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PubMed2000

Antipredator vigilance of juvenile and adult thirteen-lined ground squirrels and the role of nutritional need.

Juvenile thirteen-lined ground squirrels, Spermophilus tridecemlineatus, are less vigilant (i.e. they spend less time visually scanning the environment) than adults. To determine whether nutritional need was a potential cause of this difference, we supplemented two groups of free-ranging juveniles during the predispersal stage, while juveniles were still near and around the natal burrows. The high-energy food group (HEF: 11 squirrels) received peanut butter and oats while the low-energy food group (LEF: seven squirrels) received lettuce. Adults (14 squirrels) were also supplemented, but due to their greater home range sizes, it was not feasible to classify them as either HEF or LEF. To evaluate the effect of supplementation on antipredator vigilance, the behavioural act of visually scanning for predators, we videotaped individuals while they were foraging above ground during 5-min observation periods. Each squirrel was observed and weighed during three time periods over 23 days. From the videotape, we extracted measures of time spent vigilant, locomoting and foraging. All three categories of squirrels gained mass over the study period, but the HEF juveniles rapidly exceeded that of the LEF juveniles. Early in the study, LEF and HEF juveniles did not significantly differ in either body mass or time budgets, and, initially, both juvenile groups were similar to adults in the amount of time devoted to vigilance. Later in the study, the behaviour of HEF juveniles closely resembled that of adults (increased time devoted to vigilance and decreased time devoted to foraging), while LEF juveniles decreased vigilance and increased their foraging time. This study indicates that for thirteen-lined ground squirrels the lower vigilance of juveniles is due, at least in part, to the greater nutritional needs of young animals with consequent increases in foraging, which is largely incompatible with vigilance. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2006

Vigilance, alertness, or sustained attention: physiological basis and measurement.

Vigilance is a term with varied definitions but the most common usage is sustained attention or tonic alertness. This usage of vigilance implies both the degree of arousal on the sleep-wake axis and the level of cognitive performance. There are many interacting neural and neurotransmitter systems that affect vigilance. Most studies of vigilance have relied on states where the sleep-wake state is altered, e.g. drowsiness, sleep-deprivation, and CNS-active drugs, but there are factors ranging from psychophysics to motivation that may impact vigilance. While EEG is the most commonly studied physiologic measure of vigilance, various measures of eye movement and of autonomic nervous system activity have also been used. This review paper discusses the underlying neural basis of vigilance and its assessment using physiologic tools. Since, assessment of vigilance requires assessment of cognitive function this aspect is also discussed.

Arousal↗
PubMed1994

Sleep apnea and vigilance performance in a community-dwelling older sample.

Impaired vigilance performance has been reported in older subjects with sleep apnea syndrome (SAS). The current study is an attempt to extend these findings and to investigate additional factors that might have implications for vigilance in the older adult. Fifty-nine older adults [age: 62 +/- 5 (mean +/- SD), range 54-75 years; respiratory disturbance index (RDI): 8.8 +/- 14.4 (mean +/- SD), range 0-67.5] were categorized as SAS or NotSAS, based on various classification criteria [i.e. apnea index (AI) > or = 5, and 10, RDI > or = 5, 10 and 15], and were compared on their vigilance performance as assessed by the computer program "Steer Clear". Vigilance performance did not discriminate the groups, independent of how they were formed. Groups were then formed based on vigilance performance (HiVig vs. LowVig) and compared on assorted sleep variables, periodic leg movements, and self-reported hypersomnolence and depression. Only age discriminated vigilance performance (an inverse relationship), accounting for 31% of the observed variance. Our findings suggest that subject selection may unintentionally bias findings regarding the neuropsychological functioning of individuals with SAS, that vigilance may be impaired only in relatively more "severe" SAS, and that severity of SAS in older adults may not be well characterized by current classification standards. Age clearly impacted vigilance performance, despite the constricted age range sampled, and should be taken into account in future research.

Age Factors↗
PubMed1997

The effect of electronic record keeping and transesophageal echocardiography on task distribution, workload, and vigilance during cardiac anesthesia.

BACKGROUND: Electronic anesthesia record keeping (EARK) systems increasingly are used in the operating room, but studies have only recently begun to investigate their effect on anesthesia task performance. Teak analysis, workload assessment, and vigilance assessment techniques were used to study senior residents providing anesthesia for coronary artery bypass graft (CABG) procedures. The impact on anesthesia residents' workload of the routine use of transesophageal echocardiography (TEE) also was examined. METHODS: Before each case, the record keeping system was randomly selected as either electronic (Distek ARKIVE; EARK) or traditional manual recording (MAN). Twenty CABG procedures (10 EARK and 10 MAN) were examined, with observation commencing with anesthetic induction and terminating on initiation of cardiopulmonary bypass. The activities of each resident, divided into 32 task categories (e.g., "laryngoscopy," "observe monitors," etc.), were recorded by a trained observer using a computer. The response latency to a randomly activated alarm light was used as a measure of vigilance ("vigilance latency"). Workload was rated by subject and observer at random 10- to 15-min intervals throughout the case. Data analysis included calculation of workload density (number of tasks/min multiplied by task-specific workload values) and task-links (relationship between sequential tasks). RESULTS: The two groups had a similar distribution of tasks before intubation. In only 4 of the 20 cases studied did any manual record keeping occur before intubation. After intubation, the EARK group spent less time record keeping and using the TEE but more time observing the monitors and conversing with the attending physician than the MAN group did. All subjects reported significantly higher workload scores before intubation compared with after intubation. Similarly, vigilance latency was greater before intubation compared with after intubation (57 vs. 31 s; P < 0.001). There were no significant differences between the two record keeping groups in subjective workload scores, workload density, or vigilance latency. During TEE use, vigilance latency was significantly longer, and workload density was greater than during other monitoring or recording tasks. CONCLUSIONS: This study provides an objective description of the task distribution and workload during the administration of anesthesia for cardiac surgery. Under the conditions of this study. EARK use modestly decreased the time spent record keeping during the postintubation prebypass period. However, there was no effect of EARK either on vigilance or several measures of workload. TEE use was associated with increased workload and possibly decreased vigilance.

Anesthesiology↗
PubMed1997

Early experience of the European Medical Devices Vigilance System.

The new European system for the regulation of medical devices is currently being introduced incrementally, having begun in 1993 with a view to completion around the turn of the century. Although still it its relative infancy there has already been valuable experience gained in relation to certain device types. The system is based upon three EC Directives; the first covering active implantable devices is now fully in force; with the second covering most other devices, currently within a transition phase. The Directives fully recognise the importance of stringent post market surveillance, one key element of which involves the reporting of certain device related incidents to and between the regulatory authorities of Member States (Competent Authorities). The objective behind the reporting requirements, or "Vigilance System", is to protect patients and other users by reducing the chance of the same types of incidents reoccurring in different places across the European Economic Area (EEA). As Competent Authority for the UK, the Medical Devices Agency was one of the first to put the System into effect and continues to play a leading role. In broad terms, Vigilance requires manufacturers to notify Competent Authorities of incidents, known as Vigilance Cases, in which a device led to or might have led to the death or serious injury of patients or users. In addition they must also provide similar notification of device recalls undertaken for a technical or medical reason. For their part, Competent Authorities are required to share certain details of Vigilance Cases between each other, and with the European Commission. While mandatory incident reporting is not a new concept outside Europe, Vigilance is unique in attempting to coordinate this across nineteen different countries with different languages and cultures. Even after four years, there remains some confusion among industry and regulators alike over exactly what is required and how best to achieve it. In particular there is an element of concern among manufacturers over apparent variations in interpretation being demonstrated by different Competent Authorities. Although derived from an inherently sensible and straight forward objective, in practice Vigilance raises a myriad of questions such as when, how and to whom should reports be made, and perhaps most fundamentally, exactly which incidents should be reported. The Directives themselves offer little clarification, and in recognition of this the Commission drew up the EC Guidelines on the Medical Devices Vigilance System. These Guidelines, while not legally binding offer practical and invaluable answers to these and many other important questions. Ongoing improvements to the Guidelines appear to be the best way to try to "level the playing field" across the EEA. Considerable effort continues to be made to fine tune this document with input representing regulatory and industry interests and it is hoped that a second revision may be available next year. Vigilance is gaining popularity as a model for adoption outside the EEA, particularly as it begins to overcome the operational hurdles characteristic of the first "live running" of any new system.

Equipment and Supplies↗
PubMed1999

Within-group vigilance in red colobus and redtail monkeys.

In theory, animals are expected to relax vigilance in the safety of large groups. Four controlled studies of primates have failed to detect relaxed vigilance as group size increases. The counter-intuitive behavior of primates might arise if another component of vigilance increases with group size, masking any decrease in outward, anti-predator vigilance. Surveillance of associates is a major component of primate vigilance and might be expected to increase with group size due to an increase in competitive interactions. The present analysis uses data on glances toward associates to determine if within-group surveillance is related to group size in wild red colobus and redtail monkeys of Uganda. Although males glance at associates more frequently during mating periods and females glance at associates more often when infants are young or out of contact, there was no evidence of a group-size effect on within-group surveillance. As with previous studies, primate vigilance patterns reflect reproductive strategies such as infant protection and mate defense. This study joins several others that indicate that primate vigilance is unresponsive to group size. New models that take into account association patterns below the level of the group may be needed.

Adaptation, Biological↗
PubMed1999

Back to the basics of antipredatory vigilance: can nonvigilant animals detect attack?

Many birds and mammals respond to a heightened risk of predation, especially that associated with smaller group sizes, with an increase in vigilance. All interpretations of the way in which vigilance responds to changes in predation risk assume that animals feeding with their heads down (i.e. animals in a nonvigilant state) cannot detect approaching predators. We provide the first explicit test of this assumption by 'flying' a mounted hawk down a 15-m chute towards actively feeding, free-living, dark-eyed juncos, Junco hyemalis. Juncos were targeted individually for simulated attack when they had either a 'head-down' view up the chute, or a completely unobstructed view; a junco with a head-down view could see up the chute only when it lowered its head to feed. Juncos with an unobstructed view almost always detected the hawk at the maximum distance of 15 m. Juncos with a head-down view usually detected the attack at a distance of 10-15 m against a grey background, but detection distances were shorter when attacks occurred against a camouflaged background. The results demonstrate that these birds have a considerable ability to detect approaching predators even when not overtly vigilant, although their detection ability is greater when they raise their heads. Vigilance sequences, therefore, probably consist of bouts of low-quality detection (active feeding) interspersed with bouts of higher-quality detection (overt vigilance) that can only be accomplished at the expense of feeding. This realization has major implications for current interpretations of the vigilance group size effect and antipredator vigilance in general. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1995

Memory and vigilance training to improve social perception in schizophrenia.

Previous research has suggested that social cue recognition in schizophrenia may be significantly associated with visual vigilance and verbal memory. Therefore, we predicted that subjects who participated in a cognitive rehabilitation program that incorporated vigilance and memory training strategies would show significantly better social cue recognition than subjects participating in vigilance training alone. Forty subjects with a DSM-III-R diagnosis of schizophrenia or schizoaffective disorder were randomly assigned to either a vigilance-alone or a vigilance-plus-memory training condition. Results showed that subjects in the vigilance-plus-memory condition were able to identify social cues in the videotaped training materials significantly better than subjects in the vigilance-alone condition. This difference was evident in an independent measure of social cue recognition and was present at a 48 h follow-up. Implications for future development of cognitive rehabilitation for schizophrenia were discussed.

Attention↗
PubMed2006

Large arterial elasticity varies as a function of gender and racism-related vigilance in black youth.

BACKGROUND: This exploratory study examined the relationship of gender and racism-related vigilance to baseline and task-induced changes in large arterial elasticity (LAE). METHODS: The convenience sample consisted of 153 black youth (M age = 11.5 years, SD = 1.4) who were normotensive. Large arterial elasticity was measured via pulse wave contour analysis, before, during, and after a sequentially administered digit forward and digit backward task. Racism-related vigilance was reported by participants. RESULTS: Although findings from general linear models indicated that the independent effects of gender and racism-related vigilance were not significantly related to LAE (baseline, reactivity, or recovery) (all p > .05), these analyses showed that gender and racism-related vigilance interacted to predict baseline LAE (p < .02) and task-induced changes (reactivity only) in LAE (p < .006). Follow-up regression analyses explicating the pattern of these interaction effects indicated that 1) racism-related vigilance was marginally and inversely related to baseline LAE among boys (p < .06) but not in girls (p > .21); and, 2) racism-related vigilance was positively and significantly associated with task-induced changes (reactivity) in LAE among boys (p < .008) but not in girls (p > .30). CONCLUSIONS: The relationship between racism-related vigilance and LAE varies as a function of gender, and may have longer-term implications for between and within-group disparities in cardiovascular health.

Adolescent↗
PubMed1990

Primary disorder of vigilance: a novel explanation of inattentiveness, daydreaming, boredom, restlessness, and sleepiness.

We present a novel condition, designated as a primary disorder of vigilance, that has symptoms which overlap those of attention deficit-hyperactivity disorder. Vigilance is the state of being watchful, awake, and alert. When vigilance is lost, the individual has difficulty sustaining attention. The most obvious evidence of lowered vigilance is motor restlessness (fidgeting and moving about, yawning and stretching, talkativeness, or a combination of these) to improve alertness when sitting or standing still or when involved in tasks requiring continuous mental performance. When prevented from being active to stay awake, persons with lowered vigilance will stare off, daydream, show minor hyperactivity, and finally may fall asleep. They will also have decreasing attention to current activities and usually avoid or lose interest in structured or repetitive activities (complaining of boredom and monotony). The primary disorder of vigilance (for which criteria have been established) is a dominantly inherited condition with onset in early childhood and worsening symptoms with age. Persons with the primary disorder of vigilance have a remarkably kind and caring temperament. When untreated this disorder can cause chronic failure at school and work, but when properly recognized it responds well to treatment with stimulant medication and schedules that avoid sameness and repetition.

Arousal↗
PubMedDate not supplied

Assessing nighttime vigilance through a three-letter cancellation task (3-LCT): effects of daytime sleep with temazepam or placebo.

Nocturnal sleepiness is a common complaint suffered by night-shift workers, especially in conditions of an abrupt shift of the wake-sleep cycle. Alertness management strategies can minimize the adverse effects of sleep loss and circadian rhythm desynchronization and promote optimal vigilance in operational settings. Within these strategies. one possibility is to use short periods of "prophylactic sleep" (before long periods of work), which can be facilitated by hypnotics. Vigilance can be evaluated by means of several tests which, sometimes, imply procedures and devices not easily employable in operational settings. In such conditions pencil and paper tests of vigilance can be very useful in the assessment of attentional performance degradation due to sleep loss and/or inversion of the sleep-wake cycle. In this study we evaluated the sensitivity of a three-Letter Cancellation Task (3-LCT) in revealing nighttime variations of vigilance in a laboratory simulation of acute night shift, after a diurnal sleep with placebo (PLC) or temazepam (TMZ). Nocturnal levels of vigilance were also assessed using the Maintenance of Wakefulness Test (MWT) and the Multiple Sleep Latency Test (MSLT). All tests were administered four times at 2-h intervals during nighttime after a daytime sleep. Results show that the 3-LCT is sensitive to variations of vigilance occurring during a laboratory simulation of acute night shift. We also found some effects of TMZ, which in the first nocturnal session caused a slowing down of visuoattentive performance. Nocturnal variations of vigilance detected through the 3-LCT were similar to those revealed by means of MSLT, while the ability to maintain wakefulness was substantially spared during the night.

Adult↗
PubMed2006

Vigilance and fatigue following traumatic brain injury.

Research findings have suggested that individuals with traumatic brain injury (TBI) show greater psychophysiological and subjective costs associated with performing vigilance tasks, but have not examined relationships with fatigue. The present study aimed to investigate vigilance and its relationship with subjective and objective fatigue measures. Forty-six TBI participants and 46 controls completed a 45-minute vigilance task. They also completed a subjective fatigue scale (the VAS-F) and a selective attention task before and after the vigilance task, and had their blood pressure (BP) monitored. TBI participants performed at a lower level on the vigilance task, but performed at a similar level across the duration of the task. Higher subjective fatigue ratings on the VAS-F were associated with more misses on the vigilance task for TBI participants. TBI participants showed greater increases in diastolic BP, and these were associated with greater increases in subjective fatigue ratings on the VAS-F. A subgroup of TBI participants showed a decline in performance on the vigilance task and also showed disproportionate increases in subjective fatigue. Findings provide support for the coping hypothesis, suggesting that TBI individuals expend greater psychophysiological costs in order to maintain stable performance over time, and that these costs are also associated with subjective increases in fatigue.

Adolescent↗
PubMed2004

Electrophysiological correlates of vigilance during a continuous performance test in healthy adults.

The present study evaluated patterns of electrophysiological activity associated with sustained vigilance in healthy adults. Quantitative electroencephalographs (QEEG) were recorded during the performance of a Continuous Performance Test (CPT). Participants were divided into low and high vigilance groups based upon their reaction time changes between the early and late portions of the CPT. Coherence measures were calculated from the QEEG across the baseline, early CPT, and late CPT experimental conditions. Participants in the low vigilance group had higher baseline and CPT frontal to posterior coherence in the alpha and beta bands suggestive of a less vigilant state throughout the entire study. Additionally, the low vigilance group had a significantly greater beta 1 band coherence drop from baseline to the initial portion of the CPT than the high vigilance group. The combined groups had significantly lower amounts of right hemisphere frontal to posterior coherence across a number of frequency bands throughout all of the phases of the study when compared to the homologous left hemisphere sites. These interhemispheric coherence differences are consistent with vigilance network theories that implicate the right frontal and parietal lobes in the maintenance of sustained attention (M. I. Posner & M. E. Raichle, 1994).

Adult↗
PubMedDate not supplied

Temporal and spatial patterns of the clinical surveillance of BSE in France, analysed from January 1991 to May 2002 through a vigilance index.

Between 1991 and mid 2000, the surveillance of Bovine Spongiform Encephalopathy (BSE) in France was based solely on clinical surveillance through a Mandatory Reporting System. Since 2000, the implementation of active surveillance programmes using rapid tests, as a complementary tool targeted at dead and slaughtered cattle has shown that part of the BSE cases were not detected with the clinical surveillance. In order to obtain a better knowledge of the strength of the clinical surveillance, we analysed a vigilance index defined as the ratio of negative clinical suspicions to the cattle population in the region and period of interest. The temporal analysis of the vigilance index showed that it did not vary much between 1991 and 1999, increased sharply since 2000, and then decreased partly in 2001. The geographical analysis of the variations of the vigilance index was performed at the department level by comparing the observed number of negative clinical suspicions per department to the expected number, computed on the basis of the national average index and standardised on the production type of the cattle - dairy versus beef suckling cattle. As assumed, the data followed a Poisson distribution. We observed a high geographical variation of the vigilance index: ten departments out of 91 presented a significantly higher vigilance index than the national one, and four a significantly lower vigilance index. The vigilance index showed that the clinical surveillance was heterogeneous during the past twelve years, both in time and geographic location, in a range of one to ten. So the apparent trend in the BSE epidemic during this period as well as the differences in the spatial incidence of BSE have to be analysed with caution.

Animals↗
PubMed1986

Contribution to the search for vigilance-indicative EEG variables. Results of a controlled, double-blind study with pyritinol in elderly patients with symptoms of mental dysfunction.

We used a clinical pharmacological model to test pyritinol versus placebo in patients with mental deficiency and a clinical diagnosis of beginning chronic brain syndrome. Following a two weeks' washout phase, 50 patients were randomly allocated to two treatment groups of 25 patients each, receiving either 200 mg pyritinol three times daily, or placebo under double-blind conditions. The treatment period lasted 8 weeks. To be included in the study, patients had to have at least 50% subvigil phases in the 15-min EEG resting recording. We define such behaviour as a neurophysiological disturbance of vigilance. Scores in the Benton test were to be 2 points below the expected value, and/or the NAF score was to be above a standard value attained in an old peoples' home (greater than or equal to 14). We used this clinical pharmacological model for an internal validation of our Vigilance Index (VI). According to our definition, the Vigilance Index should express vigilance in the sense of an optimalization of the neuronal system to enable this system to perform better. The delta F power and the alpha slow-wave index have been considered as vigilance-indicative variables in the EEG. We believe that vigilance can be better expressed by a multidimensional approach, which takes into account all EEG elements that express vigilance, such as the replacement of the occipital basic rhythm (e.g. alpha or beta rhythm) into slow waves, the lowering of the dominant occipital frequency (be it an alpha or beta frequency), the anteriorization of the basic rhythm in the occipital field to the frontal region.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Human vigilance in railway and long-haul flight operation.

Human operators in transport operations are often confronted with monotony, boredom, and irregular work schedules. This situation has become increasingly more acute because of the growing automation of systems. This paper presents methodology and preliminary results for two field studies on the vigilance of train drivers and long-range aircrews. The aim of these studies was to identify factors that can modify vigilance and to elaborate several specific solutions for reactivation. The method is based on the collection of physiological data in the field and on task observation of the operators. The recorded physiological data (EEG, EOG, EKG) permit an evaluation of vigilance and mental workload. The rest-activity cycles are estimated by actometry. The use of EEG and EOG are discussed in relation to monotony and sleep deprivation. For pilots, results show a high occurrence of decreased vigilance, particularly during phases of low workload (i.e., when cruising). Furthermore, it was shown that these periods of lowered vigilance can occur at the same time for two crew members. A great number of incidents of decreased vigilance were also observed for the train drivers. These incidents occurred even though the operators sometimes had high levels of activity. A direct relation was also noted between sleep duration and the onset of rest. These studies provide several means for maintaining vigilance during activities and improving the system of work schedule rotation.

Adult↗
PubMed2005

Cognitive coping with the threat of rape: vigilance and cognitive avoidance.

Individual differences in women's avoidant and vigilant style in coping with the threat of rape were explored in four studies. In the first study, 97 women read a rape scenario and completed measures of cognitive vigilance and avoidance. They also provided ratings of fear of rape and anticipated coping problems in case of sexual assault. Vigilance was associated with significantly higher levels of fear of rape and anticipation of more severe coping problems. No effects were found for cognitive avoidance. Study 2 replicated these findings with a sample of 275 women. In addition, it showed that high vigilance was associated with significantly more rape-preventive behaviors. Study 3, including 172 women, was an online study on the effect of cognitive coping style on fear of rape, anticipated coping problems, and two behavioral measures of rape avoidance. High vigilance was related to higher levels of fear of rape, anticipation of more severe coping problems, and more rape-preventive behaviors. Finally, Study 4 (N=210) showed that individual differences in cognitive coping style affected rape-related affect and behavior in the absence of a rape scenario, underlining the chronic salience of the threat of rape for women. Vigilance was positively related to fear of rape, rape-avoidance behavior, and anticipated coping problems. In contrast, a negative relationship was found between cognitive avoidance and fear of rape, rape-avoidance strategies, and anticipated coping problems. Across the four studies, no evidence was found for an interactive effect of cognitive avoidance and vigilance, as suggested by the construct of repression versus sensitization. The findings are discussed in the light of previous research on repression-sensitization in coping with threatening information.

Adaptation, Psychological↗
PubMed1986

Vigilance, sleep and epilepsy.

The correlations between vigilance and epilepsy are manifold. Nearly all epileptic seizures cause a diminution of vigilance extending to unconsciousness. Many of the influences triggering or inhibiting epileptic seizures produce alterations of vigilance or are produced by them. Nearly all chemical influences more or less cause diminution of vigilance. The enhancement of vigilance may inhibit seizures. Decreasing vigilance may act vice versa. As a means to enhance vigilance afferent stimuli are able to trigger seizures. This may be accomplished when singular or rhythmic stimulation of afferents gets the already excited neuronal system oscillating. This principle is also responsible for the strong correlation between triggering of seizures and the sleep/waking cycle with its different grades of neuronal synchronization. On the other hand, inhibition of seizures is possible by a continuously applied stimulation load, which may disturb the increasing excitatory oscillation. Also, conditioning may trigger or inhibit seizures. But the EEG biofeedback only is used to decrease abnormal neuronal activity.

Arousal↗