Auditory processing abnormalities in schizotypal personality disorder: an fMRI experiment using tones of deviant pitch and duration.
BACKGROUND
One of the cardinal features of schizotypal personality disorder (SPD) is language abnormalities. The focus of this study was to determine whether or not there are also processing abnormalities of pure tones differing in pitch and duration in SPD.


METHODS
Thirteen neuroleptic-naïve male subjects met full criteria for SPD and were group-matched on age and parental socio-economic status to 13 comparison subjects. Verbal learning was measured with the California Verbal Learning Test. Heschl's gyrus volumes were measured using structural MRI. Whole-brain fMRI activation patterns in an auditory task of listening to tones including pitch and duration deviants were compared between SPD and control subjects. In a second and separate ROI analysis we found that peak activation in superior temporal gyrus (STG), Brodmann Areas 41 and 42, was correlated with verbal learning and clinical measures derived from the SCID-II interview.


RESULTS
In the region of the STG, SPD subjects demonstrated more activation to pitch deviants bilaterally (p<0.001); and to duration deviants in the left hemisphere (p=0.005) (two-sample t). SPD subjects also showed more bilateral parietal cortex activation to duration deviants. In no region did comparison subjects activate more than SPD subjects in either experiment. Exploratory correlations for SPD subjects suggest a relationship between peak activation on the right for deviant tones in the pitch experiment with odd speech and impaired verbal learning. There was no difference between groups on Heschl's gyrus volume.


CONCLUSIONS
These data suggest that SPD subjects have inefficient or hyper-responsive processing of pure tones both in terms of pitch and duration deviance that is not attributable to smaller Heschl's gyrus volumes. Finally, these auditory processing abnormalities may have significance for the odd speech heard in some SPD subjects and downstream language and verbal learning deficits.
Serious Mental Illness Program, VA Boston Healthcare System, Psychiatry 116A-RC, 940 Belmont St., Brockton, MA 02401, United States. chandlee_dickey@hms.harvard.edu
Chandlee C
CC
Dickey
Istvan A
IA
Morocz
Margaret A
MA
Niznikiewicz
Martina
M
Voglmaier
Sarah
S
Toner
Usman
U
Khan
Mark
M
Dreusicke
Seung-Schik
SS
Yoo
Martha E
ME
Shenton
Robert W
RW
McCarley
D000328:Adult; D001288:Attention / Q000502:physiology; D001308:Auditory Perceptual Disorders / Q000175:diagnosis* / Q000503:physiopathology; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000503:physiopathology; D010897:Pitch Discrimination / Q000502:physiology*; D012016:Reference Values; D012564:Schizophrenic Language; D012569:Schizotypal Personality Disorder / Q000175:diagnosis* / Q000503:physiopathology; D013702:Temporal Lobe / Q000503:physiopathology*; D013998:Time Perception / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology