Preliminary evidence for reduced auditory lateral suppression in schizophrenia.

BACKGROUND

Well-documented auditory processing deficits such as impaired frequency discrimination and reduced suppression of auditory brain responses in schizophrenia (SZ) may contribute to abnormal auditory functioning in everyday life. Lateral suppression of non-stimulated neurons by stimulated neurons has not been extensively assessed in SZ and likely plays an important role in precise encoding of sounds. Therefore, this study evaluated whether lateral suppression of activity in auditory cortex is impaired in SZ.

METHODS

SZ participants and control participants watched a silent movie with subtitles while listening to trials composed of a 0.5s control stimulus (CS), a 3s filtered masking noise (FN), and a 0.5s test stimulus (TS). The CS and TS were identical on each trial and had energy corresponding to the high energy (recurrent suppression) or low energy (lateral suppression) portions of the FN. Event-related potentials were recorded and suppression was measured as the amplitude change between CS and TS.

RESULTS

Peak amplitudes of the auditory P2 component (160-260ms) showed reduced lateral but not recurrent suppression in SZ participants.

CONCLUSIONS

Reduced lateral suppression in SZ participants may lead to overlap of neuronal populations representing different auditory stimuli. Such imprecise neural representations may contribute to the difficulties SZ participants have in discriminating complex stimuli in everyday life.