Working memory related gamma oscillations in schizophrenia patients

Başar-Eroğlu, Canan; Brand, Andreas; Hildebrandt, Helmut; Kedzior, Karina Karolina; Mathes, Birgit; Schmiedt, Christina

doi:10.1016/j.ijpsycho.2006.07.007

Cited by 205 publications

(162 citation statements)

References 52 publications

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“…The finding that g-oscillatory activity was most pronounced at N-back conditions of greatest difficulty is consistent with earlier studies examining the role of g-oscillatory activity and WM (Basar-Eroglu et al, 2007;Howard et al, 2003;Meltzer et al, 2008). For example, Howard et al (2003) first showed a linear increase in g-oscillatory power with WM load in epileptic patients performing the Sternberg WM task (Howard et al, 2003).…”

Section: Discussionsupporting

confidence: 89%

“…These authors contend that measures of evoked g-activity may better mitigate such effects from miniature saccadic activity on this neurophysiological phenomenon (Yuval-Greenberg et al, 2008). Considering that induced g-activity may reflect involuntary eye movements with emerging evidence supporting the association of evoked g-activity with WM (Howard et al, 2003;Meltzer et al, 2008;Basar-Eroglu et al, 2007), we selected to measure the effect of rTMS on evoked g-activity.…”

Section: Discussionmentioning

confidence: 99%

“…Both evoked and induced g-activities have been associated with sensory and cognitive processing (Lutzenberger et al, 1995;Muller et al, 1996;Cho et al, 2006). Moreover, induced g-oscillatory activity has been shown to increase with increased cognitive control (Cho et al, 2006), whereas other studies have shown that evoked g-oscillatory activity increases with cognitive demand in WM paradigms (Howard et al, 2003;Basar-Eroglu et al, 2007;Meltzer et al, 2008). As such, we measured the mean evoked g-power from frontal electrodes while the participants completed the N-back task before (pre) and after (post) rTMS was administered over the right and left DLPFC.…”

Section: Eeg Measurement Of Evoked C-oscillatory Activitymentioning

confidence: 99%

“…For example, the N-back task requires participants to determine whether the current stimulus is the same stimulus that was presented 'N' trials back, thus allowing the evaluation of increasing cognitive demand (ie, WM load) on g-oscillatory activity. Further, a growing body of evidence has shown increased g-oscillatory activity with cognitive demand (Howard et al, 2003;Meltzer et al, 2008;Basar-Eroglu et al, 2007). For example, Cho et al (2006) reported that g-oscillatory activity increased with the increased cognitive control in the frontal regions that was related to performance (Cho et al, 2006), suggesting that g is modulated by cognitive demand, which may underlie WM performance.…”

Section: Introductionmentioning

confidence: 99%

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Potentiation of Gamma Oscillatory Activity through Repetitive Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex

Barr

Farzan

Rusjan

et al. 2009

Neuropsychopharmacol

104

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Neuronal oscillations in the gamma (g) frequency range (30-50 Hz) have been associated with cognition. Working memory (WM), a cognitive task involving the on-line maintenance and manipulation of information, elicits increases in g oscillations with greater cognitive demand, particularly in the dorsolateral prefrontal cortex (DLPFC). The generation and modulation of g oscillations have been attributed to inhibitory interneuron networks that use g -aminobutyric acid (GABA) as their principal neurotransmitter. Repetitive transcranial magnetic stimulation (rTMS) represents a non-invasive method to stimulate the cortex that has been shown to modify cognition and GABA inhibitory mechanisms, particularly with higher frequencies (ie, 10-20 Hz). We measured the effect of high-frequency rTMS applied to the DLPFC on g-oscillations elicited during the N-back WM task in healthy individuals. Active rTMS significantly increased g-oscillations generated during the N-back conditions with the greatest cognitive demand. Further, no significant changes were found in other frequency ranges, suggesting that rTMS selectively modulates g-oscillations in the frontal brain regions. These findings provide important insights into the neurophysiological mechanisms that underlie higher-order cognitive processes, and suggest that rTMS may be used as a cognitive enhancing strategy in neuropsychiatric disorders that suffer from cognitive deficits.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Eeg Measurement Of Evoked C-oscillatory Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Potentiation of Gamma Oscillatory Activity through Repetitive Transcranial Magnetic Stimulation of the Dorsolateral Prefrontal Cortex

Barr

Farzan

Rusjan

et al. 2009

Neuropsychopharmacol

104

View full text Add to dashboard Cite

show abstract

“…These studies have found schizophrenia patients to exhibit relatively lower frequency (Spencer et al, 2004) and decreased synchrony (Spencer et al, 2003) of an oscillation that is phase-locked to motor response in a Gestalt perception task, although others have found preserved gamma power in a different Gestalt perception task (Uhlhaas et al, 2006). Task demands with a stronger PFC-dependence have also revealed gamma deficits in schizophrenia patients, including impaired frontal gamma power (measured by magnetoencephalography) during mental arithmetic performance (Kissler et al, 2000) and an inability to mount increased delay-period gamma power in response to increasing working memory load during the N-Back (Basar-Eroglu et al, 2007). Our research group has reported that schizophrenia patients exhibit impaired frontal induced gamma power during preparatory cognitive control processes (Cho et al, 2006), suggesting a physiological mechanism to link impaired BOLD responses in the DLPFC with impaired cognitive control (Barch et al, 2001;Holmes et al, 2005;MacDonald and Carter, 2003;MacDonald et al, 2005;Perlstein et al, 2003;Snitz et al, 2005;Yoon et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Gamma Oscillatory Power is Impaired During Cognitive Control Independent of Medication Status in First-Episode Schizophrenia

Minzenberg

Firl

Yoon

et al. 2010

Neuropsychopharmacol

217

169

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Schizophrenia is characterized by impaired cognitive control associated with prefrontal cortex dysfunction, but the underlying pathophysioloical mechanisms remain unknown. Higher cognitive processes are associated with cortical oscillations in the gamma range, which are also impaired in chronic schizophrenia. We tested whether cognitive control-related gamma deficits are observed in firstepisode patients, and whether they are associated with antipsychotic medication exposure. Fifty-three first-episode schizophrenia patients (21 without antipsychotic medication treatment) and 29 healthy control subjects underwent electroencephalography (EEG) during performance of a preparatory cognitive control task (preparing to overcome prepotency or POP task). The first-episode schizophrenia patient group was impaired (relative to the control group) on task performance and on delay-period gamma power at each of the three subgroups of frontal electrodes. The unmedicated patient subgroup was similarly impaired compared with controls, and was not different on these measures compared with the medicated patient subgroup. In contrast, delay-period theta power was not impaired in the full patient group nor in the unmedicated patient subgroup. Impaired cognitive control-related gamma cortical oscillatory activity is present at the first psychotic episode in schizophrenia, and is independent of medication status. This suggests that altered local circuit function supporting high-frequency oscillatory activity in prefrontal cortex ensembles may serve as the pathophysiological substrate of cognitive control deficits in schizophrenia.

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