Why is it that we can be tickled but cannot tickle ourselves? Although the sensory stimulus remains the same in both cases, when we move ourselves our brains construct predictions about the sensory consequences of our own actions and accordingly modulate their own sensory input. This phenomenon, in which sensory responses during movement are attenuated, is called sensory gating, and has been widely reported.
Using an animal model of active sensing, the rodent whisker system, we show that higher brain regions gate or modulate sensory inflow during movement. Animals were trained to localize objects with their whiskers using a real-time Stateflow® model that rewarded object contacts with water. Using high-impedance electrodes to record brain activity at the first stage of sensory processing, we found that responses to the same contact were smaller during movement. This was found to be under the control of top-down feedback projections.
Predictive signals were also recorded showing such object contacts were internally predicted and therefore possibly gated out. Therefore, the brain controls its own input dynamically, using internal predictions to shape perception.
