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Cortical oscillatory activity is critical for working memory as revealed by deficits in early-onset schizophrenia

Haenschel, C., Bittner, R. A., Waltz, J., Haertling, F., Wibral, M., Singer, W., Linden, D. E. J. and Rodriguez, E. (2009). Cortical oscillatory activity is critical for working memory as revealed by deficits in early-onset schizophrenia. Journal of Neuroscience, 29(30), pp. 9481-9489. doi: 10.1523/JNEUROSCI.1428-09.2009

Abstract

Impairments in working memory (WM) are a core cognitive deficit in schizophrenia. Neurophysiological models suggest that deficits during WM maintenance in schizophrenia may be explained by abnormalities in the GABAergic system, which will lead to deficits in high-frequency oscillations. However, it is not yet clear which of the three WM phases (encoding, maintenance, retrieval) are affected by dysfunctional oscillatory activity. We investigated the relationship between impairments in oscillatory activity in a broad frequency range (3–100 Hz) and WM load in the different phases of WM in 14 patients with early-onset schizophrenia and 14 matched control participants using a delayed matching to sample paradigm.

During encoding, successful memorization was predicted by evoked theta, alpha, and beta oscillatory activity in controls. Patients showed severe reductions in the evoked activity in these frequency bands. During early WM maintenance, patients showed a comparable WM load-dependent increase in induced alpha and gamma activity to controls. In contrast, during the later maintenance phase, patients showed a shift in the peak of induced gamma activity to the lower WM load conditions. Finally, induced theta and gamma activity were reduced in patients during retrieval.

Our findings suggest that the WM deficit in schizophrenia is associated with impaired oscillatory activity during all phases of the task and that the cortical storage system reaches its capacity limit at lower loads. Inability to maintain oscillatory activity in specific frequency bands could thus result in the information overload that may underlie both cognitive deficits and psychopathological symptoms of schizophrenia.

Publication Type: Article
Additional Information: Copyright © 2016 by the Society for Neuroscience. PubMed ID: 19641111. The published article can be found at http://dx.doi.org/10.1523/JNEUROSCI.1428-09.2009.
Publisher Keywords: Event-related oscillations; EEG; schizophrenia; visual working memory; encoding; human.
Subjects: R Medicine
Departments: Cass Business School > Finance
URI: http://openaccess.city.ac.uk/id/eprint/14803
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