Early auditory gamma band response abnormalities in first hospitalized schizophrenia.
BACKGROUND
Abnormalities in coherent cortical circuit functioning, reflected in gamma band activity (to approximately 40 Hz), may be a core deficit in schizophrenia. The early auditory gamma band response (EAGBR) is a neurophysiologically simple probe of circuit functioning in primary auditory cortex. We examined the EAGBR in first hospitalized schizophrenia to assess whether it was reduced at first hospitalization.


METHODS
Wavelet evoked power and intertrial phase locking of the EAGBR at Fz to standard tones during an oddball target detection task were examined in 28 first hospitalized schizophrenia patients (10 female) and 44 control subjects (17 female).


RESULTS
At first hospitalization EAGBR trial-to-trial phase locking and evoked power were significantly reduced in patients. Although reduced overall in patients, greater total symptoms were significantly associated with greater gamma phase locking and power. Additionally, greater EAGBR power was marginally associated with greater positive factor scores, hallucinations, and thinking disturbance.


CONCLUSIONS
Abnormalities of gamma band functioning in local auditory sensory circuits are present in schizophrenia at first hospitalization further evidence that basic sensory processes are impaired in schizophrenia. It remains to be determined whether the EAGBR becomes permanently impaired with disease progression, and if its reduction is specific to schizophrenia.
Department of Psychiatry, Harvard Medical School, Boston, MA 02115, USA.
Grantley W
GW
Taylor
Robert W
RW
McCarley
Dean F
DF
Salisbury
D000161:Acoustic Stimulation; D000328:Adult; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006760:Hospitalization; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D011571:Psychoacoustics; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D013223:Statistics as Topic; D013997:Time Factors; D055815:Young Adult