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Biomedical subjects

C Gottesmann

Publications and source records attributed to C Gottesmann.

At least 73 records · Page 4Linked to original sources
PubMed1984

Intermediate stage of sleep in the cat.

Intermediate stage of sleep, previously described in the rat, was studied in the cat. The intermediate stage was a short-lasting episode, represented in the EEG activity by cortical spindles, which was accompanied by theta activity in the hippocampus. The cortical EEG spindles appeared simultaneously with hippocampal theta or on its background. Sometimes, geniculo-occipital waves were recorded during this stage. Such an episode of a few such episodes in sequence occurred frequently just before the paradoxical sleep and occasionally just after it. The amplitude of the positive fourth component of the somesthetic evoked potential induced in the S1 cortex by stimulation of the ventrobasal complex, was lower during the intermediate stage than during the other stages of the sleep-waking cycle. The EEG pattern of the intermediate stage was periodically observed under Nembutal anesthesia at the expense of paradoxical sleep and in acute cerveau isolé preparation. The results suggest that activatory ascending influences from the brainstem, which modulate waking processes, gradually decrease during slow sleep and are the lowest during the intermediate stage, when the influences for paradoxical sleep are still negligible.

Animals↗
PubMed1982

The central responsiveness of the acute cerveau isolé rat.

The electrophysiological patterns of the frontal cortex and dorsal hippocampus were studied in the acute cerveau isolé rat. Central and peripheral stimulations were performed in order to modulate these patterns. The results showed that the permanent alternation of high amplitude spindle bursts and low voltage activity in the anterior neocortex of the acute cerveau isolé was influenced neither by olfactory nor by posterior hypothalamic stimulation. In contrast, these two kinds of stimulation easily modulated the continuous low frequency theta rhythm, recorded in the dorsal hippocampus, in terms of amplitude and in overall frequency. This modulation of the theta rhythm in the acute cerveau isolé rat mimics the changes observed when the normal rat comes from the intermediate stage of sleep (as characterized in the the acute intercollicular transected rat by high amplitude spindle bursts at frontal cortex level and low frequency theta activity in the dorsal hippocampus) to rapid sleep. These results further suggest that, during the intermediate stage (as in the cerveau isolé preparation), the hippocampus montonous theta activity appears through a brainstem disinhibitory process releasing the forebrain limbic pacemaker(s). During the following rapid sleep phase, the theta rhythm would be modulated by pontine activity influences acting on the theta generators.

Animals↗
PubMed1982

Transmission in the ventrobasal complex of thalamus during rapid sleep and wakefulness in the homolaterally neodecorticated rat.

The thalamic input was assessed from the amplitude of field evoked potential induced antidromically in the lemniscus medialis by ventrobasal complex stimulation. In the control rats, the amplitude of the antidromic response was greater during waking with theta activity in the dorsal hippocampus, i.e., in the attentive and/or psychomotor active animal, than during waking without theta rhythm. During rapid sleep, the antidromic response also transiently increased in amplitude during the bursts of rapid eye movements. After homolateral neodecortication, the difference between the two waking states disappeared in terms of the magnitude of the evoked response, while during rapid sleep the enhanced response during periods of eye movement bursts was still present. The thalamic output was studied by measuring the amplitude of postsynaptic field evoked potential induced by lemniscal stimulation. In control rats, the responsiveness level was higher during waking without theta as related to waking with theta and during rapid sleep as compared to rapid sleep periods with eye movement bursts. Homolateral decortication did not affect the characteristic modulations of thalamic output both during waking and rapid sleep. Results show that ventrobasal complex transmission is modulated: (i) during waking with theta by both corticofugal presynaptic and extracortical postsynaptic processes, (ii) during eye movement bursts of rapid sleep by an extracortical presynaptic control.

Afferent Pathways↗
PubMed1981

Hippocampal theta activity in the acute cerveau isolé cat.

In three cerveau isole cats, cortical and hippocampal EEG activity were recorded. In the cortical records, spindles alternated with low-voltage activity, whereas theta activity dominated in the hippocampus. The amount and frequency of theta were similar to those described previously for the pretrigeminal cat. In confirmation of previous results on rats, although cortical EEG activity differs in cerveau isole cat and pretrigeminal cat, both preparations show domination of theta activity in the hippocampus. It is concluded that the mesencephalic transection eliminates inhibitory effects from the lower brainstem on generators of the theta rhythm.

Animals↗
PubMed1980

The acute pretrigeminal rat.

In five rats the brainstem was transected at the pretrigeminal level. In the frontal cortex, desynchronized EEG activity dominated, while in the dorsal hippocampus theta activity of low frequency (about 4 cycle/s) was almost continuously present. Olfactory and visual stimuli and electrical stimulation of the posterior hypothalamus induced or increased cortical EEG desynchronization and increased the regularity and the frequency of the theta activity in the hippocampus. However, visual stimuli were effective only in three rats. Ocular responses (pupillary dilatation, eye movements) were never observed to any stimulation. It is suggested that similarly as in the pretrigeminal cat, the isolated cerebrum is awake in the pretrigeminal rat.

Animals↗
PubMed1980

Electroencephalographic recordings during parachute jump sessions.

Electroencephalographic (EEG) recordings of experienced parachutists were done by means of telemetry before, during, and after jumps of up to 3500m. During free-fall and after stabilization, alpha rhythm was recorded from several alpha reactive subjects when they closed their eyes. No pathological EEG recordings were obtained during the different phases of the jump.

Alpha Rhythm↗
PubMed1980

Intermediate stage of sleep and acute cerveau isolé preparation in the rat.

The acute cerveau isole rat shows spindle bursts of large amplitude alternating with low voltage activity in the frontal cortex and continuous theta rhythm in the dorsal hippocampus. These patterns closely resemble an "intermediate" stage of sleep-waking cycle, when the forebrain structures seem to be functionally disconnected from the brainstem.

Animals↗
PubMed1978

Somesthetic cortex reactivity during sleeping and waking in the rat.

The cortical S1 responsiveness was studied by unique and coupled stimuli of non-maximal intensity applied to somesthetic radiations. The reactivity is highest during sleep with slow waves, lowest during active waking, intermediate during non-active waking and rapid sleep. The recovery of responsiveness presents an exactly opposite form and begins at a long interstimulus delay (greater than 150 msec).

Animals↗
PubMed1976

Study of contingent negative variation and the post-imperative wave in the presence of interference.

The aim of this investigation was to study ways of inducing prolonged contingent negative variations (CNV) in human subjects. Fourteen subjects underwent the following experimental procedure: 1st day: 2 CNVs in control conditions were recorded (16 successive trials, each with standard S1--S2 paradigm). 2nd day: 5 successive CNVs were recorded:(1) control; (2) labyrinthine stimulation before 1st, 5th, 9th and 13th trials with simple mental calculation performed between S1 and S2, i.e. during CNV; (3) mental calculation only; (4) labyrinthine stimulation only; (5) control. None of the three interference situations caused any significant changes in the mean and maximal CNV amplitudes measured between S1 and S2. On the other hand, the post-imperative part of the CNV was significantly (P less than 0.025) prolonged but only in the situation where 2 types of interference were applied at the same time. This increase disappeared with removal of the double interference. This change, which matches that observed spontaneously and reversibly in certain mental patients in the acute phase of their illness, seems to reflect a transient alteration of the psychophysiological state of the subject. The possibility of inducing these changes in a normal subject could serve as a means of determining the individual threshold of stress.

Adult↗
PubMed1975

[Influence of interfering stimuli on contingent negative variation].

The aim of this study was to examine the influence of interfering stimuli on subjects' C.N.V. With a labyrinthic stimulation before association S1-S2 and arithmetic calculation task between S1 and S2, the C.N.V. showed a statistically significant variation (P less than 0.025): it became prolonged after the response to S2. Provocation of a prolonged C.N.V. could be used as criterion to determine an individual threshold of stress.

Contingent Negative Variation↗
PubMed1975

[Postimperative negativity of the contigent negative variations: a critical index of a stress reaction in the normal subject?].

21 subjects were recorded during two experimental sessions: 1st session: 2 CNVs in control conditions; 2nd session: 1) control CNV, 2) CNV and arithmetic calculation, 3) CNV and labyrinthine stimulation, 4) CNV, arithmetic calculation and labyrinthine stimulation, 5) control CNV. The results obtained show a post-imperative extension of the CNV in the situation 2: arithmetic calculation (P less than 0.025) and 4: double interference (P less than 0.05).

Ear, Inner↗