Sensory-based and higher-order operations contribute to abnormal emotional prosody processing in schizophrenia: an electrophysiological investigation

Background. Schizophrenia is characterized by deficits in emotional prosody (EP) perception. However, it is not
clear which stages of processing prosody are abnormal and whether the presence of semantic content contributes to
the abnormality. This study aimed to examine event-related potential (ERP) correlates of EP processing in 15 chronic
schizophrenia individuals and 15 healthy controls.
Method. A total of 114 sentences with neutral semantic content [sentences with semantic content (SSC) condition]
were generated by a female speaker (38 with happy, 38 with angry, and 38 with neutral intonation). The same
sentences were synthesized and presented in the ‘pure prosody ’ sentences (PPS) condition where semantic content
was unintelligible.
Results. Group differences were observed for N100 and P200 amplitude : patients were characterized by more
negative N100 for SSC, and more positive P200 for angry and happy SSC and happy PPS. Correlations were found
between delusions and P200 amplitude for happy SSC and PPS. Higher error rates in the recognition of EP were also
observed in schizophrenia : higher error rates in neutral SSC were associated with reduced N100, and higher error
rates in angry SSC were associated with reduced P200.
Conclusions. These results indicate that abnormalities in prosody processing occur at the three stages of EP
processing, and are enhanced in SSC. Correlations between P200 amplitude for happy prosody and delusions suggest
a role that abnormalities in the processing of emotionally salient acoustic cues may play in schizophrenia
symptomatology. Correlations between ERP and behavioral data point to a relationship between early sensory
abnormalities and prosody recognition in schizophrenia.
This work was supported by two doctoral grants
(doctoral grant no. SFRH/BD/35882/2007 and research
grant no. PTDC/PSI-PCL/116626/2010) from
Fundac¸a˜o para a Cieˆncia e a Tecnologia (FCT, Portugal)
awarded to A.P.P., and by two grants from the
National Institute of Mental Health (no. RO1 MH
040799 awarded to R.W.M. and no. RO3 MH 078036
awarded to M.A.N.)