Opposite effects of lateralised transcranial alpha versus gamma stimulation on spatial attention

AbstractSpatial attention relatively increases the power of neural 10-Hz alpha oscillations in the hemisphere ipsilateral to attention. The functional roles of lateralised oscillations for attention are unclear. Here, 20 human participants performed a dichotic listening task under continuous transcranial alternating current stimulation (tACS) at alpha (10 Hz, vs sham) or gamma (47 Hz, vs sham) frequency, targeting left temporo-parietal cortex. Participants attended to four spoken numbers presented to one ear, while ignoring numbers on the other ear. As predicted, we found that alpha-tACS contralateral to the attended ear decreased recall of attended targets. Notably, gamma-tACS reversed the effect. Results provide a proof of concept that externally amplified oscillations can enhance spatial attention and facilitate attentional selection of speech. Furthermore, opposite effects of alpha versus gamma oscillations support the view that, across modalities, states of high alpha are incommensurate with active neural processing as reflected by states of high gamma.

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Rhythmic Gamma Stimulation Affects Bistable Perception

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00781 ◽

2015 ◽

Vol 27 (7) ◽

pp. 1298-1307 ◽

Cited By ~ 19

Author(s):

Yuranny Cabral-Calderin ◽

Carsten Schmidt-Samoa ◽

Melanie Wilke

Keyword(s):

Gamma Oscillations ◽

Physical Stimulus ◽

Healthy Human ◽

Posterior Cortex ◽

Alpha Oscillations ◽

Bistable Perception ◽

Motion Stimulus ◽

Transcranial Alternating Current Stimulation ◽

Human Participants

When our brain is confronted with ambiguous visual stimuli, perception spontaneously alternates between different possible interpretations although the physical stimulus remains the same. Both alpha (8–12 Hz) and gamma (>30 Hz) oscillations have been reported to correlate with such spontaneous perceptual reversals. However, whether these oscillations play a causal role in triggering perceptual switches remains unknown. To address this question, we applied transcranial alternating current stimulation (tACS) over the posterior cortex of healthy human participants to boost alpha and gamma oscillations. At the same time, participants were reporting their percepts of an ambiguous structure-from-motion stimulus. We found that tACS in the gamma band (60 Hz) increased the number of spontaneous perceptual reversals, whereas no significant effect was found for tACS in alpha (10 Hz) and higher gamma (80 Hz) frequencies. Our results suggest a mechanistic role of gamma but not alpha oscillations in the resolution of perceptual ambiguity.

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Selective modulation of interhemispheric connectivity by transcranial alternating current stimulation influences binaural integration

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2015488118 ◽

2021 ◽

Vol 118 (7) ◽

pp. e2015488118

Author(s):

Basil C. Preisig ◽

Lars Riecke ◽

Matthias J. Sjerps ◽

Anne Kösem ◽

Benjamin R. Kop ◽

...

Keyword(s):

Brain Connectivity ◽

Sensory Information ◽

Alternating Current ◽

Phase Lag ◽

Perceptual Integration ◽

Dichotic Listening Task ◽

Interhemispheric Connectivity ◽

Transcranial Alternating Current Stimulation ◽

Auditory Cortices ◽

Listening Task

Brain connectivity plays a major role in the encoding, transfer, and integration of sensory information. Interregional synchronization of neural oscillations in the γ-frequency band has been suggested as a key mechanism underlying perceptual integration. In a recent study, we found evidence for this hypothesis showing that the modulation of interhemispheric oscillatory synchrony by means of bihemispheric high-density transcranial alternating current stimulation (HD-TACS) affects binaural integration of dichotic acoustic features. Here, we aimed to establish a direct link between oscillatory synchrony, effective brain connectivity, and binaural integration. We experimentally manipulated oscillatory synchrony (using bihemispheric γ-TACS with different interhemispheric phase lags) and assessed the effect on effective brain connectivity and binaural integration (as measured with functional MRI and a dichotic listening task, respectively). We found that TACS reduced intrahemispheric connectivity within the auditory cortices and antiphase (interhemispheric phase lag 180°) TACS modulated connectivity between the two auditory cortices. Importantly, the changes in intra- and interhemispheric connectivity induced by TACS were correlated with changes in perceptual integration. Our results indicate that γ-band synchronization between the two auditory cortices plays a functional role in binaural integration, supporting the proposed role of interregional oscillatory synchrony in perceptual integration.

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Creativity and Attention: Insights From the Dichotic Listening Task

PsycEXTRA Dataset ◽

10.1037/e637752009-001 ◽

2009 ◽

Author(s):

Oshin A. Vartanian ◽

Colin Martindale ◽

Jessica Matthews ◽

Jonna M. Kwiatkowski

Keyword(s):

Dichotic Listening ◽

Dichotic Listening Task ◽

Listening Task

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HEMISPHERIC PERFORMANCE IN DETECTING PROSODY: A COMPETITIVE DICHOTIC LISTENING TASK

Perceptual and Motor Skills ◽

10.2466/pms.71.6.479-486 ◽

1990 ◽

Vol 71 (6) ◽

pp. 479 ◽

Cited By ~ 1

Author(s):

JOHN V. HERRERO

Keyword(s):

Dichotic Listening ◽

Dichotic Listening Task ◽

Listening Task

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Previously reward-associated sounds interfere with goal-directed auditory processing

Quarterly Journal of Experimental Psychology ◽

10.1177/1747021821990033 ◽

2021 ◽

pp. 174702182199003

Author(s):

Andy J Kim ◽

David S Lee ◽

Brian A Anderson

Keyword(s):

Visual Processing ◽

Auditory Processing ◽

Dichotic Listening ◽

Auditory Information ◽

Correct Identification ◽

Subsequent Test ◽

Dichotic Listening Task ◽

Listening Task ◽

Task Irrelevant ◽

Visual Domain

Previously reward-associated stimuli have consistently been shown to involuntarily capture attention in the visual domain. Although previously reward-associated but currently task-irrelevant sounds have also been shown to interfere with visual processing, it remains unclear whether such stimuli can interfere with the processing of task-relevant auditory information. To address this question, we modified a dichotic listening task to measure interference from task-irrelevant but previously reward-associated sounds. In a training phase, participants were simultaneously presented with a spoken letter and number in different auditory streams and learned to associate the correct identification of each of three letters with high, low, and no monetary reward, respectively. In a subsequent test phase, participants were again presented with the same auditory stimuli but were instead instructed to report the number while ignoring spoken letters. In both the training and test phases, response time measures demonstrated that attention was biased in favour of the auditory stimulus associated with high value. Our findings demonstrate that attention can be biased towards learned reward cues in the auditory domain, interfering with goal-directed auditory processing.

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Superimposed gratings induce diverse response patterns of gamma oscillations in primary visual cortex

Scientific Reports ◽

10.1038/s41598-021-83923-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Bin Wang ◽

Chuanliang Han ◽

Tian Wang ◽

Weifeng Dai ◽

Yang Li ◽

...

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Field Potential ◽

Gamma Oscillations ◽

Neural Mechanisms ◽

Model Parameters ◽

Response Patterns ◽

Region Difference ◽

High Gamma ◽

Spiking Activity

AbstractStimulus-dependence of gamma oscillations (GAMMA, 30–90 Hz) has not been fully understood, but it is important for revealing neural mechanisms and functions of GAMMA. Here, we recorded spiking activity (MUA) and the local field potential (LFP), driven by a variety of plaids (generated by two superimposed gratings orthogonal to each other and with different contrast combinations), in the primary visual cortex of anesthetized cats. We found two distinct narrow-band GAMMAs in the LFPs and a variety of response patterns to plaids. Similar to MUA, most response patterns showed that the second grating suppressed GAMMAs driven by the first one. However, there is only a weak site-by-site correlation between cross-orientation interactions in GAMMAs and those in MUAs. We developed a normalization model that could unify the response patterns of both GAMMAs and MUAs. Interestingly, compared with MUAs, the GAMMAs demonstrated a wider range of model parameters and more diverse response patterns to plaids. Further analysis revealed that normalization parameters for high GAMMA, but not those for low GAMMA, were significantly correlated with the discrepancy of spatial frequency between stimulus and sites’ preferences. Consistent with these findings, normalization parameters and diversity of high GAMMA exhibited a clear transition trend and region difference between area 17 to 18. Our results show that GAMMAs are also regulated in the form of normalization, but that the neural mechanisms for these normalizations might differ from those of spiking activity. Normalizations in different brain signals could be due to interactions of excitation and inhibitions at multiple stages in the visual system.

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Frontal eye field microstimulation induces task-dependent gamma oscillations in the lateral intraparietal area

Journal of Neurophysiology ◽

10.1152/jn.00323.2012 ◽

2012 ◽

Vol 108 (5) ◽

pp. 1392-1402 ◽

Cited By ~ 15

Author(s):

Elsie Premereur ◽

Wim Vanduffel ◽

Pieter R. Roelfsema ◽

Peter Janssen

Keyword(s):

Spatial Attention ◽

Field Potential ◽

Gamma Oscillations ◽

Oculomotor Control ◽

Saccade Target ◽

Frontal Eye Field ◽

Alpha Power ◽

Lateral Intraparietal Area ◽

Electrical Microstimulation ◽

Gamma Power

Macaque frontal eye fields (FEF) and the lateral intraparietal area (LIP) are high-level oculomotor control centers that have been implicated in the allocation of spatial attention. Electrical microstimulation of macaque FEF elicits functional magnetic resonance imaging (fMRI) activations in area LIP, but no study has yet investigated the effect of FEF microstimulation on LIP at the single-cell or local field potential (LFP) level. We recorded spiking and LFP activity in area LIP during weak, subthreshold microstimulation of the FEF in a delayed-saccade task. FEF microstimulation caused a highly time- and frequency-specific, task-dependent increase in gamma power in retinotopically corresponding sites in LIP: FEF microstimulation produced a significant increase in LIP gamma power when a saccade target appeared and remained present in the LIP receptive field (RF), whereas less specific increases in alpha power were evoked by FEF microstimulation for saccades directed away from the RF. Stimulating FEF with weak currents had no effect on LIP spike rates or on the gamma power during memory saccades or passive fixation. These results provide the first evidence for task-dependent modulations of LFPs in LIP caused by top-down stimulation of FEF. Since the allocation and disengagement of spatial attention in visual cortex have been associated with increases in gamma and alpha power, respectively, the effects of FEF microstimulation on LIP are consistent with the known effects of spatial attention.

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Controlled photo-discharge of dust in a complex plasma

Journal of Plasma Physics ◽

10.1017/s002237782100043x ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

Michael McKinlay ◽

Edward Thomas

Keyword(s):

High Intensity ◽

Dusty Plasmas ◽

Lanthanum Hexaboride ◽

Magnetized Plasma ◽

Background Plasma ◽

Proof Of Concept ◽

Langmuir Probes ◽

Complex Plasma ◽

Dust Charge ◽

Selection Of

One of the limitations in studying dusty plasmas is that many of the important properties of the dust (like the charge) are directly coupled to the surrounding plasma conditions rather than being determined independently. The application of high-intensity ultraviolet (UV) sources to generate discharging photoelectric currents may provide an avenue for developing methods of controlling dust charge. Careful selection of the parameters of the UV source and dust material may even allow for this to be accomplished with minimal perturbation of the background plasma. The Auburn Magnetized Plasma Research Laboratory (MPRL) has developed a ‘proof-of-concept’ experiment for this controlled photo-discharging of dust; a high-intensity, near-UV source was used to produce large changes in the equilibrium positions of lanthanum hexaboride ( $\textrm {LaB}_6$ ) particles suspended in an argon DC glow discharge with negligible changes in the potential, density and temperature profiles of the background plasma. The shifts in equilibrium position of the dust are consistent with a reduction in dust charge. Video analysis is used to quantify the changes in position, velocity and acceleration of a test particle under the influence of the UV and Langmuir probes are used to measure the effects on the plasma.

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