Transcranial alternating stimulation in a high gamma frequency range applied over V1 improves contrast perception but does not modulate spatial attention

2012 ◽  
Vol 5 (4) ◽  
pp. 484-491 ◽  
Author(s):  
Bence Laczó ◽  
Andrea Antal ◽  
Robert Niebergall ◽  
Stefan Treue ◽  
Walter Paulus
Keyword(s):  
Spatial Attention ◽  
Frequency Range ◽  
Gamma Frequency ◽  
High Gamma ◽  
Contrast Perception

scholarly journals Untangling cortico-striatal connectivity and cross-frequency coupling in L-DOPA-induced dyskinesia

2015 ◽  
Author(s):  
Jovana Belic ◽  
Per Halje ◽  
Ulrike Richter ◽  
Per Petersson ◽  
Jeanette Hellgren Kotaleski
Keyword(s):  
Primary Motor Cortex ◽  
Effective Connectivity ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Frequency Range ◽  
Gamma Frequency ◽  
High Gamma ◽  
Freely Behaving ◽  
Beta Frequency ◽  
Cross Frequency Coupling

We simultaneously recorded local field potentials in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats in order to study the features directly related to pathological states such as parkinsonian state and levodopa-induced dyskinesia. We analysed the spectral characteristics of the obtained signals and observed that during dyskinesia the most prominent feature was a relative power increase in the high gamma frequency range at around 80 Hz, while for the parkinsonian state it was in the beta frequency range. Here we show that during both pathological states effective connectivity in terms of Granger causality is bidirectional with an accent on the striatal influence on the cortex. In the case of dyskinesia, we also found a high increase in effective connectivity at 80 Hz. In order to further understand the 80- Hz phenomenon, we performed cross-frequency analysis and observed characteristic patterns in the case of dyskinesia but not in the case of the parkinsonian state or the control state. We noted a large decrease in the modulation of the amplitude at 80 Hz by the phase of low frequency oscillations (up to ~10 Hz) across both structures in the case of dyskinesia. This may suggest a lack of coupling between the low frequency activity of the recorded network and the group of neurons active at ~80 Hz.

scholarly journals Role of Interneuron Diversity in the Cortical Microcircuit for Attention

2008 ◽  
Vol 99 (5) ◽  
pp. 2158-2182 ◽  
Author(s):  
Calin I. Buia ◽  
Paul H. Tiesinga
Keyword(s):  
Firing Rate ◽  
Spatial Attention ◽  
Cortical Area ◽  
Receptive Fields ◽  
Biophysical Model ◽  
Testable Hypothesis ◽  
Frequency Range ◽  
Area V4 ◽  
Gamma Frequency ◽  
Feature Based

Receptive fields of neurons in cortical area V4 are large enough to fit multiple stimuli, making V4 the ideal place to study the effects of selective attention at the single-neuron level. Experiments have revealed evidence for stimulus competition and have characterized the effect thereon of spatial and feature-based attention. We developed a biophysical model with spiking neurons and conductance-based synapses. To account for the comprehensive set of experimental results, it was necessary to include in the model, in addition to regular spiking excitatory (E) cells, two types of interneurons: feedforward interneurons (FFI) and top-down interneurons (TDI). Feature-based attention was mediated by a projection of the TDI to the FFI, stimulus competition was mediated by a cross-columnar excitatory connection to the FFI, whereas spatial attention was mediated by an increase in activity of the feedforward inputs from cortical area V2. The model predicts that spatial attention increases the FFI firing rate, whereas feature-based attention decreases the FFI firing rate and increases the TDI firing rate. During strong stimulus competition, the E cells were synchronous in the beta frequency range (15–35 Hz), but with feature-based attention, they became synchronous in the gamma frequency range (35–50 Hz). We propose that the FFI correspond to fast-spiking, parvalbumin-positive basket cells and that the TDI correspond to cells with a double-bouquet morphology that are immunoreactive to calbindin or calretinin. Taken together, the model results provide an experimentally testable hypothesis for the behavior of two interneuron types under attentional modulation.

scholarly journals In your phase: neural phase synchronisation underlies visual imagery of faces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrés Canales-Johnson ◽  
Renzo C. Lanfranco ◽  
Juan Pablo Morales ◽  
David Martínez-Pernía ◽  
Joaquín Valdés ◽  
...  
Keyword(s):  
Long Range ◽  
Visual Imagery ◽  
Brain Activity ◽  
Neural Connectivity ◽  
Frequency Range ◽  
Subjective Impression ◽  
Gamma Frequency ◽  
Gamma Range ◽  
Theta Frequency ◽  
Socially Relevant

AbstractMental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of “seeing with the mind’s eye”. In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli has not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.

scholarly journals Altered effective connectivity in migraine patients during emotional stimuli: a multi-frequency magnetoencephalography study

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Jing Ren ◽  
Qun Yao ◽  
Minjie Tian ◽  
Feng Li ◽  
Yueqiu Chen ◽  
...  
Keyword(s):  
Brain Activity ◽  
Effective Connectivity ◽  
Temporal Cortex ◽  
Primary Headache ◽  
Clustering Coefficient ◽  
Frequency Range ◽  
Emotional Stimuli ◽  
Emotional Modulation ◽  
Gamma Frequency ◽  
Wide Range

Abstract Background Migraine is a common and disabling primary headache, which is associated with a wide range of psychiatric comorbidities. However, the mechanisms of emotion processing in migraine are not fully understood yet. The present study aimed to investigate the neural network during neutral, positive, and negative emotional stimuli in the migraine patients. Methods A total of 24 migraine patients and 24 age- and sex-matching healthy controls were enrolled in this study. Neuromagnetic brain activity was recorded using a whole-head magnetoencephalography (MEG) system upon exposure to human facial expression stimuli. MEG data were analyzed in multi-frequency ranges from 1 to 100 Hz. Results The migraine patients exhibited a significant enhancement in the effective connectivity from the prefrontal lobe to the temporal cortex during the negative emotional stimuli in the gamma frequency (30–90 Hz). Graph theory analysis revealed that the migraine patients had an increased degree and clustering coefficient of connectivity in the delta frequency range (1–4 Hz) upon exposure to positive emotional stimuli and an increased degree of connectivity in the delta frequency range (1–4 Hz) upon exposure to negative emotional stimuli. Clinical correlation analysis showed that the history, attack frequency, duration, and neuropsychological scales of the migraine patients had a negative correlation with the network parameters in certain frequency ranges. Conclusions The results suggested that the individuals with migraine showed deviant effective connectivity in viewing the human facial expressions in multi-frequencies. The prefrontal-temporal pathway might be related to the altered negative emotional modulation in migraine. These findings suggested that migraine might be characterized by more universal altered cerebral processing of negative stimuli. Since the significant result in this study was frequency-specific, more independent replicative studies are needed to confirm these results, and to elucidate the neurocircuitry underlying the association between migraine and emotional conditions.

Phasic basal ganglia activity associated with high-gamma oscillation during sleep in a songbird

2012 ◽  
Vol 107 (1) ◽  
pp. 424-432 ◽  
Author(s):  
Shin Yanagihara ◽  
Neal A. Hessler
Keyword(s):  
Basal Ganglia ◽  
Phase Locking ◽  
Critical Role ◽  
Field Potential ◽  
Vocal Plasticity ◽  
Song System ◽  
Gamma Frequency ◽  
High Gamma ◽  
Area X

The basal ganglia is thought to be critical for motor control and learning in mammals. In specific basal ganglia regions, gamma frequency oscillations occur during various behavioral states, including sleeping periods. Given the critical role of sleep in regulating vocal plasticity of songbirds, we examined the presence of such oscillations in the basal ganglia. In the song system nucleus Area X, epochs of high-gamma frequency (80–160 Hz) oscillation of local field potential during sleep were associated with phasic increases of neural activity. While birds were awake, activity of the same neurons increased specifically when birds were singing. Furthermore, during sleep there was a clear tendency for phase locking of spikes to these oscillations. Such patterned activity in the sleeping songbird basal ganglia could play a role in off-line processing of song system motor networks.

Gamma frequency range based EEG analysis for epilepsy detection

2010 ◽  
Vol 2 (1) ◽  
pp. 15 ◽  
Author(s):  
Y. Padmasai ◽  
K. Subba Rao ◽  
C. Raghavendra Rao ◽  
S. Sita Jayalakshmi
Keyword(s):  
Eeg Analysis ◽  
Frequency Range ◽  
Gamma Frequency

scholarly journals Divergent paths to seizure-like events

2019 ◽  
Author(s):  
Neela K. Codadu ◽  
Robert Graham ◽  
Richard J. Burman ◽  
R. Thomas Jackson-Taylor ◽  
Joseph V. Raimondo ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Brain Slices ◽  
Field Potential ◽  
Gamma Frequency ◽  
Adult Mice ◽  
Epileptiform Discharges ◽  
Seizure Models ◽  
High Gamma ◽  
Interictal Discharges

AbstractAimMuch debate exists about how the brain transitions into an epileptic seizure. One source of confusion is that there are likely to be critical differences between experimental seizure models. To address this, we compared the evolving activity patterns in two, widely used, in vitro models of epileptic discharges.MethodsWe compared brain slices, prepared in the same way from young adult mice, that were bathed either in 0 Mg2+, or 100µM 4AP, artificial cerebrospinal fluid.ResultsWe find that while local field potential recordings of epileptiform discharges in the two models appear broadly similar, patch-clamp analysis reveals an important difference in the relative degree of glutamatergic involvement. 4AP affects parvalbumin-expressing interneurons more than other cortical populations, destabilizing their resting state and inducing spontaneous bursting behavior. Consequently, the most prominent pattern of transient discharge (“interictal event”) in this model is almost purely GABAergic, although the transition to seizure-like events (SLEs) involves pyramidal recruitment. In contrast, interictal discharges in 0 Mg2+ are only maintained by a very large glutamatergic component that also involves transient discharges of the interneurons. Seizure-like events in 0 Mg2+ have significantly higher power in the high gamma frequency band (60-120Hz) than these events do in 4AP, and are greatly delayed in onset by diazepam, unlike 4AP events.ConclusionsThe 0 Mg2+ and 4AP models display fundamentally different levels of glutamatergic drive, demonstrating how ostensibly similar pathological discharges can arise from different sources. We contend that similar interpretative issues will also be relevant to clinical practice.

Eye Therapy Effects on Visual Stress based on Electroencephalogram Signals

2015 ◽  
Vol 74 (6) ◽  
Author(s):  
Norlaili Mat Safri ◽  
Siti Nurainn Fayyadhah Adnan
Keyword(s):  
Frequency Band ◽  
Eye Drops ◽  
Search Performance ◽  
Visual Test ◽  
Test Task ◽  
Computer Screen ◽  
Gamma Frequency ◽  
Visual Stress ◽  
Eeg Data ◽  
High Gamma

Eye therapy such as eye massages, has been designed to reduce eye problems and improve blood circulation of the eyes. When reading, the signs and symptoms of visual exhaustion are related to visual stress and people may make use of eye therapy to reduce this visual stress. It is well-known that a relaxed mind can be analysed via the study of an electroencephalogram signal. In this paper, we investigated the effect of eye therapy on visual stress by analysing brain signals (EEG) in frequency domain. Ten subjects participated. In the control task, subjects were asked to relax while EEG data were captured for two minutes. The next part was a visual test task, where the subjects were asked to search for a specific word in a text displayed on a computer screen while their EEG data were recorded. One visual test was performed without prior eye therapy, while the other three visual test tasks were performed following different eye therapy routines. The visual test task was completed fastest when subjects received eye drops and eye massages prior to the visual test. The difference between the visual test with and without prior eye therapy can be observed in the high-gamma frequency band, where with eye therapy, the high-gamma frequency band significantly increases in the frontal, temporal and occipital areas, and the word search performance was improved, with a shorter time needed to complete the task. In conclusion, the high-gamma frequency band may be an indicator to study visual stress, while specific eye-therapy routines may contribute to better eye and brain performance in word searching in a text displayed on a computer screen.

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

2017 ◽  
Author(s):  
Malte Wöstmann ◽  
Johannes Vosskuhl ◽  
Jonas Obleser ◽  
Christoph S. Herrmann
Keyword(s):  
Spatial Attention ◽  
Gamma Oscillations ◽  
Proof Of Concept ◽  
Functional Roles ◽  
Dichotic Listening Task ◽  
High Gamma ◽  
Transcranial Alternating Current Stimulation ◽  
Human Participants ◽  
Listening Task ◽  
Selection Of

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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