Conference paper – 55th Annual Conference of the German Society for Biomedical Engineering (BMT 2021)
“Dry EEG recordings for detection of left, right hand, tongue and feet movements”
Milana Komosar¹, Uwe Graichen1,2, Patrique Fiedler1, Jens Haueisen1
1Biomedical Engineering, TU Ilmenau, Ilmenau, Germany
2Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
Brain-computer interfaces (BCI) are powerful tools that can be particularly helpful for people with motor disabilities. Recently developed dry EEG sensors could significantly simplify the use of EEG and greatly expand its field of application. In the presented study, EEG data recorded during real and imaginary movements of the left and right hand, tongue and both feet were analysed. The study demonstrated that with the help of EEG systems equipped with dry sensors, BCI technologies can be applied outside of laboratories, non-invasively, quickly, and easily.
Conference paper and talk – European Association for Vision and Eye Research (EVER2021)
“Neuronal sources of visually evoked potentials using selective color opponent channel Stimulation”
Sascha Klee1,2, Dietmar Link²
1 Department of General Health Studies, Division Biostatistics and Data Science, Karl Landsteiner University of Health Science, Krems, Austria
2 Department of Optoelectrophysiological Engineering, Technische Universität Ilmenau, Ilmenau, German
The retinal stages of color processing have been extensively researched in recent years. Of particular interest is the link between color perception disorders and various pathologies of the visual sense. Using the example of glaucoma, a diagnostic relevance could already be shown in own work. In contrast, the cortical stages, especially the spatial distribution of visual processing are less understood. It is known that many cells in the visual cortex respond to color. However, what kind of computations these cells perform on their visual input, and what are their temporal and spatial properties are still under debate. In this study, we aimed to analyze the neuronal sources of visually evoked potentials using selective color opponent channel stimulations. The study was conducted on 10 healthy subjects (6 male, 4 female, 1 eye each, mean age 25.5±5.1 yr). All subjects were free of eye diseases. Normal color vision was checked with Ishihara and Stilling-Velhagen plates. To modulate selective activity in the S-cone and L/M-cone driven channels (the related cells are: short-wavelength absorbing: S-cone, medium-wavelength absorbing: M-cone, long-wavelength-absorbing: L-cone) we presented two silent substitution flash sequences (total of 200 stimuli) in a full circle with a diameter of 22°. Electroencephalography was performed using a 64-channel amplifier system (Theraprax, neuroConn GmbH, Germany) in combination with Ag/AgCl ring electrodes (B10-S-200, EASYCAP GmbH, Germany). The preprocessed data were analyzed with source localization software (CURRY v4.6, Compumedics, USA). For each subject a realistically shaped volume conductor was constructed by a boundary element model. Our findings showed that neural processing occurs in the same areas of the visual cortex for stimuli with different spectral properties. The signals of S- and L/M-cone driven channels are transmitted in distinct pathways to the cortex. Thus, the observed latency differences might be caused by different anatomical and functional properties of these pathways (see graphic below).