scholarly journals No evidence for entrainment: endogenous gamma oscillations and rhythmic flicker responses coexist in visual cortex

2020 ◽  
Author(s):  
Katharina Duecker ◽  
Tjerk P. Gutteling ◽  
Christoph S. Herrmann ◽  
Ole Jensen
Keyword(s):  
Visual Cortex ◽  
Human Brain ◽  
Visual Stimulation ◽  
Gamma Oscillations ◽  
Photic Stimulation ◽  
Neuronal Populations ◽  
Frequency Entrainment ◽  
Flicker Response ◽  
Neuronal Processes

AbstractMotivated by the plethora of studies associating gamma oscillations (∼30-100 Hz) with various neuronal processes, including inter-regional communication and neuroprotection, we asked if endogenous gamma oscillations in the human brain can be entrained by rhythmic photic stimulation. The photic drive produced a robust Magnetoencephalography (MEG) response in visual cortex up to frequencies of about 80 Hz. Strong, endogenous gamma oscillations were induced using moving grating stimuli as repeatedly shown in previous research. When superimposing the flicker and the gratings, there was no evidence for phase or frequency entrainment of the endogenous gamma oscillations by the photic drive. Rather – as supported by source modelling – our results show that the flicker response and the endogenous gamma oscillations coexist and are generated by different neuronal populations in visual cortex. Our findings challenge the notion that neuronal entrainment by visual stimulation generalises to cortical gamma oscillations.

scholarly journals Sensory-driven and spontaneous gamma oscillations engage distinct cortical circuitry

2016 ◽  
Vol 115 (4) ◽  
pp. 1821-1835 ◽  
Author(s):  
Cristin G. Welle ◽  
Diego Contreras
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Oscillation Amplitude ◽  
Gamma Oscillations ◽  
Gamma Oscillation ◽  
Inhibitory Neurons ◽  
Sensory Representation ◽  
Cortical Circuitry ◽  
Mouse Visual Cortex

Gamma oscillations are a robust component of sensory responses but are also part of the background spontaneous activity of the brain. To determine whether the properties of gamma oscillations in cortex are specific to their mechanism of generation, we compared in mouse visual cortex in vivo the laminar geometry and single-neuron rhythmicity of oscillations produced during sensory representation with those occurring spontaneously in the absence of stimulation. In mouse visual cortex under anesthesia (isoflurane and xylazine), visual stimulation triggered oscillations mainly between 20 and 50 Hz, which, because of their similar functional significance to gamma oscillations in higher mammals, we define here as gamma range. Sensory representation in visual cortex specifically increased gamma oscillation amplitude in the supragranular (L2/3) and granular (L4) layers and strongly entrained putative excitatory and inhibitory neurons in infragranular layers, while spontaneous gamma oscillations were distributed evenly through the cortical depth and primarily entrained putative inhibitory neurons in the infragranular (L5/6) cortical layers. The difference in laminar distribution of gamma oscillations during the two different conditions may result from differences in the source of excitatory input to the cortex. In addition, modulation of superficial gamma oscillation amplitude did not result in a corresponding change in deep-layer oscillations, suggesting that superficial and deep layers of cortex may utilize independent but related networks for gamma generation. These results demonstrate that stimulus-driven gamma oscillations engage cortical circuitry in a manner distinct from spontaneous oscillations and suggest multiple networks for the generation of gamma oscillations in cortex.

scholarly journals Balance between inhibitory cell types is necessary for flexible frequency switching in adult mouse visual cortex

2020 ◽  
Author(s):  
Justin W. M. Domhof ◽  
Paul H. E. Tiesinga
Keyword(s):  
Visual Cortex ◽  
Visual Stimulation ◽  
Time Window ◽  
Pyramidal Cells ◽  
Gamma Oscillations ◽  
Neuron Network ◽  
Beta Oscillations ◽  
Frequency Bands ◽  
Adult Mice ◽  
Gamma Rhythms

Neuronal networks in rodent primary visual cortex (V1) can generate oscillations in different frequency bands depending on the network state and the level of visual stimulation. High-frequency gamma rhythms, for example, dominate the network’s spontaneous activity in adult mice but are attenuated upon visual stimulation, during which the network switches to the beta band instead. The spontaneous LFP of juvenile mouse V1, however, mainly contains beta oscillations and presenting a stimulus does not elicit drastic changes in collective network oscillations. We study, in a spiking neuron network model, the mechanism in adult mice that allows for flexible switches between multiple frequency bands and contrast this to the network structure in juvenile mice that do not posses this flexibility. The model is comprised of excitatory pyramidal cells (PCs) and two types of inhibitory interneurons: the parvalbumin expressing (PV) interneuron, which produces gamma oscillations, and the somatostatin expressing (SOM) cell, which generates beta rhythms. Our model simulations suggest that both of these oscillations are generated by a pyramidal-interneuron gamma (PING) mechanism. Furthermore, prominent gamma and beta oscillations in, respectively, the spontaneous and visually evoked activity of the simulated network only occurred within the same network configuration when there was a balance between both types of interneurons so that SOM neurons are able to shape the dynamics of the pyramidal-PV cell subnetwork without dominating dynamics. Taken together, our results demonstrate that the effective strengths of PV and SOM cells must be balanced for experimentally observed V1 dynamics in adult mice. Moreover, since spontaneous gamma rhythms emerge during the well-known critical period, our findings support the notion that PV cells become integrated in the circuit of this cortical area during this time window and additionally indicate that this integration comprises an overall increase in their synaptic strength.

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.

Flexible Frequency Switching in Adult Mouse Visual Cortex Is Mediated by Competition between Parvalbumin and Somatostatin Expressing Interneurons

2021 ◽  
pp. 1-41
Author(s):  
Justin W. M. Domhof ◽  
Paul H. E. Tiesinga
Keyword(s):  
Visual Cortex ◽  
Network Model ◽  
Visual Stimulation ◽  
Field Potential ◽  
Pyramidal Cells ◽  
Gamma Oscillations ◽  
Neuron Network ◽  
Frequency Bands ◽  
Adult Mice ◽  
Beta Rhythms

Neuronal networks in rodent primary visual cortex (V1) can generate oscillations in different frequency bands depending on the network state and the level of visual stimulation. High-frequency gamma rhythms, for example, dominate the network's spontaneous activity in adult mice but are attenuated upon visual stimulation, during which the network switches to the beta band instead. The spontaneous local field potential (LFP) of juvenile mouse V1, however, mainly contains beta rhythms and presenting a stimulus does not elicit drastic changes in network oscillations. We study, in a spiking neuron network model, the mechanism in adult mice allowing for flexible switches between multiple frequency bands and contrast this to the network structure in juvenile mice that lack this flexibility. The model comprises excitatory pyramidal cells (PCs) and two types of interneurons: the parvalbumin-expressing (PV) and the somatostatinexpressing (SOM) interneuron. In accordance with experimental findings, the pyramidal-PV and pyramidal-SOM cell subnetworks are associated with gamma and beta oscillations, respectively. In our model, they are both generated via a pyramidal-interneuron gamma (PING) mechanism, wherein the PCs drive the oscillations. Furthermore, we demonstrate that large but not small visual stimulation activates SOM cells, which shift the frequency of resting-state gamma oscillations produced by the pyramidal-PV cell subnetwork so that beta rhythms emerge. Finally, we show that this behavior is obtained for only a subset of PV and SOM interneuron projection strengths, indicating that their influence on the PCs should be balanced so that they can compete for oscillatory control of the PCs. In sum, we propose a mechanism by which visual beta rhythms can emerge from spontaneous gamma oscillations in a network model of the mouse V1; for this mechanism to reproduce V1 dynamics in adult mice, balance between the effective strengths of PV and SOM cells is required.

scholarly journals The gamma response to colour hue in humans: Evidence from MEG

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243237
Author(s):  
Gavin Perry ◽  
Nathan W. Taylor ◽  
Philippa C. H. Bothwell ◽  
Colette C. Milbourn ◽  
Georgina Powell ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Frequency Response ◽  
Visual Stimulation ◽  
Gamma Oscillations ◽  
Colour Space ◽  
Long Wavelength ◽  
Gamma Frequency ◽  
Full Screen ◽  
Gamma Power ◽  
Oscillatory Response

It has recently been demonstrated through invasive electrophysiology that visual stimulation with extended patches of uniform colour generates pronounced gamma oscillations in the visual cortex of both macaques and humans. In this study we sought to discover if this oscillatory response to colour can be measured non-invasively in humans using magnetoencephalography. We were able to demonstrate increased gamma (40–70 Hz) power in response to full-screen stimulation with four different colour hues and found that the gamma response is particularly strong for long wavelength (i.e. red) stimulation, as was found in previous studies. However, we also found that gamma power in response to colour was generally weaker than the response to an identically sized luminance-defined grating. We also observed two additional responses in the gamma frequency: a lower frequency response around 25–35 Hz that showed fewer clear differences between conditions than the gamma response, and a higher frequency response around 70–100 Hz that was present for red stimulation but not for other colours. In a second experiment we sought to test whether differences in the gamma response between colour hues could be explained by their chromatic separation from the preceding display. We presented stimuli that alternated between each of the three pairings of the three primary colours (red, green, blue) at two levels of chromatic separation defined in the CIELUV colour space. We observed that the gamma response was significantly greater to high relative to low chromatic separation, but that at each level of separation the response was greater for both red-blue and red-green than for blue-green stimulation. Our findings suggest that the stronger gamma response to red stimulation cannot be wholly explained by the chromatic separation of the stimuli.

Neurofeedback Training of Gamma Oscillations in Monkey Primary Visual Cortex

2019 ◽  
Vol 29 (11) ◽  
pp. 4785-4802 ◽  
Author(s):  
L Chauvière ◽  
W Singer
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Stimulation ◽  
Brain Activity ◽  
Gamma Oscillations ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Feedback Signal ◽  
Sensory Cortices ◽  
Distinct Frequency

Abstract In humans, neurofeedback (NFB) training has been used extensively and successfully to manipulate brain activity. Feedback signals were derived from EEG, fMRI, MEG, and intracranial recordings and modifications were obtained of the BOLD signal, of the power of oscillatory activity in distinct frequency bands and of single unit activity. The purpose of the present study was to examine whether neuronal activity could also be controlled by NFB in early sensory cortices whose activity is thought to be influenced mainly by sensory input rather than volitional control. We trained 2 macaque monkeys to enhance narrow band gamma oscillations in the primary visual cortex by providing them with an acoustic signal that reflected the power of gamma oscillations in a preselected band and rewarding increases of the feedback signal. Oscillations were assessed from local field potentials recorded with chronically implanted microelectrodes. Both monkeys succeeded to raise gamma activity in the absence of visual stimulation in the selected frequency band and at the site from which the NFB signal was derived. This suggests that top–down signals are not confined to just modulate stimulus induced responses but can actually drive or facilitate the gamma generating microcircuits even in a primary sensory area.

MicroVolt Variations of The Human Brain (Quantitative Electroencephalography) Display Differential Torque Effects During West-East versus North-South Orientation in the Geomagnetic Field

2016 ◽  
Vol 12 (2) ◽  
pp. 4255-4259
Author(s):  
Michael A Persinger ◽  
David A Vares ◽  
Paula L Corradini
Keyword(s):  
Human Brain ◽  
Geomagnetic Field ◽  
Neuronal Cell ◽  
Single Subject ◽  
Additional Energy ◽  
Actual Measurement ◽  
Neuronal Processes ◽  
Basic Physics ◽  
Order Of Magnitude ◽  
The Moment

                The human brain was assumed to be an elliptical electric dipole. Repeated quantitative electroencephalographic measurements over several weeks were completed for a single subject who sat in either a magnetic eastward or magnetic southward direction. The predicted potential difference equivalence for the torque while facing perpendicular (west-to-east) to the northward component of the geomagnetic field (relative to facing south) was 4 μV. The actual measurement was 10 μV. The oscillation frequency around the central equilibrium based upon the summed units of neuronal processes within the cerebral cortices for the moment of inertia was 1 to 2 ms which are the boundaries for the action potential of axons and the latencies for diffusion of neurotransmitters. The calculated additional energy available to each neuron within the human cerebrum during the torque condition was ~10-20 J which is the same order of magnitude as the energy associated with action potentials, resting membrane potentials, and ligand-receptor binding. It is also the basic energy at the level of the neuronal cell membrane that originates from gravitational forces upon a single cell and the local expression of the uniaxial magnetic anisotropic constant for ferritin which occurs in the brain. These results indicate that the more complex electrophysiological functions that are strongly correlated with cognitive and related human properties can be described by basic physics and may respond to specific geomagnetic spatial orientation.

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