Disturbances in processing simple acoustic changes in a stream
of stimuli have been widely reported in patients with
schizophrenia, but little is know about auditory feature
conjunction in these individuals. This study was designed to
examine the extent to which patients with schizophrenia
automatically process changes in conjunction of auditory features
by using event-related brain potentials. Seventeen patients
and 17 age-matched controls were presented with frequent low
pitch tones at 45° to the left of center and frequent high
pitch tones at 45° to the right of center while performing
a continuous visual serial-choice reaction time task. The sequence
of auditory stimuli included rare conjunction-deviants comprised
of a different combination of features (e.g., low pitch tone
at 45° right) and double-deviant tones that differed from
the standard tones in both pitch and location (i.e., middle
pitch at 0° azimuth). Conjunction-deviant stimuli elicited
an MMN wave that was maximum at frontocentral sites. Compared
with controls, the MMN to conjunction-deviant was reduced in
patients and was more centrally distributed. Double-deviant
sounds generated a biphasic MMN followed by a P3a wave at central
sites. Both MMN and P3a were reduced in patients compared with
controls. These results show that patients with schizophrenia
have difficulty in automatically detecting changes in a combination
of auditory features as well as orienting to what
“normally” would be considered salient by healthy
individuals.