We have many different types of neurons within our peripheral somatosensory system. In addition to basic mechanoreceptors, we have neurons corresponding to pain sensations, and channels that are temperature sensitive. However, one phenomenon that was not explained at the neuronal level until recently, is the sensation of stroking. On the behavioral level, we know that stroking or grooming is pleasurable in such phenomenon as maternal care. But how is this transduced at the molecular level?
Researchers in David Anderson’s lab at Caltech recently discovered a class of neurons that selectively responds to “massage-like” stimulations. Experiments were performed in-vivo to directly measure the effect of certain stimulations. Calcium imaging, a type of imaging designed to study activity of neurons, was used in the spinal cord, where the cell bodies of neurons projecting to the periphery are located. After mice were pinched, poked, and light-touch stroked on their paws, the researchers found that a subset of neurons was selectively activated to only the light-touch stimulus.