Robert Oostenveld - Academia.edu (original) (raw)

Papers by Robert Oostenveld

2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2013

Neuronal source estimation is a general tool for analyzing spatiotemporal dynamics in human EEG. ... more Neuronal source estimation is a general tool for analyzing spatiotemporal dynamics in human EEG. Despite rapidly-evolving interest in human brain, there are few EEG based source estimation tools in rodent brain. Therefore, we implemented source estimation tool in a mouse model, using the FieldTrip open-source software. High resolution EEGs with a known cortical source were recorded with a recently developed 40-channel polyimide-based microelectrode under optical stimulation on optogenetially engineered mice. To obtain realistic mouse head models, the volume conduction model was extracted from in vitro mouse brain MRIs. Segmented compartments (skin and outer/inner skull) were used to form triangular meshes and then applied to the boundary element method. The high-resolution EEGs recorded during various optogenetic stimulation of the mouse brain were inversely source reconstructed using minimum-norm estimate. Estimated source locations and strengths were reconstructed, and their error was calculated to evaluate FieldTrip-based source localization algorithm. In summary, source localization imaging of the mouse brain was successfully achieved, using freely-available open source software. This will be useful to investigate the functional dynamics of mouse brain in noninvasive measure.

Human-Computer Interaction Series, 2010

We first review the range of standalone and MATLAB-based software currently freely available to B... more We first review the range of standalone and MATLAB-based software currently freely available to BCI researchers. We then discuss two MATLAB-centered solutions for realtime data streaming, the environments FieldTrip (Donders Institute, Nijmegen) and DataSuite (DataRiver, Producer, MatRiver) (Swartz Center, La Jolla). We illustrate the relative simplicity of coding BCI feature extraction and classification under MATLAB (The Mathworks, Inc.) using a minimalist BCI example, and then describe BCILAB (Team PhyPa, Berlin), a new BCI package that uses the data structures and extends the capabilities of the widely used EEGLAB signal processing environment.

PLoS ONE, 2013

The mouse model is an important research tool in neurosciences to examine brain function and dise... more The mouse model is an important research tool in neurosciences to examine brain function and diseases with genetic perturbation in different brain regions. However, the limited techniques to map activated brain regions under specific experimental manipulations has been a drawback of the mouse model compared to human functional brain mapping. Here, we present a functional brain mapping method for fast and robust in vivo brain mapping of the mouse brain. The method is based on the acquisition of high density electroencephalography (EEG) with a microarray and EEG source estimation to localize the electrophysiological origins. We adapted the Fieldtrip toolbox for the source estimation, taking advantage of its software openness and flexibility in modeling the EEG volume conduction. Three source estimation techniques were compared: Distribution source modeling with minimum-norm estimation (MNE), scanning with multiple signal classification (MUSIC), and single-dipole fitting. Known sources to evaluate the performance of the localization methods were provided using optogenetic tools. The accuracy was quantified based on the receiver operating characteristic (ROC) analysis. The mean detection accuracy was high, with a false positive rate less than 1.3% and 7% at the sensitivity of 90% plotted with the MNE and MUSIC algorithms, respectively. The mean center-to-center distance was less than 1.2 mm in single dipole fitting algorithm. Mouse microarray EEG source localization using microarray allows a reliable method for functional brain mapping in awake mouse opening an access to cross-species study with human brain. Citation: Lee C, Oostenveld R, Lee SH, Kim LH, Sung H, et al. (2013) Dipole Source Localization of Mouse Electroencephalogram Using the Fieldtrip Toolbox. PLoS ONE 8(11): e79442.

PLoS ONE, 2012

Independent component analysis (ICA) and blind source separation (BSS) methods are increasingly u... more Independent component analysis (ICA) and blind source separation (BSS) methods are increasingly used to separate individual brain and non-brain source signals mixed by volume conduction in electroencephalographic (EEG) and other electrophysiological recordings. We compared results of decomposing thirteen 71-channel human scalp EEG datasets by 22 ICA and BSS algorithms, assessing the pairwise mutual information (PMI) in scalp channel pairs, the remaining PMI in component pairs, the overall mutual information reduction (MIR) effected by each decomposition, and decomposition 'dipolarity' defined as the number of component scalp maps matching the projection of a single equivalent dipole with less than a given residual variance. The least well-performing algorithm was principal component analysis (PCA); best performing were AMICA and other likelihood/mutual information based ICA methods. Though these and other commonlyused decomposition methods returned many similar components, across 18 ICA/BSS algorithms mean dipolarity varied linearly with both MIR and with PMI remaining between the resulting component time courses, a result compatible with an interpretation of many maximally independent EEG components as being volume-conducted projections of partiallysynchronous local cortical field activity within single compact cortical domains. To encourage further method comparisons, the data and software used to prepare the results have been made available

17th International Conference on Biomagnetism Advances in Biomagnetism–Biomag2010, 2010

Free MEG and EEG data analysis software packages springing from academic research are now widely ... more Free MEG and EEG data analysis software packages springing from academic research are now widely used in published work. These toolboxes and applications are typically developed by or in close contact with researchers addressing cognitive or clinical neuroscience questions. Thus they often contain the latest methodological developments from the research community. It is therefore vital to educate MEG researchers and make them aware of the new possibilities offered by these toolboxes. The aim of this paper is to illustrate the characteristics and advantages of the various toolboxes to users and developers alike. We present each toolbox with their key features and target audience.

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, 2010

a-Motoneuron model Corticomuscular transmission Motor drive Motor unit firing a b s t r a c t Obj... more a-Motoneuron model Corticomuscular transmission Motor drive Motor unit firing a b s t r a c t Objective: Investigate the effectiveness and frequency dependence of central drive transmission via the a-motoneuron pool to the muscle. Methods: We describe a model for the simulation of a-motoneuron firing and the EMG signal as response to central drive input. The transfer in the frequency domain is investigated. Coherence between stochastical central input and EMG is also evaluated. Results: The transmission of central rhythmicities to the EMG signal relates to the spectral content of the latter. Coherence between central input to the a-motoneuron pool and the EMG signal is significant whereby the coupling strength hardly depends on the frequency in a range from 1 to 100 Hz. Common central input to pairs of a-motoneurons strongly increases the coherence levels. The often-used rectification of the EMG signal introduces a clear frequency dependence.

Journal of Neurophysiology, 2005

Topographical characteristics of motor units of the lower facial musculature revealed by means of... more Topographical characteristics of motor units of the lower facial musculature revealed by means of high-density surface EMG. . The objective of this study was to systematically characterize motor units (MUs) of the musculature of the lower face. MU endplate positions and principal muscle fiber orientations relative to facial landmarks were identified. This was done by the analysis of motor unit action potentials (MUAPs) in the surface electromyogram. Thirteen specially trained, healthy subjects performed selective contractions of the depressor anguli oris, depressor labii inferioris, mentalis, and orbicularis oris inferior muscles. Signals were recorded using recently developed, 0.3-mm thin and flexible high-density surface electromyography (sEMG) grids (120 channels). For each subject and each muscle and for different low contraction levels, representative MUAPs ("MU fingerprints") were extracted from the raw sEMG data according to their spatiotemporal amplitude characteristics. We then topographically characterized the lower facial MUs' endplate zones and main muscle fiber orientations on the individual faces of the subjects. These topographical MU parameters were spatially warped to correct for the different sizes and shapes of the faces of individual subjects. This electrophysiological study revealed a distribution of the lower facial MU endplates in more or less restricted, distinct clusters on the muscle often with eccentric locations. The results add substantially to the basic neurophysiologic and anatomical knowledge of the complex facial muscle system. They can also be used to establish objective guidelines for placement of conventional (surface or needle) EMG electrodes as well as for clinical investigations on neuromuscular diseases affecting the facial musculature. The localized endplate positions may also indicate optimal locations for botulinum toxin injection in the face.

Clinical Neurophysiology - CLIN NEUROPHYSIOL, 2003

Objective: We investigated the influence of symmetry assumptions implicit in the derivation and t... more Objective: We investigated the influence of symmetry assumptions implicit in the derivation and the use of event-related lateralized potentials (ERLs), such as the lateralized readiness potential (LRP). We describe these assumptions and demonstrate several alternative computational methods.

NeuroImage, 2009

PET and fMRI experiments have previously shown that several brain regions in the frontal and pari... more PET and fMRI experiments have previously shown that several brain regions in the frontal and parietal lobe are involved in working memory maintenance. MEG and EEG experiments have shown parametric increases with load for oscillatory activity in posterior alpha and frontal theta power. In the current study we investigated whether the areas found with fMRI can be associated with these alpha and theta effects by measuring simultaneous EEG and fMRI during a modified Sternberg task This allowed us to correlate EEG at the single trial level with the fMRI BOLD signal by forming a regressor based on single trial alpha and theta power estimates. We observed a right posterior, parametric alpha power increase, which was functionally related to decreases in BOLD in the primary visual cortex and in the posterior part of the right middle temporal gyrus. We relate this finding to the inhibition of neuronal activity that may interfere with WM maintenance. An observed parametric increase in frontal theta power was correlated to a decrease in BOLD in regions that together form the default mode network. We did not observe correlations between oscillatory EEG phenomena and BOLD in the traditional WM areas. In conclusion, the study shows that simultaneous EEG-fMRI recordings can be successfully used to identify the emergence of functional networks in the brain during the execution of a cognitive task.

Journal of Neuroscience, 2010

Brosch, Michael, Eike Budinger, and Henning Scheich. Stimulusrelated gamma oscillations in primat... more Brosch, Michael, Eike Budinger, and Henning Scheich. Stimulusrelated gamma oscillations in primate auditory cortex. J Neurophysiol . With a multielectrode system, we explored neuronal activity in the ␥ range (Ͼ40 Hz) in the primary and caudomedial auditory cortex of six anesthetized macaque monkeys. Stimuli were tone bursts of 100-to 500-ms duration that were presented at sound pressure levels of 40 -60 dB and were varied over a wide range of frequencies. These stimuli induced ␥ oscillations, not phase-locked to the onset of stimulation, in 465 of 616 multiunit clusters and at 321 of 422 sites at which field potentials were recorded. Occurrence of ␥ activity was stimulus dependent. It was mostly seen when the stimulus was at the units' preferred frequency. The incidence of ␥ activity decreased with increasing difference between stimulus frequency and preferred frequency. ␥ activity emerged 100 -900 ms after stimulus onset with highest incidence ϳ120 ms. Amplitudes of stimulus-induced ␥ oscillations in field potentials were, on average, almost twice the amplitude of spontaneously occurring ␥ oscillations. ␥ activity at different sites within the primary and the caudomedial auditory field could be synchronized at near-zero phase. Synchrony depended on the spatial distance and on the receptive fields similarity of pairs of units. It decreased with increasing distance between recording sites and increased with similarity of preferred frequencies of the pairs of units. The results indicate that stimulusinduced ␥ oscillations originate from sources in the auditory cortex. They further suggest that ␥ oscillations may provide a mechanism utilized in many parts of the sensory cortex, including the auditory cortex, to integrate neurons according to the similarity of their receptive fields.

Cognitive Brain Research, 2003

Visual spatial attentional activation of motor areas has been documented in single cell neurophys... more Visual spatial attentional activation of motor areas has been documented in single cell neurophysiology and functional imaging studies of the brain. Here, we investigate a candidate event-related brain potential representing visuospatial attentional activity in motor areas of the cortex. The investigation aimed to elucidate the neural origin and the functional characteristics of this brain potential, which has been labelled N2cc and is typically observed in spatial stimulus-response compatibility tasks. High-density EEG was recorded in 10 subjects while they performed a Simon-type spatial stimulus-response compatibility task and a control task where the same stimuli were assigned to Go-Nogo response alternatives. The N2cc showed a time course parallel to the posteriorly distributed N2pc, associated with visuospatial selection. Scalp distribution and current source density reconstructions allowed a spatial separation of N2pc and centrally distributed N2cc and were compatible with a source for the N2cc in the lateral premotor cortex. Comparisons across tasks demonstrated that the N2cc depends on bilateral response readiness, ruling out an exclusively attentional interpretation. Instead, the activity appears associated with visuospatial attentional processes that serve the selection and suppression of competing responses, in accord with a function of the dorsal premotor cortex in response selection. Together, the results consolidate the N2cc as a new ERP component relevant to the investigation of visuospatial motor processes. 

NeuroImage, 2002

Reafferent electroencephalography (EEG) potentials evoked by active or passive movement are large... more Reafferent electroencephalography (EEG) potentials evoked by active or passive movement are largely dependent on muscle spindle input, which projects to postrolandic sensory areas as well as the precentral motor cortex. The origin of these proprioception-related evoked potentials has previously been studied by using N20-P20 source locations of the median nerve somatosensory evoked potential as an landmark for postcentral area 3b. As this approach has yielded contradictory findings, likely due to spatial undersampling, we applied dipole source analysis on two independently collected sets of high-density EEG data, containing the proprioception-related N90 elicited by passive finger movement, and the N20-P20 elicited by median nerve stimulation. In addition, the influence of movement parameters on the N90 was explored by varying amplitude/duration and direction of passive movements. The results showed that the proprioceptive N90 component was not influenced by movement direction, but had a duration that covaried with the duration of the movement. Sources were localized in the precentral cortex, located on average 10 mm anterior to the N20-P20 sources. The latter result supports earlier claims that the motor cortex is involved in the generation of proprioception-related EEG potentials.

Neuron, 2011

Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and th... more Work on animals indicates that BOLD is preferentially sensitive to local field potentials, and that it correlates most strongly with gamma band neuronal synchronization. Here we investigate how the BOLD signal in humans performing a cognitive task is related to neuronal synchronization across different frequency bands. We simultaneously recorded EEG and BOLD while subjects engaged in a visual attention task known to induce sustained changes in neuronal synchronization across a wide range of frequencies.

Proceedings of the National Academy of Sciences, 2014

Paired associative stimulation (PAS), which combines repetitive peripheral nerve stimulation with... more Paired associative stimulation (PAS), which combines repetitive peripheral nerve stimulation with transcranial magnetic stimulation (TMS), may induce neuroplastic changes in somatosensory cortex (S1), possibly by long-term potentiation-like mechanisms. We used multichannel median nerve somatosensory evoked potential (MN-SSEP) recordings and two-point tactile discrimination testing to examine the location and behavioural significance of these changes. When TMS was applied to S1 near-synchronously to an afferent signal containing mechanoreceptive information, MN-SSEP changes (significant at 21-31 ms) could be explained by a change in a tangential source located in Brodmann area 3b, with their timing and polarity suggesting modification of upper cortical layers. PAS-induced MN-SSEP changes between 28 and 32 ms were linearly correlated with changes in tactile discrimination. Conversely, when the near-synchronous afferent signal contained predominantly proprioceptive information, PAS-induced MN-SSEP changes (20-29 ms) were shifted medially, and tactile performance remained stable. With near-synchronous mechanoreceptive stimulation subtle differences in the timing of the two interacting signals tended to influence the direction of tactile performance changes. PAS performed with TMS delivered asynchronously to the afferent pulse did not change MN-SSEPs. Hebbian interaction of mechanoreceptive afferent signals with TMS-evoked activity may modify synaptic efficacy in superficial cortical layers of Brodmann area 3b and is associated with timing-dependent and qualitatively congruent behavioural changes.

Brain and Language, 2008

An influential hypothesis regarding the neural basis of the mental lexicon is that semantic repre... more An influential hypothesis regarding the neural basis of the mental lexicon is that semantic representations are neurally implemented as distributed networks carrying sensory, motor and/or more abstract functional information. This work investigates whether the semantic properties of words partly determine the topography of such networks.Subjects performed a visual lexical decision task while their EEG was recorded. We compared the EEG responses to nouns with either visual semantic properties (VIS, referring to colors and shapes) or with auditory semantic properties (AUD, referring to sounds).A time–frequency analysis of the EEG revealed power increases in the theta (4–7 Hz) and lower-beta (13–18 Hz) frequency bands, and an early power increase and subsequent decrease for the alpha (8–12 Hz) band. In the theta band we observed a double dissociation: temporal electrodes showed larger theta power increases in the AUD condition, while occipital leads showed larger theta responses in the VIS condition.The results support the notion that semantic representations are stored in functional networks with a topography that reflects the semantic properties of the stored items, and provide further evidence that oscillatory brain dynamics in the theta frequency range are functionally related to the retrieval of lexical semantic information.

Neuroscience Letters, 2002

To understand spatial summation of pain processing in the brain, we investigated the cerebral evo... more To understand spatial summation of pain processing in the brain, we investigated the cerebral evoked responses to non-painful and painful contact heat stimulation (70 8C/s fast onset; intensity 2,4,6, corresponding to the individual's non-, slight and moderate pain) comparing one (1s) vs. two spots (2s) in 11 subjects while electroencephalographic signals were recorded. Significant spatial summation effects were shown only for the pain levels. For moderate pain, global field power examination isolated two peak activations for the vertex (Cz) N550 and P750 components. The single dipole modelling identified as likely the supplementary motor area, SMA area-6 source for N550, and posterior cingulate area-23 for P750. These source components showed a significantly faster (41.2 ms) latency and a shift in location from dorsal to ventral SMA of N550 toward cingulate area-31 between the 1s and 2s conditions. The temporal and spatial shift during spatial summation may reflect speeding up of the limbic affective reaction and prefrontal cognitive preparation in impending aversion and is deemed essential for integration of bodily sensations, such as pain. q

Neuroimage, 2008

Rhythmic synchronization likely subserves interactions among neuronal groups. One of the best stu... more Rhythmic synchronization likely subserves interactions among neuronal groups. One of the best studied rhythmic synchronization phenomena in the human nervous system is the beta-band (15–30 Hz) synchronization in the motor system. In this study, we imaged structures across the human brain that are synchronized to the motor system’s beta rhythm. We recorded whole-head magnetoencephalograms (MEG) and electromyograms (EMG) of left/right extensor carpi radialis muscle during left/right wrist extension. We analyzed coherence, on the one hand between the EMG and neuronal sources in the brain, and on the other hand between different brain sources, using a spatial filtering approach. Cortico-muscular coherence analysis revealed a spatial maximum of coherence to the muscle in motor cortex contralateral to the muscle in accordance with earlier findings. Moreover, by applying a two-dipole source model, we unveiled significantly coherent clusters of voxels in the ipsilateral cerebellar hemisphere and ipsilateral cerebral motor regions. The spatial pattern of coherence to the right and left arm EMG was roughly mirror reversed across the midline, in agreement with known physiology. Subsequently, we analyzed the brain-wide pattern of beta-band coherence to the motor cortex contralateral to the contracting muscle. This analysis did not reveal any convincing pattern. Because the prior cortico-muscular analysis had demonstrated the expected pattern in our data, this negative finding demonstrates a current limitation of the applied method for cortico-cortical coherence analysis. We conclude that during an isometric muscle contraction, several distributed brain regions form a brain-wide beta-band network for motor control.

Journal of Cognitive Neuroscience, 2015

■ In this study, we explore the possibility to predict the semantic category of words from brain ... more ■ In this study, we explore the possibility to predict the semantic category of words from brain signals in a free word generation task. Participants produced single words from different semantic categories in a modified semantic fluency task. A Bayesian logistic regression classifier was trained to predict the semantic category of words from single-trial MEG data. Significant classification accuracies were achieved using sensorlevel MEG time series at the time interval of conceptual preparation. Semantic category prediction was also possible using source-reconstructed time series, based on minimum norm estimates of cortical activity. Brain regions that contributed most to classification on the source level were identified. These were the left inferior frontal gyrus, left middle frontal gyrus, and left posterior middle temporal gyrus. Additionally, the temporal dynamics of brain activity underlying the semantic preparation during word generation was explored. These results provide important insights about central aspects of language production. ■ Recently, van de Nieuwenhuijzen et al. (2013) demonstrated that categorical information can be decoded from

Journal of Neuroscience, 2008

Although the resting and baseline states of the human electroencephalogram and magnetoencephalogr... more Although the resting and baseline states of the human electroencephalogram and magnetoencephalogram (MEG) are dominated by oscillations in the alpha band (ϳ10 Hz), the functional role of these oscillations remains unclear. In this study we used MEG to investigate how spontaneous oscillations in humans presented before visual stimuli modulate visual perception. Subjects had to report if there was a subtle difference in gray levels between two superimposed presented discs. We then compared the prestimulus brain activity for correctly (hits) versus incorrectly (misses) identified stimuli. We found that visual discrimination ability decreased with an increase in prestimulus alpha power. Given that reaction times did not vary systematically with prestimulus alpha power changes in vigilance are not likely to explain the change in discrimination ability. Source reconstruction using spatial filters allowed us to identify the brain areas accounting for this effect. The dominant sources modulating visual perception were localized around the parieto-occipital sulcus. We suggest that the parieto-occipital alpha power reflects functional inhibition imposed by higher level areas, which serves to modulate the gain of the visual stream.