Neural Evidence for Action-Related Somatosensory Predictions

Abstract

The tactile consequences of self-initiated movements are thought to be predicted by a forward model (FM), yet the precise neural implementation of these predictions remains unclear. In nonmotor contexts, expectations are thought to activate sensory neurons tuned toward the expected stimulus. This acts as a predictive template against which afferent sensory input is compared. It is unclear whether FM predictions have a similar neural instantiation. Here we employed time-resolved multivariate decoding on human electroencephalography during self-generated movements to examine the content of predictive neural activity. Human participants (males and females) performed index finger movements which were predictably paired with a vibration to either the index or ring finger of the opposite, passive hand. On some trials the tactile stimulus was unexpectedly omitted. Results revealed above-chance finger decoding in the premovement period supporting a predictive representation of expected stimulation location. As the movement approached, this predictive activity became similar to late-stage processing of a physical tactile stimulus. On omission trials, we found that despite the absence of afferent input, finger location could be decoded ∼120 ms after expected stimulus onset. This shows a stimulus-specific omission response. Together these findings indicate that self-generated movement preactivates neurons tuned toward expected tactile consequences.