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Friedhelm C. Hummel

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9 papers

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NeurIPS Conference 2025 Conference Paper

EPFL-Smart-Kitchen: An Ego-Exo Multi-Modal Dataset for Challenging Action and Motion Understanding in Video-Language Models

Andy Bonnetto
Haozhe Qi
Franklin Leong
Matea Tashkovska
Mahdi Rad
Solaiman Shokur
Friedhelm C. Hummel
Silvestro Micera

Understanding behavior requires datasets that capture humans while carrying out complex tasks. The kitchen is an excellent environment for assessing human motor and cognitive function, as many complex actions are naturally exhibited in kitchens from chopping to cleaning. Here, we introduce the EPFL-Smart-Kitchen-30 dataset, collected in a noninvasive motion capture platform inside a kitchen environment. Nine static RGB-D cameras, inertial measurement units (IMUs) and one head-mounted HoloLens~2 headset were used to capture 3D hand, body, and eye movements. The EPFL-Smart-Kitchen-30 dataset is a multi-view action dataset with synchronized exocentric, egocentric, depth, IMUs, eye gaze, body and hand kinematics spanning 29. 7 hours of 16 subjects cooking four different recipes. Action sequences were densely annotated with 33. 78 action segments per minute. Leveraging this multi-modal dataset, we propose four benchmarks to advance behavior understanding and modeling through 1) a vision-language benchmark, 2) a semantic text-to-motion generation benchmark, 3) a multi-modal action recognition benchmark, 4) a pose-based action segmentation benchmark. We expect the EPFL-Smart-Kitchen-30 dataset to pave the way for better methods as well as insights to understand the nature of ecologically-valid human behavior. Code and data are available at https: //amathislab. github. io/EPFL-Smart-Kitchen

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YNIMG Journal 2022 Journal Article

Evaluating reproducibility and subject-specificity of microstructure-informed connectivity

Philipp J. Koch
Gabriel Girard
Julia Brügger
Andéol G. Cadic-Melchior
Elena Beanato
Chang-hyun Park
Takuya Morishita
Maximilian J. Wessel

Tractography enables identifying and evaluating the healthy and diseased brain's white matter pathways from diffusion-weighted magnetic resonance imaging data. As previous evaluation studies have reported significant false-positive estimation biases, recent microstructure-informed tractography algorithms have been introduced to improve the trade-off between specificity and sensitivity. However, a major limitation for characterizing the performance of these techniques is the lack of ground truth brain data. In this study, we compared the performance of two relevant microstructure-informed tractography methods, SIFT2 and COMMIT, by assessing the subject specificity and reproducibility of their derived white matter pathways. Specifically, twenty healthy young subjects were scanned at eight different time points at two different sites. Subject specificity and reproducibility were evaluated using the whole-brain connectomes and a subset of 29 white matter bundles. Our results indicate that although the raw tractograms are more vulnerable to the presence of false-positive connections, they are highly reproducible, suggesting that the estimation bias is subject-specific. This high reproducibility was preserved when microstructure-informed tractography algorithms were used to filter the raw tractograms. Moreover, the resulting track-density images depicted a more uniform coverage of streamlines throughout the white matter, suggesting that these techniques could increase the biological meaning of the estimated fascicles. Notably, we observed an increased subject specificity by employing connectivity pre-processing techniques to reduce the underlaying noise and the data dimensionality (using principal component analysis), highlighting the importance of these tools for future studies. Finally, no strong bias from the scanner site or time between measurements was found. The largest intraindividual variance originated from the sole repetition of data measurements (inter-run).

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YNIMG Journal 2021 Journal Article

Enhancing visual motion discrimination by desynchronizing bifocal oscillatory activity

Roberto F. SALAMANCA-GIRON
Estelle Raffin
Sarah B. ZANDVLIET
Martin Seeber
Christoph M. Michel
Paul Sauseng
Krystel R. HUXLIN
Friedhelm C. Hummel

Visual motion discrimination involves reciprocal interactions in the alpha band between the primary visual cortex (V1) and mediotemporal areas (V5/MT). We investigated whether modulating alpha phase synchronization using individualized multisite transcranial alternating current stimulation (tACS) over V5 and V1 regions would improve motion discrimination. We tested 3 groups of healthy subjects with the following conditions: (1) individualized In-Phase V1alpha-V5alpha tACS (0° lag), (2) individualized Anti-Phase V1alpha-V5alpha tACS (180° lag) and (3) sham tACS. Motion discrimination and EEG activity were recorded before, during and after tACS. Performance significantly improved in the Anti-Phase group compared to the In-Phase group 10 and 30 min after stimulation. This result was explained by decreases in bottom-up alpha-V1 gamma-V5 phase-amplitude coupling. One possible explanation of these results is that Anti-Phase V1alpha-V5alpha tACS might impose an optimal phase lag between stimulation sites due to the inherent speed of wave propagation, hereby supporting optimized neuronal communication.

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YNICL Journal 2017 Journal Article

Synergistic but independent: The role of corticospinal and alternate motor fibers for residual motor output after stroke

Robert Schulz
Eunhee Park
Jungsoo Lee
Won Hyuk Chang
Ahee Lee
Yun-Hee Kim
Friedhelm C. Hummel

BACKGROUND: Brain imaging has shown that not only the cortico-spinal tract (CST), but also alternate corticofugal motor fibers (aMF), such as the cortico-rubro-spinal and cortico-reticulo-spinal tract, influence residual motor output after stroke. So far, studies mainly have investigated each tract separately. A combined analysis of CST and aMF with assessment of their interactive role, i.e., that structural integrity of one tract influences the functional role of the structural integrity of the other, is pending. METHODS: 39 late subacute stroke patients (aged 59.4 ± 12.0 years, 100 ± 11 days after stroke) were included. Probabilistic tractography was used to reconstruct CST and aMF. Fractional anisotropy (FA) was calculated as a measure of microstructural integrity. Multiple-linear-regression analysis was used to associate tract-related FA with residual motor output and to determine interactions between CST and aMF. RESULTS: = 0.882). Thus, these data suggest that aMF and CST explain residual motor output in stroke patients in a synergistic, but mainly independent manner. CONCLUSIONS: The structural states of the CST and also - to a smaller degree - of the aMF correlate with residual motor output in late subacute stroke patients. Based on this statistical modeling with all inherent limitations, the novel finding of an absence of a significant interaction between both tracts in regard of their functional role, suggests that both corticofugal pathways act synergistically but largely independently. These findings add to the understanding of the functional role of different corticofugal motor fibers and their interactions for motor output after stroke.

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YNIMG Journal 2016 Journal Article

Dynamic causal modelling of EEG and fMRI to characterize network architectures in a simple motor task

Marlene Bönstrup
Robert Schulz
Jan Feldheim
Friedhelm C. Hummel
Christian Gerloff

Dynamic causal modelling (DCM) has extended the understanding of brain network dynamics in a variety of functional systems. In the motor system, DCM studies based on functional magnetic resonance imaging (fMRI) or on magneto-/electroencephalography (M/EEG) have demonstrated movement-related causal information flow from secondary to primary motor areas and have provided evidence for nonlinear cross-frequency interactions among motor areas. The present study sought to investigate to what extent fMRI- and EEG-based DCM might provide complementary and synergistic insights into neuronal network dynamics. Both modalities share principal similarities in the formulation of the DCM. Thus, we hypothesized that DCM based on induced EEG responses (DCM–IR) and on fMRI would reveal congruent task-dependent network dynamics. Brain electrical (63-channel surface EEG) and Blood Oxygenation Level Dependent (BOLD) signals were recorded in separate sessions from 14 healthy participants performing simple isometric right and left hand grips. DCM–IR and DCM–fMRI were used to estimate coupling parameters modulated by right and left hand grips within a core motor network of six regions comprising bilateral primary motor cortex (M1), ventral premotor cortex (PMv) and supplementary motor area (SMA). We found that DCM–fMRI and DCM–IR similarly revealed significant grip-related increases in facilitatory coupling between SMA and M1 contralateral to the active hand. A grip-dependent interhemispheric reciprocal inhibition between M1 bilaterally was only revealed by DCM–fMRI but not by DCM–IR. Frequency-resolved coupling analysis showed that the information flow from contralateral SMA to M1 was predominantly a linear alpha-to-alpha (9–13Hz) interaction. We also detected some cross-frequency coupling from SMA to contralateral M1, i. e. , between lower beta (14–21Hz) at the SMA and higher beta (22–30Hz) at M1 during right hand grip and between alpha (9–13Hz) at SMA and lower beta (14–21Hz) at M1 during left hand grip. In conclusion, the strategy of informing EEG source-space configurations with fMRI-derived coordinates, cross-validating basic connectivity maps and analysing frequency coding allows for deeper insight into the motor network architecture of the human brain. The present results provide evidence for the robustness of non-invasively measured causal information flow from secondary motor areas such as SMA towards M1 and further contribute to the validation of the methodological approach of multimodal DCM to explore human network dynamics.

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YNICL Journal 2016 Journal Article

Voxel-based lesion-symptom mapping of stroke lesions underlying somatosensory deficits

Sarah Meyer
Simon S. Kessner
Bastian Cheng
Marlene Bönstrup
Robert Schulz
Friedhelm C. Hummel
Nele De Bruyn
Andre Peeters

The aim of this study was to investigate the relationship between stroke lesion location and the resulting somatosensory deficit. We studied exteroceptive and proprioceptive somatosensory symptoms and stroke lesions in 38 patients with first-ever acute stroke. The Erasmus modified Nottingham Sensory Assessment was used to clinically evaluate somatosensory functioning in the arm and hand within the first week after stroke onset. Additionally, more objective measures such as the perceptual threshold of touch and somatosensory evoked potentials were recorded. Non-parametric voxel-based lesion-symptom mapping was performed to investigate lesion contribution to different somatosensory deficits in the upper limb. Additionally, structural connectivity of brain areas that demonstrated the strongest association with somatosensory symptoms was determined, using probabilistic fiber tracking based on diffusion tensor imaging data from a healthy age-matched sample. Voxels with a significant association to somatosensory deficits were clustered in two core brain regions: the central parietal white matter, also referred to as the sensory component of the superior thalamic radiation, and the parietal operculum close to the insular cortex, representing the secondary somatosensory cortex. Our objective recordings confirmed findings from clinical assessments. Probabilistic tracking connected the first region to thalamus, internal capsule, brain stem, postcentral gyrus, cerebellum, and frontal pathways, while the second region demonstrated structural connections to thalamus, insular and primary somatosensory cortex. This study reveals that stroke lesions in the sensory fibers of the superior thalamocortical radiation and the parietal operculum are significantly associated with multiple exteroceptive and proprioceptive deficits in the arm and hand.

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YNICL Journal 2015 Journal Article

White matter integrity of premotor–motor connections is associated with motor output in chronic stroke patients

Robert Schulz
Hanna Braass
Gianpiero Liuzzi
Vanessa Hoerniss
Patricia Lechner
Christian Gerloff
Friedhelm C. Hummel

Corticocortical functional interactions between the primary motor cortex (M1) and secondary motor areas, such as the dorsal (PMd) and ventral (PMv) premotor cortices and the supplementary motor area (SMA) are relevant for residual motor output after subcortical stroke. We hypothesized that the microstructural integrity of the underlying white matter tracts also plays a role in preserved motor output. Using diffusion-tensor imaging we aimed at (i) reconstructing individual probable intrahemispheric connections between M1 and the three secondary areas (PMd, PMv, SMA) and (ii) examining the extent to which the tract-related microstructural integrity correlates with residual motor output. The microstructural integrity of the tract connecting ipsilesional M1 and PMd was significantly associated with motor output (R = 0.78, P = 0.02). The present results support the view that ipsilesional secondary motor areas such as the PMd might support M1 via corticocortical connections to generate motor output after stroke.

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YNICL Journal 2014 Journal Article

Altered intrahemispheric structural connectivity in Gilles de la Tourette syndrome

Bastian Cheng
Hanna Braass
Christos Ganos
Andras Treszl
Katja Biermann-Ruben
Friedhelm C. Hummel
Kirsten Müller-Vahl
Alfons Schnitzler

Gilles de la Tourette syndrome (GTS) is a common developmental neuropsychiatric disorder characterized by tics and frequent psychiatric comorbidities, often causing significant disability. Tic generation has been linked to disturbed networks of brain areas involved in planning, controlling and execution of actions, particularly structural and functional disorders in the striatum and cortico-striato-thalamo-cortical loops. We therefore applied structural diffusion tensor imaging (DTI) to characterize changes in intrahemispheric white matter connectivity in cortico-subcortical circuits engaged in motor control in 15 GTS patients without psychiatric comorbidities. White matter connectivity was analyzed by probabilistic fiber tractography between 12 predefined cortical and subcortical regions of interest. Connectivity values were combined with measures of clinical severity rated by the Yale Global Tic Severity Scale (YGTSS). GTS patients showed widespread structural connectivity deficits. Lower connectivity values were found specifically in tracts connecting the supplementary motor areas (SMA) with basal ganglia (pre-SMA-putamen, SMA-putamen) and in frontal cortico-cortical circuits. There was an overall trend towards negative correlations between structural connectivity in these tracts and YGTSS scores. Structural connectivity of frontal brain networks involved in planning, controlling and executing actions is reduced in adult GTS patients which is associated with tic severity. These findings are in line with the concept of GTS as a neurodevelopmental disorder of brain immaturity.

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YNIMG Journal 2013 Journal Article

Two brakes are better than one: The neural bases of inhibitory control of motor memory traces

Paul Sauseng
Christian Gerloff
Friedhelm C. Hummel

Inhibitory control of actions is one important aspect in daily life to warrant adequate context related behavior. Alpha activity (oscillatory brain activity around 10Hz) has been suggested to play a major role for the implementation of inhibitory control. In the present study electrophysiological correlates of voluntary suppression of acquired, memorized motor actions have been compared to the suppression of novel motor actions. Multichannel EEG analyses of alpha power and alpha phase coherence were used. Healthy subjects were asked to inhibit the execution of either well-trained, memorized or untrained, novel sequential finger movements depending on the respective context. An increase of focal upper alpha activity at bilateral sensorimotor cortices was found during suppression of movements independent of whether these were memorized or novel. This represents a memory unspecific mechanism of motor cortical inhibition. In contrast, interregional phase synchronization between frontal and (left) central recording sites showed a differential effect with decoupling during suppression of memorized movements which was not the case with novel ones. Increase of fronto-central coupling at upper alpha frequency during retrieval of the memory trace and decrease during suppression of retrieval were obtained. This further supports the view of the functional relevance of upper alpha oscillations as a mechanism of context-dependent sustained inhibition of memory contents.

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