Sensory-evoked propagating waves of activity in the primary sensory cortices: poorly understood, yet ubiquitous.

Any sensory stimulus evokes a propagating wave of activity in the corresponding sensory cortex that exceeds its topographical boundaries within the primary sensory map. Hama and colleagues (Hama N, Kawai M, Ito S-I, Hirota A. J Neurophysiol 119: 1934-1946, 2018) provided a first study, in the tactile modality, of the interactions between two successively evoked waves. We argue that the difficulty in finding a simple rule to account for all the various observed interactions calls for an effort to clarify the mechanisms and substrates of the propagating waves and their role in sensory processing.