Showing papers by "Gert Pfurtscheller published in 1992"
TL;DR: It was found that alpha band activity can be enhanced over the visual region during a motor task, or during a visual task over the sensorimotor region, which means ERD and ERS can be observed at nearly the same time.
961 citations
TL;DR: The EEG was analysed in the 10 Hz band and in four 40 Hz bands by calculation of ERD time courses and ERD maps, whereby a ERD is characterized by a movement-related band power decrease, and a close to C3 localized 10 Hz ERD was found.
Abstract: Nineteen-channel EEG was recorded with closely spaced electrodes overlaying the left sensorimotor cortex during self-paced, voluntary right finger movements. Three right-handed people served as subjects. The EEG was analysed in the 10 Hz band (10-12 Hz) and in four 40 Hz bands (34-36, 36-38, 38-40, 40-42) by calculation of ERD time courses and ERD maps, whereby a ERD is characterized by a movement-related band power decrease. In all three subjects a close to C3 localized 10 Hz ERD was found, starting about 2 s prior to movement onset and continuing during movement. Along with this 10 Hz ERD a localized and short-lasting (about 0.5 s) burst of 40 Hz oscillations was embedded around movement onset. This can be interpreted as indicating that planning of movement is accompanied by a desynchronization of central mu rhythm and a generation of 40 Hz oscillations.
217 citations
TL;DR: Event-related desynchronization (ERD) of alpha components was studied in 10 subjects in a visuoverbal judgment task and there is evidence that topographical ERD patterns can be stable for about 300–400 ms.
Abstract: SummaryEvent-related desynchronization (ERD) of alpha components was studied in 10 subjects in a visuoverbal judgment task. EEG was recorded from 29 electrodes: ERD. measured by percentage of alpha power decrease, was calculated in 125-ms intervals and displayed in a time course over 7-s intervals a
143 citations
TL;DR: Event-related desynchronization (ERD) was quantified in the 8-10 Hz and 10-12 Hz bands in single-trial data and used as training input for a neural network comprised of a learning vector quantizer (LVQ).
67 citations
01 Jan 1992
TL;DR: Together with the discovery of alpha waves in human scalp electroencephalograms by Berger (1930), blocking was reported in response to a light stimulation and reports of an enhancement of alpha band activity as a response to visual stimulation and tactile stimulation.
Abstract: Together with the discovery of alpha waves in human scalp electroencephalograms (EEG) by Berger (1930), blocking was reported in response to a light stimulation. Triggered by the pioneering research of Berger, other groups focused on blocking or desynchronization of alpha and beta waves after visual afferences as well as after somatosensory stimulation or movement (Jasper and Andrews 1938; Jasper and Penfield 1949; Gastaut et al., 1952; Chatrian et al., 1959). Besides these findings of alpha or beta wave attenuation after sensory stimulation or with voluntary movement, there were also reports of an enhancement of alpha band activity as a response to visual stimulation (Morrell, 1966; Creutzfeldt et al., 1969) and tactile stimulation (Kreitman and Shaw, 1965).
66 citations
TL;DR: EEG classification using Learning Vector Quantization (LVQ) is introduced on the basis of a Brain-Computer Interface built in Graz, where a subject controlled a cursor in one dimension on a monitor using potentials recorded from the intact scalp.
Abstract: EEG classification using Learning Vector Quantization (LVQ) is introduced on the basis of a Brain-Computer Interface (BCI) built in Graz, where a subject controlled a cursor in one dimension on a monitor using potentials recorded from the intact scalp. The method of classification with LVQ is described in detail along with first results on a subject who participated in four on-line cursor control sessions. Using this data, extensive off-line experiments were performed to show the influence of the various parameters of the classifier and the extracted features of the EEG on the classification results.
39 citations
TL;DR: The study reports on the possibility of classifying sleep stages in infants using an artificial neural network, using polygraphic data from 4 babies aged 6 weeks, 6 months and 1 year for classification and the teaching input was provided by a human expert.
Abstract: The study reports on the possibility of classifying sleep stages in infants using an artificial neural network. The polygraphic data from 4 babies aged 6 weeks, 6 months and 1 year recorded over 8 hours were available for classification. From each baby 22 signals were recorded, digitized and stored on an optical disc. Subsets of these signals and additional calculated parameters were used to obtain data vectors, each of which represents an interval of 30 sec. For classification, two types of neural networks were used, a Multilayer Perceptron and a Learning Vector Quantizer. The teaching input for both networks was provided by a human expert. For the 6 sleep classes in babies aged 6 months, a 65% to 80% rate of correct classification (4 babies) was obtained for the testing data not previously seen.
22 citations
01 Oct 1992
TL;DR: The envelope and the instantaneous main frequency of the filtered EEG signal, calculated by the Hilbert-Transform, are used as features and a Learning Vector Quantizer was used to predict the sides of the hand movements.
Abstract: New effective features, extracted from single trial EEG data measured on the human scalp capable of hand movement prediction are reported. The envelope and the instantaneous main frequency of the filtered (8–12'Hz) EEG signal, calculated by the Hilbert-Transform, are used as features. The EEG responses of right- and left-hand movements are studied. A Learning Vector Quantizer (LVQ) was used to predict the sides of the hand movements. The classification accuracy was about 90 percent.
19 citations
TL;DR: In contrast to the negativity which is terminated following delivery of the response stimulus, the ERD persisted during the motor reaction showing a similar pattern some hundreds of milliseconds before and after movement onset.
Abstract: The foreperiod of a motor reaction to an impending stimulus is accompanied by a slow negative wave of the event-related potential, the "contingent negative variation" (CNV), when the imperative stimulus follows at a fixed interval to a warning stimulus. Using similar experimental paradigms, an event-related desynchronization (ERD) in the alpha range occurs indicating cortical activation before and during motor acts. Both EEG-parameters were quantified for four subjects using the following experimental design: One second after a non-informative warning signal (WS) a cue was presented that indicated by which hand the subject had to respond quickly after presentation of a reaction stimulus (RS); subjects were requested to respond by pressing a button with their left or right thumb. EEG-signals were recorded unipolarly from 17 electrodes. Average ERPs and ERD were computed for all electrode sites for trials with left and right hand movements, respectively, and topographically displayed in simultaneous amplitude and ERD-maps. CNV and ERD could be observed simultaneously over similar brain regions, namely central over the motor cortex, frontal with possible location over the supplementary motor area (SMA) and also covering the parietal region. While the CNV had a interindividually different and wide distribution, the ERD calculated for the upper alpha band mapped focally over the electrode sites C3 and C4 overlaying primary sensorimotor structures, with a contralateral dominance. In contrast to the negativity which is terminated following delivery of the response stimulus, the ERD persisted during the motor reaction showing a similar pattern some hundreds of milliseconds before and after movement onset.(ABSTRACT TRUNCATED AT 250 WORDS)
15 citations
TL;DR: In a 73-year-old patient complete areflexia of the cerebral and peripheral nerves following the rupture of an aneurysm of the basilar artery was diagnosed and spectral analysis of electroencephalography revealed an irreversible shift of peak within the low frequency bands.
Abstract: In a 73-year-old patient complete areflexia of the cerebral and peripheral nerves following the rupture of an aneurysm of the basilar artery was diagnosed. During apnea testing the spectral analysis of electroencephalography (EEG) revealed an irreversible shift of peak from 6 to 3 Hz within the low frequency bands. These findings suggest that apnea testing in patients with primary lesion of the brain stem should be carried out only after an isoelectric EEG.
12 citations
01 Oct 1992
TL;DR: One-dimensional control of a cursor on a computer monitor based on the differentiation of two cortical activation patterns measured by two EEG channels is described.
Abstract: Planning and preparing voluntary finger movements result in a specific topographical pattern of event-related desynchronization (ERD) in the alpha band. These patterns generated for planning left and right hand movements show large enough differences to be seperable by a Learning Vector Quantizer (LVQ). This paper describes one-dimensional control of a cursor on a computer monitor based on the differentiation of two cortical activation patterns measured by two EEG channels.
14 Jun 1992
TL;DR: A system is described which should assist the physician during an EMG (electromyographic) examination and in the diagnostic process and should help to reduce the examination time.
Abstract: A system is described which should assist the physician during an EMG (electromyographic) examination and in the diagnostic process and should help to reduce the examination time. For the realization of the system, a multiprocessor environment (transputer network) is used to build a fully integrated system on which tasks like data acquisition, signal display in real time, signal processing and analysis with different methods, expert system and general program management can run in parallel and easily communicate with one another. The prototype of the expert system consists of about 200 rules which are responsible for planning the examination process, doing the parameter classification, and giving information about the type of lesion. >
01 Oct 1992
TL;DR: In this paper, non-linear time sequence analysis has been performed on infants sleep measurement data in order to get better insight into the respiration processes, and the correlation integral characterizes the dynamics of the signal (respiration) and estimates its degrees of freedom.
Abstract: Non-linear time sequence analysis has been performed on infants sleep measurement data in order to get better insight into the respiration processes. As a first step, respiration data during different sleep stages are analyzed with nonlinear dynamic methods. Especially, the correlation integral and its slope are computed. The correlation integral characterizes the dynamics of the signal (respiration) and estimates its degrees of freedom. Changes of the dimension during sleep could be used as an indication of a high SIDS-risc (Sudden Infant Death Syndrom).
01 Oct 1992
TL;DR: In this paper, learning vector quantization (LVQ) and the top-down induction of decision trees (TDIDT) were applied on 8-hour sleep data from infants.
Abstract: Besides statistical methods, various Artificial Intelligence approaches can be used for sleep classification. Learning vector quantization (LVQ) and the top-down induction of decision trees (TDIDT) were applied on 8-hour sleep data from infants. It was shown that with a combination of TDIDT and LVQ the input dimension of the LVQ can be reduced without decreasing the classification accuracy. Classification accuracy was between 67 and 76%, depending on the infant.
Journal Article•
TL;DR: Brainstem auditory evoked potentials (BAEP) were performed in a total of 20 subjects with the diagnosis of coma dépassé and the control group consisted of 33 healthy volunteers to investigate the presence, latency and amplitude of the single BAEP-components and the variations of the stimulus artifact.
Abstract: Brainstem auditory evoked potentials (BAEP) were performed in a total of 20 subjects (mean age 33.2 +/- 15.1 years; severe head injury in most cases) with the diagnosis of coma depasse. The control group consisted of 33 healthy volunteers (mean age 26.9 +/- 5.3 years). The presence, latency and amplitude of the single BAEP-components and the variations of the stimulus artifact were evaluated. The mean amplitudes of the stimulus artifact of the brain dead subjects were calculated (means +/- SD) to be 0.26 +/- 0.12 microV (control group: 0.11 +/- 0.03 microV). Pathological alterations of the mechanics of the inner ear as well as extracerebral changes in conductivity or stimulus related depolarization processes in extracerebral parts of the auditory system were taken into consideration to be possible reasons for this significant (p less than 0.001; t-test) difference.
01 Oct 1992
TL;DR: The study reports on the possibility of classifying sleep stages in infants with a Learning Vector Quantizer, and the polygraphic data recorded over 8 hours from 4 babies aged 6 months were subject to classification.
Abstract: The study reports on the possibility of classifying sleep stages in infants with a Learning Vector Quantizer. The polygraphic data recorded over 8 hours from 4 babies aged 6 months were subject to classification. From each baby 22 signals were recorded, digitized and stored on an optical disc. Subsets of these signals and additionally calculated parameters were used to form data vectors in intervals of 30 sec. The teaching input was formed by a human expert. For classification a Learning Vector Quantizer (LVQ3) was trained on the labelled data vectors from 3 babies after which it was tested on the remaining fourth baby. Correct classification rates varied between 40 and 74%.