scholarly journals Causally investigating cortical dynamics and signal processing by targeting natural system attractors with precisely timed stimulation

2018 ◽  
Author(s):  
Dmitriy Lisitsyn ◽  
Udo A. Ernst
Keyword(s):  
Visual Cortex ◽  
Cognitive Processing ◽  
Brain Activity ◽  
Intrinsic Noise ◽  
Visual Signals ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Response Characteristics ◽  
Stimulation Pulse ◽  
Signal Routing

1AbstractElectrical stimulation is a promising tool for interacting with neuronal dynamics to identify neural mechanisms that underlie cognitive function. Since effects of a single short stimulation pulse typically vary greatly and depend on the current network state, many experimental paradigms have rather resorted to continuous or periodic stimulation in order to establish and maintain a desired effect. However, such an approach explicitly leads to forced and ‘unnatural’ brain activity. Further, continuous stimulation can make it hard to parse the recorded activity and separate neural signal from stimulation artifacts. In this study we propose an alternate strategy: by monitoring a system in realtime, we use the existing preferred states or attractors of the network and to apply short and precise pulses in order to switch between its preferred states. When pushed into one of its attractors, one can use the natural tendency of the system to remain in such a state to prolong the effect of a stimulation pulse, opening a larger window of opportunity to observe the consequences on cognitive processing. To elaborate on this idea, we consider flexible information routing in the visual cortex as a prototypical example. When processing a stimulus, neural populations in the visual cortex have been found to engage in synchronized gamma activity. In this context, selective signal routing is achieved by changing the relative phase between oscillatory activity in sending and receiving populations (communication through coherence, CTC). In order to explore how perturbations interact with CTC, we investigate a biophysically realistic network exhibiting similar synchronization and signal routing phenomena. We develop a closed-loop stimulation paradigm based on the phase-response characteristics of the network and demonstrate its ability to establish desired synchronization states. By measuring information content throughout the model, we evaluate the effect of signal contamination caused by the stimulation in relation to the magnitude of the injected pulses and intrinsic noise in the system. Finally, we demonstrate that, up to a critical noise level, precisely timed perturbations can be used to artificially induce the effect of attention by selectively routing visual signals to higher cortical areas.

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.

Auditory modulation of oscillatory activity in extra-striate visual cortex and its contribution to audio–visual multisensory integration: A human intracranial EEG study

2012 ◽  
Vol 25 (0) ◽  
pp. 198
Author(s):  
Manuel R. Mercier ◽  
John J. Foxe ◽  
Ian C. Fiebelkorn ◽  
John S. Butler ◽  
Theodore H. Schwartz ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Multisensory Integration ◽  
Multisensory Processing ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Additive Model ◽  
Oscillatory Activity ◽  
Time Frequency ◽  
Electrical Brain Activity ◽  
Sensory Cortices

Investigations have traditionally focused on activity in the sensory cortices as a function of their respective sensory inputs. However, converging evidence from multisensory research has shown that neural activity in a given sensory region can be modulated by stimulation of other so-called ancillary sensory systems. Both electrophysiology and functional imaging support the occurrence of multisensory processing in human sensory cortex based on the latency of multisensory effects and their precise anatomical localization. Still, due to inherent methodological limitations, direct evidence of the precise mechanisms by which multisensory integration occurs within human sensory cortices is lacking. Using intracranial recordings in epileptic patients () undergoing presurgical evaluation, we investigated the neurophysiological basis of multisensory integration in visual cortex. Subdural electrical brain activity was recorded while patients performed a simple detection task of randomly ordered Auditory alone (A), Visual alone (V) and Audio–Visual stimuli (AV). We then performed time-frequency analysis: first we investigated each condition separately to evaluate responses compared to baseline, then we indexed multisensory integration using both the maximum criterion model (AV vs. V) and the additive model (AV vs. A+V). Our results show that auditory input significantly modulates neuronal activity in visual cortex by resetting the phase of ongoing oscillatory activity. This in turn leads to multisensory integration when auditory and visual stimuli are simultaneously presented.

scholarly journals Lip movements entrain the observers’ low-frequency brain oscillations to facilitate speech intelligibility

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Hyojin Park ◽  
Christoph Kayser ◽  
Gregor Thut ◽  
Joachim Gross
Keyword(s):  
Visual Cortex ◽  
Speech Processing ◽  
Speech Intelligibility ◽  
Brain Activity ◽  
Low Frequency ◽  
Visual Speech ◽  
Visual Signals ◽  
Partial Coherence ◽  
Auditory Speech ◽  
Oscillatory Brain Activity

During continuous speech, lip movements provide visual temporal signals that facilitate speech processing. Here, using MEG we directly investigated how these visual signals interact with rhythmic brain activity in participants listening to and seeing the speaker. First, we investigated coherence between oscillatory brain activity and speaker’s lip movements and demonstrated significant entrainment in visual cortex. We then used partial coherence to remove contributions of the coherent auditory speech signal from the lip-brain coherence. Comparing this synchronization between different attention conditions revealed that attending visual speech enhances the coherence between activity in visual cortex and the speaker’s lips. Further, we identified a significant partial coherence between left motor cortex and lip movements and this partial coherence directly predicted comprehension accuracy. Our results emphasize the importance of visually entrained and attention-modulated rhythmic brain activity for the enhancement of audiovisual speech processing.

scholarly journals Visual cortex responds to transient sound changes without encoding complex auditory dynamics

2019 ◽  
Author(s):  
David Brang ◽  
John Plass ◽  
Aleksandra Sherman ◽  
William C. Stacey ◽  
Vibhangini S. Wasade ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Auditory Cortex ◽  
Visual Signals ◽  
Oscillatory Activity ◽  
Auditory Signal ◽  
Auditory Information ◽  
Fine Grained ◽  
Neural Origin ◽  
Environmental Events ◽  
Visual Cortical

Sounds enhance visual cortical sensitivity for co-occurring visual signals. Previous research has demonstrated that this facilitation occurs through crossmodal modulations of cortical oscillatory activity. However, the neural origin of these signals and auditory information conveyed by this mechanism remain poorly understood. Using intracranial electroencephalography (iEEG) in humans, we examined the sensitivity of visual cortex to three different forms of auditory information: rhythmic entrainment to sounds, auditory onset responses, and auditory offset responses. Subcortical auditory neurons exhibit frequency following behaviors in response to amplitude-modulated sounds, with oscillatory activity entrained at the rhythmic rate of the auditory signal. This auditory response is paralleled in the visual system by the entrainment of visual neurons to the rhythmic rate of flashing strobe lights. In contrast, ~20% of neurons in auditory cortex do not entrain to amplitude modulations but respond only to the onsets and/or offsets of auditory stimuli. In visual cortex, amplitude-modulated sounds elicited transient onset and offset responses in multiple areas, but no entrainment to the sounds’ modulations frequencies. These results suggest that auditory information conveyed to visual cortex does not include temporally fine-grained stimulus dynamics encoded by the auditory midbrain and thalamus but, rather, a temporally segmented representation of auditory events that emerges only in auditory cortex. Crossmodal responses were maximal in low-level visual cortex, potentially implicating a direct pathway for rapid interactions between low-to-mid-level auditory and visual cortices. This mechanism may facilitate perception by time-locking visual computations to environmental events marked by discontinuities in auditory input.

scholarly journals Exploring alterations in sensory pathways in migraine

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Noemi Meylakh ◽  
Luke A. Henderson
Keyword(s):  
Visual Cortex ◽  
Sensory Processing ◽  
Brain Activity ◽  
Activity Patterns ◽  
Oscillatory Activity ◽  
Somatosensory Processing ◽  
Somatosensory Cortices ◽  
And Gender ◽  
The Right ◽  
Sensory Processes

Abstract Background Migraine is a neurological disorder characterized by intense, debilitating headaches, often coupled with nausea, vomiting and sensitivity to light and sound. Whilst changes in sensory processes during a migraine attack have been well-described, there is growing evidence that even between migraine attacks, sensory abilities are disrupted in migraine. Brain imaging studies have investigated altered coupling between areas of the descending pain modulatory pathway but coupling between somatosensory processing regions between migraine attacks has not been properly studied. The aim of this study was to determine if ongoing functional connectivity between visual, auditory, olfactory, gustatory and somatosensory cortices are altered during the interictal phase of migraine. Methods To explore the neural mechanisms underpinning interictal changes in sensory processing, we used functional magnetic resonance imaging to compare resting brain activity patterns and connectivity in migraineurs between migraine attacks (n = 32) and in healthy controls (n = 71). Significant differences between groups were determined using two-sample random effects procedures (p < 0.05, corrected for multiple comparisons, minimum cluster size 10 contiguous voxels, age and gender included as nuisance variables). Results In the migraine group, increases in infra-slow oscillatory activity were detected in the right primary visual cortex (V1), secondary visual cortex (V2) and third visual complex (V3), and left V3. In addition, resting connectivity analysis revealed that migraineurs displayed significantly enhanced connectivity between V1 and V2 with other sensory cortices including the auditory, gustatory, motor and somatosensory cortices. Conclusions These data provide evidence for a dysfunctional sensory network in pain-free migraine patients which may be underlying altered sensory processing between migraine attacks.

scholarly journals Perception of cuts in different editing styles

2021 ◽  
Author(s):  
Celia Andreu-Sánchez ◽  
Miguel-Ángel Martín-Pascual
Keyword(s):  
Visual Cortex ◽  
Electrical Activity ◽  
Cognitive Processing ◽  
Brain Activity ◽  
The Other ◽  
Music Video ◽  
Video Clips ◽  
Hollywood Movies ◽  
Initial Hypothesis ◽  
Processing Zone

The goal of this work is to explain how the cuts and their insertion in different editing styles influence the attention of viewers. The starting hypothesis is that viewers’ response to cuts varies depending on whether they watch a movie with a classical versus a messy or chaotic editing style. To undertake this investigation, we created three videos with the same narrative content and duration but different editing styles. One video was a fixed one-shot movie. Another video followed a classical editing style, based on the rules of classic Hollywood movies, according to David Bordwell’s studies. The other video used a chaotic style, beyond post-classic, which broke the classical rules of continuity and was inspired by music video clips. We showed these stimuli to 40 subjects while recording their brain activity using the electroencephalography (EEG) technique. The results showed that cuts reduce the eyeblink frequency during the second after they are seen. Since blinking is a well-known attention marker, we propose that cuts increase viewers’ attention. Cuts initiate a flow of electrical activity from the visual cortex to the cognitive processing zone in the prefrontal area. We also found that the different editing styles in which cuts are inserted affected perception, confirming the initial hypothesis. These results could be of great interest and utility for creators of audiovisual content and the management of attention in their work.

scholarly journals Exploring Alterations in Sensory Pathways in Migraine

2021 ◽  
Author(s):  
Noemi Meylakh ◽  
Luke A. Henderson
Keyword(s):  
Visual Cortex ◽  
Sensory Processing ◽  
Brain Activity ◽  
Activity Patterns ◽  
Oscillatory Activity ◽  
Somatosensory Processing ◽  
Somatosensory Cortices ◽  
And Gender ◽  
The Right ◽  
Sensory Processes

Abstract BackgroundMigraine is a neurological disorder characterized by intense, debilitating headaches, often coupled with nausea, vomiting and sensitivity to light and sound. Whilst changes in sensory processes during a migraine attack have been well-described, there is growing evidence that even between migraine attacks, sensory abilities are disrupted in migraine. Brain imaging studies have investigated altered coupling between areas of the descending pain modulatory pathway but coupling between somatosensory processing regions between migraine attacks has not been properly studied. The aim of this study was to determine if ongoing functional connectivity between visual, auditory, olfactory, gustatory and somatosensory cortices are altered during the interictal phase of migraine. MethodsTo explore the neural mechanisms underpinning interictal changes in sensory processing, we used functional magnetic resonance imaging to compare resting brain activity patterns and connectivity in migraineurs between migraine attacks (n= 32) and in healthy controls (n=71). Significant differences between groups were determined using two-sample random effects procedures (p<0.05, corrected for multiple comparisons, minimum cluster size 10 contiguous voxels, age and gender included as nuisance variables). ResultsIn the migraine group, increases in infra-slow oscillatory activity were detected in the right primary visual cortex (V1), secondary visual cortex (V2) and third visual complex (V3), and left V3. In addition, resting connectivity analysis revealed that migraineurs displayed significantly enhanced connectivity between V1 and V2 with other sensory cortices including the auditory, gustatory, motor and somatosensory cortices. ConclusionsThese data provide evidence for a dysfunctional sensory network in pain-free migraine patients which may be underlying altered sensory processing between migraine attacks.

Skipping Breakfast Affects the Early Steps of Cognitive Processing

2019 ◽  
Vol 33 (2) ◽  
pp. 109-118
Author(s):  
Andrés Antonio González-Garrido ◽  
Jacobo José Brofman-Epelbaum ◽  
Fabiola Reveca Gómez-Velázquez ◽  
Sebastián Agustín Balart-Sánchez ◽  
Julieta Ramos-Loyo
Keyword(s):  
Working Memory ◽  
Cognitive Processing ◽  
Task Difficulty ◽  
Brain Activity ◽  
Reaction Times ◽  
Brain Potentials ◽  
Brain Functioning ◽  
Attentional Processes ◽  
Electrical Brain Activity ◽  
Skipping Breakfast

Abstract. It has been generally accepted that skipping breakfast adversely affects cognition, mainly disturbing the attentional processes. However, the effects of short-term fasting upon brain functioning are still unclear. We aimed to evaluate the effect of skipping breakfast on cognitive processing by studying the electrical brain activity of young healthy individuals while performing several working memory tasks. Accordingly, the behavioral results and event-related brain potentials (ERPs) of 20 healthy university students (10 males) were obtained and compared through analysis of variances (ANOVAs), during the performance of three n-back working memory (WM) tasks in two morning sessions on both normal (after breakfast) and 12-hour fasting conditions. Significantly fewer correct responses were achieved during fasting, mainly affecting the higher WM load task. In addition, there were prolonged reaction times with increased task difficulty, regardless of breakfast intake. ERP showed a significant voltage decrement for N200 and P300 during fasting, while the amplitude of P200 notably increased. The results suggest skipping breakfast disturbs earlier cognitive processing steps, particularly attention allocation, early decoding in working memory, and stimulus evaluation, and this effect increases with task difficulty.

Intraoperative localization of spatially and spectrally distinct resting-state networks in Parkinson’s disease

2020 ◽  
Vol 132 (4) ◽  
pp. 1234-1242 ◽  
Author(s):  
Paolo Belardinelli ◽  
Ramin Azodi-Avval ◽  
Erick Ortiz ◽  
Georgios Naros ◽  
Florian Grimm ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Network Effects ◽  
Brain Activity ◽  
Dynamic Imaging ◽  
Oscillatory Activity ◽  
Network Information ◽  
Novel Approach ◽  
Electrophysiological Recordings ◽  
Intraoperative Localization

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for symptomatic Parkinson’s disease (PD); the clinical benefit may not only mirror modulation of local STN activity but also reflect consecutive network effects on cortical oscillatory activity. Moreover, STN-DBS selectively suppresses spatially and spectrally distinct patterns of synchronous oscillatory activity within cortical-subcortical loops. These STN-cortical circuits have been described in PD patients using magnetoencephalography after surgery. This network information, however, is currently not available during surgery to inform the implantation strategy.The authors recorded spontaneous brain activity in 3 awake patients with PD (mean age 67 ± 14 years; mean disease duration 13 ± 7 years) during implantation of DBS electrodes into the STN after overnight withdrawal of dopaminergic medication. Intraoperative propofol was discontinued at least 30 minutes prior to the electrophysiological recordings. The authors used a novel approach for performing simultaneous recordings of STN local field potentials (LFPs) and multichannel electroencephalography (EEG) at rest. Coherent oscillations between LFP and EEG sensors were computed, and subsequent dynamic imaging of coherent sources was performed.The authors identified coherent activity in the upper beta range (21–35 Hz) between the STN and the ipsilateral mesial (pre)motor area. Coherence in the theta range (4–6 Hz) was detected in the ipsilateral prefrontal area.These findings demonstrate the feasibility of detecting frequency-specific and spatially distinct synchronization between the STN and cortex during DBS surgery. Mapping the STN with this technique may disentangle different functional loops relevant for refined targeting during DBS implantation.

scholarly journals An Analysis of the External Validity of EEG Spectral Power in an Uncontrolled Outdoor Environment during Default and Complex Neurocognitive States

2021 ◽  
Vol 11 (3) ◽  
pp. 330
Author(s):  
Dalton J. Edwards ◽  
Logan T. Trujillo
Keyword(s):  
External Validity ◽  
Spectral Power ◽  
Brain Activity ◽  
Outdoor Environment ◽  
Oscillatory Activity ◽  
Brain State ◽  
Beta Band ◽  
Eeg Spectral Power ◽  
Eeg Power ◽  
Human Participants

Traditionally, quantitative electroencephalography (QEEG) studies collect data within controlled laboratory environments that limit the external validity of scientific conclusions. To probe these validity limits, we used a mobile EEG system to record electrophysiological signals from human participants while they were located within a controlled laboratory environment and an uncontrolled outdoor environment exhibiting several moderate background influences. Participants performed two tasks during these recordings, one engaging brain activity related to several complex cognitive functions (number sense, attention, memory, executive function) and the other engaging two default brain states. We computed EEG spectral power over three frequency bands (theta: 4–7 Hz, alpha: 8–13 Hz, low beta: 14–20 Hz) where EEG oscillatory activity is known to correlate with the neurocognitive states engaged by these tasks. Null hypothesis significance testing yielded significant EEG power effects typical of the neurocognitive states engaged by each task, but only a beta-band power difference between the two background recording environments during the default brain state. Bayesian analysis showed that the remaining environment null effects were unlikely to reflect measurement insensitivities. This overall pattern of results supports the external validity of laboratory EEG power findings for complex and default neurocognitive states engaged within moderately uncontrolled environments.

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