Movement-related potentials point towards an impaired tuning of reafferent sensory feedback by preceding motor activation in schizophrenia

The link between focal motor system activation and reafferent sensory feedback is thought to be crucial for the perception that a movement is actively performed. In this article, we examine how schizophrenia affects the relationship between motor and somatosensory system activation. Movement-related potential source analysis allowed us to separate and compare motor activation deficits and reafferent feedback processing. We analyzed lateralized movement-related potentials during choice reaction movements in 16 subjects with schizophrenia/schizoaffective disorder. These subjects had partial remissions with predominantly negative symptoms and were compared to an age-matched healthy control group. In the schizophrenia/schizoaffective group, dipole source analysis indicated a significantly reduced lateralized sensorimotor activation immediately preceding movement execution. In contrast, activation by reafferent feedback was relatively unimpaired. Subjects with schizophrenia/schizoaffective disorder lacked a focal motor and reafferent sensory processing correlation, which can be identified through a significantly different regression slope from healthy controls. Reduced action-related motor system activation in subjects with schizophrenia/schizoaffective disorder was associated with preserved activation by reafferent sensory feedback. Most importantly, motor-sensory tuning, i.e. a specific enhancement of sensory information necessary to monitor movements, could not be found in subjects with schizophrenia/schizoaffective disorder. Our data provide further evidence for disturbed motor-sensory interactions in schizophrenia.