Till Nierhaus

Publications (12) View all

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  Available from: Till Nierhaus

  Article: Internal ventilation system of MR scanners induces specific EEG artifact during simultaneous EEG-fMRI.

  Till Nierhaus, Christopher Gundlach, Dominique Goltz, Sabrina Thiel, Burkhard Pleger, Arno Villringer
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  ABSTRACT: During simultaneous EEG-fMRI acquisition, the EEG signal suffers from tremendous artifacts caused by the scanner "environment". Particularly, gradient artifacts and the ballistocardiogram have been well characterized, along with methods to eliminate them. Here, we describe another systematic artifact in the EEG signal, which is induced by the internal ventilation system of Siemens TRIO and VERIO MR scanners. A ventilation-level dependent vibration induces specific peaks in the frequency spectrum of the EEG. These frequency peaks are in the range of physiologically relevant brain rhythms (gamma frequency range), and thus interfere with their reliable acquisition. This ventilation dependent artifact was most prominent on the electrodes placed directly on the subject's head, so it is not sufficient to simply place the EEG's amplifier outside the scanner tube. Instead, the ventilator must be switched off to fully eliminate the ventilator's artificial manipulation of EEG recordings. Without the internal ventilator system being on, the temperature within the scanner tube may rise, thus requiring shorter scanning sessions or an additional external ventilation system.
  NeuroImage 02/2013; · 5.89 Impact Factor
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  Chapter: fMRI for the Assessment of Functional Connectivity

  Till Nierhaus, Daniel Margulies, Xiangyu Long, Arno Villringer
  02/2012; , ISBN: 978-953-51-0097-3
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  Article: Characterizing acupuncture stimuli using brain imaging with FMRI--a systematic review and meta-analysis of the literature.

  Wenjing Huang, Daniel Pach, Vitaly Napadow, Kyungmo Park, Xiangyu Long, Jane Neumann, Yumi Maeda, Till Nierhaus, Fanrong Liang, Claudia M Witt
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  ABSTRACT: The mechanisms of action underlying acupuncture, including acupuncture point specificity, are not well understood. In the previous decade, an increasing number of studies have applied fMRI to investigate brain response to acupuncture stimulation. Our aim was to provide a systematic overview of acupuncture fMRI research considering the following aspects: 1) differences between verum and sham acupuncture, 2) differences due to various methods of acupuncture manipulation, 3) differences between patients and healthy volunteers, 4) differences between different acupuncture points. We systematically searched English, Chinese, Korean and Japanese databases for literature published from the earliest available up until September 2009, without any language restrictions. We included all studies using fMRI to investigate the effect of acupuncture on the human brain (at least one group that received needle-based acupuncture). 779 papers were identified, 149 met the inclusion criteria for the descriptive analysis, and 34 were eligible for the meta-analyses. From a descriptive perspective, multiple studies reported that acupuncture modulates activity within specific brain areas, including somatosensory cortices, limbic system, basal ganglia, brain stem, and cerebellum. Meta-analyses for verum acupuncture stimuli confirmed brain activity within many of the regions mentioned above. Differences between verum and sham acupuncture were noted in brain response in middle cingulate, while some heterogeneity was noted for other regions depending on how such meta-analyses were performed, such as sensorimotor cortices, limbic regions, and cerebellum. Brain response to acupuncture stimuli encompasses a broad network of regions consistent with not just somatosensory, but also affective and cognitive processing. While the results were heterogeneous, from a descriptive perspective most studies suggest that acupuncture can modulate the activity within specific brain areas, and the evidence based on meta-analyses confirmed some of these results. More high quality studies with more transparent methodology are needed to improve the consistency amongst different studies.
  PLoS ONE 01/2012; 7(4):e32960. · 4.09 Impact Factor
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  Article: Acoustic processing of temporally modulated sounds in infants: evidence from a combined near-infrared spectroscopy and EEG study.

  Silke Telkemeyer, Sonja Rossi, Till Nierhaus, Jens Steinbrink, Hellmuth Obrig, Isabell Wartenburger
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  ABSTRACT: Speech perception requires rapid extraction of the linguistic content from the acoustic signal. The ability to efficiently process rapid changes in auditory information is important for decoding speech and thereby crucial during language acquisition. Investigating functional networks of speech perception in infancy might elucidate neuronal ensembles supporting perceptual abilities that gate language acquisition. Interhemispheric specializations for language have been demonstrated in infants. How these asymmetries are shaped by basic temporal acoustic properties is under debate. We recently provided evidence that newborns process non-linguistic sounds sharing temporal features with language in a differential and lateralized fashion. The present study used the same material while measuring brain responses of 6 and 3 month old infants using simultaneous recordings of electroencephalography (EEG) and near-infrared spectroscopy (NIRS). NIRS reveals that the lateralization observed in newborns remains constant over the first months of life. While fast acoustic modulations elicit bilateral neuronal activations, slow modulations lead to right-lateralized responses. Additionally, auditory-evoked potentials and oscillatory EEG responses show differential responses for fast and slow modulations indicating a sensitivity for temporal acoustic variations. Oscillatory responses reveal an effect of development, that is, 6 but not 3 month old infants show stronger theta-band desynchronization for slowly modulated sounds. Whether this developmental effect is due to increasing fine-grained perception for spectrotemporal sounds in general remains speculative. Our findings support the notion that a more general specialization for acoustic properties can be considered the basis for lateralization of speech perception. The results show that concurrent assessment of vascular based imaging and electrophysiological responses have great potential in the research on language acquisition.
  Frontiers in psychology. 01/2011; 1:62.
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  Article: Interhemispheric interactions between the human primary somatosensory cortices.

  Patrick Ragert, Till Nierhaus, Leonardo G Cohen, Arno Villringer
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  ABSTRACT: In the somatosensory domain it is still unclear at which processing stage information reaches the opposite hemispheres. Due to dense transcallosal connections, the secondary somatosensory cortex (S2) has been proposed to be the key candidate for interhemispheric information transfer. However, recent animal studies showed that the primary somatosensory cortex (S1) might as well account for interhemispheric information transfer. Using paired median nerve somatosensory evoked potential recordings in humans we tested the hypothesis that interhemispheric inhibitory interactions in the somatosensory system occur already in an early cortical processing stage such as S1. Conditioning right S1 by electrical median nerve (MN) stimulation of the left MN (CS) resulted in a significant reduction of the N20 response in the target (left) S1 relative to a test stimulus (TS) to the right MN alone when the interstimulus interval between CS and TS was between 20 and 25 ms. No such changes were observed for later cortical components such as the N20/P25, N30, P40 and N60 amplitude. Additionally, the subcortically generated P14 response in left S1 was also not affected. These results document the existence of interhemispheric inhibitory interactions between S1 in human subjects in the critical time interval of 20-25 ms after median nerve stimulation.
  PLoS ONE 01/2011; 6(2):e16150. · 4.09 Impact Factor