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 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 Comparison of tuning properties of gamma and high-gamma power in local field potential (LFP) versus electrocorticogram (ECoG) in visual cortex

2019 ◽  
Author(s):  
Agrita Dubey ◽  
Supratim Ray
Keyword(s):  
Visual Cortex ◽  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Orientation Contrast ◽  
High Gamma ◽  
Gamma Power ◽  
Electrocorticogram Ecog ◽  
Local Field Potential Lfp

AbstractElectrocorticogram (ECoG), obtained from macroelectrodes placed on the cortex, is typically used in drug-resistant epilepsy patients, and is increasingly being used to study cognition in humans. These studies often use power in gamma (30-70 Hz) or high-gamma (>80 Hz) ranges to make inferences about neural processing. However, while the stimulus tuning properties of gamma/high-gamma power have been well characterized in local field potential (LFP; obtained from microelectrodes), analogous characterization has not been done for ECoG. Using a hybrid array containing both micro and ECoG electrodes implanted in the primary visual cortex of two female macaques, we compared the stimulus tuning preferences of gamma/high-gamma power in LFP versus ECoG and found them to be surprisingly similar. High-gamma power, thought to index the average firing rate around the electrode, was highest for the smallest stimulus (0.3° radius), and decreased with increasing size in both LFP and ECoG, suggesting local origins of both signals. Further, gamma oscillations were similarly tuned in LFP and ECoG to stimulus orientation, contrast and spatial frequency. This tuning was significantly weaker in electroencephalogram (EEG), suggesting that ECoG is more like LFP than EEG. Overall, our results validate the use of ECoG in clinical and basic cognitive research.

scholarly journals Orientation and color tuning of the human visual gamma rhythm

2021 ◽  
Author(s):  
Ye Li ◽  
William Bosking ◽  
Michael S Beauchamp ◽  
Sameer A Sheth ◽  
Daniel Yoshor ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Large Scale ◽  
Brain Activity ◽  
Population Level ◽  
Gamma Oscillations ◽  
Cell Orientation ◽  
Population Activity ◽  
Color Tuning ◽  
Human Visual Cortex ◽  
Gamma Rhythm

Narrowband gamma oscillations (NBG: ~20-60Hz) in visual cortex reflect rhythmic fluctuations in population activity generated by underlying circuits tuned for stimulus location, orientation, and color. Consequently, the amplitude and frequency of induced NBG activity is highly sensitive to these stimulus features. For example, in the non-human primate, NBG displays biases in orientation and color tuning at the population level. Such biases may relate to recent reports describing the large-scale organization of single-cell orientation and color tuning in visual cortex, thus providing a potential bridge between measurements made at different scales. Similar biases in NBG population tuning have been predicted to exist in the human visual cortex, but this has yet to be fully examined. Using intracranial recordings from human visual cortex, we investigated the tuning of NBG to orientation and color, both independently and in conjunction. NBG was shown to display a cardinal orientation bias (horizontal) and also an end- and mid-spectral color bias (red/blue and green). When jointly probed, the cardinal bias for orientation was attenuated and an end-spectral preference for red and blue predominated. These data both elaborate on the close, yet complex, link between the population dynamics driving NBG oscillations and known feature selectivity biases in visual cortex, adding to a growing set of stimulus dependencies associated with the genesis of NBG. Together, these two factors may provide a fruitful testing ground for examining multi-scale models of brain activity, and impose new constraints on the functional significance of the visual gamma rhythm.

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.

scholarly journals Functionally Distinct Gamma Range Activity Revealed by Stimulus Tuning in Human Visual Cortex

2019 ◽  
Vol 29 (20) ◽  
pp. 3345-3358.e7 ◽  
Author(s):  
Eleonora Bartoli ◽  
William Bosking ◽  
Yvonne Chen ◽  
Ye Li ◽  
Sameer A. Sheth ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Human Visual Cortex ◽  
Gamma Range

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.

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