 — Spontaneous behaviors drive multidimensional, brain-wide population activity

Story: 1. Neurons in the brain are very chatty: they fire action potentials, their basic unit of communication, even when there is nothing to communicate. For example in this video, in visual cortex recordings in complete darkness. Lots of chatting: pic.twitter.com/QCmHLhAI9x

— Marius Pachitariu (@marius10p) April 22, 2018

Even when your eyes are closed, your sensory cortices — even your visual cortex — are transmitting plenty of data. In this recent research, the authors looked at mouse visual cortex using two-photon calcium imaging, covering more than 11,000 neurons simultaneously (!!!). They sought to understand where this noise was coming from: Was it just background noise — useless, in fact — as some neuroscientists argue? Or was it meaningful, representing something relevant to, but not exactly the same as, vision (as other neuroscientists have argued)?

The answer became half clear when they looked at the animal’s overall behavior. Half of the chatter in the recorded neurons was explainable (i.e. correlated closely) with large-scale motor behaviors like whisking, moving eyes (even in the dark), and moving other orofacial muscles.

Though this leaves the rest of the chatter unexplained, it means that we now have a great place to look: Behavior. As Adam Calhoun puts it on his blog post about this very paper;

The brain evolved to produce behavior. In my opinion there is no way to understand the brain – any of it – if you don’t understand the behavior that the animal is producing.

The code for the analyses, and the data, are available on GitHub.