Early perceptual anomaly of negative facial expression in depression: An event-related potential study.

Depressed patients have a demonstrated cognitive bias in emotional information processing. However, it is unknown how early perceptual processing is modulated by emotional stimuli in depression. To examine this question, we studied 22 depressed patients and 22 healthy controls performing a cued target-response task with emotional facial expression as the cue. The early perceptual processes were examined using event-related potential (ERP) components, i.e., P1 and N170. Results showed that depressed patients had larger P1 amplitudes than healthy controls, implying that early perceptual abnormality for face processing in depression may occur as early as the P1 stage. There was no significant interaction between emotion types and groups on P1 amplitudes, which suggested that cognitive biases in depression might not yet have arisen. Following the P1 stage, N170 amplitudes for sad faces were larger than for other emotion types in depressed patients, whereas N170 amplitudes for happy faces were larger than for other emotion types in healthy controls. These results implied that depressed patients might have a perceptual bias associated with sad emotions, which may be detectable from the N170 time window. In summary, this study provides new insights for understanding the negative cognitive bias in depression using the electroneurophysiological biomarker N170.