Electrographic Arousal Research Articles

Dopamine in the ventral tegmental area facilitates emergence from general anesthesia.

Taylor et al . (1) showed that optogenetic activation of dopaminergic neurons in the ventral tegmental area (VTA) during continuous, steady-state isoflurane-induced general anesthesia produced electrographic arousal, and restored the righting reflex in mice. Systemic administration of the D1 receptor antagonist SCH-23390 before optical stimulation greatly attenuated electrographic and behavioral arousal. Transfection of VTA neurons with a vector carrying channelrhodopsin 2 (ChR2) allowed optical activation, and optical stimulation in control mice transfected with a vector lacking ChR2 did not induce arousal.

Cortical evoked potentials and behavioral reactivity to photic stimuli in freely moving rats

Averaged evoked potentials at the visual cortex (VER) were studied in relation to behavioral reactivity to photic stimuli during operant behavior for food reinforcement. The VERs showed highly systematic increases in late components with repetition of the sensory stimuli. Amplitude of late components related inversely to behavioral indices of reactivity, but the correlations between these measures were low to moderate. Control experiments involving other freely moving and curarized animals served to evaluate various behavioral and stimulus factors in the VER changes. The results were interpreted in terms of habituation of ‘arousal reactions’, for which additional supporting data were provided. Electrographic arousal, however, was viewed as a varying substrate of all behavior, which complicates relationships between VERs and any single index of behavioral reactivity to stimuli in freely moving subjects.

A Study on the Invasive Hippocampal θ-Waves to the Cortex

Publisher Summary This chapter presents the experiments that are designed to investigate: (1) general features of the cortical “iso-hippocampal rhythm” (IHR), (2) the cortical distribution of the IHR, (3) conditions for the appearance of the cortical IHR, and (4) the cortical excitability during the IHR. The chapter uses the term IHR to denote the activity of extra-hippocampal structures which continues at least for 2 sec at frequencies of the θ of 4-7 c/sec and waxes and wanes in synchrony with the θ-waves of the hippocampus. The IHR activity could appear spontaneously, but it is much easier to induce it by the arousal stimulation. The IHRs presented in the chapter are mainly obtained by the electrical stimulation of the brain stem structures. One of the electrographic arousal states is characterized by cortical desynchronization and hippocampal synchronization. It is reported by Yoshii and associates that the cortical desynchronization sometimes contains a well-developed activity at the frequency-band corresponding to the hippocampal θwaves. The cortical activity with IHR is supposed to be moderately aroused and excludes the indifferent impulses coming to the cortex for inducing the correct performance in the conditioned and learned behavior.

Fundamental and Clinical Studies on the Neural Mechanism of Sleep

Publisher Summary This chapter discusses the fundamental and clinical studies on the neural mechanism of sleep. The low voltage fast neo-cortical pattern that had been considered to be characteristic of the waking state, could be recorded also during a fairly deep stage of sleep called activated sleep. The importance of this discovery lies not only in the paradoxical dissociation between the behavioral sleep with dreaming and the electrographic arousal pattern, but also in its contribution to the electrographic identification of the sleep cycle. By using adult cats with chronically implanted cortical and subcortical electrodes, the electric activity of various structures of the brain was recorded together with the eye movements, electromyography of the posterior neck muscles and electrocardiogram. The low voltage fast neocortical patterns during arousal and the S-A stage were very similar, however when analyzed by using the automatic frequency analyzer, the neocortical activity during the S-A stage contained more & activity compared with that of the arousal stage when the rapid eye movements were appearing. Evoked potentials in the specific sensory systems induced by direct electrical stimulation of the brain, such as potential in the visual cortex evoked by single shock to the optic tract, had short latency positive components and following negative components.

The pharmacological properties of a potent neurotropic compound from the dibenzothiazepine group

The new compound HF-2159 (2-chloro-ll-(4'-methyl)piperazino-dibenzo-[b,f] [1,4]-thiazepine) studied in this paper in comparison with chlorpromazine shows the following properties: 1. Inhibition of motor drive, as manifested in the locomotor activity of mice and in the ‘open field’ test with rats. Its effectiveness here is respectively six and sixteen times greater than that of chlorpromazine. In both species of animals HF-2159 is only half as toxic as chlorpromazine. 2. Cataleptic action, which in rats is more than five times as strong as that of chlorpromazine. 3. Inhibition of apomorphine—induced gnawing in rats, an effect roughly thirty times as intense as that of chlorpromazine. 4. Temperature-lowering action in rats and rabbits, in the same range as that exerted by chlorpromazine. 5. Inhibition of the electrographic arousal reaction elicited by stimulation of the mesencephalic reticular formation, of an intensity not otherwise encountered in neuroleptic drugs with strong cataleptic activity. 6. Further, HF-2159 relaxes decerebration rigidity in cats, and is active in the usual analgesia tests. 7. HF-2159 has only slight and transitory effects on circulation, and no notable action on the autonomie nervous system (pupillary size, salivation, heart rate, bowel function). On the basis of the present pharmacological results, the compound may be expected to exert a neuroleptic effect in clinical use.

Comparative thresholds of cortex, vestibular system and reticular formation in wakefulness, sleep and rapid eye movement periods

1. 1. Thresholds for evoking movement by stimulating cortex and vestibular nerves, and for behavioral and electrographic arousal by mesencephalic RF stimulation have been studied in 5 cats bearing implanted electrodes. These thresholds were recorded as the animals passed spontaneously from wakefulness into drowsiness, sleep, and low voltage fast ECoG and rapid eye movement periods (REMPs). 2. 2. Threshold for evoking cortico-spinal movement is lowest in the waking animal, increases in drowsiness, and becomes still higher in sleep. During REMPs threshold is lower than in sleep and is nearly as low as in relaxed wakefulness. 3. 3. In a single episode of low voltage ECoG, threshold for cortico-spinal movement is lower during bursts of REM than in the periods of ocular quiescence. 4. 4. Vestibular and RF stimulation thresholds increase from wakefulness to sleep similarly to cortical thresholds. By contrast, however, vestibular and RF thresholds are higher in REMPs than in sleep, and vestibular threshold is higher during REMs than in the lulls between bursts of ocular activity. 5. 5. We conclude that the neocortex is activated during REMPs, compared with sleep. 6. 6. Our findings, and other data suggest that sleep and REMPs represent qualitatively different processes rather than quantitatively different aspects (lightness or depth) of a single state of sleep.

Humoral Regulation of Sleep and Wakefulness by Hypnogenic and Activating Dialysable Factors

This chapter discusses a study of humoral regulation of sleep and wakefulness by hypnogenic and activating dialysable factors. Dialysis of cerebral venous blood was performed on rabbits during sleep induced by electrical stimulation of the medio-central intralaminary thalamus, or during sustained wakefulness elicited by stimulation of the activating reticular system in the midbrain. From the whole dialysate (30 ml) obtained during 80 min from the stimulated donor animal, 20 ml were injected intravenously to normal free-moving animals (recipient). The latters' behavior was filmed and analyzed with a kinesimeter, and the electrical brain activity was continuously recorded. The results showed that injection of dialysate from a sleeping donor elicits in the recipient a moderate sleep, which does not differ in behavior and electroencephalogram (EEG)from normal sleep. The action of dialysate from sleeping donors is significantly different from that of control donors after sham-stimulation of the thalamus. Injection of dialysate from alert donors elicits a behavioral and electrographic arousal with numerous symptoms of rhinodiencephalic type. These sleep and arousal effects induced in the recipients by injection of dialysate from sleeping or alert donors suggest that dialysable humoral factors play a role in the mediation of sleep and wakefulness.

DIALYSIS OF SLEEP AND WAKING FACTORS IN BLOOD OF THE RABBIT.

Dialysis of cerebral venous blood was performed on rabbits during sleep induced by electrical stimulation of the hypnogenic thalamic system or during sustained wakefulness elicited by stimulation of the activating reticular system. The injection of dialysate from a sleeping donor elicited in a normal recipient a moderate sleep which did not differ from normal sleep according to the behavior of the animal and the pattern of the electroencephalogram. The action of the dialysate obtained from sleeping donors was significantly different from that obtained from control donors after sham-stimulation of the thalamus. Injection of dialysate from alert donors elicited a behavioral and electrographic arousal with rhinodiencephalic activation symptoms. These results suggest that dialyzable humoral factors play a role in the mediation of sleep and wakeleness.

Humoral influences of induced sleep and arousal upon electrical brain activity of animals with crossed circulation

Cross circulation experiments were performed on rabbits to determine whether an electrographic sleeplike state induced in the donor by thalamic stimulation, or an electrographic arousal induced by reticular stimulation, influence the recipient brain by extraneuronal humoral mechanisms. We found that stimulation of the mediocentral intralaminary thalamus in the donor induces a significant increase of the delta voltage (computed with an automatic frequency analyzer) after four stimulations (142 ± 20.6%). Synchronously the recipient, crossed with the donor, shows a statistically significant increase of the delta voltage (121 ± 13.3%), usually after the fourth stimulation of the donor. Liminal stimulation of the midbrain reticular system in the donor induces arousal, with significant decrease in delta voltage to 48 ± 13.3% after the first and second stimulation. Parallel to this, the delta voltage decreases significantly in the recipient, to 68 ± 10.6% after the first and second stimulation. These electrographic and statistical results bring new evidence of the possibility that the brain activity of the recipient animal in cross circulation experiments can be influenced humorally by the donor in which experimental sleep or arousal are induced.

Defensive conditioning of electrographic arousal with delayed and differentiated auditory stimuli

1. 1. In three cats, a delayed (2 min.) auditory conditioned stimulus associated with moderate shock to the skin, produced in the electrographic sleep record a characteristic pattern of: ( a) an initial brief activation followed by ( b) a more prolonged period of synchrony, changing usually midway through the CS to ( c) a return of activation enduring to the delivery of the unconditioned stimulus. Recording points leading in the development of activation and showing the greatest resistance to synchrony were auditory cortex, reticular formation, and hippocampus. Points showing the reciprocal predominance of synchrony and resistance to activation were in association cortex. 2. 2. The degree and duration of synchrony present during the first half of the CS varied inversely with the intensity of the US and directly with the progression of trials in a given daily session. Synchrony was not definitely present until the conditioned stimulus had been extended longer than one minute. 3. 3. A differentiated stimulus of 20 sec. duration, applied after full differentiation in combination with the CS during the early synchrony response, briefly desynchronized that response, without disturbing the total duration of synchrony or the overall conditioned electrographic response pattern. 4. 4. When combined with the CS and associated to a withholding of reinforcement, the differentiated stimulus evoked marked synchrony during the standardized activation response to the second half of the delayed conditioned stimulus. 5. 5. Interpretations of these findings in relation to Pavlovian inhibition, hypnogenic inhibition theory of sleep, and competitive interactions in the brain are discussed.

Topischer Einflu� des Coffein auf das Gehirn

The central stimulating action of Coffein was electrophysiologically investigated on the conscious rabbit. Coffein induces, like most central stimulating drugs, an electrographic arousal pattern. In opposition to most central acting stimulating drugs investigated up to now, its action remains detectable in the so called „cerveau isole“. Activation of the ascending reticular system by coffein could not be demonstrated, but a definite decrease in excitability of the intralaminary medio-thalamic recruiting system could be ascertained. Since this system develops apparently a moderating action on the cortex, this suppression of a thalamic inhibitory function explains the stimulating action of coffein on behaviour, as well as activation of the cortex, with its typical electrographic pattern (desynchronization of the basic cortical rhythm, suppression of spindles activity and decrease of the recruiting cortical response elicited by stimulation of the mediothalamic recruiting system). Since coffein develops its stimulating action by means of a mediothalamic inhibition and not by activation of the ascending reticular system, this drug belongs to a group of psychotonic1 drugs, which has not yet been specified.