Very early preterm infants (VPIs) are exposed to unpredictable noise in neonatal intensive care units. Their ability to perceive moderate acoustic environmental changes has not been fully investigated. Physiological values of the 598 isolated sound peaks (SPs) that were 5–10 and 10–15 dB slow-response A (dBA) above background noise levels and that occured during infants’ sleep varied significantly, indicating that VPIs detect them. Exposure to 10–15 dBA SPs during active sleep significantly increased mean heart rate and decreased mean respiratory rate and mean systemic and cerebral oxygen saturations relative to baseline. VPIs are sensitive to changes in their nosocomial acoustic environment, with a minimal signal-to-noise ratio (SNR) threshold of 5–10 dBA. These acoustic changes can alter their well-being. In this observational study, we evaluated their differential auditory sensitivity to sound-pressure level (SPL) increments below 70–75 dBA equivalent continuous level in their incubators. Environmental (SPL and audio recording), physiological, cerebral, and behavioral data were prospectively collected over 10 h in 26 VPIs (GA 28 (26–31) wk). SPs emerging from background noise levels were identified and newborns’ arousal states at the time of SPs were determined. Changes in parameters were compared over 5-s periods between baseline and the 40 s following the SPs depending on their SNR thresholds above background noise.

Aims: To evaluate the sensitivity of infants born very preterm (IBVPs) to sound pressure levels (SPL) increments below 70 dBA Leq in their "naturalistic" acoustic environments and to determine their impact on the well-being of IBVPs. Methods: Environmental (SPL and audio recording), physiological (heart and respiratory rates; systemic oxygenations), cerebral oxygenation (by NIRS) and behavioral data were prospectively collected over 10 hours in 26 IBVPs (median gestational age (GA), 28 weeks; range 26-31 weeks) on postnatal day 17 [4-50]. Sound peaks (SPs) emerging from background noise during nonhandling periods were identified and classified. Newborns‘ arousal states were determined. Changes in parameters were compared over 5 sec periods between baseline and the 40 sec following the SPs. Results: A total of 1369 SPs (5 to 15 dBA above background noise) were identified. Among the 598 SPs occurring during sleep, physiological values varied significantly, indicating that IBVPs clearly detect these SPs. Exposure to 10-15 dBA SPs during active sleep significantly increased mean heart rate +3.6 beats/min (p=0.03), and significantly decreased mean respiratory rate -6.2 breaths/min (p=0.02), and mean systemic (-2.5%, p< 0.001) and cerebral (-1.3%, p=0.006) saturations relative to baseline. Exposure to 10-15 and 5-10 dBA SPs during active sleep led to awakening in 46.7% and 30.6% of cases, respectively. Conclusions: IBVPs are sensitive to changes in their auditory environment, with a minimal signal-to-noise ratio threshold of 5-10 dBA. These auditory changes can alter their well-being and disrupt their sleep. These findings emphasize the importance of sound abatement for IBVPs n NICU.

We assessed the effects of time-on-task on cognitive control expressed by the CRN/Nc and the extent to which motivation modulates this relationship. We utilized two groups of participants, who were told that their performance would (evaluation condition) or would not (control condition) be evaluated online. Both groups performed a version of the Eriksen Flanker Task for 60 min. We observed classical vigilance lowering, manifested by a progressive performance decline with time-on-task, in the control, but not in the evaluation, condition. In the latter, performance remained stable throughout the task. ERP analysis indicated the same interaction in our main component of interest, the CRN/Nc, whose amplitude decreased from the first to the last period in the control condition but remained stable over time in the evaluation condition. To our knowledge, this study is the first to demonstrate the impact of motivation on monitoring processes as indexed by the correct response negativity, in the context of a prolonged task. Vigilance lowering caused by a repetitive and prolonged flanker task, results in compromised response control and compromised control of correct responses. Our results suggest that alterations in ACC functioning may underlie vigilance decline and can be viewed as evidence that the action monitoring functions of the ACC can be positively affected by motivation.

Introduction: Developmental care strategies imply to avoid any signs of discomfort or withdrawal in very preterm infant(VPI). Cries are major expressions of distress and can occur without any exogenous stimulation. Little is known about their effects on newborns' physiological homeostasis. Methods: Environmental, behavioral data (video and audio recording) and physiological data (heart and respiratory rates-HR and RR, systemic and regional cerebral oxygenations-SaO2 and rSO2) were prospectively collected during 10 hours in 18 VPI (median gestational age-GA, 28 [27-31] weeks). Only episodes of “spontaneous” cries were analysed. Changes in parameters were compared over 5 seconds periods between baseline and the 40 seconds following the beginning of cry. Results: A total of 13(72%) VPIs have presented 210 episodes of “spontaneous” cries, with a median number of 9 [0-63] cries per child during the study period. Physiological values varied significantly: a decreased mean HR (- 4.8 beats/min +/− 5.3: p < 0.01), which despite an increased mean RR (+ 5.6 cycles/min +/− 7.3: p < 0.05) results in a decreased mean SaO2 (- 1.8% +/− 2.3: p < 0.05) associated with a decreased mean rSO2 (- 2.5% +/− 3: p <0.05). No significant effects of GA or of the intensity of crying on the responses were observed. Conclusion: Spontaneous cries can alter the homeostasis of VPIs. Their frequent occurrences and their possible adverse consequences underline the need for a better observation of VPIs' behaviour and an adequate answer to them, which both could benefit from individualized developmental care strategies.

The present studyintended to investigate the effectsof nocturnal railway noise on thethree components of attention(alertness, orientation and executivecontrol), and on subjective ratingsof sleep quality, fatigue, wellbeingand discomfort. These effectswere studied in young (mean age =25.8 years) and middle aged (meanage = 52.4 years) subjects, for dayand shift workers. Following aquiet night, a moderately noisynight (40 dBA) and a highly noisynight (50 BA), 38 subjects performedtwo 30-min cognitive tasks(Attention Network Test andStroop task) and filled out a shortquestionnaire. Results show thatnocturnal railway noise worsenedsubjective evaluations, mainly interms of sleep quality and noisediscomfort in a dose-dependentmanner. Young subjects were moresensitive to the effects of noise thanmiddle-aged subjects, as seen bythe self-estimations of sleep qualityand noise discomfort. Furthermore,the shift workers' ratings of sleepquality were independent of noiseconditions. The effects on cognitiveperformance, however, were veryweak. The only decrement observedthe next morning was anincrease in reaction time in theStroop task after the moderatelynoisynight. We found no effect ofnoise on any of the three componentsof attention, suggesting thatnocturnal railway noise, at leastwhen experienced during a singlenight at these noise levels, is unlikelyto produce marked effects onattentional mechanisms. The use ofmore sensitive indicators, such asblink rate or event-related brainpotentials, could allow investigationof possible impairments ofthese attentional networks afternoisy nights.

The purpose of the present study is to analyse the effects of task complexity on the EEG spectral parameters and the extent to which age modulates this relationship. Subjects were divided into a junior and a senior group and engaged in a simple and a complex version of “Go/No go” tasks. Cognitive, subjective and electrophysiological data were combined. Our results indicated that there was an increase in alpha power over time only in the junior group in the simple task and the senior group in the complex one, suggesting that, depending on age, the increase in alpha band vary in a different way according with the degree of task complexity and could reflect some different phenomena. Cognitive performance were independent of age but for the main dimensions of motivation, seniors had higher scores, and they were less sleepy than juniors. Finally, this study showed correlations between cognitive performance, subjective evaluations and electrophysiological measures, and their value for understanding the subject’s engagement in a task.

OBJECTIVES:Many studies have demonstrated that patients with Obstructive Sleep Apnea Syndrome (OSAS), a very common sleep-related breathing disorder, are usually impaired in their driving ability because of decreased sleep quality. However, most of the simulation procedures in laboratories are designed to create monotonic conditions with low traffic density, if any, thereby leading to a dramatic decrease in performance in OSAS patients because of the lack of stimulation. The aim of this study was therefore to evaluate driving abilities in OSAS patients involved in a driving simulation task with medium traffic density, in order to replicate as far as possible real world conditions. The behavioral and physiological attributes likely to predict driving performance in these patients were also investigated. METHODS:After a normal night of sleep, 12 OSAS patients and 8 healthy controls performed 6 driving sessions during a 24-h period of sustained wakefulness. Driving performances (speed, lateral position, distances...) were measured and correlated to sleep parameters and to a waking EEG recorded during the task. RESULTS:Compared to controls, patients showed difficulties in speed adjustment. However, they maintained longer inter-vehicle distances, including during overtaking. Their waking EEG, while driving, showed increased spectral power in theta (3.9-7.8Hz) but also in beta (12.7-29.2Hz) activity, alpha power (7.9-12.6Hz) being increased in both groups due to sustained wakefulness. Poor sleep indices were correlated to increased theta and beta activities, as well as to more cautious behavior. DISCUSSION:In medium traffic density conditions, driving performance in OSAS patients remained at near normal levels, but with more cautious behavior than controls. This could be the result of a bigger effort to stay awake, as suggested by an increased beta activity in these patients.

It is well known that most patients with obstructive sleep apnoea/hypopnoea syndrome (OSAHS) suffer sleepiness, although the underlying mechanisms of this relationship remain unclear. The present study examined the relationship between nocturnal variables and the subsequent waking electroencephalogram (EEG), in order to determine if sleepiness was related to OSAHS severity and due to sleep fragmentation or to nocturnal hypoxaemia.In total, 12 moderate-to-severe OSAHS patients underwent a total sleep night followed by a 24-h period of sustained wakefulness where the waking EEG was measured every hour.The results showed that alpha (7.9-12.6 Hz) and beta (12.7-29.2 Hz) activities were strongly related to OSAHS severity, mainly reflected by the apnoea index. Moreover, spectral power in most of the waking EEG components was significantly correlated with nocturnal hypoxaemia indices, namely alpha and beta activity when hypoxaemia becomes severe. However, no correlation was found between the waking EEG and sleep fragmentation parameters.In conclusion, the present results suggest that the difficulty in maintaining an optimal level of alertness, reflected by a higher activity in awake alpha and beta bands (7.9-29.2 Hz) in obstructive sleep apnoea/hypopnoea syndrome, was better explained by: 1) the apnoea as opposed to the hypopnoea index; and 2) nocturnal hypoxaemia as opposed to sleep fragmentation.

Sleep inertia (SI) is a transient period occurring immediately after awakening, usually characterized by performance decrement. When sleep is sufficient, SI is moderate, and produces few or no deficit. When it is associated with prior sleep deprivation, SI shows dose-dependent negative effects on cognitive performance, especially when subjects have been awaken in slow wave sleep (SWS). In the present study, spectral analysis was applied during the last 10 min before and the first 10 min after awakening, and during 1 h after awakening while subjects performed the Stroop test. Seventeen subjects were divided into a Control group who slept 8 h, and a Sleep Deprived group who slept only 2 h. The results show that performance was normal in the Control group, whereas reaction time was increased during the first half hour and error level during the second half hour in the Sleep Deprived group. Spectral analysis applied on the waking EEG during the whole test session showed that alpha activity was increased in both groups, but theta power only in the Sleep Deprived group. There was a high positive correlation in sleep deprived subjects between delta power during the last 10 min of sleep and subsequent performance decrement in speed and accuracy. Comparison of individual records showed a high positive correlation between spectral power before and after awakening in the Control group (generally in the sense of an increased frequency band), but no correlation was found in the Sleep Deprived group who exhibited a rather disorganized pattern. We discuss these results in terms of incoherence in the EEG continuity during sleep offset after prior sleep loss, which could partly account for the performance decrement observed during SI in sleep deprived subjects.

When exposed to cold, the hands need to be protected against heat loss not only in order to reduce thermal discomfort, but also to keep their efficiency. Although gloves are usually the most common protection, their thermal insulation is generally unknown. The aim of this study was to measure the heat losses from a gloved hand with a special interest in local variations. Using a calorimetric hand placed in a cold box, several types of gloves were tested. The results indicated that depending on the glove and on the area covered the heat loss reduction may vary from almost 60% to 90%. When the least efficient pair of gloves was excluded, heat exchange coefficients varied from 1.8 to 4.8 W/m2 per degrees C for the palm and from 4.2 to 6.2 W/m2 per degrees C for the back of the hand. The three medium fingers seemed to be equally treated, with a heat exchange coefficient variation of 6.3-9.0 W/m2 per degrees C. The thumb and the little finger, which require better insulation, exhibited higher local heat transfer coefficients of 8.3-12.7 W/m2 per degrees C. Some practical aspects are evoked.

Extensive research has demonstrated that shiftwork produces deleterious effects on health because of the desynchrony it induces in the biological clock. The problem is even more crucial for older workers who present, in addition, various decrements in their cognitive functioning, particularly on attention and memory. The present study assessed whether age was related to task complexity as a function of time of day and time-on-task in a rapid rotating work-rest schedule. 24 subjects (12 juniors: 20–30 years and 12 seniors: 50–60 years) performed either a simple task (visual discrimination) or a complex task (descending subtraction) on three different moments of the day simulating the main shifts (morning, evening, and night). Analysis indicated that an age effect was only present on the more complex task, which was demanding in attentional resources and memory load. Seniors had no deficit in performance on the simple task compared to juniors. The effect of time of day was restricted to the simple task for both age groups. However, some differential strategies appear to distinguish juniors and seniors, specifically on accuracy during the night, suggesting that subjects of different ages cope with cognitive tasks in different ways and that perhaps some adverse effects apparently associated with aging could be counteracted by efficient strategies, but not others.

Several studies have shown significant correlations among factors such as sex, age, and hormone levels with performance on mental rotation tasks. To perform spatial rotation also seems to be related to cognitive abilities such as musical skills. The present experiment investigated a possible relationship for enhanced spatial abilities, as observed in near-sighted subjects, with mental rotation performance. 39 near-sighted and 21 normal-sighted subjects were tested on a mental rotation task using two-dimensional representations of three-dimensional objects. Near-sighted subjects displayed fewer errors in possible rotations than normal-sighted subjects. There was no difference in errors between groups in identification of mirror images (“impossible rotations”). Results were interpreted in terms of a relation between enhanced reliance on nonvisual information by near-sighted subjects and improved spatial representation.

The present experiment was designed to assess daily fluctuations of visual discriminability, a function reflecting the resolution power of the visual sensitivity by measure of a differential threshold. Sixteen subjects underwent a visual discrimination threshold task (using the constant method) in a protocol allowing one point every 2h over the 24h period. The results show that the visual discrimination threshold is low in the morning and increases progressively over the day, reaching a first peak at 22:00. During the night, the same pattern occurs, with low threshold levels at the beginning of the night and high levels at the end. This profile is quite different from that of detection threshold variations, suggesting that the two visual functions are under the control of different underlying mechanisms. Two interpretations could account for this discrepancy. The first relates to different oscillators in the eye for detection and discrimination. The second refers to a possible linkage of visual discriminability with the sleep-wake cycle since threshold measures were systematically low (i.e., high resolution power) after long sleep periods.

Thirty male subjects participated in four experiments under showers to explore the sensitivities to water temperature and to its slow or rapid fluctuations. After having set the water temperature, at constant flow rate, at either a thermoneutral or a preferred level, subjects were asked to detect thermal changes or to report their thermosensory and affective judgments associated with water temperature changes. Results of water temperature, skin temperature, and subjective estimates showed that skin temperature for thermally neutral sensation under a shower were very similar to those observed in air, and such a thermoneutral level produced no discomfort. Preferred water temperature was slightly warmer and led to slightly elevated skin temperatures, warmth, and pleasantness estimates. Skin sensitivity to water thermal changes was very acute during slow and even more acute during rapid thermal transients. The conclusions of the present study are of value in the production of appropriate equipment to provide thermal comfort to people taking showers.

The aim of this study was to explore the influence of task complexity and time of day on middleaged shift-workers. Two groups of twelve subjects participated to this experiment: one Junior group (aged 20-30) and one Senior group (aged 50-60). Performance was assessed in two tasks involving different cognitive load: a simple visual discrimination task and a complex mental arithmetic test. The former was considered as an immediate processing task requiring little memory and attention, whereas the latter required a high mental load in working memory and attention. The subjects were tested in both tasks at three different times of the day simulating the main shifts: morning, evening and night. In each task, the test session lasted 60 minutes, divided into two 30-minute periods separated by a 20-minute rest. The results showed slower mental processing in both tasks in Seniors revealed by increased reaction time. Accuracy was also decreased, but only in the complex arithmetic test with an increase in error rate which was not observed in the simple perceptual task. Mental speed in the calculation task was decreased in both groups during the night session, but there was no time-of-day effect in the simple task. The time course of accuracy during the second period of the night session showed increased errors in Juniors but a decreasing trend in Seniors. Altogether, these results demonstrate that performance deficits due to age appear rather early in the lifespan, particularly when tasks involve high memory and attention load. However, the opposite profiles between Seniors and Juniors on accuracy during the night suggest a possible difference in strategies between young and old subjects which could help Seniors to partly counteract their deficits due to age.