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H Petsche

Publications and source records attributed to H Petsche.

At least 19 recordsLinked to original sources
PubMed1998

Synchronization between prefrontal and posterior association cortex during human working memory.

We measured coherence between the electroencephalogram at different scalp sites while human subjects performed delayed response tasks. The tasks required the retention of either verbalizable strings of characters or abstract line drawings. In both types of tasks, a significant enhancement in coherence in the theta range (4-7 Hz) was found between prefrontal and posterior electrodes during 4-s retention intervals. During 6-s perception intervals, far fewer increases in theta coherence were found. Also in other frequency bands, coherence increased; however, the patterns of enhancement made a relevance for working memory processes seem unlikely. Our results suggest that working memory involves synchronization between prefrontal and posterior association cortex by phase-locked, low frequency (4-7 Hz) brain activity.

Cerebral Cortex↗
PubMed1997

[Contribution of spontaneous EEG to understanding cognitive functions].

Probability mapping of amplitude and coherence based on spectral analysis of the on-going EEG turned out to yield information on the cooperation of brain areas during cognitive processes. The method is based on comparing these two parameters during the performance of a mental task with the respective values of the EEG at rest before and after the task. For each of six frequency bands, spanning and entire EEG spectrum, the signs of significant changes of these parameters at the recording electrodes (19) and between all recording sites (19 x 18) are entered into schematic maps, representing the brain as seen from both sides and from the top. The results have proved to be largely task-specific for mental processes in both groups and individual studies. They are considered as electrical manifestations of differential attention. Since they may encompass EEG periods of even several minutes, these maps allow observations of average EEG characteristics even in complex, long-lasting mental accomplishments. The usefulness of the method is illustrated by four examples: doing mental arithmetic, listening to and composing music, simultaneous interpretation and contemplating and memorizing pictures.

Action Potentials↗
PubMed1997

The reflection of cognitive tasks in EEG and MRI and a method of its visualization.

Up until recently, neurology was dominated by localisatory thinking. Language and other so-called "centers" were considered to be centers of command controlling the respective functions. Today, there is general agreement that, instead, for every brain function numerous brain regions must act together. For the exploration of these manifold topographic cooperations produced by cognitive tasks, coherence of long-term EEG periods proved to be a proficient parameter for the representation of functionally essential connections. Because of the unequivocal meaningfulness of absolute coherence values, instead, only the signs of significant differences between coherence values during cognitive tasks and periods of EEG at rest before and after the task were considered for all possible electrode pairings and charted on schematic maps of the brain. In addition, the signs of significant changes of amplitude were entered. This procedure was performed for each of 6 frequency bands and for the 19 electrodes of the 10/20 system, thus yielding 171 possible plus or minus values for coherence and 19 for amplitude, respectively. The positions of the electrodes were marked by an MRI contrast medium. After the EEG, MRI examination was performed. The MRI data were segmented and the cortex was mapped onto a plane using a method similar to cartography. The exact electrode positions are registered from a similarly obtained map of the scalp and the electrode position pattern is used as basis for the coherence graphs. A detailed map of the cortex based on the segmented MRI data with the electrode positions marked is provided as a reference enabling allocation of the electrodes to the cortical structures. The usefulness of this procedure is demonstrated with a single subject by means of different cognitive tasks including musical thinking.

Aged↗
PubMed1997

The possible meaning of the upper and lower alpha frequency ranges for cognitive and creative tasks.

This study is aimed at verifying the functional independence of two frequency bands within the alpha range. It is based on experiments that examined the role of these two hands with regard to the amount of local electrogenesis (amplitude) and the cooperation of brain areas (coherence) in mental tasks concerning: (1) visual perception and imagery; (2) listening to and composing music; (3) verbal and visual creativity; and (4) aspects of mood. In all experiments EEG were recorded for at least 1 min during each task, separated one from another by at rest periods of at least equal lengths. EEG electrodes were pasted according to the 10/20 system (averaged ear lobes as reference). After FFT power was calculated for all 19 electrodes, coherence was estimated for all possible electrode pairs (i.e. 171). This was done for six frequency ranges between 1.5 and 31.5 Hz, the alpha range having been divided into two (7.5-9 Hz and 9.5-12.5 Hz). The spectral parameters obtained during each task were compared with those of the merged EEG at rest, significant changes (P < or = 0.01-P < or = 0.05) were entered into schematic maps of the brain. Generally, fewer differences were found for amplitude than for coherence. In all four tasks concerning visual perception the clearest differences were found in single person studies. But also in group studies more or less distinct differences were found between alpha 1 and 2. Also in the series with music the two alpha bands did not behave uniformly, nor were uniform features found in the two series of musically trained and untrained subjects. Distinct discrepancies were also found in a verbal and visual imagery task. With respect to mood, only elevated mood was correlated with a decrease of coherence in alpha 2 and an increase of amplitude in alpha 1. This study though hinting at a different functional significance of these two alpha bands, however, does not allow to draw any conclusions as to their distinct functional meanings. Generally, the long-term coherence changes observed under these different mental tasks support the idea that part of information processing in the brain is reflected by the EEG. Structural peculiarities and microelectrode recordings of the cortex support this conclusion.

Adult↗
PubMed1997

Persistent patterns of brain activity: an EEG coherence study of the positive effect of music on spatial-temporal reasoning.

Motivated by predictions from the structured trion model of the cortex, behavioral experiments have demonstrated a causal short-term enhancement of spatial-temporal reasoning in college students following exposure to a Mozart sonata, but not in control conditions. The coherence analysis of electroencephalogram (EEG) recordings is well suited to the neurophysiological investigation of this behavioral enhancement. Here we report the presence of right frontal and left temporo-parietal coherent activity induced by listening to Mozart which carried over into the spatial-temporal tasks in three of our seven subjects. This carry-over effect was compared to EEG coherence analysis of spatial-temporal-tasks after listening to text. We suggest that these EEG coherence results provide the beginnings of understanding of the neurophysiological basis of the causal enhancement of spatial-temporal reasoning by listening to specific music. The observed long-lasting coherent EEG pattern might be evidence for structured sequences in cortical dynamics which extend over minutes.

Adult↗
PubMed1996

EEG aspects of mentally playing an instrument.

This pilot study examines the possibility to detect activities of SMA by means of EEG coherence analysis in a female professional violoncellist. The proband was asked, for 5 min each, to listen to a piece of music (she knew by heart), to imagine playing this piece and to imagine playing scales. The experiment was repeated after 5 days. Consistent significant coherence changes with respect to the averaged EEG at rest were plotted as probability maps. For each of these three tasks different coherence patterns emerged. Among the electrodes next to SMA, Fz was most involved while playing scales, less while imagining playing the same piece and still less while just listening to it.

Adult↗
PubMed1996

Approaches to verbal, visual and musical creativity by EEG coherence analysis.

Our approach to coherence analysis of the on-going EEG yields data on the cooperation between all possible electrode sites of the 10/20 system. This procedure compares epochs during mental activity with epochs of EEG at rest and takes into account only significant differences which are represented as lines between the respective electrodes on maps of the brain surface. The patterns thus obtained reflect the temporal average of the changes of the overall coherence pattern caused by any mental task. They are interpreted as reflecting differential attention required for the achievement of the mental task in question. Acts of creative thinking, be it verbally, visually or musically, are characterized by more coherence increases between occipital and frontopolar electrode sites than any other mental tasks. The results are interpreted by a stronger involvement of long cortico-cortical fibre systems in creative tasks.

Attention↗
PubMed1993

Brain electrical mechanisms of bilingual speech management: an initial investigation.

This exploratory study deals with EEG changes in 3 professional interpreters while mentally interpreting from their mother language into foreign languages and vice versa. EEGs were recorded while interpreting and compared with the periods at rest between these periods of interpreting. Significant (P < 0.05) changes of coherence between all pairs of electrodes with respect to the averaged EEG at rest were computed for 5 frequency bands between 4 and 32 Hz. The verbal tasks were control-compared with comparable coherence measures for mental arithmetic and listening to music. Interindividual differences predominated, but certain common characteristics of the EEG measures were also found. The temporal regions were most involved in interpreting and particularly in the uppermost beta band (24-32 Hz). More coherence increases--particularly in the right hemisphere--were found while interpreting into the foreign than into the native language. Coherence changes were found to accumulate in certain regions of the scalp as pivots or focal areas which apparently have functional significance for the task in question as nodal points of information exchange and/or transfer. Such pivots were found in T3 more than in T4 (in the right-handers) and vice versa in a left-hander. Theta and alpha bands behaved differently and did not show such clear-cut differences. The results during mental arithmetic and listening to music were different from the ones while interpreting. The results give support to the conception of the cortex as a network serving the greatest possible divergence and convergence of signals.

Brain↗
PubMed1993

Sources of electric brain activity: intracortical current dipoles.

Intracortical evoked potentials after electrical stimulation of the optic nerve were simultaneously recorded from the different layers of the rabbit's visual cortex. The averaged potentials were subjected to current source density analyses. The results show that the first event after the stimulus is a current sink in layer VI according to the excitatory terminations of the specific afferent fibres of the geniculate body. Since the largest part of the specific afferents terminates in layers IV and V, the sink in those layers may be due to excitatory synaptic events there. The corresponding current sources are situated in the upper layers and are most probably passive sources due to the active sinks. This example demonstrates that the generation of intracortical electric potentials can be explained by vertically oriented current dipoles according to the anatomical peculiarities.

Animals↗
PubMed1992

Thinking with images or thinking with language: a pilot EEG probability mapping study.

This pilot EEG mapping study was designed to explore thinking processes using complex mental imagery and thought processes. EEG was recorded with 19 electrodes (10/20 system against averaged ear lobe signals) while volunteers (n = 42) performed two separate tasks: visualization of an abstract concept and interpretation of a painting. Average spectral parameters such as amplitude, local and interhemispheric coherences were computed for five frequency bands (theta, alpha, beta 1, 2 and 3). Results indicate that the frontal regions are strongly involved during these tasks as evidenced by coherence changes. Changes are also present in temporal, parietal and occipital regions and are discussed in relation to information processing with the frontal regions considering the different cognitive functions required by the tasks.

Adolescent↗
PubMed1991

An approach to a synopsis of EEG parameters, morphology of brain convolutions and mental activities.

A method for the projection of EEG data on the brain surface is proposed. The EEG data are obtained during the performance of mental tasks and represented as probability maps of power and coherence changes with respect to the averaged EEG at rest. The morphological data are obtained from 3D reconstructions of the brain by means of serial slices provided by an MRI scanner. Before scanning the positions of the EEG electrodes were marked by dummy electrodes of plexiglass filled with a contrast medium. Changes of power are color-coded and entered at the respective electrode positions, changes of coherence between the respective positions. The applicability of this procedure in the fields of psychology, psychiatry and neurology is discussed.

Adult↗
PubMed1990

Periodicity analysis of sleep EEG in the second and minute ranges--example of application in different alpha activities in sleep.

To investigate the temporal organization of EEG sleep activity in the second and minute ranges we developed a method which, based on Fourier transformation, allows the presentation of periodic oscillations of spectral power and coherence. The application of this method is demonstrated in 3 subjects with different types of alpha activity during sleep: (a) alpha-sleep pattern (a physiological variant of NREM sleep activity); (b) abnormally increased arousal alpha activity. The results show that differences in the temporal organization of these alpha activities can be determined with the following parameters: period length, duration of sequences with periodic activity, number and rate of these sequences, and proportion of periodicities generated simultaneously in the left and right hemispheres. The physiologically modulated periodicities of the alpha-sleep pattern are contrary to a stereotyped 40-60 sec periodicity of abnormal arousal alpha activity. Such abnormal periodicity corresponds to periodicities occurring in association with other sleep disturbances, such as sleep apnea or periodic movements in sleep. Periodicity analysis gives additional criteria for a more refined evaluation of normal as well as abnormal sleep structure.

Adult↗
PubMed1990

[The EEG and thinking].

The on-going EEG contains information on thinking strategies during cognitive and creative tasks and during listening to music. This was demonstrated by a method taking use of the fact that both the amount of local current production and the degree of electric coupling of brain regions is characteristically changed by mental tasks. In groups of volunteers the significant changes of absolute power and coherence caused by different mental tasks are computed and entered into schematic brain maps (EEG probability maps). The results indicate the existence of general brain strategies even in mental activities as specific as those referred to above. Moreover, several relationships between EEG, psychological test scores, degree of special education and intelligence were found. Studies with extreme value validation according to intelligence and creativity test scores yielded significant differences between the groups of the best and the poorest performers during a creative task in the EEG. The EEG thus can be conceived of as deterministic chaos with different degrees of organization according to its information content. In this context, the question arises as to a possible function of the EEG for the optimization of thinking processes.

Cognition↗
PubMed1989

Effect of lithium on the EEG of healthy males and females. A probability mapping study.

This study is based on 20 healthy volunteers (10 males and 10 females). Between 675 and 1,225 mg lithium carbonate per day was applied for 10 days. EEG was recorded before (day 0) and after lithium intake (day 10) with 19 electrodes and quantified by spectrum analyses. Absolute power and coherence values, between adjacent electrodes and between electrodes on homologous sites of both hemispheres, were computed for five frequency bands. For the evaluation of differences of the EEG parameters obtained on days 0 and 10, a nonparametric paired permutation test was applied. The obtained descriptive error probabilities were presented in topographic maps. Under lithium, the absolute power increased in the entire frequency range, but most distinct in the theta and beta 1 band. The local coherence analyses revealed a clear lateralization: increase in the left hemisphere and decrease in the right. The interhemispheric coherence decreased occipitally and frontally. A comparison of the EEG changes under lithium in males and females showed clear differences in the topographic distribution of power as well as coherence changes.

Adult↗
PubMed1988

Probability mapping: power and coherence analyses of cognitive processes.

In recent years different mapping techniques have proved to be an efficient means in studying cognitive processes. Our approach is based on recordings with 19 EEG channels and the computation of spectral parameters. Power and coherence values are obtained from the EEG of control recordings and recordings during the performance of cognitive tasks and are compared for significant differences. The statistical procedures used yield descriptive error probabilities for the rejection of the null hypothesis which are mapped either colour coded or by black and white squares. The usefulness of this method is demonstrated on a mental cube rotation study involving 31 students, 13 males and 18 females. One essential result during the performance of this test is an increase of theta power only in females. As far as local coherence and the theta band are concerned, males show increased values right parietally and right temporo-occipitally; opposed to this, in females the left hemisphere is more affected. In the beta bands, local coherence increases in males right parietally and left temporo-occipitally. Contrary to this, in females the parietal increase of local coherence is more accentuated in the left hemisphere but temporo- occipital coherence is increased in the right hemisphere. In both sexes interhemispheric parietal coherence increases during cube rotation suggesting increased functional couplings between the hemispheres. This study demonstrates that the inclusion of the coherence parameter in brain mapping furthers the detection of sex and hemispheric differences during the performance of cognitive tasks.

Adult↗
PubMed1986

Paroxysmal neuronal depolarizations in the rat motorcortex in vivo: intracellular injection of the calcium agonist BAY K 8644.

Epileptic activity was elicited in the rat's motor cortex by local application of penicillin. At the neuronal level it consisted of typical paroxysmal depolarization shifts. The calcium agonist BAY K 8644 was injected into neurons showing such a discharge pattern. The application of this drug increased amplitude and after depolarization of paroxysmal neuronal depolarizations.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1985

On-going EEG in depression: a topographic spectral analytical pilot study.

Spontaneous EEG activities recorded with 19 electrodes (10-20 system) on the scalp were quantified by spectral analytical methods (power and coherence spectra) to reveal changes of power and coherence during different conditions (eyes closed/relaxed, eyes opened/relaxed, flicker stimulation, reading, listening to a story). Control subjects and depressive patients were compared. Power as well as coherence changes were found in all frequency bands. Changes in the organization of the EEG were found in different areas of both hemispheres. The EEG organization was different in control subjects and depressive patients, indicating different levels of vigilance and/or different cognitive strategies in verbal tasks in the two groups.

Adult↗