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Combined modulating effects of the general arousal and the specific hunger arousal on the olfactory bulb responses in the rat.

The combined modulating effects of the general level of arousal and specific hunger arousal on the olfactory bulb responses were investigated in the rat. Vigilance state parameters and multi-unit mitral cell activity were recorded in freely moving animals stimulated by control odours and by their usual food odour, either in the hungry or the satiated state. The nutritionally modulated bulb responses towards food odour were observed only for high arousal level (wakefulness). In rapid eye movement sleep (REMS), no olfactory response occurred. In slow wave sleep (SWS), one observed either a high bulb responsiveness to stimuli with neocortical arousal, or a general inexcitability. Each odorous stimulus in SWS elicited a higher neocortical arousal rate in the hungry than in the satiated state, as did food odour compared with control odours in both nutritional states. In SWS, a progressive alteration of the nutritionally modulated responses occurred at first at the bulb level and later for inner structures. Rats fed 2 h a day displayed a reversed circadian sleep-waking cycle and a lower SWS proportion compared with rats fed ad libitum. The hunger arousal could quantitatively and qualitatively modulate the activity of structures regulating the sleep-waking pattern.

Animals

Effects of sexual arousal on schizophrenics: a comparative test of hypotheses derived from ego psychology and arousal theory.

Two divergent theories make differential predictions with regard to the impact of sexual stimulation on schizophrenics. Relative to normals, psychoanalytic ego psychology predicts greater sexual arousal in schizophrenics, while the arousal theories predict decreased responsiveness. Fourteen chronic nonparanoid schizophrenic outpatient males and 16 normal males participated in a 2X2 mixed factor experiment with one between factor (schizophrenics vs. normals) and one within factor (sexual vs. neutral stimuli). Dependent measures included looking time, associative sexual responses, associative response latencies, and self-report ratings. A significant interaction for looking time provided empirical support for the psychoanalytic ego psychological position, Results suggest that schizophrenics are less defensive than normals in regard to looking at sexual stimuli, theoretically because of ego deficits that adversely affect repression and other mechanisms of defense.

Adolescent

Skin potential and EMG changes induced by cutaneous electrical stimulation. I. Normal man in arousing and non-arousing environment.

Skin potential and EMG responses induced in normal man by electrical stimuli applied to the skin were recorded in the four limbs in order to study somato-sympathetic and somato-motor reflexes. Different patterns of responses were observed in different conditions: alarm, habituation, sensitization and arousal. During alarm, sensitization and arousal, the responses were present in the four limbs; during habituation, the responses were only present in the stimulated and in the contralateral limb. Three sensory thresholds to cutaneous electrical stimulation were identified in habituated subjects: tactile, tingling and pain. Cutaneous and EMG responses appeared at tingling threshold. A relationship between skin potential level and skin potential response was observed.

Adolescent

Arousal and cognition: word arousal and visual search.

The influence of target-word affective properties on information processing time in a high speed visual-search task was studied. The 24 words were embedded in random-letter matrices, with one word per matrix. Subjects (5 male, 5 female) were tested. Words extreme on emotionality (positive vs negative affect) yielded significantly longer latencies than neutral words. The results were discussed in the light of related list-learning and problem-solving research.

Arousal

Autonomic arousal as a cognitive cue in stressful situations.

The need for further investigation and integration in a real world situation is demonstrated in a critical review of the literature on autonomic feedback and attribution of arousal in stressful situations. In the present study, actual autonomic arousal, arbitrary feedback of arousal, and attributions for arousal were manipulated in a dental clinic where the subjects were awaiting oral surgery. The main prediction was that cognized arousal (due either to perception of actual arousal or to arbitrary feedback about arousal level) in the absence of a nonemotional attribution for that cognized arousal would lead to higher subjective report of anxiety and to greater avoidance than would be found with either of these conditions unmet. The results on the subjective report measure generally supported this hypothesis. In addition, arbitrary feedback about arousal level did not interact with the actual arousal manipulation; nor did it produce changes in pulse rate or blood pressure, further supporting a cognitive interpretation of the effects of autonomic arousal on subjective report. However, the study illustrates difficulties in inducing beneficial beliefs in the real world. And the manipulations generally did not affect the behavioral measure, probably due to the expected consequences of that behavior.

Adolescent

Relations between behavioral arousal and plasma cortisol levels in monkeys performing repeated free-operant avoidance sessions.

The commonly believed hypothesis that increases in adrenocorticoid levels sensitively reflect behavioral arousal was tested by subjecting monkeys to repeated sessions of free-operant avoidance; these sessions produced varying degrees of behavioral arousal over time, which were quantified by a behavioral scoring technique. Cortisol was reliably elevated only in the most aroused subjects early in the first avoidance session. Although subjects were still aroused later in the session, cortisol had returned to basal levels. During subsequent avoidance sessions, cortisol returned to basal levels and did not increase significantly even when arousal was further manipulated by the superimposition of unavoidable shock during the final avoidance session. The addition of unavoidable shock was associated with a significant correlation between arousal, as reflected by increases in response rate, and magnitude of change, usually decreases, in mean cortisol levels. The frequent occurrence of dissociations between cortisol levels and behavioral arousal, as reflected by behavioral score, operant rate, and shock frequency, indicates that cortisol levels are of little use as a neuroendocrine index of arousal.

Adrenocorticotropic Hormone

Micro-arousals during nocturnal sleep.

In 8 young adult human subjects EEG- and polygraphic characteristics of transient shifts towards arousal (micro-arousal, MA) have been studied during sleep under five different experimental conditions in 40 night sessions. Out of the five applied experimental situations, two (psychostimulant application and sensory stimulation) resulted in a shift of the balance between the systems of sleep and arousal towards an increased activity of the arousal system, while an other condition (rebound following partial sleep deprivation) led to an opposite change to a rise in "sleep pressure". An inverse correlation has been found between the frequency of MA and the depth of sleep, a finding consistently observed in every subject and in every experimental situation. During the process of sleep periodic changes in the dispersity of MA could be seen; the number of MA-s decreased and increased according to the descending and ascending slope of the sleep cycles. During the ascending slope of cycles there was a coupling between the occurence of MA-s and the changes of phases. Increases in the level of activation and in sleep pressure did not influence the occurrence of MA-s. Increasing the tone of the arousal system in chemical way, or by means of enhancing the phasic sensory input resulted in a reduction of the difference between the number of MA on the descending and ascending slopes of cycles. During the phases of sleep, the spontaneous occurrence of MA-s went parallel with the possibility to evoke MA-s by sensory stimuli. These data show that MA is a regular phenomenon of nocturnal sleep; MA manifests itself as a result of phasic functioning of the reticular arousal system and plays a role in the organization of those periods of the sleep cycle, which tend toward arousal. It is suggested that MA-phenomenon is considered a standard measure of sleep and that it could represent an indicator of the function of the arousal system controlled by external or internal mechanisms during sleep.

Acoustic Stimulation

Vigilance and arousal in depressive states.

An experiment was performed to investigate predictions of vigilance performance among depressive patients, based on the assumptions that vigilance would vary in a predictable manner with level of arousal, and that levels of arousal among diagnostic categories of depressive patients are well known. It was found that psychotic depressives, presumed to be hypo-aroused relative to normals, exhibited poor signal detection performances and committed few false positive errors relative to normals. This was consistent with predictions. Neurotic depressives, presumed to be hyper-aroused relative to normals, detected fewer signals than did normals, but also made more false positive errors than normals. Again this was consistent with predictions. A measure of arousal in experimental subjects, namely barbiturate tolerance, was found to directly relate to the false positive error rate in all subjects. The relationship between arousal and total signal detection rate was significantly curvilinear, and an 'inverted U' (quadratic) function provided the best fit. This justified the conclusion that vigilance performance is a function of at least that component of arousal measured by barbiturate tolerance.

Acoustic Stimulation

Differential arousal response to gustatory stimuli in the awake rabbit.

ECoG arousal response as elicited by deionized water and by several concentrations of sweet, salty, sour and bitter tasting substances, all applied intraorally, were studied in the awake restrained rabbit. The study was carried out on 17 chronic preparations of adult male animals (2.6 kg average body weight). Water as a stimulant was presented in 60 trials and tastants across qualities and concentrations in 245 trials. Arousal was quantitatively characterized by its duration, frequency increment and amplitude decrement as compared to prestimulus conditions. Arousal induced by tastants was compared to that induced by water. Water and tastants induced arousals differentiable by the parameters measured. Further, most tastants produced a dose-dependent response. Comparison of ECoG and behavioral data clearly indicate that tastants inducing behavioral aversion also produce an arousal which significantly differs from response to water while behavioral preference was found not to show similar correspondence with ECoG data. The possibility of using arousal as an objective indicator for taste aversion is discussed.

Acetates

Auditory arousal thresholds of good sleepers and poor sleepers with and without flurazepam.

Auditory arousal thresholds of good (N = 12) and poor (N = 12) sleepers (sleep onset insomniacs) were obtained during stage 2, stage 4, and REM sleep at various times of the night. Despite claims of being "light" sleepers who are easily awakened by noise, poor sleeper auditory arousal thresholds were the same as those of good sleepers. Flurazepam (30 mg) increased the auditory arousal thresholds of poor sleepers (N = 6), but the increase was statistically significant only during the period of peak effect which occurred 1--2 hr after ingestion. Consistent with poor sleeper complaints of trouble falling asleep, the return to sleep (i.e., sleep latency) was significantly longer for poor than for good sleepers following stimulus arousals during the first stage 2 and first stage 4 periods of the night. Sleep latencies for good and poor sleepers did not differ significantly following subsequent arousals. The sleep latency following the first stage 2 stimulus arousal was significantly reduced in poor sleepers during flurazepam-induced sleep.

Acoustic Stimulation

Effects of arousal level on olfactory sensitivity.

36 college students participated in a study designed to determine the effect of induced changes in arousal on olfactory sensitivity. Each subject's sensitivity was measured under conditions of low, moderate, and high arousal. The results showed that sensitivity was significantly decreased under both low and high arousal but not under moderate arousal. No difference between the conditions of low and high arousal was found. The results are discussed in terms of the inverted-U shaped function between arousal and performance.

1-Propanol

Comparison of induced and spontaneous arousals in hibernating hedgehogs.

Respiratory and circulatory differences between periodic spontaneous arousals and induced arousals in hibernating hedgehogs were studied in a constant ambient temperature of + 4.2 +/- 0.5 oC. The increase in O2 consumption, blood pressure and heart rate was faster during induced arousals than during periodic spontaneous arousals. Based on our present studies we suggest that even the smallest stimulus able to induce the awakening is sufficient to modify the process so that it differs markedly from a spontaneous arousal.

Animals

Hyperactive behavior and EEG arousal reactions in children.

EEG arousal reactions and parameters of spontaneous EEG activity were studied in two extreme groups of behavior problem children (11 hyperactives and 11 non-hyperactives), selected on the basis of a rating of motor restlessness the core symptom of the "hyperactivity syndrome". The EEG was recorded in three reaction time experiments: a tone light conditioning paradigm and two series with random stimulation. An automatic analysis of EEG parameters was employed to describe the time functions of alpha amplitudes in the single trial. The main findings are: 1. In periods free from stimulation, hyperactive children have higher alpha and beta amplitudes, more alpha waves and a smaller amount of beta waves. This indicates a lower state of EEG arousal in the hyperactives. 2. The amplitude reduction to tone (in the single trial) develops more slowly in the hyperactive group. This group difference increases over the experimental situations. 3. The arousal responses to tone, in terms of the level of maximum amplitude reduction, become comparably weaker in the hyperactives across the experiments. 4. Under all experimental conditions the hyperactives exhibit shorter arousal responses to the light stimulus than the non-hyperactive children. 5. Reaction time performance of the groups is clearly different, hyperactives showing the longer latencies. 6. Although conditional changes in the arousal reactions to both stimuli are reliably demonstrable in all children, the groups show no difference in the corresponding measures. These findings are discussed under the aspects of activation and of attention behavior of the subjects.

Acoustic Stimulation

Relationship of arousal threshold to sleep stage distribution and subjective estimates of depth and quality of sleep.

The relationship of arousal threshold, amounts of various sleep stages, and subjective rating of sleep was studied in two separate experiments involving 7 and 26 young adult subjects, respectively. Electroencephalographic sleep stage data, subjective response data, and arousal threshold data were collected over a series of nights in the sleep laboratory. Only nonsignificant relationships were found between magnitude of arousal threshold and amounts of various sleep stages or subjective rating of sleep quality in between-subjects analyses. However, when the nights representing extremes in arousal threshold were examined within-subject, it was found that nights of high threshold were accompanied by subjective reports of significantly better sleep in both studies and by a significant decrease in the amount of stage W in one study. Arousal threshold was not related to subjective depth of sleep in either study. Rather, subjective ratings of depth of sleep were significantly related to the amount of EEG-defined wakefulness and stage 1.

Adolescent

Reversal of DOPA-induced arousal in reserpine-treated rabbits and mice by histidine.

1 The behavioural effects induced by histidine were studied in two species. In rabbits, sedation was assessed by the presence of blepharospasm, loss of righting reflex, and loss of response to painful stimuli. In mice, sedation and arousal were assessed by changes in the locomotor activity, exploratory activity, and minimal electroshock seizure threshold.2 The administration of histidine to normal rabbits or mice, in doses of 800 mg/kg and 1000 mg/kg respectively, had no apparent effect on behaviour. Moreover, it did not affect the behavioural excitation induced by L-DOPA (100 mg/kg i.v. in rabbits and 750 mg/kg i.p. in mice) in these animals.3 The administration of histidine with or after L-DOPA in reserpine-treated rabbits (2.5 mg/kg i.v.) or mice (5 mg/kg, i.p.) produced sedation. This sedative effect was dose-dependent.4 The sedative effects induced by histidine after DOPA-induced arousal in reserpine-treated rabbits and mice were prevented by prior injection of the histamine H(1)-receptor blockers, chlorpheniramine (2.5 mg/kg) or diphenhydramine (5 mg/kg).5 Imipramine (7 to 10 mg/kg, i.v.)-induced arousal in reserpine-treated rabbits was also reversed by histidine infusion.6 The infusion of 5-hydroxytryptophan (100 mg/kg, i.v.) with L-DOPA, or of arginine (450 mg/kg, i.v.) with or after L-DOPA, or of histamine (100 mug/kg), i.v.) after L-DOPA, did not affect the DOPA-induced arousal in reserpine-treated rabbits.7 These findings indicate that histamine, formed centrally from exogenous histidine, and released in increased amounts at the synapses in reserpine-treated animals, possesses a central sedative effect. This effect may be sufficient to antagonize the behavioural excitation induced by high levels of catecholamines in the brain of these animals when aroused by L-DOPA administration.8 It is concluded that in addition to the other monoamines, histamine may also be implicated in the regulation of brain excitability.

Animals

Memory performance after arousal from different sleep stages.

Learning material was presented to independent groups of subjects either after arousal from non-Rapid Eye Movement (non-REM) sleep, after arousal from REM sleep, or under conditions of no prior sleep. Measures of immediate and subsequent free recall were taken. Memory performance was found to be impaired where learning took place after non-REM arousal. This was manifest in the number of categories recalled, over both immediate and subsequent recall, and in the number of items recalled per category over subsequent recall. It was suggested that the memory performance decrement after non-REM arousal may be understood in terms of a retrieval deficit as well as a coding deficit. It is possible that the former is consequent upon a lower general level of arousal, whereas the latter is specific to memory.

Arousal

Arousal, ventilatory, and airway responses to bronchopulmonary stimulation in sleeping dogs.

We studied waking, ventilatory, and reflex tracheal smooth muscle (TSM) responses to tracheobronchial irritation or lung inflation in three sleeping dogs. The dogs breathed through a cuffed endotracheal tube, and airflow was measured with a pneumotachograph. TSM tone was monitored directly by measuring pressure in the water-filled cuff of the endotracheal tube. Mild degrees of tracheobronchia irritation, produced by squirting 0.1--1.0 ml of water into the lower trachea, or by having the dogs inhale one breath of acetic acid vapor (concentration 17 ppm), generally caused arousal from slow-wave sleep (SWS), but not from rapid-eye-movement (REM) sleep. During wakefulness the irritant stimuli caused coughing and TSM constriction; during SWS or REM sleep, these responses occurred only if the stimulus first produced arousal. In contrast, stimulation of pulmonary stretch receptors by lung inflation did not cause arousal, but readily produced apnea and TSM relaxation during SWS. The results indicate that cough and airway smooth muscle constriction in response to bronchopulmonary irritant stimuli do not occur in the absence of arousal, and that arousal responses to such stimuli are depressed in REM sleep.

Animals