High-frequency gamma activity (80–150Hz) is increased in human cortex during selective attention

Ray, Supratim; Niebur, Ernst; Hsiao, Steven S.; Sinai, Alon; Crone, Nathan E.

doi:10.1016/j.clinph.2007.09.136

Cited by 214 publications

(186 citation statements)

References 55 publications

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“…S7b). These findings may relate to the proposal that, in the human neocortex, ''low gamma'' (30-60 Hz) and ''high gamma'' (Ϸ60-250 Hz but typically focused on 80-150 Hz) can be distinguished (27) and may result from independent physiological mechanisms with different functions (26)(27)(28). Given the heterogeneity in nomenclature, we reserve the term ''gamma'' to denote the lower high-frequency ranges that have been characterized as inhibition-based (40).…”

Section: Discussionmentioning

confidence: 99%

“…Gamma oscillations (30-100 Hz) have also received special attention because of their proposed role in functions such as sensory binding (18), selective attention (19-21), transient neuronal assembly formation (22), and information transmission and storage (23-25). The existence of physiologically meaningful neocortical oscillations at even higher frequencies, above the traditional gamma range, has been reported as well (10,(26)(27)(28). In rodents, for example, brief sharp-wave associated ripples (120-200 Hz) appear in the hippocampal formation during slow wave sleep, immobility and consummatory behavior, characteristically in the absence of theta waves (2, 29).…”

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confidence: 99%

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Dynamic cross-frequency couplings of local field potential oscillations in rat striatum and hippocampus during performance of a T-maze task

Tort

Kramer

Thorn

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

745

770

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Oscillatory rhythms in different frequency ranges mark different behavioral states and are thought to provide distinct temporal windows that coherently bind cooperating neuronal assemblies. However, the rhythms in different bands can also interact with each other, suggesting the possibility of higher-order representations of brain states by such rhythmic activity. To explore this possibility, we analyzed local field potential oscillations recorded simultaneously from the striatum and the hippocampus. As rats performed a task requiring active navigation and decision making, the amplitudes of multiple high-frequency oscillations were dynamically modulated in task-dependent patterns by the phase of cooccurring theta-band oscillations both within and across these structures, particularly during decision-making behavioral epochs. Moreover, the modulation patterns uncovered distinctions among both high-and low-frequency subbands. Cross-frequency coupling of multiple neuronal rhythms could be a general mechanism used by the brain to perform networklevel dynamical computations underlying voluntary behavior.amplitude modulation ͉ gamma ͉ theta O scillations in neural population voltage activity are universal phenomena (1). Among brain rhythms, theta oscillations in local field potentials (LFPs) recorded in the hippocampus are prominent during active behaviors (2-5), and these have long been intensively analyzed in the rodent in relation to spatial navigation (6), memory (7), and sleep (8). Theta-band rhythms (4-12 Hz) are now known to occur in other cortical (9-12) and subcortical (12-15) regions, however, including the striatum (14-17), studied here. Gamma oscillations (30-100 Hz) have also received special attention because of their proposed role in functions such as sensory binding (18), selective attention (19-21), transient neuronal assembly formation (22), and information transmission and storage (23-25). The existence of physiologically meaningful neocortical oscillations at even higher frequencies, above the traditional gamma range, has been reported as well (10,(26)(27)(28). In rodents, for example, brief sharp-wave associated ripples (120-200 Hz) appear in the hippocampal formation during slow wave sleep, immobility and consummatory behavior, characteristically in the absence of theta waves (2, 29).The oscillatory activities conventionally assigned to different frequency bands are not completely independent (2-4, 9, 10, 30). In one type of interaction, the phase of low-frequency rhythms modulates the amplitude of higher-frequency oscillations (9, 10, 30). For example, theta phase is known to modulate gamma power in rodent hippocampal and cortical circuits (2-4, 31), and the phase of theta rhythms recorded in the human neocortex can modulate wide-band (60-200 Hz) high-frequency oscillations (10). Such theta-gamma nesting is thought to play a role in sequential memory organization and maintenance of working memory, and more generally in ''phase coding' ' (25, 31). Based on evidence suggesting that theta rhythms i...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Dynamic cross-frequency couplings of local field potential oscillations in rat striatum and hippocampus during performance of a T-maze task

Tort

Kramer

Thorn

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

745

770

View full text Add to dashboard Cite

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“…It is beyond the scope of the present study to compare these various methods. Application of FDR to EEG data was reported with respect to event-related electrocorticographic gamma activity (Ray et al, 2008). There were no statistical time-frequency studies with type I error control regarding the changes associated with EEG spikes.…”

Section: Discussionmentioning

confidence: 99%

Detection of changes of high-frequency activity by statistical time-frequency analysis in epileptic spikes

Kobayashi¹,

Jacobs²,

Gotman³

2009

Clinical Neurophysiology

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Objective-A novel type of statistical time-frequency analysis was developed to elucidate changes of high-frequency EEG activity associated with epileptic spikes.Methods-The method uses the Gabor Transform and detects changes of power in comparison to background activity using t-statistics that are controlled by the false discovery rate (FDR) to correct type I error of multiple testing. The analysis was applied to EEGs recorded at 2000 Hz from three patients with mesial temporal lobe epilepsy.Results-Spike-related increase of high-frequency oscillations (HFOs) was clearly shown in the FDR-controlled t-spectra: it was most dramatic in spikes recorded from the hippocampus when the hippocampus was the seizure onset zone (SOZ). Depression of fast activity was observed immediately after the spikes, especially consistently in the discharges from the hippocampal SOZ. It corresponded to the slow wave part in case of spike-and-slow-wave complexes, but it was noted even in spikes without apparent slow waves. In one patient, a gradual increase of power above 200 Hz preceded spikes.Conclusions-FDR-controlled t-spectra clearly detected the spike-related changes of HFOs that were unclear in standard power spectra.Significance-We developed a promising tool to study the HFOs that may be closely linked to the pathophysiology of epileptogenesis.

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“…Because of low-pass filtering of the visual system, it is difficult to evoke synchrony in the high-gamma range (16,17). Such neural synchrony (75-150 Hz) has recently also been associated with selective attention (28,29). Further work, with stimulation techniques that directly target cortical circuits, is required to examine the effects of externally modulating synchrony in this frequency range.…”

Section: Discussionmentioning

confidence: 99%

Gamma flicker triggers attentional selection without awareness

Bauer

Cheadle

Parton

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Gamma band modulations in neural activity have been proposed to mediate attentional processes. To support a causal link between gamma activity and attentional selection, we attempt to evoke gamma oscillations by a 50-Hz subliminal flicker. We find that a subliminal 50-Hz flicker at a target location, before target presentation, speeds up and enhances target detection and discrimination. This effect is specific to the middle of the gamma range because it is not evident at <35-Hz flicker. It requires 300 ms to build up, dissipates within 250 ms of flicker offset, and shows a tendency to invert after 500 ms. The results are discussed in relation to a role for gamma band neural synchrony in the allocation of visual attention.visual attention ͉ neural synchrony ͉ gamma ͉ psychophysics ͉ subliminal T he nature of the neural mechanisms underlying visual attention-the ability of humans and animals to select a limited number of stimuli from the multitude simultaneously present in the visual field for prioritized processing-remains a fundamental problem in visual neuroscience (1). A complete theory of visual attention must explain how the relative salience of selected stimuli is enhanced in neural terms, even though they are often not singled out by increased firing rates (2, 3). One recently proposed solution is the ''Attention-Gamma'' hypothesis, according to which synchronized gamma band (40-70 Hz) modulations in neural activity mediate attentional processes (4-10). This hypothesis is supported by a correlation, across trials, between the speed of behavioral responses in a visual detection task and the power in the gamma frequency range of V4 neurons (10-12). In these studies, Fries, Womelsdorf, and colleagues demonstrated that top-down visual attention is associated with internal gamma band synchrony in task-specific neural populations, which could be generated by top-down attentional modulations (13, 14). Thus, it is possible that selected neural representations are given a gamma band oscillatory tag by a top-down attention mechanism (15). If this is the case, it may be possible to trigger the effects of selective attention (enhanced selection and perception) by externally evoking gamma band oscillations of the relevant neural representation, thus mimicking the attentional tag.To test this hypothesis, we examined whether external stimulus flicker at a specific location, which is expected to evoke phaselocked neural activity at the same frequency, results in attentional orientation to that location in the absence of conscious detection of the flicker; if the flicker were detectable, it could lead to an orienting of attention toward its location as a result of exogenous or endogenous processes that are not specific to the temporal modulation. To test whether subliminally evoked neural synchronization has an attentional effect, we built on recent studies demonstrating that visual flicker in the midgamma band range (40-70 Hz) entrains periodic neural responses at the same frequency in the visual cortex [refs. 16 and 17; ...

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High-frequency gamma activity (80–150Hz) is increased in human cortex during selective attention

Cited by 214 publications

References 55 publications

Dynamic cross-frequency couplings of local field potential oscillations in rat striatum and hippocampus during performance of a T-maze task

Dynamic cross-frequency couplings of local field potential oscillations in rat striatum and hippocampus during performance of a T-maze task

Detection of changes of high-frequency activity by statistical time-frequency analysis in epileptic spikes

Gamma flicker triggers attentional selection without awareness

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