The cerebellum contributes to somatosensory cortical activity during self-produced tactile stimulation

We used fMRI to examine neural responses when subjects experienced a tactil e stimulus that was either self-produced or externally produced. The somato sensory cortex showed increased levels of activity when the stimulus was ex ternally produced. In the cerebellum there was less activity associated wit h, a movement that generated a tactile stimulus than with a movement that d id not. This difference suggests that the cerebellum is involved in predict ing the specific sensory consequences of movements and providing the signal that is used to attenuate the sensory response to self-generated stimulati on. In this paper, we use regression analyses to test this hypothesis expli citly. Specifically, we predicted that activity in the cerebellum contribut es to the decrease in somatosensory cortex activity during self-produced ta ctile stimulation. Evidence in favor of this hypothesis was obtained by dem onstrating that activity in the thalamus and primary and secondary somatose nsory cortices significantly regressed on activity in the cerebellum when t actile stimuli were self-produced but not when they were externally produce d. This supports the proposal that the cerebellum is involved in predicting the sensory consequences of movements. In the present study, this predicti on is accurate when tactile stimuli are self-produced relative to when they are externally produced, and is therefore used to attenuate the somatosens ory response to the former type of tactile stimulation but not the latter. (C) 1999 Academic Press.