One deficit associated with schizophrenia (SZ) is the reduced ability to
distinguish self-caused sensations from those due to external sources. This
reduced sense of agency (SoA, subjective awareness of control over one’s
actions) is hypothesized to result from a diminished utilization of internal
monitoring signals of self-movement (i.e., efference copy) which subsequently
impairs forming and utilizing sensory prediction errors (differences between the
predicted and actual sensory consequences resulting from movement). Another
important function of these internal monitoring signals is the facilitation of
higher-order mechanisms related to motor learning and control. Current
predictive-coding models of adaptation postulate that the sensory consequences
of motor commands are predicted based on internal action-related information,
and that ownership and control of motor behavior is modified in various contexts
based on predictive processing. Here, we investigated the connections between
SoA and motor adaptation. Schizophrenia patients (SZP, N=30) and non-psychiatric
control subjects (HC, N=31) adapted to altered movement visual feedback and
applied the motor recalibration to untested contexts (i.e., the spatial
generalization). Although adaptation was similar for SZP and controls, the
extent of generalization was significantly less for SZP; movement trajectories
made by patients to the furthest untrained target (135°) before and after
adaptation were largely indistinguishable. Interestingly, deficits in
generalization were correlated with positive symptoms of psychosis in SZP (e.g.,
hallucinations). Generalization was also associated with measures of SoA across
both SZP and HC, emphasizing the role action awareness plays in motor behavior,
and suggesting that misattributing agency, even in HC, manifests in abnormal
motor performance.