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18
A neural mass model for MEG/EEG: coupling and neuronal dynamics
- NeuroImage
, 2003
"... Although MEG/EEG signals are highly variable, systematic changes in distinct frequency bands are commonly encountered. These frequency-specific changes represent robust neural correlates of cognitive or perceptual processes (for example, alpha rhythms emerge on closing the eyes). However, their func ..."
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Cited by 81 (21 self)
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Although MEG/EEG signals are highly variable, systematic changes in distinct frequency bands are commonly encountered. These frequency-specific changes represent robust neural correlates of cognitive or perceptual processes (for example, alpha rhythms emerge on closing the eyes). However, their functional significance remains a matter of debate. Some of the mechanisms that generate these signals are known at the cellular level and rest on a balance of excitatory and inhibitory interactions within and between populations of neurons. The kinetics of the ensuing population dynamics determine the frequency of oscillations. In this work we extended the classical nonlinear lumped-parameter model of alpha rhythms, initially developed by Lopes da Silva and colleagues [Kybernetik 15 (1974) 27], to generate more complex dynamics. We show that the whole spectrum of MEG/EEG signals can be reproduced within the oscillatory regime of this model by simply changing the population kinetics. We used the model to examine the influence of coupling strength and propagation delay on the rhythms generated by coupled cortical areas. The main findings were that (1) coupling induces phase-locked activity, with a phase shift of 0 or π when the coupling is bidirectional, and (2) both coupling and propagation delay are critical determinants of the MEG/EEG spectrum. In forthcoming articles, we will use this model to (1) estimate how neuronal interactions are expressed in MEG/EEG oscillations and establish the construct validity of various indices of nonlinear coupling, and (2) generate event-related transients to derive physiologically informed basis functions for statistical modelling of average evoked responses.
Meditation and the neuroscience of consciousness: An introduction. NewYork
, 2007
"... The overall goal of this chapter is to explore the initial findings of neuroscientific research ..."
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Cited by 39 (7 self)
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The overall goal of this chapter is to explore the initial findings of neuroscientific research
Modelling event-related responses in the brain
- NeuroImage
, 2005
"... The aim of this work was to investigate the mechanisms that shape evoked electroencephalographic (EEG) and magneto-encephalographic (MEG) responses. We used a neuronally plausible model to characterise the dependency of response components on the models parameters. This generative model was a neural ..."
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Cited by 38 (9 self)
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The aim of this work was to investigate the mechanisms that shape evoked electroencephalographic (EEG) and magneto-encephalographic (MEG) responses. We used a neuronally plausible model to characterise the dependency of response components on the models parameters. This generative model was a neural mass model of hierarchically arranged areas using three kinds of inter-area connections (forward, backward and lateral). We investigated how responses, at each level of a cortical hierarchy, depended on the strength of connections or coupling. Our strategy was to systematically add connections and examine the responses of each successive architecture. We did this in the context of deterministic responses and then with stochastic spontaneous activity. Our aim was to show, in a simple way, how event-related dynamics depend on extrinsic connectivity. To emphasise the importance of nonlinear interactions, we tried to disambiguate the components of event-related potentials (ERPs) or event-related fields
Meditation and the neuroscience of consciousness
- In
, 2007
"... brain plasticity, mind-brain-body interaction, physiological baseline, reflexive awareness, Buddhism, compassion, open presence, Śamatha, neurophenomenology. The overall goal of this essay is to explore the initial findings of neuroscientific research on meditation; in doing so, the essay also sugge ..."
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Cited by 14 (0 self)
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brain plasticity, mind-brain-body interaction, physiological baseline, reflexive awareness, Buddhism, compassion, open presence, Śamatha, neurophenomenology. The overall goal of this essay is to explore the initial findings of neuroscientific research on meditation; in doing so, the essay also suggests potential avenues of further inquiry. The essay consists of three sections that, while integral to the essay as a whole, may also be read independently. The first section, “Defining Meditation, ” notes the need for a more precise understanding of meditation as a scientific explanandum. Arguing for the importance of distinguishing the particularities of various traditions, the section presents the theory of meditation from the paradigmatic perspective of Buddhism, and it discusses the difficulties encountered when working with such theories. The section includes an overview of three practices that have been the subject of research, and it ends with a strategy for developing a questionnaire to more precisely define a practice under examination. The second section, “the Intersection of Neuroscience and Meditation, ” explores some scientific motivations for the neuroscientific examination of meditation in terms of its potential impact on the brain and body of long-term practitioners. After an overview of the mechanisms of mind-body interaction, this section addresses the use of first-person expertise, especially in relation to the potential for research on the neural counterpart of subjective experience. In general terms, the section thus Page 2 points to the possible contributions of research on meditation to the neuroscience of consciousness. The final section, “Neuroelectric and Neuroimaging Correlates of Meditation,” reviews the most relevant neuroelectric and neuroimaging findings of research conducted to date, including some preliminary correlates of the previously discussed Buddhist practices.
Generation and control of cortical gamma: findings from simulation at two scales.
"... Abstract. A continuum model of electrocortical activity was applied separately at centimetric and macrocolumnar scales, permitting analysis of interaction between scales. State equations included effects of retrograde action potential propagation in dendritic trees, and kinetics of AMPA, GABA and NM ..."
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Cited by 2 (1 self)
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Abstract. A continuum model of electrocortical activity was applied separately at centimetric and macrocolumnar scales, permitting analysis of interaction between scales. State equations included effects of retrograde action potential propagation in dendritic trees, and kinetics of AMPA, GABA and NMDA receptors. Parameter values were provided from independent physiological and anatomical estimates. Realistic field potentials and pulse rates were obtained, including resonances in the alpha/theta and gamma ranges, 1 / background activity, and autonomous gamma activity. Zero-lag synchrony and travelling waves occurred as complementary aspects of cortical transmission, and lead/lag relations between excitatory and inhibitory cell populations varied systematically around transition to autonomous gamma oscillation. f 2 Properties of the simulations can account for generation and control of gamma activity. All factors acting on excitatory/inhibitory balance controlled the onset and offset of gamma oscillation. Autonomous gamma was initiated by focal excitation of excitatory cells, and suppressed by laterally spreading trans-cortical excitation, which acted on both excitatory and inhibitory cell populations. Consequently, although spatially extensive non-specific reticular activation tended to suppress autonomous gamma, spatial variation of reticular activation could preferentially select fields of synchrony.
Neural Mass Activity, Bifurcations and Epilepsy
, 2011
"... In this manuscript we propose a general framework for studying neural mass models defined by ordinary differential equations. By studying the bifurcations of the solutions to these equations and their sensitivity to noise we establish an important relation, similar to a dictionary, between their beh ..."
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Cited by 1 (0 self)
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In this manuscript we propose a general framework for studying neural mass models defined by ordinary differential equations. By studying the bifurcations of the solutions to these equations and their sensitivity to noise we establish an important relation, similar to a dictionary, between their behaviors and normal and pathological, especially epileptic, cortical patterns of activity. We then apply this framework to the analysis of two models that feature most phenomena of interest, the Jansen and Rit model, and the slightly more complex model recently proposedby Wendling and Chauvel. This model-based approach allows to test various neurophysiological hypotheses on the origin of pathological cortical behaviors and to investigate the effect of medication. We also study the effects of the stochastic nature of the inputs which gives us clues about the origins of such important phenomena as inter-ictal spikes, inter-ical bursts and fast onset activity, that are of particular relevance in epilepsy.
Behavioral/Systems/Cognitive Cued Spatial Attention Drives Functionally Relevant Modulation of the Mu Rhythm in Primary Somatosensory Cortex
"... Cued spatial attention modulates functionally relevant alpha rhythms in visual cortices in humans. Here, we present evidence for analogous phenomena in primary somatosensory neocortex (SI). Using magnetoencephalography, we measured changes in the SI mu rhythm containing mu-alpha (7-14 Hz) and mu-be ..."
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Cued spatial attention modulates functionally relevant alpha rhythms in visual cortices in humans. Here, we present evidence for analogous phenomena in primary somatosensory neocortex (SI). Using magnetoencephalography, we measured changes in the SI mu rhythm containing mu-alpha (7-14 Hz) and mu-beta (15-29 Hz) components. We found that cued attention impacted mu-alpha in the somatopically localized hand representation in SI, showing decreased power after attention was cued to the hand and increased power after attention was cued to the foot, with significant differences observed 500 -1100 ms after cue. Mu-beta showed differences in a time window 800 -850 ms after cue. The visual cue also drove an early evoked response beginning ϳ70 ms after cue with distinct peaks modulated with cued attention. Distinct components of the tactile stimulus-evoked response were also modulated with cued attention. Analysis of a second dataset showed that, on a trial-by-trial basis, tactile detection probabilities decreased linearly with prestimulus mu-alpha and mu-beta power. These results support the growing consensus that cue-induced alpha modulation is a functionally relevant sensory gating mechanism deployed by attention. Further, while cued attention had a weaker effect on the allocation of mu-beta, oscillations in this band also predicted tactile detection.
Reviewed by:
, 2011
"... doi: 10.3389/fnsys.2011.00013 The arbitration–extension hypothesis: a hierarchical interpretation of the functional organization of the basal ganglia ..."
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doi: 10.3389/fnsys.2011.00013 The arbitration–extension hypothesis: a hierarchical interpretation of the functional organization of the basal ganglia
Revision Manuscript NIMG-07-262-2
, 2007
"... A comparative study of different artefact removal algorithms for EEG signals acquired during functional MRI ..."
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A comparative study of different artefact removal algorithms for EEG signals acquired during functional MRI
