Visual Grouping and the Focusing of Attention Induce Gamma-band Oscillations at Different Frequencies in Human Magnetoencephalogram Signals

2006 ◽  
Vol 18 (11) ◽  
pp. 1850-1862 ◽  
Author(s):  
Juan R. Vidal ◽  
Maximilien Chaumon ◽  
J. Kevin O'Regan ◽  
Catherine Tallon-Baudry
Keyword(s):  
Short Term Memory ◽  
Implementation Process ◽  
Visual Display ◽  
Gamma Oscillations ◽  
Gamma Band ◽  
Visual Grouping ◽  
Gamma Range ◽  
High Gamma ◽  
The One ◽  
Attentional Filter

Neural oscillatory synchrony could implement grouping processes, act as an attentional filter, or foster the storage of information in short-term memory. Do these findings indicate that oscillatory synchrony is an unspecific epiphenomenon occurring in any demanding task, or that oscillatory synchrony is a fundamental mechanism involved whenever neural cooperation is requested? If the latter hypothesis is true, then oscillatory synchrony should be specific, with distinct visual processes eliciting different types of oscillations. We recorded magnetoencephalogram (MEG) signals while manipulating the grouping properties of a visual display on the one hand, and the focusing of attention to memorize part of this display on the other hand. Grouping-related gamma oscillations were present in all conditions but modulated by the grouping properties of the stimulus (one or two groups) in the high gamma-band (70–120 Hz) at central occipital locations. Attention-related gamma oscillations appeared as an additional component whenever attentional focusing was requested in the low gamma-band (44–66 Hz) at parietal locations. Our results thus reveal the existence of a functional specialization in the gamma range, with grouping-related oscillations showing up at higher frequencies than attention-related oscillations. The pattern of oscillatory synchrony is thus specific of the visual process it is associated with. Our results further suggest that both grouping processes and focused attention rely on a common implementation process, namely, gamma-band oscillatory synchrony, a finding that could account for the fact that coherent percepts are more likely to catch attention than incoherent ones.

scholarly journals The visual cortex produces a signal in the gamma band in response to broadband visual flicker

2021 ◽  
Author(s):  
Alexander Zhigalov ◽  
Katharina Duecker ◽  
Ole Jensen
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Gamma Oscillations ◽  
Early Response ◽  
Dominant Frequency ◽  
Gamma Band ◽  
Input Current ◽  
Alpha Band ◽  
Constant Input ◽  
Gamma Range

AbstractThe aim of this study is to uncover the network dynamics of the human visual cortex by driving it with a broadband random visual flicker. We here applied a broadband flicker (1–720 Hz) while measuring the MEG and then estimated the temporal response function (TRF) between the visual input and the MEG response. This TRF revealed an early response in the 40–60 Hz gamma range as well as in the 8–12 Hz alpha band. While the gamma band response is novel, the latter has been termed the alpha band perceptual echo. The gamma echo preceded the alpha perceptual echo. The dominant frequency of the gamma echo was subject-specific thereby reflecting the individual dynamical properties of the early visual cortex. To understand the neuronal mechanisms generating the gamma echo, we implemented a pyramidal-interneuron gamma (PING) model that produces gamma oscillations in the presence of constant input currents. Applying a broadband input current mimicking the visual stimulation allowed us to estimate TRF between the input current and the population response (akin to the local field potentials). The TRF revealed a gamma echo that was similar to the one we observed in the MEG data. Our results suggest that the visual gamma echo can be explained by the dynamics of the PING model even in the absence of sustained gamma oscillations.

scholarly journals The visual cortex produces gamma band echo in response to broadband visual flicker

2021 ◽  
Vol 17 (6) ◽  
pp. e1009046
Author(s):  
Alexander Zhigalov ◽  
Katharina Duecker ◽  
Ole Jensen
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Gamma Oscillations ◽  
Early Response ◽  
Dominant Frequency ◽  
Gamma Band ◽  
Input Current ◽  
Alpha Band ◽  
Constant Input ◽  
Gamma Range

The aim of this study is to uncover the network dynamics of the human visual cortex by driving it with a broadband random visual flicker. We here applied a broadband flicker (1–720 Hz) while measuring the MEG and then estimated the temporal response function (TRF) between the visual input and the MEG response. This TRF revealed an early response in the 40–60 Hz gamma range as well as in the 8–12 Hz alpha band. While the gamma band response is novel, the latter has been termed the alpha band perceptual echo. The gamma echo preceded the alpha perceptual echo. The dominant frequency of the gamma echo was subject-specific thereby reflecting the individual dynamical properties of the early visual cortex. To understand the neuronal mechanisms generating the gamma echo, we implemented a pyramidal-interneuron gamma (PING) model that produces gamma oscillations in the presence of constant input currents. Applying a broadband input current mimicking the visual stimulation allowed us to estimate TRF between the input current and the population response (akin to the local field potentials). The TRF revealed a gamma echo that was similar to the one we observed in the MEG data. Our results suggest that the visual gamma echo can be explained by the dynamics of the PING model even in the absence of sustained gamma oscillations.

scholarly journals Hippocampal gamma-band oscillopathy in a mouse model of Fragile X Syndrome

2021 ◽  
Author(s):  
Evangelia Pollali ◽  
Jan-Oliver Hollnagel ◽  
Guersel Caliskan
Keyword(s):  
Signaling Pathways ◽  
Fragile X Syndrome ◽  
Metabotropic Glutamate Receptor ◽  
Fragile X ◽  
Muscarinic Acetylcholine Receptor ◽  
Gamma Oscillations ◽  
Gamma Band ◽  
Gamma Range ◽  
Dependent Learning

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability arising from the loss of fragile X mental retardation protein (FMRP), a protein that plays a central role in neuronal function and plasticity. FXS patients show sensory hypersensitivity, hyperarousal and hippocampus-dependent learning deficits that can be recapitulated in the FMR1 KO mice. Enhanced metabotropic glutamate receptor (mGluR) signaling and muscarinic acetylcholine receptor (mAChR) signaling in the FMR1 KO mouse are implicated as the primary causes of the disease pathogenesis. Furthermore, glutamatergic kainate receptor (KAR) function is reduced in the cortex of the FMR1 KO mice. Of note, activation of these signaling pathways leads to slow gamma-range oscillations in the hippocampus in vitro and abnormal gamma oscillations have been reported in FMR1 KO mice and patients with FXS. Thus, we hypothesized that aberrant activation of these receptors leads to the observed gamma oscillopathy. We recorded gamma oscillations induced by either cholinergic agonist carbachol (CCh), mGluR1/5 agonist Dihydroxyphenylglycine (DHPG) or ionotropic glutamatergic agonist KA from the hippocampal CA3 in WT and FMR1 KO mice in vitro. We show a specific increase in the power of DHPG- and CCh-induced gamma oscillations and reduction in the synchronicity of gamma oscillations induced by KA. We further elucidate an aberrant spiking activity during CCh-induced and kainate-induced gamma oscillations which may underlie the altered gamma oscillation synchronization in the FMR1 KO mice. Last, we also noted a reduced incidence of spontaneously-occurring hippocampal sharp wave-ripple events. Our study provides further evidence for aberrant hippocampal rhythms in the FMR1 KO mice and identifies potential signaling pathways underlying gamma band oscillopathy in FXS.

scholarly journals Distinct Narrow and Broadband Gamma Responses in Human Visual Cortex

2019 ◽  
Author(s):  
Eleonora Bartoli ◽  
William Bosking ◽  
Ye Li ◽  
Michael S. Beauchamp ◽  
Daniel Yoshor ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Critical Role ◽  
Visual Stimuli ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Systematic Change ◽  
Human Visual Cortex ◽  
Gamma Range ◽  
High Gamma ◽  
Differential Properties

AbstractHigh frequency activity (> 30 Hz) in the neocortical local field potential, typically referred to as the ‘gamma’ range, is thought to have a critical role in visual perception and cognition more broadly. Historically, animal studies recording from visual cortex documented clear narrowband gamma oscillations (NBG; ∼20-60 Hz) in response to visual stimuli. However, invasive measurements from human neocortex have highlighted a different broadband or ‘high’ gamma response (BBG; ∼70-150+ Hz). Growing evidence suggests these two forms of gamma response are distinct, but often conceptually or analytically conflated as the same ‘gamma’ response. Furthermore, recent debate has highlighted that both the occurrence and spectral properties of gamma band activity in visual cortex appears to be dependent on the attributes and class of presented visual stimuli. Using high-density intracranial recordings from human visual cortex, we integrate and extend these findings, dissociating the spectral, temporal and functional properties of NBG and BBG activity. We report results from two experiments, manipulating visual stimulus attributes (contrast-varying gratings) and class (object categories) dissecting the differential properties of NBG and BBG responses. NBG oscillations were only reliably recorded for grating stimuli, while their peak frequency varied with contrast level. Whereas BBG activity was observed in response to all stimulus classes tested, with no systematic change in its spectral features. Temporally, induced NBG was sustained throughout stimulus presentation, in opposition to a more transient response for the BBG. These findings challenge the ubiquity of ‘gamma’ activity in visual cortex, by clearly dissociating oscillatory and broadband effects.Significance StatementNeocortical narrowband gamma oscillations (∼20-60 Hz) have been implicated in vision and cognition as a mechanism for synchronizing brain regions. Efforts to study this phenomenon have revealed an additional ‘high-gamma’ range response (∼70-150+ Hz), which is broadband and non-oscillatory. These different gamma range activities are often conflated in support of the same functional role. Using invasive recordings from human visual cortex, we show that narrow and broadband gamma can be dissociated by spectral, temporal and functional response properties. While broadband gamma responses were more transient to the presentation of all stimuli, narrowband gamma responses were sustained and only occurred reliably to grating stimuli. These differences have important implications for the study, analysis and interpretation of neocortical gamma range activity.

scholarly journals Thalamocortical transmission of visual information in awake mice involves phase synchronization and spike synchrony at high gamma frequencies

2017 ◽  
Author(s):  
Samuel S. McAfee ◽  
Yu Liu ◽  
Mukesh Dhamala ◽  
Detlef H. Heck
Keyword(s):  
Sensory Processing ◽  
Spike Activity ◽  
Visual Information ◽  
Gamma Oscillations ◽  
High Contrast ◽  
Beta Oscillations ◽  
Gamma Frequency ◽  
Gamma Range ◽  
High Gamma ◽  
The Brain

Abstract:Synchronization of neuronal spike activity is thought to play a key role in the transmission of information for sensory processing in the brain, and this synchronization is influenced by oscillatory population activity occurring in multiple frequency ranges at multiple stages of sensory pathways. In the neocortex, gamma frequency oscillations appear to play an important role in synchronizing neuronal ensembles and allowing for selective communication between regions, yet relatively little is known about whether gamma oscillations facilitate transmission of sensory information from thalamus to cortex. Here, we investigate the role of gamma oscillations in promoting synchronous spike activity between the visual thalamus (dLGN) and primary visual cortex (V1) in awake mice, a model sensory system with prominent gamma oscillations that are modulated by visual input. We demonstrate that transmission of visual information to cortex involves phase-synchronized oscillations in the high gamma range (50-90Hz), with concomitant millisecond-scale synchronization of thalamic and cortical spike activity. Transition from a full-field gray image to a high-contrast checkerboard image caused gamma activity to rapidly increase in amplitude, frequency, and bandwidth, yet the gamma oscillations in dLGN and V1 maintained a consistent phase relationship. High contrast stimulation also caused an increase in amplitude of oscillations in the beta and low gamma range, but those were not associated with synchronous thalamic activity. These results indicate a role for high gamma oscillations in mediating the functional connectivity between thalamic and cortical neurons in the visual pathway, a similar role to beta oscillations in primates.Significance statement:The mechanisms by which neurons selectively communicate are essential to our understanding of how the brain processes information. Abundant evidence suggests that cortical sensory processing involves the synchronization of high frequency electric field oscillations known as gamma oscillations, which allow groups of neurons to synchronize their spike activity in order to collaboratively process sensory input. Here, we show that oscillations and spikes in the visual thalamocortical pathway of the mouse exhibit synchrony across a broad high gamma frequency range (50-90Hz), suggesting these oscillations play an important role in the relay of visual information to the cortex. This is substantially different from oscillations observed in monkeys, in which gamma is absent in thalamus and beta oscillations support thalamocortical relay.

scholarly journals Case Report: High-Gamma Oscillations on an Ictal Electroencephalogram in a Newborn Patient With Hypoxic–Ischemic Encephalopathy

2021 ◽  
Vol 9 ◽  
Author(s):  
Akihito Takeuchi ◽  
Takushi Inoue ◽  
Makoto Nakamura ◽  
Misao Kageyama ◽  
Tomoyuki Akiyama ◽  
...  
Keyword(s):  
Animal Studies ◽  
Gamma Oscillations ◽  
Gamma Band ◽  
Lower Limbs ◽  
Hypoxic Ischemic Encephalopathy ◽  
Neonatal Seizures ◽  
Time Frequency ◽  
Emergency Cesarean ◽  
High Gamma ◽  
Ischemic Encephalopathy

Fast oscillations (FOs) >40 Hz in electroencephalograms (EEGs) are associated with ictogenesis and epileptogenesis in adults and children with epilepsy. However, only a few previous studies showed FOs in neonates. Reported frequencies of such neonatal FOs were in the low-gamma (<60 Hz) band and, therefore, they were not high compared to those in pediatric patients. We herein report a newborn patient with severe hypoxic–ischemic encephalopathy (HIE), who showed pathological FOs with a frequency in the high-gamma band. She was born at a gestational age of 39 weeks 4 days by emergency cesarean section because of non-reassuring fetal status. She had focal motor seizures involving unilateral upper and lower limbs lasting for tens of seconds on days 0, 1, 4, 5, 8, and 9 and subclinical seizures on days 4–11. Phenobarbital (PB) was intravenously administered on days 0, 2, 4, 5, and 6. We found FOs that were superimposed on the ictal delta activities using visual inspection and time–frequency analysis on 8–11 days of age. Among them, we detected high-gamma (71.4–100 Hz) oscillations that appeared to be temporally independent of low-gamma activities in the ictal EEG on 11 days of age. To the best of our knowledge, this is one of the earliest reports showing pathological FOs with a frequency of >60 Hz in the high-gamma band in human neonatal seizures, which were previously observed in animal studies. Further studies are needed to elucidate the pathophysiology of ictal FOs in neonatal seizures.

scholarly journals Prediction of Speech Onset by Micro-Electrocorticography of the Human Brain

2021 ◽  
pp. 2150025
Author(s):  
Emanuela Delfino ◽  
Aldo Pastore ◽  
Elena Zucchini ◽  
Maria Francisca Porto Cruz ◽  
Tamara Ius ◽  
...  
Keyword(s):  
Motor Preparation ◽  
Gamma Oscillations ◽  
Design Parameters ◽  
Technological Advances ◽  
High Gamma ◽  
Highly Correlated ◽  
The One ◽  
Definition Of ◽  
Key Steps ◽  
Physiological Markers

Recent technological advances show the feasibility of offline decoding speech from neuronal signals, paving the way to the development of chronically implanted speech brain computer interfaces (sBCI). Two key steps that still need to be addressed for the online deployment of sBCI are, on the one hand, the definition of relevant design parameters of the recording arrays, on the other hand, the identification of robust physiological markers of the patient’s intention to speak, which can be used to online trigger the decoding process. To address these issues, we acutely recorded speech-related signals from the frontal cortex of two human patients undergoing awake neurosurgery for brain tumors using three different micro-electrocorticographic ([Formula: see text]ECoG) devices. First, we observed that, at the smallest investigated pitch (600[Formula: see text][Formula: see text]m), neighboring channels are highly correlated, suggesting that more closely spaced electrodes would provide some redundant information. Second, we trained a classifier to recognize speech-related motor preparation from high-gamma oscillations (70–150[Formula: see text]Hz), demonstrating that these neuronal signals can be used to reliably predict speech onset. Notably, our model generalized both across subjects and recording devices showing the robustness of its performance. These findings provide crucial information for the design of future online sBCI.

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

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.

scholarly journals Identified Cellular Correlates of Neocortical Ripple and High-Gamma Oscillations during Spindles of Natural Sleep

Neuron ◽  
2016 ◽  
Vol 92 (4) ◽  
pp. 916-928 ◽  
Author(s):  
Robert G. Averkin ◽  
Viktor Szemenyei ◽  
Sándor Bordé ◽  
Gábor Tamás
Keyword(s):  
Gamma Oscillations ◽  
Natural Sleep ◽  
High Gamma
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