Schizophrenia patients demonstrate impaired emotional processing that may be due, in part, to impaired facial emotionrecognition. This study examined event-related potential (ERP) responses to emotional faces in schizophrenia patients and controls to determine when, in the temporal processing stream, patient abnormalities occur.
16 patients and 16 healthy control participants performed a facial emotionrecognition task. Very sad, somewhat sad, neutral, somewhat happy, and very happy faces were each presented for 100 ms. Subjects indicated whether each face was “Happy”, “Neutral”, or “Sad”. Evoked potential data were obtained using a 32-channel EEG system.
Controls performed better than patients in recognizing facial emotions. In patients, better recognition of happy faces correlated with less severe negative symptoms. Four ERP components corresponding to the P100, N170, N250, and P300 were identified. Group differences were noted for the N170 “face processing” component that underlies the structural encoding of facial features, but not for the subsequent N250 “affect modulation” component. Higher amplitude of the N170 response to sad faces was correlated with less severe delusional symptoms. Although P300 abnormalities were found, the variance of this component was explained by the earlier N170 response.
Patients with schizophrenia demonstrate abnormalities in early visual encoding of facial features that precedes the ERP response typically associated with facial affect recognition. This suggests that affectrecognition deficits, at least for happy and sad discrimination, are secondary to faulty structural encoding of faces. The association of abnormal face encoding with delusions may denote the physiological basis for clinical misidentification syndromes.
–by Bruce Turetsky, Christian Kohler, Tim Indersmitten, Mahendra Bhati, Dorothy Charbonnier, Ruben Gur