The perception of emotion-free faces in schizophrenia: a magneto-encephalography study

Abstract

Objective: To analyze how patients suffering from schizophrenia perceive faces of unknown individuals that show no actual emotions in order to investigate the attribution of meanings to a relatively non-significant but complex sensory experience.

Design: Analysis of baseline and poststimulation magneto-encephalographic recordings. The stimuli consisted of four pictures with neutral emotional expression of male and female faces of Spanish individuals unknown to research subjects.

Participants: Twelve right-handed patients suffering from schizophrenia (DSM IV-TR criteria), age 18-65, with active delusional activity (SAPS score in delusions above 39) and 15 right-handed sex- and age-matched control subjects.

Results: Compared to controls patients have a significant higher activity of both hemispheres (0-700 ms) being the activity in the right hemisphere (RH) higher than in the left hemisphere (LH). Patients also have a higher activity on the middle fusiform gyrus (BA 37) in the LH (200-300 ms), on the superior temporal areas (BA 22, 41 and 42) in both hemispheres (100-700 ms) and on the temporal pole (BA 38) in the RH (300-400 ms) and a lower activity in the LH of the latter.

Conclusions: The areas that are more activated in our study are those involved in the process of thinking, in attributing meanings to perceptions and in activities such as theory of mind, which are essential for social interaction. The anterior temporal areas less activated indicate a reduced semantic memory for faces that could explain the social withdrawal of schizophrenia. These alterations are suggestive of a dysfunction of left hemisphere neuronal networks.