Twitching Whiskers Tell All

Our fingers run over surfaces; our eyes are in constant motion. This is all part of “active sensing,” key principles of which have now been uncovered by the team of Prof. Ehud Ahissar of the Neurobiology Department.

We intuitively understand that fingers moving upon surfaces should provide the brain with information very different from that acquired by merely touching a surface without movement, yet experiments have nearly always kept the organs stationary. Working with doctoral student Marcin Szwed and Dr. Knarik Bagdasarian, Ahissar tracked neuron transmissions of rats’ whiskers, which sweep back and forth to locate objects in their immediate vicinity, and thus are an ideal tool for studying the active aspects of perception. They found that two previously unknown basic types of neurons came into play. The first, which they called whisking neurons, responds solely to the whisking motion itself, even if the whiskers don’t touch an object. The second, which they dubbed touch neurons, informs the brain about the surface being touched. The scientists were able to discern subtypes in the second category, which came into play during different stages of contact. Ahissar’s team published these results in Neuron.