| Home > Departments > Center for Experimental Medicine > Department of Neurophysiology and Pathophysiology > MEG
Research Group: | |
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| [head of group:] | |
| Dr. Sci.nat. Jörg Hipp | |
| [group members:] | |
| Dr.rer.nat. Gernot Supp Postdoc | |
| MSc Christine Carl PhD Student | |
| Dipl.Psych. Claudia Domnick PhD Student | |
| MSc David Hawellek PhD Student | |
| MSc Dirk HJ Snijders PhD Student | |
| Christiane Reissmann Technical Assistant | |
| Gerhard Steinmetz Engineer | |
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| [research topics:] | |
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| [measurement of magnetic brain signals:] | |
| A super-conducting quantum interference device (SQUID) enables to detect extremely small magnetic fields originating from ongoing currents in the nervous tissue of the human brain. By means of the SQUID technology these extremely weak biomagnetic fields are measured in a non-invasive manner, even sparing the subject/patient from any physical contact with the device. In detail, MEG rests upon the physical principal that currents flowing across the dendritic membran of pyramidal neurons that constitute the cerebral cortex generate extra-cranially measurable magnetic fields. In respect to the source of brain signals, MEG is closely related to electroencephalography (EEG), which has developed to be an integral part of clinical diagnostics over the last decades. One principal advantage of using MEG is that brain activity is detected with a high temporal and spatial resolution. | |
| [brain oscillation and synchronisation:] | |
| The MEG captures neuronal oscillations generated by populations of synchronously oscillating neurons. From a functional perspective such neural oscillations might be of crucial importance, since they were shown to play a profound role for neuronal communication, exemplarily in binding object features into a coherent percept. Specifically, our work aims at investigating the idea that neuronal synchronization gives rise to the formation of representational states in human awareness and enables response selection in sensorimotor brain areas. One particular focus of our research is the visual system of the human brain, which may constitute a paradigmatic case for the mechanism of binding that integrates information processed in different, locally apart cortical areas into coherent object representations. Tools of signals analysis such as time-frequency transformation and beam-forming algorithms allow us to locate sources of brain oscillations and their ongoing mutual synchronisation. Furthermore, by means of multivariate autoregressive (MVAR) modelling we seek to uncover the hierarchy of neuronal communication within dynamic brain networks. Various experimental paradigm and different stimulation designs including cognitive, attentional and pharmacological modulations are applied to analyse the various faces of oscillatory processes in the human brain. | |
| [conciousness and selective attention:] | |
| We investigate and characterize the neuronal basis of distinct representational stages and conscious awareness by exploring brain signals of normal human subjects and patients. Stimuli of different sensory qualities - i.e. visual, auditory or somatosensory stimulation - are used to analyze the influence of attention and conscious awareness on brain responses. In particular, we seek to understand the precise role of temporal binding in multi-sensory integration and cross-modal interactions in the human brain. Furthermore, the involvement of neural synchrony and conscious awareness is explored. One of the key functions of selective attention is to enhance perceptual acuity and reduce stimulus ambiguity. Early-selection theories predict brain mechanisms that amplify relevant information and suppress irrelevant information at early stages of information processing. This amplification and suppression of early sensory processing might be exploited to direct attention to a specific feature (e.g. a distinct shape or tone), stimulus configuration or a sensory scene. Research in our laboratory sets the focus on different aspects of conscious awareness and mechanisms of selective attention including intra- and inter-modal attention highlighting the role of oscillatory brain responses. | |
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| [pain processing:] | |
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| The general goal here is to obtain a deeper understanding of the CNS pathways and mechanisms involved in pain processing and pain modulation during normal physiologic and pathologic states. In particular, we pursue oscillatory brain activity in response to painful stimuli. The dynamics and plasticity of the involved brain network are studied by systematically altering somatic stimulation parameters and by monitoring the behavioural effects to drug application or attentional demands. Spatial and temporal changes in the network activity patterns are correlated with human psychophysical behaviour in order to determine their functional significance. | |
| [multisensory processing:] | |
| Inputs from multiple sensory modalities such as simultaneous visual and auditory stimulation are integrated at several stages of cortical processing. Studies in our laboratory focus on short (sensory) and longer latency (cognitive) multisensory processing and the role of oscillatory brain responses in multisensory integration. One research focus is the examination of integrative multisensory processing using naturalistic stimuli (i.e. multisensory speech and multisensory objects). | |
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