scholarly journals Brain Oscillation Entrainment by Perceptible and Non-perceptible Rhythmic Light Stimulation

2021 ◽  
Vol 2 ◽  
Author(s):  
Katharina Lingelbach ◽  
Alexander M. Dreyer ◽  
Isabel Schöllhorn ◽  
Michael Bui ◽  
Michael Weng ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Light Emitting Diode ◽  
Covert Attention ◽  
Oscillatory Activity ◽  
Attention Condition ◽  
Light Stimulation ◽  
Rhythmic Stimulation ◽  
Overt Attention ◽  
Central Regions ◽  
Rhythmic Light Stimulation

Objective and Background: Decades of research in the field of steady-state visual evoked potentials (SSVEPs) have revealed great potential of rhythmic light stimulation for brain–computer interfaces. Additionally, rhythmic light stimulation provides a non-invasive method for entrainment of oscillatory activity in the brain. Especially effective protocols enabling non-perceptible rhythmic stimulation and, thereby, reducing eye fatigue and user discomfort are favorable. Here, we investigate effects of (1) perceptible and (2) non-perceptible rhythmic light stimulation as well as attention-based effects of the stimulation by asking participants to focus (a) on the stimulation source directly in an overt attention condition or (b) on a cross-hair below the stimulation source in a covert attention condition.Method: SSVEPs at 10 Hz were evoked with a light-emitting diode (LED) driven by frequency-modulated signals and amplitudes of the current intensity either below or above a previously estimated individual threshold. Furthermore, we explored the effect of attention by asking participants to fixate on the LED directly in the overt attention condition and indirectly attend it in the covert attention condition. By measuring electroencephalography, we analyzed differences between conditions regarding the detection of reliable SSVEPs via the signal-to-noise ratio (SNR) and functional connectivity in occipito-frontal(-central) regions.Results: We could observe SSVEPs at 10 Hz for the perceptible and non-perceptible rhythmic light stimulation not only in the overt but also in the covert attention condition. The SNR and SSVEP amplitudes did not differ between the conditions and SNR values were in all except one participant above significance thresholds suggested by previous literature indicating reliable SSVEP responses. No difference between the conditions could be observed in the functional connectivity in occipito-frontal(-central) regions.Conclusion: The finding of robust SSVEPs even for non-intrusive rhythmic stimulation protocols below an individual perceptibility threshold and without direct fixation on the stimulation source reveals strong potential as a safe stimulation method for oscillatory entrainment in naturalistic applications.

scholarly journals LIP activity in the interstimulus interval of a change detection task biases the behavioral response

2015 ◽  
Vol 114 (5) ◽  
pp. 2637-2648 ◽  
Author(s):  
Fabrice Arcizet ◽  
Koorosh Mirpour ◽  
Daniel J. Foster ◽  
Caroline J. Charpentier ◽  
James W. Bisley
Keyword(s):  
Eye Movements ◽  
Change Detection ◽  
Behavioral Response ◽  
Interstimulus Interval ◽  
Detection Task ◽  
Covert Attention ◽  
Change Detection Task ◽  
Lateral Intraparietal Area ◽  
Overt Attention ◽  
The World

When looking around at the world, we can only attend to a limited number of locations. The lateral intraparietal area (LIP) is thought to play a role in guiding both covert attention and eye movements. In this study, we tested the involvement of LIP in both mechanisms with a change detection task. In the task, animals had to indicate whether an element changed during a blank in the trial by making a saccade to it. If no element changed, they had to maintain fixation. We examine how the animal's behavior is biased based on LIP activity prior to the presentation of the stimulus the animal must respond to. When the activity was high, the animal was more likely to make an eye movement toward the stimulus, even if there was no change; when the activity was low, the animal either had a slower reaction time or maintained fixation, even if a change occurred. We conclude that LIP activity is involved in both covert and overt attention, but when decisions about eye movements are to be made, this role takes precedence over guiding covert attention.

scholarly journals Effects of an active visuomotor steering task on covert attention

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Samuel Tuhkanen ◽  
Jami Pekkanen ◽  
Esko Lehtonen ◽  
Otto Lappi
Keyword(s):  
Driving Simulator ◽  
Peripheral Vision ◽  
Visual Scene ◽  
Covert Attention ◽  
Control Task ◽  
Complex Dynamic ◽  
The Road ◽  
Overt Attention ◽  
Active Steering ◽  
Complex Visual Stimulus

In complex dynamic tasks such as driving it is essential to be aware of potentially important targets in peripheral vision. While eye tracking methods in various driving tasks have provided much information about drivers’ gaze strategies, these methods only inform about overt attention and provide limited grounds to assess hypotheses concerning covert attention. We adapted the Posner cue paradigm to a dynamic steering task in a driving simulator. The participants were instructed to report the presence of peripheral targets while their gaze was fixed to the road. We aimed to see whether and how the active steering task and complex visual stimulus might affect directing covert attention to the visual periphery. In a control condition, the detection task was performed without a visual scene and active steering. Detection performance in bends was better in the control task compared to corresponding performance in the steering task, indicating that active steering and the complex visual scene affected the ability to distribute covert attention. Lower targets were discriminated slower than targets at the level of the fixation circle in both conditions. We did not observe higher discriminability for on-road targets. The results may be accounted for by either bottom-up optic flow biasing of attention, or top-down saccade planning.

scholarly journals Alterations in resting-state activity and functional connectivity in children with 22q11.2 deletion syndrome

2021 ◽  
Author(s):  
Joanne L Doherty ◽  
Adam C Cunningham ◽  
Samuel JRA Chawner ◽  
Hayley M Moss ◽  
Diana C Dima ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Genetic Risk ◽  
Risk Group ◽  
22Q11.2 Deletion Syndrome ◽  
High Risk Group ◽  
Oscillatory Activity ◽  
Deletion Syndrome ◽  
22Q11.2 Deletion ◽  
Band Activity

Background While genetic risk factors for psychiatric and neurodevelopmental disorders have been identified, the neurobiological route from genetic risk to neuropsychiatric outcome remains unclear. 22q11.2 deletion syndrome (22q11.2DS) is a copy number variant (CNV) syndrome associated with high rates of neurodevelopmental and psychiatric disorders including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and schizophrenia. Alterations in neural integration and cortical connectivity have been linked to the spectrum of neuropsychiatric disorders seen in 22q11.2DS and may be a mechanism by which the CNV acts to increase risk. Despite this, few studies have investigated electrophysiological connectivity in this high-risk group. Studying children with 22q11.2DS provides a unique paradigm to identify brain markers of neurodevelopmental impairment and to relate these to underlying biology. Methods Magnetoencephalography (MEG) was used to investigate resting-state cortical oscillatory patterns in 34 children with 22q11.2DS and 25 controls aged 10-17 years old. Oscillatory activity and functional connectivity across six frequency bands were compared between groups. Regression analyses were used to explore the relationships between these measures, IQ and neurodevelopmental symptoms. Results Children with 22q11.2DS had atypical oscillatory activity and functional connectivity across multiple frequency bands (delta, beta and gamma bands). In the 22q11.2DS group, low frequency (alpha band) activity was negatively associated with cognitive ability and positively associated with ASD and ADHD symptoms. Frontal high frequency (gamma band) activity and connectivity were positively associated with ASD and ADHD symptoms, while posterior gamma activity was negatively associated with ASD symptoms. Conclusions These findings highlight that haploinsufficiency at the 22q11.2 locus alters both local and long-range cortical circuitry, which could be a mechanism underlying neurodevelopmental vulnerability in this high risk group.

scholarly journals In pursuit of visual attention: SSVEP frequency-tagging moving targets

2019 ◽  
Author(s):  
Peter de Lissa ◽  
Roberto Caldara ◽  
Victoria Nicholls ◽  
Sebastien Miellet
Keyword(s):  
Visual Attention ◽  
Visual Processing ◽  
Perceptual Load ◽  
Peripheral Region ◽  
Covert Attention ◽  
Neural Responses ◽  
Moving Targets ◽  
Overt Attention ◽  
Eeg Recordings ◽  
Practical Implications

AbstractPrevious research has shown that visual attention does not always exactly follow gaze direction, leading to the concepts of overt and covert attention. However, it is not yet clear how such covert shifts of visual attention to peripheral regions impact the processing of the targets we directly foveate as they move in our visual field. The current study utilised the co-registration of eye-position and EEG recordings while participants tracked moving targets that were embedded with a 30 Hz frequency tag in a Steady State Visually Evoked Potentials (SSVEP) paradigm. When the task required attention to be divided between the moving target (overt attention) and a peripheral region where a second target might appear (covert attention), the SSVEPs elicited by the tracked target at the 30 Hz frequency band were significantly lower than when participants did not have to covertly monitor for a second target. Our findings suggest that neural responses of overt attention are reduced when attention is divided between covert and overt areas. This neural evidence is in line with theoretical accounts describing attention as a pool of finite resources, such as the perceptual load theory. Altogether, these results have practical implications for many real-world situations where covert shifts of attention may reduce visual processing of objects even when they are directly being tracked with the eyes.

scholarly journals A connectome-based, corticothalamic model of state- and stimulation-dependent modulation of rhythmic neural activity and connectivity

2019 ◽  
Author(s):  
John D Griffiths ◽  
Anthony Randal McIntosh ◽  
Jeremie Lefebvre
Keyword(s):  
Functional Connectivity ◽  
Brain Stimulation ◽  
Brain Activity ◽  
Low Frequency ◽  
Rhythmic Activity ◽  
Clinical Applications ◽  
Oscillatory Activity ◽  
Neural Mass Model ◽  
Brain Connectome ◽  
The Impact

AbstractRhythmic activity in the brain fluctuates with behaviour and cognitive state, through a combination of coexisting and interacting frequencies. At large spatial scales such as those studied in human M/EEG, measured oscillatory dynamics are believed to arise primarily from a combination of cortical (intracolumnar) and corticothalamic rhythmogenic mechanisms. Whilst considerable progress has been made in characterizing these two types of neural circuit separately, relatively little work has been done that attempts to unify them into a single consistent picture. This is the aim of the present paper. We present and examine a whole-brain, connectome-based neural mass model with detailed long-range cortico-cortical connectivity and strong, recurrent corticothalamic circuitry. This system reproduces a variety of known features of human M/EEG recordings, including a 1/f spectral profile, spectral peaks at canonical frequencies, and functional connectivity structure that is shaped by the underlying anatomical connectivity. Importantly, our model is able to capture state-(e.g. idling/active) dependent fluctuations in oscillatory activity and the coexistence of multiple oscillatory phenomena, as well as frequency-specific modulation of functional connectivity. We find that increasing the level of sensory or neuromodulatory drive to the thalamus triggers a suppression of the dominant low frequency rhythms generated by corticothalamic loops, and subsequent disinhibition of higher frequency endogenous rhythmic behaviour of intra-columnar microcircuits. These combine to yield simultaneous decreases in lower frequency and increases in higher frequency components of the M/EEG power spectrum during states of high sensory or cognitive drive. Building on this, we also explored the effect of pulsatile brain stimulation on ongoing oscillatory activity, and evaluated the impact of coexistent frequencies and state-dependent fluctuations on the response of cortical networks. Our results provide new insight into the role played by cortical and corticothalamic circuits in shaping intrinsic brain rhythms, and suggest new directions for brain stimulation therapies aimed at state-and frequency-specific control of oscillatory brain activity.Author SummaryOne of the most distinctive features of brain activity is that it is highly rhythmic. Developing a better understanding of how these rhythms are generated, and how they can be controlled in clinical applications, is a central goal of modern neuroscience. Here we have developed a computational model that succinctly captures several key aspects of the rhythmic brain activity most easily measurable in human subjects. In particular, it provides both a conceptual and a concrete mathematical framework for understanding the well-established experimental observation of antagonism between high- and low-frequency oscillations in human brain recordings. This dynamic has important implications for how we understand the modulation of rhythmic activity in diverse cognitive states relating to arousal, attention, and cognitive processing. As we demonstrate, our model also provides a tool for investigating and improving the use of rhythmic brain stimulation in clinical applications.

scholarly journals A BCI-Based Study on the Relationship Between the SSVEP and Retinal Eccentricity in Overt and Covert Attention

2021 ◽  
Vol 15 ◽  
Author(s):  
Yajun Zhou ◽  
Li Hu ◽  
Tianyou Yu ◽  
Yuanqing Li
Keyword(s):  
Peripheral Vision ◽  
Stimulus Frequency ◽  
Covert Attention ◽  
Retinal Eccentricity ◽  
Overt Attention ◽  
Computer Interfaces ◽  
Behavioral Studies ◽  
Average Accuracy ◽  
Visual Tasks ◽  
Attentional Tasks

Covert attention aids us in monitoring the environment and optimizing performance in visual tasks. Past behavioral studies have shown that covert attention can enhance spatial resolution. However, electroencephalography (EEG) activity related to neural processing between central and peripheral vision has not been systematically investigated. Here, we conducted an EEG study with 25 subjects who performed covert attentional tasks at different retinal eccentricities ranging from 0.75° to 13.90°, as well as tasks involving overt attention and no attention. EEG signals were recorded with a single stimulus frequency to evoke steady-state visual evoked potentials (SSVEPs) for attention evaluation. We found that the SSVEP response in fixating at the attended location was generally negatively correlated with stimulus eccentricity as characterized by Euclidean distance or horizontal and vertical distance. Moreover, more pronounced characteristics of SSVEP analysis were also acquired in overt attention than in covert attention. Furthermore, offline classification of overt attention, covert attention, and no attention yielded an average accuracy of 91.42%. This work contributes to our understanding of the SSVEP representation of attention in humans and may also lead to brain-computer interfaces (BCIs) that allow people to communicate with choices simply by shifting their attention to them.

scholarly journals No advantage for separating overt and covert attention in visual search

2020 ◽  
Author(s):  
Joseph MacInnes ◽  
Ómar I. Jóhannesson ◽  
Andrey Chetverikov ◽  
Arni Kristjansson
Keyword(s):  
Information Processing ◽  
Visual Search ◽  
Change Blindness ◽  
Task Demands ◽  
Covert Attention ◽  
Search Performance ◽  
Overt Attention ◽  
Complex Scenes ◽  
Improved Performance ◽  
Gaze Position

We move our eyes roughly three times every second while searching complex scenes, but covert attention helps to guide where we allocate those overt fixations. Covert attention may be allocated reflexively or voluntarily, and speeds the rate of information processing at the attended location. Reducing access to covert attention hinders performance, but it is not known to what degree the locus of covert attention is tied to the current gaze position. We compared visual search performance in a traditional gaze contingent display with a second task where a similarly sized contingent window is controlled with a mouse allowing a covert aperture to be controlled independently from overt gaze. Larger apertures improved performance for both mouse and gaze contingent trials suggesting that covert attention was beneficial regardless of control type. We also found evidence that participants used the mouse controlled aperture independently of gaze position, suggesting that participants attempted to untether their covert and overt attention when possible. This untethering manipulation, however, resulted in an overall cost to search performance, a result at odds with previous results in a change blindness paradigm. Untethering covert and overt attention may therefore have costs or benefits depending on the task demands in each case.

Healthy and Pathological Neurocognitive Aging: Spectral and Functional Connectivity Analyses Using Magnetoencephalography

2019 ◽  
Author(s):  
Gianluca Susi ◽  
Jaisalmer de Frutos-Lucas ◽  
Guiomar Niso ◽  
Su Miao Ye-Chen ◽  
Luis Antón Toro ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Aging Process ◽  
Healthy Aging ◽  
Oscillatory Activity ◽  
Good Resolution ◽  
Brain Areas ◽  
Spectral Content ◽  
Pathological Conditions ◽  
Neurocognitive Aging ◽  
Invasive Techniques

Oscillatory activity present in brain signals reflects the underlying time-varying electrical discharges within and between ensembles of neurons. Among the variety of non-invasive techniques available for measuring of the brain’s oscillatory activity, magnetoencephalography (MEG) presents a remarkable combination of spatial and temporal resolution, and can be used in resting-state or task-based studies, depending on the goals of the experiment. Two important kinds of analysis can be carried out with the MEG signal: spectral a. and functional connectivity (FC) a. While the former provides information on the distribution of the frequency content within distinct brain areas, FC tells us about the dependence or interaction between the signals stemming from two (or among many) different brain areas. The large frequency range combined with the good resolution offered by MEG makes MEG-based spectral and FC analyses able to highlight distinct patterns of neurophysiological alterations during the aging process in both healthy and pathological conditions. Since disruption in spectral content and functional interactions between brain areas could be accounted for by early neuropathological changes, MEG could represent a useful tool to unveil neurobiological mechanisms related to the cognitive decline observed during aging, particularly suitable for the detection of functional alterations, and then for the discovery of potential biomarkers in case of pathology. The aging process is characterized by alterations in the spectral content across the brain. At the network level, FC studies reveal that older adults experience a series of changes that make them more vulnerable to cognitive interferences. While special attention has been dedicated to the study of pathological conditions (in particular, mild cognitive impairment and Alzheimer’s disease), the lack of studies addressing the features of FC in healthy aging is noteworthy. This area of research calls for future attention because it is able to set the baseline from which to draw comparisons with different pathological conditions.

The Functional Language Network

2017 ◽  
Author(s):  
Angela D. Friederici ◽  
Noam Chomsky
Keyword(s):  
Functional Connectivity ◽  
Information Transfer ◽  
Inferior Frontal Gyrus ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Neural Basis ◽  
Functional Neural Network ◽  
Ventral Pathway ◽  
Open Issue ◽  
Language Network

How information content is encoded and decoded in the sending and receiving brain areas is still an open issue. A possible though speculative view is that encoding and decoding requires similarity at the neuronal level in the encoding and decoding regions. This chapter discusses the functional neural network of language. It first describes the language network at the neurotransmitter level and then discusses the available data at the level of functional connectivity and oscillatory activity. Section 1 looks at the neural basis of information transfer, namely at the neurotransmitters which are crucially involved in the transmission of information from one neuron to the next. Section 2 uses functional connectivity analyses to provide information about how different brain regions work together. They allow us to make statements about which regions work together, and moreover, about the direction of the information flow between these. Section 3 models the language circuit as a a dynamic temporo-frontal network with initial input-driven information processed bottom-up from the auditory cortex to the frontal cortex along the ventral pathway, with semantic information reaching the anterior inferior frontal gyrus, and syntactic information reaching the posterior inferior frontal gyrus.

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