Ralph Huonker

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Functional magnetic resonance imaging (fMRI) hypothesis testing based on the blood oxygenation level dependent (BOLD) contrast mechanism typically involves a search for a positive effect during a specific task relative to a control state. However, aside from positive BOLD signal changes there is converging evidence that neuronal responses within various(More)
Somatosensory signals modulate activity throughout a widespread network in both of the brain hemispheres: the contralateral as well as the ipsilateral side of the brain relative to the stimulated limb. To analyze the ipsilateral somatosensory brain areas that are engaged during limb stimulation, we performed functional magnetic resonance imaging (fMRI) in(More)
Following stroke, many patients suffer from chronic motor impairment and reduced somatosensation in the stroke-affected body parts. Recent experimental studies suggest that temporary functional deafferentation (TFD) of parts of the stroke-affected upper limb or of the less-affected contralateral limb might improve the sensorimotor capacity of the(More)
Cortical reorganization occurs within the primary somatosensory and the primary motor cortex after amputation of the arm or forearm. Here we report on a patient showing cortical reorganization after amputation of his right index finger. Our findings indicate that the neural networks within the area of the amputated finger in the somatosensory cortex (SI)(More)
In animals simple passive co-activation causes a fusion and expansion of the involved cortical representations. We used passive tactile finger co-activation for 40 min to investigate cortical representational changes in the human somatosensory cortex. Magnetic source imaging revealed that the euclidean distance between median and ulnar nerve somatosensory(More)
Repeated auditory stimulation results usually in a response decrement of event-related potential components. In the current study, we investigated the impact of the interstimulus interval (ISI) on the response decrement. Healthy subjects were stimulated with trains of five tones, with an ISI of 600, 1,200, or 1,800 ms within the trains. Auditory evoked(More)
Recent research indicates that areas of the primary somatosensory (SI) and primary motor cortex show massive cortical reorganization after amputation of the upper arm, forearm or fingers. Most of these studies were carried out months or several years after amputation. In the present study, we describe cortical reorganization of areas in the SI of a patient(More)
Biological research about dyslexia has been conducted using various neuroimaging methods like functional Magnetic Resonance Imaging (fMRI) or Electroencephalography (EEG). Since language functions are characterized by both distributed network activities and speed of processing within milliseconds, high temporal as well as high spatial resolution of(More)
Several functional brain imaging studies of pain using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have shown that painful stimulation causes activation of different brain areas. The aim of the present study was to develop and implement painful stimulation of the trigeminal nerve, which can be applied with(More)
The movement-evoked field I (MEF I) component is the largest and most stable neuromagnetic component accompanying self-paced movements. In order to use MEG for studying dynamic changes in the cortical organization of movements, data about the reliability and variability of these neuromagnetic components for individual subjects must be established during(More)