Journal of Psychology & Psychotherapy
Open Access
ISSN: 2161-0487
ISSN: 2161-0487
Nithin Krishna
University of Maryland School of Medicine, USA
Posters & Accepted Abstracts: J Psychol Psychother
Working memory (WM) deficit is a core cognitive dysfunction in schizophrenia (SCZ), though its underlying mechanism remains unclear. Long-range synchronization of neuronal oscillations is presumed to mark cognitive processing and facilitate information transfer among broadly separated brain regions. Theta, alpha and gamma range phase synchronization (PS) is thought to contribute during encoding, maintenance and retrieval phases of WM. Using a novel auditory WM paradigm, we used combined EEG and MRS measures to investigate the putative functional connectivity and neurochemistry in mediating the accuracy and performance during a modified N-Back test (MNB). SCZ patients (n=50) and matched healthy controls (HC, n=50) participated in the study. The MNB task requires rapid comparisons of subtly discrete tones held in memory while resisting the interference of previous tones. EEG recording during the MNB task was used to obtain phase locking values from time frequency data. To examine the contribution of synchronization by neurochemistry, GABA & glutamate were measured using standard techniques at the medial frontal/anterior cingulate. Behaviorally, SCZ and HC performed comparably during match trials [F=.865, p=.356]; however, SCZ made more errors during mismatch trials [F=5.198, p = 0.026]. Reaction time (RT) was significantly reduced in SCZ during correct trials compared to HC (F=3.253, p=0.077). In contrast, HC had a shorter RT during incorrect trials (F=7.855, p=0.007) compared to SCZ. Higher glutamate levels were associated with increased accuracy in SZ compared to HC [r=.548, p=0.002]. In controls, there was increased bi hemisphereic and fronto-temporal, fronto-paritel PS in the alpha frequency; Studies implicate alpha-theta activation for a phonological loop during WM tasks suggesting that SCZ rely heavily on this for accurate working memory. FT PS during auditory WM tasks is significantly impaired in SCZ and is robustly associated with frontal glutamate levels, whereas functions are significantly related to frontal GABA level in NC. Our finding highlights the role of neurochemistry in the fronto-temporal circuit abnormality in SCZ.
Email: Nkrishna@psych.umaryland.edu