Early visual components (P100, N170) are disrupted in chronic schizophrenic patients: an event-related potentials study

INTRODUCTION On the basis of the Positive and Negative Syndrome Scale (PANSS), fourteen schizophrenic patients and 7 normal controls were confronted with pictures from the Ekman & Friesen series in an event-related potentials study. PROCEDURE Participants were confronted with a visual face-detection task, in which they had to detect, as quickly as possible, deviant faces amongst a train of standard stimuli (neutral faces). Deviant faces changed either on identity (different identity, neutral expression), or on emotion (same identity, happy, fearful or sad expression). RESULTS Schizophrenics exhibited a decrease in amplitude of the face N170, recorded around 170 ms at occipito-temporal sites; this was observed as well for emotional as for identity faces, which suggests a global involvement of face processing. Moreover, this decrease of the face-N170 was positively correlated to positive, but not negative, symptoms of schizophrenia. Finally, the amplitude of P100 was also decreased, which suggests that the N170 decrement would result from a more global deficit in visual processing deficit. DISCUSSION It is suggested that, in schizophrenics, an involvement of early visual processing might underlie the decreased amplitudes and the higher onset latencies of later P300 and N400 components.