48 — Encoding of Tactile Context in the Mouse Visual Cortex

Kandler et al (10.1101/199364)

Read on 08 October 2017
#neuroscience  #sensation  #whiskers  #vision  #GCaMP6 

This paper explores the concept that tactile information from a mouse’s sensory cortex is projected in realtime to visual cortex in order to contextualize visual signal. One of the most sensitive sensory signals in a mouse’s brain is whisker-touch, and this is the population that the Bonin Lab found most loudly speaks to V1. In addition, this paper shows that V1 cells are modulated in some way by this tactile information; spike-output of certain cells were altered by tactile input.

To test this, the authors blindfolded mice while they ran on a treadmill, and imaged their brains using GCaMP6 2-photon imaging as features on the treadmill brushed their whiskers. (This is a loose interpretation of the actual protocol; the mouse visual field was shielded by a plate in front of them on the treadmill, not by a cute mouse-sized blindfold.)

Compared with control populations, Kandler et al found that certain populations of V1 neurons seemed to have a (statistically significant) increase in activity (as imaged by calcium-fluorescence).

We’ve known for a long time that sensory information is conflated in the brain. But this particular sort of data-combination is interesting because it means that early sensory data are combined; V1 is the first part of cortex that gets visual information from the outside world, which means that modulation in V1 changes the way the entire brain perceives the world. (Dig: If the first person in a game of Telephone mishears something, the rest of the chain is altered.) That whisker information is added to the visual stream so early has far-reaching implications on the way we understand sense, vision, and the brain.

Whiskers are definitely a sensory first-class citizen in the mouse-brain. I’d be very curious to see if other sensory information is as soon combined in rodents, and, if not, if other species with preferred sensory systems exhibit this mixing phenomenon as well. Do dolphins, with their sensitive auditory systems, collate audition and vision?