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 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 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 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.

scholarly journals Spike Frequency Adaptation Affects the Synchronization Properties of Networks of Cortical Oscillators

1998 ◽  
Vol 10 (4) ◽  
pp. 837-854 ◽  
Author(s):  
Sharon M. Crook ◽  
G. Bard Ermentrout ◽  
James M. Bower
Keyword(s):  
Pyramidal Cells ◽  
Rhythmic Activity ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Frequency Range ◽  
Cortical Dynamics ◽  
Gamma Frequency ◽  
Frequency Adaptation ◽  
Theta Frequency ◽  
Synchronous Behavior

Oscillations in many regions of the cortex have common temporal characteristics with dominant frequencies centered around the 40 Hz (gamma) frequency range and the 5–10 Hz (theta) frequency range. Experimental results also reveal spatially synchronous oscillations, which are stimulus dependent (Gray&Singer, 1987;Gray, König, Engel, & Singer, 1989; Engel, König, Kreiter, Schillen, & Singer, 1992). This rhythmic activity suggests that the coherence of neural populations is a crucial feature of cortical dynamics (Gray, 1994). Using both simulations and a theoretical coupled oscillator approach, we demonstrate that the spike frequency adaptation seen in many pyramidal cells plays a subtle but important role in the dynamics of cortical networks. Without adaptation, excitatory connections among model pyramidal cells are desynchronizing. However, the slow processes associated with adaptation encourage stable synchronous behavior.

Increased Gamma Oscillatory Activity in the Subthalamic Nucleus During Tremor in Parkinson's Disease Patients

2009 ◽  
Vol 101 (2) ◽  
pp. 789-802 ◽  
Author(s):  
M. Weinberger ◽  
W. D. Hutchison ◽  
A. M. Lozano ◽  
M. Hodaie ◽  
J. O. Dostrovsky
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Subthalamic Nucleus ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Neuronal Firing ◽  
Oscillatory Activity ◽  
Frequency Range ◽  
Resting Tremor ◽  
Gamma Frequency

Rest tremor is one of the main symptoms in Parkinson's disease (PD), although in contrast to rigidity and akinesia, the severity of the tremor does not correlate well with the degree of dopamine deficiency or the progression of the disease. Studies suggest that akinesia in PD patients is related to abnormal increased beta (15–30 Hz) and decreased gamma (35–80 Hz) synchronous oscillatory activity in the basal ganglia. Here we investigated the dynamics of oscillatory activity in the subthalamic nucleus (STN) during tremor. We used two adjacent microelectrodes to simultaneously record neuronal firing and local field potential (LFP) activity in nine PD patients who exhibited resting tremor during functional neurosurgery. We found that neurons exhibiting oscillatory activity at tremor frequency are located in the dorsal region of STN, where neurons with beta oscillatory activity are observed, and that their activity is coherent with LFP oscillations in the beta frequency range. Interestingly, in 85% of the 58 sites examined, the LFP exhibited increased oscillatory activity in the low gamma frequency range (35–55 Hz) during periods with stronger tremor. Furthermore, in 17 of 26 cases where two LFPs were recorded simultaneously, their coherence in the gamma range increased with increased tremor. When averaged across subjects, the ratio of the beta to gamma coherence was significantly lower in periods with stronger tremor compared with periods of no or weak tremor. These results suggest that resting tremor in PD is associated with an altered balance between beta and gamma oscillations in the motor circuits of STN.

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 Gamma Frequency–Range Abnormalities to Auditory Stimulation in Schizophrenia

1999 ◽  
Vol 56 (11) ◽  
pp. 1001 ◽  
Author(s):  
Jun Soo Kwon ◽  
Brian F. O'Donnell ◽  
Gene V. Wallenstein ◽  
Robert W. Greene ◽  
Yoshio Hirayasu ◽  
...  
Keyword(s):  
Auditory Stimulation ◽  
Frequency Range ◽  
Gamma Frequency

scholarly journals Strong gamma frequency oscillations in the adolescent prefrontal cortex

2021 ◽  
Author(s):  
Zhengyang Wang ◽  
Balbir Singh ◽  
Xin Zhou ◽  
Christos Constantinidis
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Adolescent Development ◽  
Adult Stage ◽  
Delay Period ◽  
Local Network ◽  
Frequency Range ◽  
Gamma Frequency ◽  
Power Increase ◽  
Gamma Power

AbstractWorking memory ability continues to mature into adulthood in both humans and non-human primates. At the single neuron level, adolescent development is characterized by increased prefrontal firing rate in the delay period, but less is known about how coordinated activity between neurons is altered. Local field potentials (LFP) provide a window into the computation carried out by the local network. To address the effects of adolescent development on LFP activity, three male rhesus monkeys were trained to perform an oculomotor delayed response task and tested at both the adolescent and adult stage. Simultaneous single-unit and LFP signals were recorded from areas 8a and 46 of the dorsolateral prefrontal cortex (dlPFC). In both the cue and delay period, power relative to baseline increased in the gamma frequency range (32 - 128 Hz). In the adult stage, high-firing neurons were also more likely to reside at sites with strong gamma power increase from baseline. For both stages, the gamma power increase in the delay was selective for sites with neuron encoding stimulus information in their spiking. Gamma power and neuronal firing did not show stronger temporal correlations. Our results establish gamma power decrease to be a feature of prefrontal cortical maturation.Significance StatementGamma-frequency oscillations in extracellular field recordings (such as LFP or EEG) are a marker of normal interactions between excitatory and inhibitory neurons in neural circuits. Abnormally low gamma power during working memory is seen in conditions such as schizophrenia. We sought to examine whether the immature prefrontal cortex similarly exhibits lower power in the gamma frequency range during working memory, in a non-human primate model of adolescence. Contrary to this expectation, the adolescent PFC exhibited stronger gamma power during the maintenance of working memory. Our findings reveal an unknown developmental maturation trajectory of gamma band oscillations and raise the possibility that schizophrenia represent an excessive state of prefrontal maturation.

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

2019 ◽  
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 have 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.

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