Brain potentials indicate poor preparation for action in schizophrenia

Impaired antisaccade performance in schizophrenia (SZ) may originate from poor task preparation, suggested by low amplitudes of the contingent negative variation (CNV) before antisaccades. To dissociate components of preparation we measured the CNV in standard pro- and antisaccades and a stimulus preceding negativity (SPN) in delayed pro- and antisaccades. In healthy controls the SPN had lower amplitudes than the CNV, reflecting mere stimulus expectation in SPN and combined stimulus expectation and action readiness in CNV. SZ patients had lower CNV amplitudes than controls, but there was no reliable indication of a general SPN reduction, suggesting a particular impairment of action readiness. The CNV and SPN amplitudes of controls were larger if tasks had incongruent (anti) compared to congruent (pro) S-R mappings. This difference was absent in SZ patients, suggesting a failure to activate specific resources for incongruent S-R mappings.