Movement-related modulation across the receptive field of neurons in the primary somatosensory cortex of the monkey.
Cutaneous signals are modulated at the various relays just preceding and during voluntary movements. In these conditions, neuronal discharge in the primary somatosensory cortex (SI) related to movement per se is still evident while discharge to air puff stimulation on the skin is diminished. This selective modulation could be explained by rapid movement-related changes in receptive field (RF) configuration. We tested this hypothesis by giving air puff stimuli at different sites within and at the edges of the RF of SI cells during rest and elbow flexions in one awake monkey. For 40 cells, analysis of the global response yielded four different types of modulation: non-modulated cells, completely gated cells, partially and uniformly modulated cells, and non-uniformly modulated cells. Cell discharge for successive 5-ms intervals was also analyzed at the different sites and showed that response uniformity across time is more robust at the RF center than at peripheral sites in the RF. While this study did not show any clear RF displacement, intra-RF excitability seems to be affected by movement in various ways at the level of the cortex. These facts could have implications for information processing during movement.