scholarly journals Neurodynamic explanation of inter-individual and inter-trial variability in cross-modal perception

2018 ◽  
Author(s):  
G. Vinodh Kumar ◽  
Shrey Dutta ◽  
Siddharth Talwar ◽  
Dipanjan Roy ◽  
Arpan Banerjee
Keyword(s):  
Large Scale ◽  
Human Subjects ◽  
Mechanistic Explanation ◽  
Gamma Band ◽  
Mcgurk Effect ◽  
Source Analysis ◽  
Alpha Band ◽  
Specific System ◽  
Empirical Estimates ◽  
Illusory Perception

AbstractA widely used experimental design in multisensory integration is the McGurk paradigm that entail illusory (cross-modal) perception of speech sounds when presented with incongruent audio-visual (AV) stimuli. However, the distribution of responses across trials and individuals is heterogeneous and not necessarily everyone in a given group of individuals perceives the effect. Nonetheless, existing studies in the field primarily focus on addressing the correlation between subjective behavior and cortical activations to reveal the neuronal mechanisms underlying the perception of McGurk effect, typically in the “frequent perceivers”. Additionally, a solely neuroimaging approach does not provide mechanistic explanation for the observed inter-trial or inter-individual heterogeneity. In the current study we employ high density electroencephalogram (EEG) recordings in a group of 25 human subjects that allow us to distinguish “frequent perceivers” from “rare perceivers” using behavioral responses as well as from the perspective of large-scale brain functional connectivity (FC). Using global coherence as a measure of large-scale FC, we find that alpha band coherence, a distinctive feature in frequent perceivers is absent in the rare perceivers. Secondly, a decrease in alpha band coherence and increase in gamma band coherence occur during illusory perception trials in both frequent and rare perceivers. Source analysis followed up with source time series reconstructions reveals a large scale network of brain areas involving frontal, temporal and parietal areas that are involved in network level processing of cross-modal perception. Finally, we demonstrate that how a biophysically realistic computational model representing the interaction among key neuronal systems (visual, auditory and multisensory cortical regions) can explain the empirical observations. Each system involves a group of excitatory and inhibitory Hindmarsh Rose neurons that are coupled amongst each other. Large-scale FC between areas is conceptualized using coupling functions and the identity of a specific system, e.g., visual/ auditory/ multisensory is chosen using empirical estimates of the time-scale of information processing in these systems. The model predicts that the disappearance of alpha band coherence observed in rare perceivers stems from a negligible direct A-V (audio-visual) coupling however, an increase in indirect interaction via multisensory node leads to enhanced gamma band and reduced alpha band coherences observed during illusory perception. Overall, we establish the mechanistic basis of large-scale FC patterns underlying cross-modal perception.

Neuronal Synchronization and Selective Color Processing in the Human Brain

2004 ◽  
Vol 16 (3) ◽  
pp. 503-522 ◽  
Author(s):  
Matthias M. Müller ◽  
Andreas Keil
Keyword(s):  
Large Scale ◽  
Time Course ◽  
Time Window ◽  
Brain Activity ◽  
Stimulus Onset ◽  
Gamma Band ◽  
Event Related Potential ◽  
Alpha Band ◽  
Color Processing ◽  
The Time Domain

In the present study, subjects selectively attended to the color of checkerboards in a feature-based attention paradigm. Induced gamma band responses (GBRs), the induced alpha band, and the event-related potential (ERP) were analyzed to uncover neuronal dynamics during selective feature processing. Replicating previous ERP findings, the selection negativity (SN) with a latency of about 160 msec was extracted. Furthermore, and similarly to previous EEG studies, a gamma band peak in a time window between 290 and 380 msec was found. This peak had its major energy in the 55to 70-Hz range and was significantly larger for the attended color. Contrary to previous human induced gamma band studies, a much earlier 40to 50-Hz peak in a time window between 160 and 220 msec after stimulus onset and, thus, concurrently to the SN was prominent with significantly more energy for attended as opposed to unattended color. The induced alpha band (9.8–11.7 Hz), on the other hand, exhibited a marked suppression for attended color in a time window between 450 and 600 msec after stimulus onset. A comparison of the time course of the 40to 50-Hz and 55to 70-Hz induced GBR, the induced alpha band, and the ERP revealed temporal coincidences for changes in the morphology of these brain responses. Despite these similarities in the time domain, the cortical source configuration was found to discriminate between induced GBRs and the SN. Our results suggest that large-scale synchronous high-frequency brain activity as measured in the human GBR play a specific role in attentive processing of stimulus features.

scholarly journals Biophysical mechanisms governing large-scale brain network dynamics underlying individual-specific variability of perception

2019 ◽  
Author(s):  
G. Vinodh Kumar ◽  
Shrey Dutta ◽  
Siddharth Talwar ◽  
Dipanjan Roy ◽  
Arpan Banerjee
Keyword(s):  
Large Scale ◽  
Realistic Model ◽  
Brain Network ◽  
Individual Variability ◽  
Emergent Behavior ◽  
Mcgurk Effect ◽  
Biophysical Model ◽  
Alpha Band ◽  
Global Coherence ◽  
Large Scale Networks

AbstractPerception necessitates interaction amongst neuronal ensembles, the dynamics of which can be conceptualized as the emergent behavior of coupled dynamical systems. Here, we propose a detailed neurobiologically realistic model that captures the neural mechanisms of inter-individual variability observed in cross-modal speech perception. From raw EEG signals recorded from human participants when they were presented with speech vocalizations of McGurk-incongruent and congruent audio-visual (AV) stimuli, we computed the global coherence metric to capture the neural variability of large-scale networks. We identified that participants’ McGurk susceptibility was negatively correlated to their alpha-band global coherence. The proposed biophysical model conceptualized the global coherence dynamics emerge from coupling between the interacting neural masses - representing the sensory specific auditory/visual areas and modality non-specific associative/integrative regions. Subsequently, we could predict that an extremely weak direct AV coupling result in a decrease in alpha band global coherence - mimicking the cortical dynamics of participants with higher McGurk susceptibility. Source connectivity analysis also showed decreased connectivity between sensory specific regions in participants more susceptible to McGurk effect, thus establishing an empirical validation to the prediction. Overall, our study provides an outline to link variability in structural and functional connectivity metrics to variability of performance that can be useful for several perception & action task paradigms.

Overcoming the Challenges of Experimental Research: Lessons From a Criminal Justice Case Study Involving TASER Exposure

2018 ◽  
Vol 42 (3) ◽  
pp. 358-385 ◽  
Author(s):  
Natalie Todak ◽  
Michael D. White ◽  
Lisa M. Dario ◽  
Andrea R. Borrego
Keyword(s):  
Criminal Justice ◽  
Large Scale ◽  
Human Subjects ◽  
Controlled Trial ◽  
Human Subjects Research ◽  
Case Study Approach ◽  
Study Approach ◽  
Randomized Controlled ◽  
The Impact

Objective: To provide guidance to criminologists for conducting experiments in light of two common discouraging factors: the belief that they are overly time-consuming and the belief that they can compromise the ethical principles of human subjects’ research. Method: A case study approach is used, based on a large-scale randomized controlled trial experiment in which we exposed participants to a 5-s TASER shock, to describe how the authors overcame ethical, methodological, and logistical difficulties. Results: We derive four pieces of advice from our experiences carrying out this experimental trial: (1) know your limitations, (2) employ pilot testing, (3) remain flexible and patient, and (4) “hold the line” to maintain the integrity of the research and the safety of human subjects. Conclusions: Criminologists have an obligation to provide the best possible evidence regarding the impact and consequences of criminal justice practices and programs. Experiments, considered by many to be the gold standard of empirical research methodologies, should be used whenever possible in order to fulfill this obligation.

scholarly journals An open source analysis framework for large-scale building energy modeling

2020 ◽  
Vol 13 (5) ◽  
pp. 487-500
Author(s):  
Brian L. Ball ◽  
Nicholas Long ◽  
Katherine Fleming ◽  
Chris Balbach ◽  
Phylroy Lopez
Keyword(s):  
Open Source ◽  
Large Scale ◽  
Building Energy ◽  
Energy Modeling ◽  
Source Analysis ◽  
Analysis Framework ◽  
Building Energy Modeling

scholarly journals Blood glutathione concentrations in a large-scale human study

1996 ◽  
Vol 42 (1) ◽  
pp. 64-70 ◽  
Author(s):  
J P Richie ◽  
L Skowronski ◽  
P Abraham ◽  
Y Leutzinger
Keyword(s):  
Sex Differences ◽  
Large Scale ◽  
Normal Values ◽  
Human Subjects ◽  
Human Study ◽  
Free Living ◽  
Highly Sensitive ◽  
Sampling Variation ◽  
Older Subjects ◽  
Highly Sensitive Detection

Abstract Little is known about the variability of blood glutathione (GSH) in human subjects. Thus, we wanted to develop and validate a rapid method for measuring GSH concentrations in whole blood and apply this method to ascertain the variation of GSH in a large-scale study of free-living adults. The assay was highly sensitive (detection limit < 5 pmol) and precise, with an interassay variation of 2.3% and a sampling variation of 3.6%. Applying this method to screen 715 adults, we observed a threefold range of GSH concentrations, with a mean of 1.02 mmol/L and CV of 17%. GSH concentrations were 8-10% greater in smokers than in nonsmokers (P < 0.001). Although we observed no sex differences for GSH, GSH/hemoglobin ratios were 8-18% greater in women < 55 years old than in older subjects (P < 0.05). The results presented here validate the use of this method for large-scale human studies and provide information on the variation and normal values of blood GSH in adults.

scholarly journals Functional Connectome of the Five-Factor Model of Personality

2018 ◽  
Vol 1 ◽  
Author(s):  
Nicola Toschi ◽  
Roberta Riccelli ◽  
Iole Indovina ◽  
Antonio Terracciano ◽  
Luca Passamonti
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Factor Model ◽  
Brain Connectivity ◽  
Five Factor Model ◽  
Mechanistic Explanation ◽  
Data Sets ◽  
Personality Differences ◽  
Human Connectome Project ◽  
Maximal Information Coefficient

Abstract A key objective of the emerging field of personality neuroscience is to link the great variety of the enduring dispositions of human behaviour with reliable markers of brain function. This can be achieved by analysing big data-sets with methods that model whole-brain connectivity patterns. To meet these expectations, we exploited a large repository of personality and neuroimaging measures made publicly available via the Human Connectome Project. Using connectomic analyses based on graph theory, we computed global and local indices of functional connectivity (e.g., nodal strength, efficiency, clustering, betweenness centrality) and related these metrics to the five-factor model (FFM) personality traits (i.e., neuroticism, extraversion, openness, agreeableness, and conscientiousness). The maximal information coefficient was used to assess for linear and nonlinear statistical dependencies across the graph “nodes”, which were defined as distinct large-scale brain circuits identified via independent component analysis. Multivariate regression models and “train/test” approaches were used to examine the associations between FFM traits and connectomic indices as well as to assess the generalizability of the main findings, while accounting for age and sex variability. Conscientiousness was the sole FFM trait linked to measures of higher functional connectivity in the fronto-parietal and default mode networks. This offers a mechanistic explanation of the behavioural observation that conscientious people are reliable and efficient in goal-setting or planning. Our study provides new inputs to understanding the neurological basis of personality and contributes to the development of more realistic models of the brain dynamics that mediate personality differences.

Analysis of Neural Interactions Explains the Activation of Occipital Cortex by an Auditory Stimulus

1998 ◽  
Vol 80 (5) ◽  
pp. 2790-2796 ◽  
Author(s):  
A. R. McIntosh ◽  
R. E. Cabeza ◽  
N. J. Lobaugh
Keyword(s):  
Auditory Stimulus ◽  
Structural Equation ◽  
Large Scale ◽  
Human Subjects ◽  
Premotor Cortex ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Equation Modeling ◽  
Occipital Area ◽  
Neural Interactions

McIntosh, A. R., R. E. Cabeza, and N. J. Lobaugh. Analysis of neural interactions explains the activation of occipital cortex by an auditory stimulus . J. Neurophysiol. 80: 2790–2796, 1998. Large-scale neural interactions were characterized in human subjects as they learned that an auditory stimulus signaled a visual event. Once learned, activation of left dorsal occipital cortex (increased regional cerebral blood flow) was observed when the auditory stimulus was presented alone. Partial least-squares analysis of the interregional correlations (functional connectivity) between the occipital area and the rest of the brain identified a pattern of covariation with four dominant brain areas that could have mediated this activation: prefrontal cortex (near Brodmann area 10, A10), premotor cortex (A6), superior temporal cortex (A41/42), and contralateral occipital cortex (A18). Interactions among these regions and the occipital area were quantified with structural equation modeling to identify the strongest sources of the effect on left occipital activity (effective connectivity). Learning-related changes in feedback effects from A10 and A41/42 appeared to account for this change in occipital activity. Influences from these areas on the occipital area were initially suppressive, or negative, becoming facilitory, or positive, as the association between the auditory and visual stimuli was acquired. Evaluating the total effects within the functional models showed positive influences throughout the network, suggesting enhanced interactions may have primed the system for the now-expected visual discrimination. By characterizing both changes in activity and the interactions underlying sensory associative learning, we demonstrated how parts of the nervous system operate as a cohesive network in learning about and responding to the environment.

U-shaped Relation between Prestimulus Alpha-band and Poststimulus Gamma-band Power in Temporal Tactile Perception in the Human Somatosensory Cortex

2018 ◽  
Vol 30 (4) ◽  
pp. 552-564 ◽  
Author(s):  
Marc André Wittenberg ◽  
Thomas J. Baumgarten ◽  
Alfons Schnitzler ◽  
Joachim Lange
Keyword(s):  
Gamma Band ◽  
Gamma Activity ◽  
Left Index Finger ◽  
Behavioral Performance ◽  
Alpha Band ◽  
Band Power ◽  
And Performance ◽  
Electrical Stimuli ◽  
Gamma Band Oscillations ◽  
Human Nervous System

Neuronal oscillations are a ubiquitous phenomenon in the human nervous system. Alpha-band oscillations (8–12 Hz) have been shown to correlate negatively with attention and performance, whereas gamma-band oscillations (40–150 Hz) correlate positively. Here, we studied the relation between prestimulus alpha-band power and poststimulus gamma-band power in a suprathreshold tactile discrimination task. Participants received two electrical stimuli to their left index finger with different SOAs (0 msec, 100 msec, intermediate SOA, intermediate SOA ± 10 msec). The intermediate SOA was individually determined so that stimulation was bistable, and participants perceived one stimulus in half of the trials and two stimuli in the other half. We measured neuronal activity with magnetoencephalography (MEG). In trials with intermediate SOAs, behavioral performance correlated inversely with prestimulus alpha-band power but did not correlate with poststimulus gamma-band power. Poststimulus gamma-band power was high in trials with low and high prestimulus alpha-band power and low for intermediate prestimulus alpha-band power (i.e., U-shaped). We suggest that prestimulus alpha activity modulates poststimulus gamma activity and subsequent perception: (1) low prestimulus alpha-band power leads to high poststimulus gamma-band power, biasing perception such that two stimuli were perceived; (2) intermediate prestimulus alpha-band power leads to low gamma-band power (interpreted as inefficient stimulus processing), consequently, perception was not biased in either direction; and (3) high prestimulus alpha-band power leads to high poststimulus gamma-band power, biasing perception such that only one stimulus was perceived.

Seroprevalence and associated risk factors of human cystic echinococcosis in some parts of Plateau State, Nigeria

2020 ◽  
Vol 41 (1) ◽  
pp. 30-34
Author(s):  
D. Bitrus ◽  
R. Weka ◽  
R. Yakubu ◽  
I.N. Ogo ◽  
J. Kamani ◽  
...  
Keyword(s):  
Risk Factors ◽  
Large Scale ◽  
Human Subjects ◽  
Companion Animals ◽  
Control Measures ◽  
Cross Sectional ◽  
Transmission Cycle ◽  
Antibody Elisa ◽  
Plateau State ◽  
Associated Risk Factors

Livestock, pets and companion animals in developing nations are plagued with several infectious diseases some of them with zoonotic potentials. Echinococcosis which is a neglected zoonotic parasitic disease is one of such diseases that affect domestic animals and man with serious health and economic impacts. A cross-sectional questionnaire and serological survey was conducted on human subjects from four Local Government Areas (LGA) of Plateau State, Nigeria, to determine knowledge, attitude and practice and their level of exposure to E. granulosus infection. Sera from 181 human subjects recruited for this study were screened for IgG antibodies to E. granulosus using a commercial ELISA kit. Overall, 6 out of the 181 (3.3%) tested sera were positive. Seropositivity was associated with subjects below 10 years (OR=5.6), study location (OR=1.8), and scavenging behaviour of dogs (OR= 1.5), but not with gender of dog owners (OR=0.7), dog ownership (OR=0.6), dog deworming practice (OR=0.3) or the use of slaughter facility and meat inspection (OR=0.6). Ignorance about the transmission cycle of E. granulosus coupled with unhygienic practices are the main risk factors for the perpetuation of the disease in the study-communities. Sensitization, awareness creation and advocacy for hygienic  practises among the communities are recommended, as a short term measure while large scale studies to determine the true prevalence and therisk factors of the disease will form the basis for possible future control measures. Keywords: Seroprevalence; Echinococcus granulosus; antibody; ELISA; human; Plateau State.

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