Recent research has shown that the useful visual field deteriorates in simulated car driving when the latter can induce a decrease in the level of activation. The first aim of this study was to verify if the same phenomenon occurs when driving is performed in a simulated road traffic situation. The second aim was to discover if this field also deteriorates as a function of the driver's age and of the vehicle's speed. Nine young drivers (from 22 to 34 years) and nine older drivers (from 46 to 59 years) followed a vehicle in road traffic during two two-hour sessions. The car-following task involved driving at 90 km.h(-1) (speed limit on road in France) in one session and at 130 km.h(-1) (speed limit on motorway in France) in the other session. While following the vehicle, the driver had to detect the changes in colour of a luminous signal located in the central part of his/her visual field and a visual signal that appeared at different eccentricities on the rear lights of the vehicles in the traffic. The analysis of the data indicates that the useful visual field deteriorates with the prolongation of the monotonous simulated driving task, with the driver's age and with the vehicle's speed. The results are discussed in terms of general interference and tunnel vision.
Nine older subjects (40-51 years) and 10 younger subjects (18-30 years) took part in two one-hour driving sessions. They performed a very monotonous task during which they had to follow a vehicle either after a complete night of sleep or after one night of sleep deprivation. While driving their useful visual field was assessed by introducing signals that would appear on the whole road scene. The analysis of the data indicates that the ability to process peripheral signals deteriorates with age, driving duration and sleep deprivation. However, the effects of these three variables on the peripheral visual ability are not similar in a dual task. The driver's useful visual field changes with age and prolongation of the monotonous driving activity according to a tunnel vision phenomenon. On the other hand, a sleep debt deteriorates the useful visual field according to a general interference phenomenon. These results are discussed in terms of decrease in the level of arousal and increase of fatigue.
IntroductIon: 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. rESuLtS: 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. dIScuSSIon: 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. MEtHodS: 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. V ery early preterm infants (VPIs) are exposed to nosocomial environmental stimuli that differ from the stimuli they encounter in utero. This new "naturalistic" milieu, especially loud noise, may interfere with their neurodevelopment and growth (1-4). This has led to specific recommendations for permissible noise criteria levels in the neonatal intensive care unit (NICU) (5-7). These recommendations were based primarily on the evaluation of the effects of noise on the developing auditory system and well-being of newborns. Most studies were experimental. Preterm newborns were exposed to 5 s of high artificial sound (8,9), including sound-pressure levels (SPLs) ranging from 80 to 100 dB (8) and to warbling tones of 100 dB (9). The most prevalent responses were an increase in heart rate (HR) (8,9) proportional to the SPL of the stimulus and a tendency toward a decrease in respiratory rate (RR) (9). Few studies have evaluated the impact of noise in the NICU on newborns' physiological stability. Unfortunately, some of these studies measured the effect of acoustic environments quite different from those in the contemporary NICU (10) or did not include preterm infants (11) or VPIs (10). Moreover, some yielded questionable results because of study design, nonreporting of background noise, and the absence of a well-defined study population (e.g., inclusion of newborns with a wide range of gestational age, GA) (12). Despite these limitations, these studies showed that a high level of environmental noise, >70-75 dB slow response A (dBA) equivalent continuous leve...
In the healthy elderly, the neuronal circuits of cognitive inhibition and conscious pain control may overlap, and brain regions engaged in response inhibition may be more involved in behavioural response of pain.
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