Theoretical models in the field of vision explain how composite images, like faces, can be broken down into fundamental elements. These decompositional theories allow neuroscientists to relate the individual characteristics that make up a visual scene, such as edges, curves, or contrasts, to their evoked brain activity. In the tactile system, compositional theories of perception are much less established.
In a study published in Science Advances, researchers from the Institut des neurosciences Paris-Saclay (NeuroPSI CNRS / UPSaclay, Gif-sur-Yvette) discovered an elegantly simple basis for explaining how such a decompositional approach can work in the rodent whisker system, an experimental model widely used to study the neurophysiological basis of touch.
Figure: The two main whisker motion features coded by the rat somatosensory cortex to account for touch sensation, credit. Evan Harrell.
Their paper reconciles theories from behavioral studies with wide-ranging neurophysiological studies and provides a unified picture for how whiskers extract tactile information and activate specific neurons in the cerebral cortex. Contacts with objects, called "sticks" in whisker parlance, constitute the first set of elements used for the decomposition of tactile objects. The second set consists of “sweeps” that brush the whiskers and in doing so create large angular displacements. The combination of "sticks" and "sweeps" in time and space informs a rodent of the location and surface texture of an object, allowing its identification.
This decompositional theory provides neuroscientists with a simple basis on which to build in future studies of tactile perception.