Expanding the response space in chronic schizophrenia: the relevance of left prefrontal cortex

Objective: This study probed the ability of people with chronic schizophrenia to control their behavior in time by requiring them to deliberately vary responses within the temporal domain (i.e., to avoid regular inter-response intervals). Methods: Thirteen schizophrenia patients performed single finger movements (at moments of their own choosing) in an event-related functional magnetic resonance imaging paradigm. Their performance was computed using the coefficient of variation of inter-response interval duration. Results: Task performance was positively correlated with activation of left lateral prefrontal cortex. Post hoc analyses revealed an inverse correlation between activation in this region and severity of attentional impairment. Conclusion: These findings implicate left lateral prefrontal cortex in the modulation of the temporal response space in schizophrenia and imply greater attentional (executive) impairment among those who fail to modulate their behavior in time.