A lasting impression

Abstract

Touch-sensitive neurons in the fingertips take previous physical contacts into account when relaying tactile information to the brain.

Keywords: human; neuroscience; sensory afferent; skin mechanics; somatosensation; touch.

Figure 1.. Previous touch shapes how current forces are represented by neurons in the fingertip.

When one of our fingertips contacts a surface (top left), a series of forces are generated which alter the viscosity and elasticity of the skin. Saal et al. recorded how these changes influenced the firing pattern (vertical orange lines; top right) of touch-sensitive neurons called mechanoreceptors (dark blue shapes) that relay information from the skin to the brain. Data were mainly collected from three of the four types of mechanoreceptor found in the skin (FA-1, SA-1 and SA-2); the fourth type (FA-2) responded far less and was largely insensitive to different forces. Saal et al. found that the mechanoreceptors displayed different response patterns: some encoded the current force (black line; bottom), some encoded the previous force (pink), and some encoded both (purple). These neuronal signals are then combined across the population, influencing how information about the current physical state of the fingertip is conveyed to the brain (blue arrow).