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PubMed2003

Attention profile in schizophrenia compared with depression: differential effects of processing speed, selective attention and vigilance.

OBJECTIVE: The aim of the study is to investigate whether subjects with schizophrenia and major depression display attention deficits for different reasons. METHOD: Subjects with schizophrenia (n = 53), recurrent major depression (n = 50) and normal controls (n = 50) were administered with 11 measures of processing speed, selective attention and vigilance. Indices of basal speed, speeded attention, non-speeded attention and vigilance were computed. RESULTS: Both clinical groups were impaired on all chronometric tests. The schizophrenic subjects were also more impaired on speeded attention compared with basal processing speed. Only the schizophrenics were impaired on the non-speeded measures of selective attention. Compared with the schizophrenics, the depressives showed a decrement in vigilance. CONCLUSION: Reduced performance on attention tests in major depression is because of a non-specific speed reduction and loss of vigilance consistent with lack of effort. In addition to generally impaired processing speed, the schizophrenic subjects exposed a deficit in selective attention, indicating executive dysfunction.

Adult↗
PubMed1998

A functional magnetic resonance imaging study of auditory vigilance with low and high information processing demands.

This study identified the brain activations associated with auditory vigilance tasks, using functional magnetic resonance imaging. We created auditory continuous performance tests (CPTs) in which a demanding task (working memory task) was made more difficult than a simple vigilance task by increasing working memory and interference filtering demands. Two cohorts of normal male controls performed significantly worse on the working memory CPT than on the vigilance task. Compared to the vigilance task, performance of the working memory task produced significant signal change in lateral and medial prefrontal cortex, precentral cortex, temporal lobe, including insula and hippocampus, parietal-occipital cortex, cingulate, thalamus, and superior colliculus. Performance and degree of activation was associated with an estimate of IQ. Further research should clarify the contributions of working memory and interference filtering to the activated network.

Adult↗
PubMed1979

Automatic measurement of the vigilance level and its possible application in psychopharmacology.

The main object of the study was to separate the specific EEG effects of psychopharmaca from changes caused by drowsiness. The study was based on quantitative evaluation of the vigilance level during five minutes of EEG recording under standardized conditions. The equation for computing the vigilance level from EEG spectra was obtained by using a training material. The segments were classified visually either as alert EEG, or as EEG marked by drowsiness. As confirmed by independent test material, the coefficients derived by means of multiple linear regression were applicable to other EEGs for estimating the vigilance level. The procedure was used in the evaluation of the psychopharmacological treatment. It was concluded that the specific EEG drug profiles were certainly influenced by the accompanying drowsiness, but the main information was still preserved. In contrast to the specific drug effect, the drug-induced sleep activity could be isolated from other events and studied separately. It was also found that after a standard stimulation, both the general trend and periodicity of the vigilance fluctuations were closely related to the psychic state of the patient.

Arousal↗
PubMed2003

[Postoperative routine use of physostigmine on vigilance, cardiovascular parameters and need of analgesics].

OBJECTIVE: A central anticholinergic syndrome (CAS) can be related to the majority of anesthetic agents, but is often not recognized as such. Thus, most anesthesiologists seem to miss the occurrence of an anticholinergic syndrome especially when agitation and/or restlessness are the major symptoms. Therefore, the following study was undertaken to test the hypothesis that routine administration of the anticholinergic agent physostigmin is of benefit for patients in regard to vigilance, the cardiovascular system and the need of analgesics easing the time in the post anesthesia care unit (PACU). METHODS: After approval by the local ethics committee and written informed consent, 100 patients undergoing a cholecystectomy or a struma resection, were given either physostigmin (n = 51) or saline 0.9 % (n = 49) in a randomized fashion. The study was conceived to block a possible isoflurane-N2O/O2 (opioid-based plus relaxant) induced central anticholinergic syndrome and to evaluate the effects on the cardiovascular system on vigilance and on postoperative analgesic demand. Following parameters were measured: systolic and diastolic blood pressure, heart rate, respiratory rate, and arterial blood gases. In addition, vigilance was determined and typical anticholinergic symptoms (disorientation, slurred speech, agitation, nausea, emesis, cardiac arrhythmia and muscle shivering) were determined 10, 20, 40 and 60 minutes following the intravenous injection of physostigmin. Also, the need for the postoperative analgesic pethidine was evaluated among the two groups. RESULTS: Except for a significant reduction in the need of analgesics, a reduced diastolic pressure and heart rate and a lower incidence of muscle shivering there was no difference among the two groups. One major side effect following the use of physostigmin was the higher incidence of nausea in the im mediate minutes following injection. This effect may be due to the rapid injection of the anticholinergic compound. Otherwise there were no detrimental effects of physostigmin in patients. CONCLUSION: From the results it can be concluded that routine administration of an anticholinergic agent results in a short term beneficial effect in regard to vigilance, a lesser incidence of muscle shivering and a lesser demand for analgesics. However, because of the low incidence of a classical central anticholinergic syndrome, routine physostigmine is only indicated when agitation is diagnosed.

Adult↗
PubMed1988

[Vigilance--a state of order or a force that produces order?].

The variety of meanings nowadays attached to the notion of "vigilance" essentially mask H. Head's original intentions when he introduced the term more than half a century ago. In an attempt to overcome the obviously existing disturbance in scientific communication, we contrast the new meanings, both with each other and with Head's original conception. We also discuss the importance of "vigilance" as a precursor of a current change of paradigms. We conclude that the original intention of "vigilance" is in line with recently elaborated proposals stressing the self-referential character of living systems. This revised notion of "vigilance" might serve as a conceptual base for empirical research taking self-reference into consideration, and hence for biological research in the true sense of the word.

Arousal↗
PubMedDate not supplied

Aging and cognitive vigilance: effects of spatial uncertainty and event rate.

Age-related differences in cognitive vigilance were examined in a task requiring identification of a target (a lowercase letter) presented at three levels of spatial uncertainty (low, moderate, and high) and in the context of a low or high event rate. Thirty-six young (18-24 years) and 36 older (60-74 years) adults participated in 30-min vigilance sessions. Increased spatial uncertainty decreased target detection rate and d' to a greater extent in older adults than in young adults. No age differences were obtained for the low-spatial-uncertainty condition. The vigilance decrement--the decline in detection rate over time--was magnified when event rate was high and when spatial uncertainty was high. The results suggest that cognitive vigilance is age sensitive when demands on visual attention capacity are increased by high event rate or spatial uncertainty.

Adolescent↗
PubMed2004

Effects of gamma-hydroxybutyrate (GHB) on vigilance states and EEG in mice.

STUDY OBJECTIVES: Gamma-hydroxybutyrate (GHB) is an endogenous neuromodulator that appears to have wide-ranging effects on vigilance and behavior. In the present study, we examined the effects of GHB on sleep-wake behavior and EEG in mice. In addition, we measured effects of GHB on body temperature and arousal or stress hormones. DESIGN: Adult male BALB/c mice were implanted with electroencephalographic and electromyographic electrodes to record vigilance states and an intraperitoneal transmitter to record body temperature. After recovery from surgery and habituation to the recording procedure, the mice were intraperitoneally injected with saline or GHB (50, 150 or 250 mg/kg) half an hour after light onset. Blood samples to measure effects of GHB on corticosterone and prolactin levels were collected in a separate group of mice. SETTING: N/A PATIENTS: N/A INTERVENTIONS: N/A RESULTS: At the lowest dose, GHB had no conspicuous effects on behavioral vigilance and electroencephalogram, nor on body temperature and endocrine measures. At the 2 higher doses, GHB induced a short period of electroencephalographic hypersynchrony in parallel to complete behavioral inactivity, an unnatural flat body posture, and nonresponsiveness to stimulation. After the highest dose of GHB, this state of reduced vigilance was associated with a decrease in body temperature, while prolactin and corticosterone levels were strongly increased. CONCLUSIONS: The results do not indicate a clear sleep-promoting effect of GHB in mice, but, at higher doses, it caused electroencephalographic hypersynchronization together with a coma-like state.

Anesthetics, Intravenous↗
PubMed1997

Relation of cerebral blood flow velocity and level of vigilance in humans.

Blood flow velocities in both middle cerebral arteries (MCA) were measured using transcranial Doppler ultrasound (TCD) in healthy subjects engaged in a continuous static visual vigilance task. Stimuli comprised white vertical gratings on a black background with a size of 5 x 5" (non-targets) or 5 x 3.5" (targets). Button presses were required to the rare (8.5%) targets. Over the 30 min session a decrease in hit rate and an increase in reaction time were seen, indicating a decrease in vigilance. These performance changes were paralleled by a decrease in flow velocity in both MCAs. No hemispheric difference was seen. These data suggest a close coupling of performance and blood flow in vigilance tasks. Modulation of cholinergic activity during the vigilance task might be the common underlying mechanism.

Adult↗
PubMed2004

A simple rule for the costs of vigilance: empirical evidence from a social forager.

It is commonly assumed that anti-predator vigilance by foraging animals is costly because it interrupts food searching and handling time, leading to a reduction in feeding rate. When food handling does not require visual attention, however, a forager may handle food while simultaneously searching for the next food item or scanning for predators. We present a simple model of this process, showing that when the length of such compatible handling time Hc is long relative to search time S, specifically Hc/S > 1, it is possible to perform vigilance without a reduction in feeding rate. We test three predictions of this model regarding the relationships between feeding rate, vigilance and the Hc/S ratio, with data collected from a wild population of social foragers (samango monkeys, Cercopithecus mitis erythrarchus). These analyses consistently support our model, including our key prediction: as Hc/S increases, the negative relationship between feeding rate and the proportion of time spent scanning becomes progressively shallower. This pattern is more strongly driven by changes in median scan duration than scan frequency. Our study thus provides a simple rule that describes the extent to which vigilance can be expected to incur a feeding rate cost.

Animals↗
PubMed1989

Predator vigilance and group size in mammals and birds: a critical review of the empirical evidence.

One commonly cited benefit to animals that forage in groups is an increase in the probability of detecting a predator, and a decrease in the time spent in predator detection. A mathematical model (Pulliam 1973) predicts a negative relationship between group size and vigilance rates. Over fifty studies of birds and mammals report that the relationship at least partly explains why individuals forage in groups. This review evaluates the strength of these conclusions based on their evidence. Those variables that may confound the relationship between vigilance and group size are outlined, and their control is assessed for each study. The variables I consider to be important include the density and type of food; competition between individuals; the proximity to both a safe place and the observer; the presence of predators; the visibility within the habitat; the composition of the group; the ambient temperature and the time of day. Based on these assessments, most of the studies fail to adequately demonstrate an unambiguous relationship between vigilance behavior and group size. Nevertheless, many studies reveal interesting features of the relationship between vigilance and group size that should provide fruitful avenues for future research.

Animals↗
PubMed1985

Memory dysfunction and vigilance: neurophysiological and psychopharmacological aspects.

Human brain function as measured by the computer-assisted spectral analyzed electroencephalogram (EEG) shows significant alterations in normal and pathological aging characterized by an increase of delta and theta activity and by a decrease of alpha and alpha-adjacent beta activity as well as by a slowing of the dominant frequency. These changes are indicative of deficits in the vigilance-regulatory systems. By the term vigilance we understand the availability and grade of organization of man's adaptive behavior, which in turn is dependent of the dynamic state of the total neural activity. An impairment of vigilance was found to be significantly correlated with the clinical symptomatology of the organic brain syndrome (OBS) as well as with mnestic performance deficits. Elderly subjects with bad memory exhibit slower activity and less alpha and alpha-adjacent beta activity than those with good memory. This was found to be true for both the time of acquisition and recall. Antihypoxidotic/nootropic drugs, such as the ergotalkaloids dihydroergotoxine and nicergoline, vincamine-alkaloids, piracetam, aniracetam, etiracetam, piridoxilate and others, induce interestingly just oppositional changes in human brain function, thereby improving vigilance. Other methods for proving therapeutic efficacy in man, like experimentally induced hypoxic hypoxidosis and the reversible alcoholic OBS, are discussed.

Alpha Rhythm↗
PubMed2000

Modulation of paired-pulse responses in the dentate gyrus: effects of normal maturation and vigilance state.

This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20-50 ms) and late (IPI = 300-1,000 ms) inhibition, and less facilitation (IPI = 50-150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development.

Animals↗
PubMed1984

The use of the EEG for assessment of vigilance changes caused by beta-blockers.

The aim of this study was to investigate the changes of vigilance caused by beta-blockers. A recently developed method to measure the vigilance fluctuations, based on the EEG spectra, was employed together with self-rating. Repeated vigilance measurements were made in 20 healthy volunteers before and after administration of placebo, propranolol and metoprolol in random sequence. Both EEG analysis and self-rating confirmed that the vigilance level was significantly decreased after administration of beta-blockers compared to placebo. No significant difference between propranolol and metoprolol could be found. The results suggest that the decrease in systolic blood pressure after beta-blockade may be responsible for the drug-induced drowsiness. However, some of the observations made in the study can be interpreted as indirect proof that central mechanisms are also involved, and that both propranolol and metoprolol have sedative properties comparable to those observed with conventional psychotropic drugs.

Adult↗
PubMed1999

A controlled daytime challenge of motor performance and vigilance in sleep bruxers.

Many etiological factors have been suggested for sleep bruxism. Among these, elevated mental and physical alertness has been proposed to characterize sleep bruxers. The present study tests the hypothesis that, during the day-time, sleep bruxers are more vigilant and more prone to react to a motor command than are control subjects. Seven sleep bruxers, diagnosed polysomnographically according to validated research criteria, were matched for age and gender to seven control subjects. A simple reaction time task was selected to assess daytime vigilance and motor responsiveness. The following physiological measures were recorded: reaction time, error rate, electroencephalography, electrocardiography, electromyography, and video detection of body movements. Analysis of these variables showed no differences between groups. During the test, bruxers and controls showed a parallel decrease in EEG vigilance and heart rate over time. Frequency of orofacial and body movements was the same in both groups, and no clenching activity was observed during the experimental test. Subjects' visual analog scale ratings revealed that both controls and bruxers were more competitive after the test than before, and bruxers were slightly more anxious than controls before and after the test. Together, the results indicate that sleep bruxers are neither more vigilant nor more prone to react to a motor command during the daytime than are control subjects.

Adult↗
PubMed1997

Effect of haloperidol on nicotine-induced enhancement of vigilance in human subjects.

We posed the question whether the cognitive enhancement caused by nicotine in human subjects is mediated by dopamine (DA) release. This issue was addressed by testing performance in the Wesnes and Warburton vigilance task after s.c. nicotine with or without concomitant oral haloperidol. The subjects were moderate (10-14 cigarettes/day) smokers after overnight deprivation of smoking. After an initial practice session, each subject participated in four further sessions spread over 2 weeks, after: placebo/placebo, placebo/haloperidol (5 mg), placebo/nicotine (0.8 mg) or nicotine/haloperidol, double-blind with a balanced ordering of drug combinations. On each occasion, performance was measured on the vigilance task, a finger tapping test, and digit span forward and backward. Nicotine improved detection sensitivity on the vigilance task, and this effect was unchanged by haloperidol; the latter compound reduced forward digit span. Thus, the improved vigilance caused by nicotine does not appear to be mediated by DA systems.

Adolescent↗
PubMed1981

Factors affecting an anaesthetist's work: some findings on vigilance and performance.

This paper reviews factors which may influence the vigilance tasks of an anaesthetist during an anaesthetic. Vigilance tasks are found to be unlike any other automatic, repetitive or monotonous tasks. While many factors affect vigilance and may result in performance decrements during psychological testing, little of this work has been done on anaesthetists. We suggest, however, that there are many parallels between findings related to vigilance in general and the type of work done by anaesthetists. Implications of major factors are discussed, and recommendations for further study are proposed.

Air Pollutants, Occupational↗
PubMed2002

The art of watching out: vigilance in women who have migraine headaches.

The author used grounded theory methodology to explore the process of vigilance in women who had migraine headaches. Twenty-two women were interviewed. The basic social problem identified for women with migraines was the need to maintain function when faced with unpredictable bouts of pain and associated distress. One way women maximized their function was through the exercise of vigilance. Vigilance in these women can be conceptualized as the art of watching out. Watching out, the core category, had four subprocesses: assigning meaning to what is, calculating the risk, staying ready, and monitoring the results. Conditions for watching out were owning the label and making the connections. Deciding what to do and acting to maximize function were consequences of vigilance.

Adaptation, Psychological↗
PubMed2004

Measurement of vigilance in 2-year-old children.

This study explored the behavioral manifestations of sustained attention in 2-year-old children and the relation between sustained attention and its neurophysiological correlates. 51 children were administered a task of vigilance (the Early Childhood Vigilance Task; ECVT), along with behavioral measures of sustained attention that are routinely used as measures of attention in this age-group. A subset of these children, n = 14, was also evaluated in an event-related potential (ERP) paradigm to identify patterns of neurophysiological activation that might be associated with sustained attention. The results supported the conceptualization of vigilance as a component of sustained attention that is related to, but distinct from, attention toward objects or activities with which one is actively engaged. Results also provided support for a specific association between vigilance and right frontal brain activity. Whereas ECVT performance was associated with ERP activation in the right frontal area, performance on more traditional behavioral measures of sustained attention was not.

Arousal↗