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J Czopf

Publications and source records attributed to J Czopf.

31 records · Page 2Linked to original sources
PubMed1985

Flash and pattern presentation and pattern-reversal evoked potentials in multiple sclerosis.

The visual evoked potential (VEP) results for 404 multiple sclerosis (MS) patients are presented. In 171 patients pattern reversal with light-emitting diode (PR (LED] VEPs and in 85 patients pattern reversal with TV (PR(TV] VEPs also were investigated. The pathologic process of MS affects the amplitude and latency of all components and the form and symmetry of responses. A complex evaluation of VEP is proposed instead of measurement of only one component. A combined flash and pattern presentation VEP evaluation may be as effective as PREPs in the detection of subclinical lesions. PR(LED) VEP seems to be more sensitive to the degree of visual disturbance and to the clinical probability of MS than the PR(TV) VEP. A statistical analysis disclosed correlation of VEP amplitude and latency data with the visual impairment, one with the duration and multiplicity (generalization) of the disease. Combination of different methods increases the discriminative power of the VEP investigation.

Adult↗
PubMed1981

Changes in neuronal transmission in the rat hippocampus during behavior.

Rats with implanted stimulating and recording microelectrodes were trained in a straight alley to repeatedly press a bar placed at one end of the alley and to run for water reward available at the other end. Stimulating the commissural input evoked field EPSP and population spike in the CA1 region while no population spike was observed in the dentate area. The amplitude of the CA1 population spike was maximum during running and smallest during drinking. Field potentials in the dentate gyrus changed in an opposite manner (drink greater than groom greater than press greater than run). Perforant path evoked cell discharges in the dentate gyrus which were maximal during drinking and smallest during running. The behavior dependent changes of the evoked potentials covaried with the frequency and power of the simultaneously recorded theta activity. Perforant path stimulation during the negative-going phase of the dentate theta cycle evoked significantly greater granule cell responses than stimuli during the positive-going phase. These observations suggest that the medical septum exerts a potent biasing effect on the efficacy of other afferent to the hippocampus.

Animals↗
PubMed1981

Hippocampal slow wave activity during appetitive and aversive conditioning in the cat.

The electrical activity of the dorsal and ventral divisions of the hippocampus was investigated quantitatively during the development of discriminative operant training and defensive conditioning. Signal-related (respondent, sign-tracking) and goal-directed (operant, 'voluntary') activities and their hippocampal electrical correlates were compared. Signal-related behaviour was accompanied by significantly higher frequency spectral peaks than lever press behaviour. Spectral peaks were higher during lever pressing in early stages of training as compared to criterion performance. In defensive conditioning overt sign-tracking behaviour disappeared but spectral peak shifts toward higher values upon signal presentation persisted. Comparison of dorsal and ventral hippocampal activity revealed high coherence values and similar frequency shifts during behaviour transitions. These findings argue against suggestions that a close relationship exists between elementary motor acts and hippocampal EEG.

Animals↗
PubMed1979

Hippocampal evoked potentials and EEG changes during classical conditioning in the rat.

Hippocampal evoked potentials (EPs) and EEG responses were studied in rats, using a classical conditioning paradigm (water, US), with a spatially discontiguous CS-US arrangement in order to separate the CS and goal-related responses. In early training, when the orienting score was high, the tone CS, instead of eliciting a definite EP, usually reset hippocampal theta activity in phase, i.e. theta rhythm became time-locked to CS. With further training, orienting activity (ORI) decreased to the preconditioning level, and this was associated with the recurrence of short-latency and high voltage hippocampal EPs, similar to those observed during habituation. This high voltage EP predicted that the animal would not orient any more towards CS. This correlation was confirmed by behavioural (satiation, shock US) and by pharmacological (scopolamine HBr, 2 mg/kg) treatments, all of which reduced the ORI score. Hippocampal EEGs also showed characteristic changes during conditioning. ORI towards CS was accompanied by higher frequency spectral peaks (9 c/sec) than response to US (7--8 c/sec). This correlation was seen both across sessions and within trials. We conclude that the above changes are related to orienting, attentional factors rather than to movement-related variables.

Animals↗
PubMed1979

Dynamic phase-shifts between theta generators in the rat hippocampus.

Winson [13] reported on two independent phase-reversed generators in the rat hippocampus. In the present study the synchrony between the two generators was investigated during the sleep-wakefulness cycle and during a behaviour-dependent discriminative learning task. Electrical activities derived from the CA 1 region and dentate gyrus were in phase during slow wave sleep but phase-reversed during the awake state and paradoxical sleep. The degree of phase-reversal was significantly higher during running than during lever pressing. These findings demonstrate that substantial changes occur within the hippocampal circuitry during dynamic shifts of behaviour.

Animals↗
PubMed1977

[The diagnostic value of the EEG in multiple sclerosis (author's transl)].

245 records of 178 multiple sclerotic patients were assessed from 110 EEG-parameters and 18 clinical points of view. According to the special code the data were stored on cards and later statistically evaluated. The following conclusions were made: 1. 64% of all records were abnormal. 2. The frequency of bilateral and generalized abnormalities was significantly higher with brain stem localization of clinical signs. 3. In the progressiv phase of the disease there was a significantly greater occurrance of bilateral slow EEG abnormalities and bilateral potentially epileptic signs (sharp waves, bilateral paroxysms). 4. Focal EEG abnormality is seldom found in multiple sclerosis.

Adolescent↗
PubMed1976

Analysis of clinical and electrophysiological findings in Jakob-Creutzfeldt disease.

Serial EEG and EMG investigations were performed in the course of a histologically verified case of Jakob-Creutzfeldt disease. Some electrophysiologic data, including visual-evoked responses were analyzed using a computer. Correlations between clinical and EEG findings suggest that the generator of the periodic discharges may be localized in some circumscribed area of the upper brain stem, probably the thalamus. The inhibitory effect of various narcotics suggests that the pacemaker of the triphasic discharges has relations to the nonspecific activating system.

Aged↗