Picture the expression on your cat’s face when you stroke it. What makes it so happy? The answer lies in a particular type of sensory neuron that responds to pleasant stroking, say scientists at the California Institute of Technology in Pasadena. The neurons, identified in mice, are similar to certain human neurons, which could explain why we enjoy a massage too.

Stroking skin produces a pleasurable sensation in many mammals, including humans, but until now, it was unclear which neurons detected that stimulus. It is easier to measure responses to pain than to pleasure, so neuroscientists have in general focused their attention on noxious stimulation.

Scientific American, nationwide, Jan. 30, 2013