Mera S Barr1, Tarek K Rajji2, Reza Zomorrodi3, Natasha Radhu3, Tony P George4, Daniel M Blumberger2, Zafiris J Daskalakis5. 1. Biobehavioural Addictions and Concurrent Disorders Laboratory (BACDRL), Addictions Division, Canada; Temerty Centre for Therapeutic Brain Intervention, Mood and Anxiety Division, Canada; Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, Canada. 2. Temerty Centre for Therapeutic Brain Intervention, Mood and Anxiety Division, Canada; Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Canada. 3. Temerty Centre for Therapeutic Brain Intervention, Mood and Anxiety Division, Canada. 4. Biobehavioural Addictions and Concurrent Disorders Laboratory (BACDRL), Addictions Division, Canada; Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, Canada. 5. Temerty Centre for Therapeutic Brain Intervention, Mood and Anxiety Division, Canada; Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, Canada. Electronic address: Jeff.Daskalakis@camh.ca.
Abstract
BACKGROUND: Working memory deficits represent a core feature of schizophrenia. These deficits have been associated with dysfunctional dorsolateral prefrontal cortex (DLPFC) cortical oscillations. Theta-gamma coupling describes the modulation of gamma oscillations by theta phasic activity that has been directly associated with the ordering of information during working memory performance. Evaluating theta-gamma coupling may provide greater insight into the neural mechanisms mediating working memory deficits in this disorder. METHODS: Thirty-eight patients diagnosed with schizophrenia or schizoaffective disorder and 38 healthy controls performed the verbal N-Back task administered at 4 levels, while EEG was recorded. Theta (4-7Hz)-gamma (30-50Hz) coupling was calculated for target and non-target correct trials for each working memory load. The relationship between theta-gamma coupling and accuracy was determined. RESULTS: Theta-gamma coupling was significantly and selectively impaired during correct responses to target letters among schizophrenia patients compared to healthy controls. A significant and positive relationship was found between theta-gamma coupling and 3-Back accuracy in controls, while this relationship was not observed in patients. CONCLUSIONS: These findings suggest that impaired theta-gamma coupling contribute to working memory dysfunction in schizophrenia. Future work is needed to evaluate the predictive utility of theta-gamma coupling as a neurophysiological marker for functional outcomes in this disorder.
BACKGROUND:Working memory deficits represent a core feature of schizophrenia. These deficits have been associated with dysfunctional dorsolateral prefrontal cortex (DLPFC) cortical oscillations. Theta-gamma coupling describes the modulation of gamma oscillations by theta phasic activity that has been directly associated with the ordering of information during working memory performance. Evaluating theta-gamma coupling may provide greater insight into the neural mechanisms mediating working memory deficits in this disorder. METHODS: Thirty-eight patients diagnosed with schizophrenia or schizoaffective disorder and 38 healthy controls performed the verbal N-Back task administered at 4 levels, while EEG was recorded. Theta (4-7Hz)-gamma (30-50Hz) coupling was calculated for target and non-target correct trials for each working memory load. The relationship between theta-gamma coupling and accuracy was determined. RESULTS: Theta-gamma coupling was significantly and selectively impaired during correct responses to target letters among schizophreniapatients compared to healthy controls. A significant and positive relationship was found between theta-gamma coupling and 3-Back accuracy in controls, while this relationship was not observed in patients. CONCLUSIONS: These findings suggest that impaired theta-gamma coupling contribute to working memory dysfunction in schizophrenia. Future work is needed to evaluate the predictive utility of theta-gamma coupling as a neurophysiological marker for functional outcomes in this disorder.
Authors: Heather Brooks; Mina Mirjalili; Wei Wang; Sanjeev Kumar; Michelle S Goodman; Reza Zomorrodi; Daniel M Blumberger; Christopher R Bowie; Zafiris J Daskalakis; Corinne E Fischer; Alastair J Flint; Nathan Herrmann; Krista L Lanctôt; Linda Mah; Benoit H Mulsant; Bruce G Pollock; Aristotle N Voineskos; Tarek K Rajji Journal: Cereb Cortex Date: 2022-04-05 Impact factor: 4.861
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