Arousal Fluctuations Research Articles

Rumination and Depression in Adolescence: Investigating Symptom Specificity in a Multiwave Prospective Study

A ruminative response style has been shown to predict depressive symptoms among youth and adults, but it is unclear whether rumination is associated specifically with depression compared with co-occurring symptoms of anxiety and externalizing behaviors. This prospective, multiwave study investigated whether baseline rumination predicted prospective elevations in depressive symptoms specifically. Rumination was assessed at baseline in a sample of early and middle adolescents (N = 350, 6–10th graders). Symptom measures of depression, anxious arousal, general internalizing, and conduct/externalizing problems with good discriminant validity were assessed at four time points over a 5-month period. Results using hierarchical linear modeling show that rumination predicted prospective fluctuations in symptoms of depression and general internalizing problems specifically but not anxious arousal or externalizing problems. Rumination predicted increasing prospective trajectories of general internalizing symptoms. Baseline rumination interacted with prospective co-occurring fluctuations of anxious arousal and externalizing behaviors over time to predict the highest levels of prospective depressive symptoms. Rumination partly mediated the sex difference (girls > boys) in depressive and internalizing symptoms.

Arousal and activation effects on physiological and behavioral responding during a continuous performance task

Based on previous work indicating different neural substrates, two aspects of energetic state, “arousal” and “activation”, have been conceptualized separately in our laboratory. “Arousal” has been defined as the energetic state at any particular time, and task-related “activation” as the task-related change in state from resting baseline to the task situation. Both are reflected in electrodermal activity and measured by skin conductance level. Our previous studies in this area have indicated that physiological responses to stimuli in a task are dependent on the arousal level at the time of stimulus presentation, rather than the task-related activation. In contrast, performance on the task is dependent on the task-related activation, rather than the current arousal level. That is, different aspects of the individual’s state determine physiological and behavioral responses. Those studies had examined between-subjects differences in arousal and activation. The present study investigated the relevance of this separation in an across-subjects examination of fluctuations in arousal and activation, and their effects on physiological and behavioral responses, during a continuous performance task. It was found that the magnitude of the phasic orienting reflex to the targets during the task was dependent mainly on arousal, rather than task-related relative activation. Reaction time improved with increasing relative activation, but not with arousal. These findings support our earlier conclusions relating to the usefulness of arousal and activation as distinguishable features of the energetics of physiological and behavioral functions.

Coupling of minor motor events and epileptiform discharges with arousal fluctuations in NFLE

We recently demonstrated that in nocturnal frontal lobe epilepsy (NFLE) highly stereotyped minor motor events (MMEs, in the form of short-lasting stereotyped movements involving the limbs, the axial musculature, and/or the head), could occur in either the presence or absence of an epileptiform discharge (ED). In lack of a systematic analysis, both MMEs and EDs were frequently observed to occur in association with arousal fluctuations. Hereby, in the same group of refractory NFLE subjects, we report a methodical neurophysiolgical investigation set out to investigate whether, and how, the arousal mechanism, monitored through visual scoring of the cyclic alternating pattern, modulates the expression of MMEs and EDs. The relationship of MMEs, EDs and arousal fluctuation was assessed in subjects explored using implanted electrodes. The occurrence of both EDs and MMEs was associated with higher level of arousal (p < 0.0001). Multivariate logistic regression analysis shows a significant effect of interaction of EDs and MMEs during CAP sleep (p < 0.001). Both MMEs and EDs are associated with arousal. We suggest that recurrence of EDs in itself can induce an increase in arousal level, which in turn, through a gate effect, facilitate the occurrence of MMEs. Thus, MMEs wouldn't be a direct effect of EDs, but rather originate from an indirect effect related to loss of cortical inhibition, which is secondary to arousal. In this perspective MMEs may be regarded as the result of aspecific dishinibition, triggered by internal epileptiform stimuli, of innate motor patterns generated by central pattern generators (CPGs). The CPG system might represent, through arousal facilitation, the substrate of the heterogeneous expression of MMEs in NFLE.

The amplitude and phase precision of 40 Hz auditory steady-state response depend on the level of arousal

The aim of this study was to investigate, in healthy subjects, the modulation of amplitude and phase precision of the auditory steady-state response (ASSR) to 40 Hz stimulation in two resting conditions varying in the level of arousal. Previously, ASSR measures have shown to be affected by the level of arousal, but the findings are somewhat controversial. Generally, ASSR is diminished in sleep but it may be increased in drowsiness. Besides, ASSR reduction has been observed in schizophrenia. However, schizophrenic patients are known to have a disturbance of arousal level, what makes it pertinent to know the effects of fluctuations in arousal on passive response to gamma-range stimulation. In nine healthy volunteers trains of 40 Hz click stimuli were applied during two conditions: in the "high arousal" condition subjects were sitting upright silently reading a book of interest; in the "low arousal" condition subjects were sitting in a reclined position with eyes closed and the lights turned off. The 64-channel EEG data was wavelet transformed and the amplitude and phase precision of the wavelet transformed evoked potential were decomposed by the recently proposed multi-subject non-negative multi-way factorization (NMWF) (Morup et al. in J Neurosci Methods 161:361-368, 2007). The estimates of these measures were subjected to statistical analysis. The amplitude and phase precision of the ASSR were significantly larger during the low arousal state compared to the high arousal condition. The modulation of ASSR amplitude and phase precision by differences in the arousal level during recording warrants caution when investigating oscillatory brain activity and interpreting the findings of reduced ASSR in schizophrenia. It also emphasizes the necessity of standardized recording procedures and monitoring the level of arousal during ASSR testing.

Prospective comparison of subjective arousal during the pre‐sleep period in primary sleep‐onset insomnia and normal sleepers

Psychophysiological insomnia (PI) is the most common insomnia subtype, representing 12-15% of all sleep centre referrals. Diagnostic guidelines describe PI as an intrinsic sleep disorder involving both hyperarousal and learned sleep-preventing associations. Whilst evidence for the first component is reasonably compelling, evidence for learned (conditioned) sleep effects is markedly lacking. Indeed, to date no study has attempted to capture directly the conditioned arousal effect assumed to characterize the disorder. Accordingly, the present study explored variations in subjective arousal over time in 15 PI participants (sleep onset type) and 15 normal sleepers (NS). Self-report measures of cognitive arousal, somatic arousal and sleepiness were taken at three time points: 3 h before bedtime (early to mid-evening); 1 h before bedtime (late evening); and in the bedroom at lights out (bedtime) across four, 24-h cycles. Fluctuations in mean arousal and sleepiness values, and in day-to-day variation were examined using analyses of variance. Participants with PI were significantly more cognitive aroused and significantly less sleepy relative to NS, within the bedroom environment. These results support the tenet of conditioned mental arousal to the bedroom, although competing explanations cannot be ruled out. Results are discussed with reference to extant insomnia models.

Different Periodicity and Time Structure of Leg Movements During Sleep in Narcolepsy/Cataplexy and Restless Legs Syndrome

To analyze periodic leg movements (PLM) during sleep in patients with narcolepsy and compare the results with those obtained in normal controls and subjects with restless legs syndrome (RLS). We recruited 40 HLA DQB1*0602-positive patients with narcolepsy/cataplexy, 22 with RLS, and 22 controls. The time structure of their polysomnographically recorded LMs was analyzed by means of an approach particularly able to consider their periodicity. Nineteen patients with narcolepsy had a PLM index greater than 15. The distribution of inter-LM intervals was clearly bimodal in RLS and narcoleptics, with 1 peak at 2 to 4 seconds and another at around 22 to 26 seconds; in the range 22 to 40 seconds, patients with RLS had values significantly higher than patients with narcolepsy. All periodicity parameters were significantly lower in the narcolepsy group. Finally, the distribution of the number of PLM per hour of sleep was bell shaped in normal controls and patients with narcolepsy, whereas patients with RLS showed a progressive decrease throughout the night. Most narcoleptic patients show a high number of LMs that are significantly less periodic than those of patients with RLS. PLM are in functional interrelationship with the cyclic alternating pattern, which is reduced in patients with narcolepsy; decreased arousal fluctuations during sleep may be one of the factors influencing the reduction in periodicity of LMs during sleep in narcolepsy.

Dysfunction of arousal systems in sleep-related migraine without aura.

Primary headaches are closely related to sleep. Modifications in the patterns of arousal during sleep have been reported in migraine, especially in the nights preceding a headache attack. We aimed at evaluating the pattern of arousal from sleep in a group of patients affected by sleep-related migraine. We enrolled 10 consecutive patients, three males and seven females, aged between 20 and 62 years, who presented frequent attacks of migraine without aura (more than five per month), closely related to sleep (more than one-half of the attacks occurred during sleep, causing an awakening). A control group was studied, matched for age and sex. Patients and controls underwent a full-night polysomnographic study, following adaptation; arousal pattern was studied by the scoring of the high-frequency EEG arousal and by the cyclic alternating pattern (CAP). Migraineurs showed a lower CAP rate in non-rapid eye movement (NREM) sleep and, in particular, a lower number of A1 phases (low-frequency, high-amplitude EEG bursts) compared with the controls. Migraineurs also showed a lower index of high-frequency EEG arousals during rapid eye movement (REM) sleep. The reduction in the CAP rate indicates a lower level of arousal fluctuation in NREM sleep. The reduced arousal index in REM suggests a dysfunction in neural structures involved in both the control of REM sleep and the pathophysiology of migraine, such as the hypothalamus and the brainstem.

P.8.a.047 Searching susceptibility loci for maniacal and depressive polarities in bipolar disorders: a sib pairs study on chromosome 12

To investigate local arousal fluctuations in adults who received ICSD-2 diagnosis of somnambulism.EEG neuroimaging (eLORETA) was utilized to compare current density distribution for 4 s epochs immediately preceding sleepwalking episode (from −4.0 s to 0 s) to the distribution during earlier 4 s epochs (from −8.0 s to −4.0 s) in 20 EEG segments from 15 patients.Comparisons between eLORETA images revealed significant (t > 4.52; p < 0.05) brain activations before onset of sleepwalking, with greater current density within beta 3 frequency range (24–30 Hz) in Brodmann areas 33 and 24.Sleepwalking motor events are associated with arousal-related activation of cingulate motor area.These results support the notion of blurred boundaries between wakefulness and NREM sleep in sleepwalking.

The biologic basis for libido

Libido refers to a fluctuating state of sexual motivation in all organisms. Sexual motivation is altered by internal factors, such as circulating steroid hormone levels and feedback from sexual stimulation; external factors, such as the presence of sexually relevant incentives; and by the cognitive processing of these factors that provides variations in sexual arousability and expectation of sexual reward. Libido thus reflects constant fluctuations in sexual arousal, desire, reward, and inhibition. Recent advances in neurochemical detection, pharmacologic analyses, and brain imaging, have helped identify neuroanatomic and neurochemical systems that regulate these four aspects of sexual function. Another important factor is the activation of central monoamine and neuropeptide systems that link incentive motivation, reward, and inhibition together with autonomic pathways that detect and relay sexual arousal. The activation of these systems by steroid hormones, and modulation by expectancy of sexual reward, are critical features of the neural “state” in which reactivity to sexual incentives is altered.

Increased periodic arousal fluctuations during non-REM sleep are associated to superior memory

Sleep has been implicated in the plastic cerebral changes that underlie learning and memory. The scientific investigation of people with exceptional memory has been relatively neglected. We report the results of a polysomnographic investigation of an individual with superior memory performance. The sleep structure, in terms of sleep induction and maintenance, as well as non-REM and REM sleep percentages, were normal. The main finding was an increased number of periodic arousal fluctuations during non-REM sleep (measured as cyclic alternating pattern, CAP) during two consecutive nights (7–8 S.D. units above that observed in age-matched controls). Since CAP rate reflects the structural organization of non-REM sleep, this observation supports the hypothesis of a link between non-REM sleep and declarative memory performance.

Increased periodic arousal fluctuations during non-REM sleep are associated to superior memory

Sleep has been implicated in the plastic cerebral changes that underlie learning and memory. The scientific investigation of people with exceptional memory has been relatively neglected. We report the results of a polysomnographic investigation of an individual with superior memory performance. The sleep structure, in terms of sleep induction and maintenance, as well as non-REM and REM sleep percentages, were normal. The main finding was an increased number of periodic arousal fluctuations during non-REM sleep (measured as cyclic alternating pattern, CAP) during two consecutive nights (7–8 S.D. units above that observed in age-matched controls). Since CAP rate reflects the structural organization of non-REM sleep, this observation supports the hypothesis of a link between non-REM sleep and declarative memory performance.

NREM parasomnias: arousal disorders and differentiation from nocturnal frontal lobe epilepsy

Parasomnias emerging from NREM sleep such as sleep walking, sleep terrors and confusional arousals are considered arousal disorders. Nocturnal video-polysomnography is the gold standard to diagnosing and differentiating parasomnias from other arousals with atypical motor behaviors such as nocturnal frontal lobe epilepsy (NFLE). This form of nocturnal seizures with prominent dystonic-dyskinetic components, in some cases genetic, has been recently identified by means of detailed video-analysis of movements during sleep. The clinical picture of parasomnias (with onset in early childhood, rare episodes of long duration, absence of stereotypy, general disappearance after puberty) is different from that of NFLE (which first occurs between the age of 10 and 20, manifests frequent complex and repetitive behaviors of short duration excluding rare prolonged seizures, nocturnal agitation, some daytime complaints such as fatigue or sleepiness, persistence into adulthood). Patients show no difference from classical sleep parameters whilst microstructure analysis shows sleep instability and arousal fluctuations in parasomnias and NFLE. In children as well, at least in our experience, the differential diagnosis between the two disorders is difficult and requires one or more complete nocturnal video-polygraphic recording. In any case the diagnosis of NFLE should be considered in children with nocturnal motor episodes or nocturnal motor agitation, when the attacks persist; this diagnosis is probably more frequent than expected.

Cyclic alternating pattern (CAP) in normal sleep: polysomnographic parameters in different age groups

Objectives: The present study aimed at offering a standardized database for cyclic alternating pattern (CAP) parameters across representative ages of life. Methods: CAP parameters were quantified in 40 healthy sleepers and polygraphically investigated in a partially sound-proof recording chamber under a standard laboratory setting. Four age groups were investigated (teenagers: 10–19 years; young adults: 20–39 years; middle-aged: 40–59 years; elderly: 60 years). Each group included 10 subjects (5 males and 5 females). Nocturnal recordings were accomplished after adaptation to the sleep laboratory that also served to rule out the presence of sleep-related disorders. The study indicated that CAP is a natural phenomenon of NREM sleep, with specific age-related characteristics across the life cycle. Results: CAP rate in NREM sleep, defined as the percentage ratio of total CAP time to total NREM sleep time, showed a U-shape profile with minimum in young adults (31.9%), maximum in the elderly group (55.3%), and intermediate values in teenagers (43.4%) and in middle-aged subjects (37.5%). The longest duration of CAP cycles was found among the older subjects (31 s). The highest amounts of subtypes A1 were identified in teenagers ( n=261), while the highest amounts of A2 and A3 subtypes occurred in the elderly group ( n=183). Across the ages, the level of arousal mostly fluctuated in stages 1 and 3, whereas stage 4 emerged as the most stable NREM stage. Overall, stage 2 better reflected the CAP values referred to as total NREM sleep. Conclusions: The periodic arousal fluctuations reflected by CAP are a natural phenomenon of NREM sleep with specific age-related variations across the life cycle.

Masking effect of motivation on ultradian rhythm.

To test the masking effect of motivation on ultradian fluctuations in arousal, we examined the self-rating scores for sleepiness, fatigue, and motivation and the electroencephalographic data for 5 male university students (age range, 18 to 20 years). They watched either an animated video series (Animation condition) intended to enhance motivation or interest or a landscape video series (Landscape condition) intended to induce lack of interest due to boredom. Each subject watched the two series for more than one week in a 3.1 x 3.1 m isolation unit. Each series was presented for 12 min. every 20 min. from 0900 to 1800. Subjective sleepiness and fatigue increased, and motivation was decreased for Landscape condition, suggesting the validity of the experimental manipulation. Closed-eye Oz-EEG alpha and beta activities fluctuated in an ultradian manner for both conditions, although slower cycles were observed at an interval of the Animation condition. The coefficients of variation of time series data were also lower for the Animation condition. These data suggest that either high motivation or absence of sleepiness or fatigue mask ultradian arousal cycles by producing fewer or slower fluctuations.

Biological determinants of P300: the effects of a barbiturate on latency and amplitude

Polich & Kok (1995) ( Biological Psychology, 41, 103–146) have recently argued that P300 is not only sensitive to specific ‘cognitive’ variables, but also to non-specific biological processes such as arousal. Fluctuations in arousal are said to be indexed by an inverse relationship between latency and amplitude. We tested this hypothesis with a drug that decreases arousal — the barbiturate secobarbital sodium. Twelve subjects performed a visual 80-20% oddball task at two levels of stimulus quality and after ingesting the drug (2.9 mg/kg body weight) or a placebo. Reaction time (RT) and P300 were collected simultaneously and the latter was analyzed on both a single trial and average basis. The RT results confirmed that secobarbital interacts with stimulus quality. Secobarbital slowed single trial P300 by about half as much as RT, and this slowing was additive with stimulus quality. Thus the two measures dissociated. Secobarbital did not influence P300 amplitude. Average P300 revealed the same pattern of results, although the size of the latency effects was somewhat attenuated. RT and P300 latency were more strongly correlated than P300 latency and amplitude. We propose that P300 latency reflected the slowing of stimulus evaluation produced by the depressant properties of the drug, and that fluctuations in arousal are not necessarily associated with a simple inverse relationship between P300 latency and amplitude.

Arousal Fluctuations in Non-Rapid Eye Movement Parasomnias

Some non-rapid eye movement (NREM) parasomnias, such as sleep-walking (SW), sleep terror (ST) and, in some aspects, sleep enuresis (SE), are considered "arousal disorders" without significant polysomnographic changes in classic sleep macrostructure. The aim of our study was to evaluate sleep microstructure and oscillations of arousal level by cyclic alternating pattern (CAP) scoring in some NREM parasomnias. Nocturnal polysomnography and videotape recording was used to study 21 patients with motor and behavioral phenomena during sleep: 13 in Group A (seven SW, six ST) with delta sleep-related episodes, eight in Group B with other parasomnias (six sleep bruxism and two SE), and six healthy controls. Classic sleep macrostructural parameters were no different in the parasomniacs and controls. Compared with the controls, our patients' sleep microstructure, scored by CAP analysis, showed increases in CAP rate (a measure of NREM instability with high level of arousal oscillation), in number of the CAP cycles, and in arousals with EEG synchronization, the increases being more significant in Group A than in Group B. An increase in sleep instability and in arousal oscillation seems to be a typical microstructural feature of delta sleep-related parasomnias and probably plays a role in triggering abnormal motor episodes during sleep in these patients.

Sleep microstructure and EEG epileptiform activity in patients with juvenile myoclonic epilepsy.

Clinical and EEG manifestations of juvenile myoclonic epilepsy (JME) occur in a strict relationship to the sleep-wake cycle, particularly to transition phases (awakening, falling asleep, afternoon relaxation after work). JME manifestations are deactivated during sleep. Because arousal fluctuations during NREM sleep may be controlled by the same neurophysiologic mechanisms regulating awakening, we studied the relationship between the cyclic alternating pattern (CAP) and JME manifestations. All-night polysomnographic recordings of 10 JME patients were analyzed for variations of epileptiform EEG abnormalities in relation to sleep stages and to different microstructural variables (NCAP, CAP, phases A and B). CAP rates (ratio between total CAP duration and total NREM sleep duration) were also calculated. Average CAP rate was 46.70%, significantly higher than that (23%) of an age-matched control group. Macrostructural analysis showed only a trend toward a slight predominance of EEG epileptiform activity during slow wave sleep but no significant correlation between spiking rates and sleep stages. Microstructural analysis confirmed the CAP modulation of EEG epileptiform activity, with maximum appearance of epileptiform abnormalities during phase A CAP (normalized spiking rate = 4.00 +/- 0.98) and strong inhibition during phase B (0.06 +/- 00.6). Intermediate values were noted during NCAP (0.54 +/- 0.27). No correlation was noted between spiking rates during NREM sleep and CAP rates, possibly indicating that in JME patients the increased CAP rate may be partially independent of epileptiform EEG activity. Our data suggest that in JME patients CAP may be a neurophysiologic oscillator organizing expression of the epileptiform discharges independent of the tendency of the individual patient to produce epileptiform EEG discharges.

Interruption of a Monotonous Activity with Complex Tasks: Effects of Individual Differences

The fluctuations of vigilance and performance for operators working in monotonous conditions were studied in laboratory. Three experimental designs were achieved on 20 subjects: — one reference condition with a vigilance task of 3 hours 30 during day time, — one experimental condition with interruptions of monotony during the vigilance task by a sustained task, during the same day time period, — the same experimental condition during night time. The purpose was to analyse the effect of breakdown in monotony on arousal and human performance and to look for individual differences in human performance. Physiological data were collected in order to study the variation of arousal. Response times and omissions were used as performance index. Individual differences can be observed for performance and vigilance. Two kinds of behavior are defined: stable subjects and subjects characterized by fluctuations both for arousal and performance during the task. During day time period, breakdown of monotony has a positive effect on performance especially for subjects with fluctuations of arousal. Night time condition creates a sleep deprivation and the consequence is that the efficiency of the reactivation due to breakdown by sustained task is not demonstrated. Results are discussed in regard of the theory of Fisk and Schneider on automated and controlled mental processing during monotonous activities.

Modifications of sleep structure induced by increasing levels of acoustic perturbation in normal subjects

In each non-REM (NREM) sleep stage, the aggregation of the arousal-related phasic events permits identification of periods of arousal fluctuation (cyclic alternating pattern or CAP) and periiods of long-lasting arousal stability (non-CAP or NCAP). As the ratio CAP time to NREM sleep time (CAP/NREM) measures the instability of arousal during sleep, any perturbing event determines an increase of CAP/NREM. On the basis of these premises, 6 healthy volunteers underwent 5 sleep recordings at increasing intensities of sound pressure level (basal condition followed by continuous white noise at 45 dBA, 55 dBA a65 dBA and 75 dBA, respectively). Besides a remarkable enhancement of CAP/NREM ( P < 0.00001), acoustic perturbation induced a significant linear increase of waking time after sleep onset, stage 2, NREM sleep, stage shifts and a significant linear decrease of stage 4, deep sleep, REM sleep and total sleep time. At each step of environmental disturbance, the values of the CAP ratio were consistent with the gradual changes of sleep organization. Although the Multiple Sleep Latency Test was unremarkable during the day following the sleep recording, CAP/NREM was significantly correlated with the personal evaluation of sleep quality ( P < 0.01). Through this model of transient situational insomnia it was possible to outline different degrees of subjective complaint depending on 3 ranges of CAP/NREM. A crucial role of CAP in the pathophysiological mechanisms of clinical insomnia is hypothesized.

Modifications of Cyclic Alternating Pattern in Sleep Apnea Syndrome

Within non-rapid eye movement sleep, two complementary modalities of arousal organization may be identified: (1) the cyclic alternating pattern (CAP), correlated with successive upward (phase A) and downward (phase B) fluctuations of arousal and arousal-related vegetative functions, and (2) non-CAP, corresponding to a relative stability of arousal and vegetative activities. In a 62-year-old overweight and heavily snoring man, complaining of excessive daytime sleepiness, three consecutive polysomnograms displayed a highly frequent occurrence of nocturnal apneas (apnea index: 15), mostly obstructive and mixed, limited to non-rapid eye movement sleep stages 1 and 2. The apneic episodes, that never occurred during non-CAP, exclusively appeared during the inhibitory phase B of CAP, whereas the following breathing resumption was mainly induced by an activating phase A pattern. The crucial effect of arousal instability on respiratory control is emphasized.