scholarly journals Binding Mechanisms in Visual Perception and Their Link With Neural Oscillations: A Review of Evidence From tACS

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrea Ghiani ◽  
Marcello Maniglia ◽  
Luca Battaglini ◽  
David Melcher ◽  
Luca Ronconi
Keyword(s):  
Visual Perception ◽  
Feature Binding ◽  
Causal Role ◽  
Oscillatory Activity ◽  
Dependent Manner ◽  
Brain Oscillations ◽  
Temporal Binding ◽  
Neurophysiological Studies ◽  
Binding Mechanisms

Neurophysiological studies in humans employing magneto- (MEG) and electro- (EEG) encephalography increasingly suggest that oscillatory rhythmic activity of the brain may be a core mechanism for binding sensory information across space, time, and object features to generate a unified perceptual representation. To distinguish whether oscillatory activity is causally related to binding processes or whether, on the contrary, it is a mere epiphenomenon, one possibility is to employ neuromodulatory techniques such as transcranial alternating current stimulation (tACS). tACS has seen a rising interest due to its ability to modulate brain oscillations in a frequency-dependent manner. In the present review, we critically summarize current tACS evidence for a causal role of oscillatory activity in spatial, temporal, and feature binding in the context of visual perception. For temporal binding, the emerging picture supports a causal link with the power and the frequency of occipital alpha rhythms (8–12 Hz); however, there is no consistent evidence on the causal role of the phase of occipital tACS. For feature binding, the only study available showed a modulation by occipital alpha tACS. The majority of studies that successfully modulated oscillatory activity and behavioral performance in spatial binding targeted parietal areas, with the main rhythms causally linked being the theta (~7 Hz) and beta (~18 Hz) frequency bands. On the other hand, spatio-temporal binding has been directly modulated by parieto-occipital gamma (~40–60 Hz) and alpha (10 Hz) tACS, suggesting a potential role of cross-frequency coupling when binding across space and time. Nonetheless, negative or partial results have also been observed, suggesting methodological limitations that should be addressed in future research. Overall, the emerging picture seems to support a causal role of brain oscillations in binding processes and, consequently, a certain degree of plasticity for shaping binding mechanisms in visual perception, which, if proved to have long lasting effects, can find applications in different clinical populations.

scholarly journals Investigating and Modulating Physiological and Pathological Brain Oscillations: The Role of Oscillatory Activity in Neural Plasticity

2019 ◽  
Vol 2019 ◽  
pp. 1-3 ◽  
Author(s):  
Andrea Guerra ◽  
Matteo Feurra ◽  
Giovanni Pellegrino ◽  
John-Stuart Brittain
Keyword(s):  
Neural Plasticity ◽  
Oscillatory Activity ◽  
Brain Oscillations

scholarly journals Perception of Rhythmic Speech Is Modulated by Focal Bilateral Transcranial Alternating Current Stimulation

2020 ◽  
Vol 32 (2) ◽  
pp. 226-240 ◽  
Author(s):  
Benedikt Zoefel ◽  
Isobella Allard ◽  
Megha Anil ◽  
Matthew H. Davis
Keyword(s):  
Speech Perception ◽  
Speech Processing ◽  
Alternating Current ◽  
Stream Segregation ◽  
Causal Role ◽  
Oscillatory Activity ◽  
Transcranial Alternating Current Stimulation ◽  
Neural Entrainment ◽  
Actual Speech

Several recent studies have used transcranial alternating current stimulation (tACS) to demonstrate a causal role of neural oscillatory activity in speech processing. In particular, it has been shown that the ability to understand speech in a multi-speaker scenario or background noise depends on the timing of speech presentation relative to simultaneously applied tACS. However, it is possible that tACS did not change actual speech perception but rather auditory stream segregation. In this study, we tested whether the phase relation between tACS and the rhythm of degraded words, presented in silence, modulates word report accuracy. We found strong evidence for a tACS-induced modulation of speech perception, but only if the stimulation was applied bilaterally using ring electrodes (not for unilateral left hemisphere stimulation with square electrodes). These results were only obtained when data were analyzed using a statistical approach that was identified as optimal in a previous simulation study. The effect was driven by a phasic disruption of word report scores. Our results suggest a causal role of neural entrainment for speech perception and emphasize the importance of optimizing stimulation protocols and statistical approaches for brain stimulation research.

scholarly journals Probing the causal role of prestimulus interregional synchrony for perceptual integration via tACS

2016 ◽  
Author(s):  
Rolandas Stonkus ◽  
Verena Braun ◽  
Jess Kerlin ◽  
Gregor Volberg ◽  
Simon Hanslmayr
Keyword(s):  
Specific Activity ◽  
Brain Regions ◽  
Causal Role ◽  
Oscillatory Activity ◽  
Perceptual Integration ◽  
After Effects ◽  
Activity Phase ◽  
Fmri Study ◽  
Transcranial Alternating Current Stimulation

The phase of prestimulus oscillations at 7-10 Hz has been shown to modulate perception of briefly presented visual stimuli. Specifically, a recent combined EEG-fMRI study suggested that a prestimulus oscillation at around 7 Hz represents open and closed windows for perceptual integration by modulating connectivity between lower order occipital and higher order parietal brain regions. We here utilized brief event-related transcranial alternating current stimulation (tACS) to specifically modulate this prestimulus 7 Hz oscillation, and the synchrony between parietal and occipital brain regions. To this end we tested for a causal role of this particular prestimulus oscillation for perceptual integration. The EEG was acquired at the same time allowing us to investigate frequency specific after effects phase-locked to stimulation offset. On a behavioural level our results suggest that the tACS did modulate perceptual integration, however, in an unexpected manner. On an electrophysiological level our results suggest that brief tACS does induce oscillatory entrainment, as visible in frequency specific activity phase-locked to stimulation offset. Together, our results do not strongly support a causal role of prestimulus 7 Hz oscillations for perceptual integration. However, our results suggest that brief tACS is capable of modulating oscillatory activity in a temporally sensitive manner.

scholarly journals Can the causal role of brain oscillations be studied through rhythmic brain stimulation?

2021 ◽  
Vol 21 (12) ◽  
pp. 2
Author(s):  
Tanya Lobo ◽  
Matthew J. Brookes ◽  
Markus Bauer
Keyword(s):  
Brain Stimulation ◽  
Causal Role ◽  
Brain Oscillations

scholarly journals Commentary: The causal role of α-oscillations in feature binding

2020 ◽  
Vol 14 ◽  
Author(s):  
Max A. Crayen ◽  
Pinar Yurt ◽  
Stefan Treue ◽  
Moein Esghaei
Keyword(s):  
Feature Binding ◽  
Causal Role

scholarly journals Transcranial alternating current stimulation (tACS) reveals causal role of brain oscillations in visual attention

2016 ◽  
Vol 16 (12) ◽  
pp. 937 ◽  
Author(s):  
Daniel Baldauf ◽  
Nir Grossman ◽  
An-Ming Hu ◽  
Ed Boyden ◽  
Robert Desimone
Keyword(s):  
Visual Attention ◽  
Alternating Current ◽  
Causal Role ◽  
Brain Oscillations ◽  
Transcranial Alternating Current Stimulation

scholarly journals Phase-locked transcranial electrical brain stimulation for tremor suppression in dystonic tremor syndromes

2021 ◽  
Author(s):  
Freek Nieuwhof ◽  
Ivan Toni ◽  
Arthur W.G. Buijink ◽  
Anne-Fleur van Rootselaar ◽  
Bart P.C. van de Warrenburg ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Brain Regions ◽  
Causal Role ◽  
Clinical Feature ◽  
Dependent Manner ◽  
Dystonic Tremor ◽  
Phase Cycle ◽  
Phase Lags ◽  
Post Hoc

Background: Tremor is a common and burdensome symptom in patients with dystonia, which is clinically heterogeneous and often resistant to treatment. The pathophysiology is suggested to involve abnormal activity in the cerebellum and motor cortex, but the causal role of these brain regions remains to be established. Transcranial alternating current stimulaton (TACS) can suppress rhytmic cerebral activity in other tremor disorders when phase-locked to the ongoing arm tremor, but the effect on dystonic tremor syndromes is unknown. Objective/Hypothesis: We aimed to establish the causal role of the cerebellum and motor cortex in dystonic tremor syndromes, and explore the therapeutic efficacy of phase-locked TACS. Methods: We applied phase-locked TACS over the ipsilateral cerebellum (N=14) and contralateral motor cortex (N=17) in dystonic tremor syndrome patients, while patients assumed a tremor-evoking posture. We measured tremor power using accelerometery during 30s stimulation periods at 10 different phase-lags (36-degrees increments) between tremor and TACS for each target. Post-hoc, TACS-effects were related to a key clinical feature: the jerkiness (regularity) of tremor. Results: Cerebellar TACS modulated tremor amplitude in a phase-dependent manner, such that tremor amplitude was suppressed or enhanced at opposite sides of the phase-cycle. This effect was specific for patients with non-jerky (sinusoidal) tremor (n=10), but absent in patients with jerky (irregular) tremor (n=4). Phase-locked stimulation over the motor cortex did not modulate tremor amplitude. Conclusions: This study indicates that the cerebellum plays a causal role in the generation of (non-jerky) dystonic tremor syndrome. Our findings suggest pathophysiologic heterogeneity between patients with dystonic tremor syndrome, which mirrors clinical variability.

scholarly journals The causal role of α-oscillations in feature binding

2019 ◽  
Vol 116 (34) ◽  
pp. 17023-17028 ◽  
Author(s):  
Yanyu Zhang ◽  
Yifei Zhang ◽  
Peng Cai ◽  
Huan Luo ◽  
Fang Fang
Keyword(s):  
Large Scale ◽  
Brain Network ◽  
Feature Binding ◽  
Causal Role ◽  
Human Cognition ◽  
Neural Oscillations ◽  
Switch Rate ◽  
Transcranial Alternating Current Stimulation ◽  
Large Scale Networks

The binding problem—how to integrate features into objects—poses a fundamental challenge for the brain. Neural oscillations, especially γ-oscillations, have been proposed as a potential mechanism to solve this problem. However, since γ-oscillations usually reflect local neural activity, how to implement feature binding involving a large-scale brain network remains largely unknown. Here, combining electroencephalogram (EEG) and transcranial alternating current stimulation (tACS), we employed a bistable color-motion binding stimulus to probe the role of neural oscillations in feature binding. Subjects’ perception of the stimulus switched between its physical binding and its illusory (active) binding. The active binding has been shown to involve a large-scale network consisting of spatially distant brain areas. α-Oscillations presumably reflect the dynamics of such large-scale networks, especially due to volume conduction effects in EEG. We found that, relative to the physical binding, the α-power decreased during the active binding. Additionally, individual α-power was negatively correlated with the time proportion of the active binding. Subjects’ perceptual switch rate between the 2 bindings was positively correlated with their individual α-frequency. Furthermore, applying tACS at individual α-frequency decreased the time proportion of the active binding. Moreover, delivering tACS at different temporal frequencies in the α-band changed subjects’ perceptual switch rate through affecting the active binding process. Our findings provide converging evidence for the causal role of α-oscillations in feature binding, especially in active feature binding, thereby uncovering a function of α-oscillations in human cognition.

scholarly journals Perception of rhythmic speech is modulated by focal bilateral tACS

2019 ◽  
Author(s):  
Benedikt Zoefel ◽  
Isobella Allard ◽  
Megha Anil ◽  
Matthew H Davis
Keyword(s):  
Speech Perception ◽  
Speech Processing ◽  
Stream Segregation ◽  
Causal Role ◽  
Oscillatory Activity ◽  
Auditory Stream Segregation ◽  
Neural Entrainment ◽  
Actual Speech ◽  
Speech Presentation

AbstractSeveral recent studies have used transcranial alternating stimulation (tACS) to demonstrate a causal role of neural oscillatory activity in speech processing. In particular, it has been shown that the ability to understand speech in a multi-speaker scenario or background noise depends on the timing of speech presentation relative to simultaneously applied tACS. However, it is possible that tACS did not change actual speech perception but rather auditory stream segregation. In this study, we tested whether the phase relation between tACS and the rhythm of degraded words, presented in silence, modulates word report accuracy. We found strong evidence for a tACS-induced modulation of speech perception, but only if the stimulation was applied bilaterally using ring electrodes (not for unilateral left hemisphere stimulation with square electrodes). These results were only obtained when data was analyzed using a statistical approach that was identified as optimal in a previous simulation study. The effect was driven by a phasic disruption of word report scores. Our results suggest a causal role of neural entrainment for speech perception and emphasize the importance of optimizing stimulation protocols and statistical approaches for brain stimulation research.

Sign in / Sign up

Export Citation Format

Share Document