Friederike U. Hohlefeld

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Brain-Computer Interfaces can suffer from a large variance of the subject conditions within and across sessions. For example vigilance fluctuations in the individual , variable task involvement, workload etc. alter the characteristics of EEG signals and thus challenge a stable BCI operation. In the present work we aim to define features based on a variant(More)
We introduce quasi-movements and define them as volitional movements which are minimized by the subject to such an extent that finally they become undetectable by objective measures. They are intended as overt movements, but the absence of the measurable motor responses and the subjective experience make quasi-movements similar to motor imagery. We used the(More)
Previous neuroimaging studies based on neurovascular coupling have shown that stroke affects both, strength and spatial extent of brain activation during upper limb movements. Here, we investigated the sub-second amplitude dynamics of a direct neuronal measure, i.e., event-related desynchronization (ERD) of EEG oscillations during finger movements, in(More)
Overt and covert movements (e.g., motor imagery) have been frequently demonstrated to engage common neuronal substrates in the motor system. However, it is an open question whether this similarity is also present during early stages of stimulus-processing. We utilized the high temporal resolution of multi-channel electroencephalography (EEG) in order to(More)
'Repetition suppression' (RS) denotes the decrease of neural responses to repeated external sensory stimuli. We showed that RS can be also triggered by internal processes alone. When individuals perform repetitive covert movements, that is, motor imagery or quasi-movements, both of which are associated with pericentral cortical activity without muscle(More)
Although thalamic deep brain stimulation is an effective treatment for patients with essential tremor, little is known about its effect on cortical neural dynamics. Therefore, we investigated long-range temporal correlations and spectral power in electroencephalographic recordings of patients during OFF versus ON bilateral thalamic deep brain stimulation in(More)
In everyday life one may encounter both unpredictable and self-initiated, hence anticipated, events. Here, we analyzed the effects of self-initiated auditory stimulus presentation on P3 and N2 components in an oddball paradigm. If the stimulus sequence was fully self-determined, both components were attenuated in comparison with computer-controlled(More)
OBJECTIVE Motor recovery after stroke is attributed to neuronal plasticity, however not all post-stroke neuronal changes relate to regaining fine motor control. Corticomuscular coherence (CMC) is a measure allowing to trace neuronal reorganizations which are functionally relevant for motor recovery. Contrary to previous studies which were performed only in(More)
A good example of inferential processes in perception is long-range apparent motion (AM), the illusory percept of visual motion that occurs when two spatially distinct stationary visual objects are presented in alternating sequence. The AM illusion is strongest at presentation frequencies around 3 Hz. At lower presentation frequencies, the percept varies(More)
The somatotopic layout of the primary somatosensory cortex is known for its fine spatial structure as delineated in single cell recordings and macroscopic EEG evoked responses. While a gross somatotopic layout has been revealed also for neuronal oscillations responding to sensorimotor stimulation of distant body parts (e.g. hand vs. foot), it is still(More)
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