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G Curcio

Publications and source records attributed to G Curcio.

7 recordsLinked to original sources
PubMed2001

Auditory evoked responses upon awakening from sleep in human subjects.

The hypothesis that a state of hypoarousal upon awakening should lead to a decrease in amplitude and an increase in latency of the N1-P2 components of the Auditory Evoked Potentials (AEPs) as compared to presleep wakefulness levels, was evaluated after two nocturnal awakenings and after the final morning awakening from a 7.5-h night of sleep. The amplitude of the N1-P2 complex was reduced upon awakening as compared to presleep wakefulness levels, but only following the first nocturnal awakening, scheduled after the first 2 h of sleep. This result is interpreted as indicating a link between slow wave sleep amount, mainly present during the first part of the night, and lowered levels of brain activation upon awakening. The reaction times, recorded concomitantly to AEPs, were more sensitive to the negative effects of sleep inertia.

Adult↗
PubMed2001

Sleepiness: evaluating and quantifying methods.

The aim of this literature review is to analyze the methods mainly used for evaluating and quantifying the complex phenomenon of sleepiness. The most common distinction is between subjective measures or self-evaluations, performance decrement measures, measures for evaluating sleep propensity and measures of arousal decrease. Techniques mainly used in specialized literature will be briefly presented and commented upon, evaluating their sensitivity, advantages and limitations. We conclude that: (a) different measures inevitably are differently sensitive to sleepiness fluctuations; (b) the amount of prior sleep is strongly relevant in quantifying sleepiness levels; (c) subjective and behavioral measures show a higher level of vulnerability to external and motivational factors.

Attention↗
PubMed2001

Antero-posterior EEG changes during the wakefulness-sleep transition.

OBJECTIVES: To investigate the brain topography of the human sleep EEG along the antero-posterior axis during the wakefulness-sleep transition, by means of both a single Hz analysis and a grouped-frequency analysis of EEG changes. METHODS: EEG power values were calculated across a 1-28 Hz frequency range in a 1 Hz resolution during the wakefulness-sleep transition of 7 normal subjects. Topographical changes were assessed from C3-A2, C4-A1, Fpz-A1, Fz-A1, Cz-A1, Pz-A1, Oz-A1 recordings, after averaging individual time series, aligned with respect to the onset of stage 2. RESULTS: The single Hz analysis showed that before sleep onset (SO), the <7 Hz slow frequencies were more prominent at the more anterior scalp locations; this anterior prominence was counterbalanced by a reciprocal prevalence across the >8 Hz frequencies of EEG activity from the occipital areas; while the >13 Hz fast frequencies were not characterized by significant antero-posterior differences. After SO, more EEG power was found in the range of slow frequencies at the centro-frontal scalp locations and a second peak of EEG activity was also revealed within the range of the sigma frequency, higher at the centro-parietal scalp locations. No consistent topographical changes were observed within the range of faster EEG frequencies. Grouped-frequency analysis confirmed these results, also pointing to different changes in the alpha frequency as a function of the SO point. CONCLUSIONS: The results suggest that: (a) the alpha rhythm spreads anteriorly as the transition progresses; (b) several anterior areas first synchronize EEG activity; (c) the functional meaning of the EEG bands during the SO period should be partially revised with regard at least to alpha rhythm; (d) SO coincides with the start of stage 2.

Adult↗
PubMed1997

Assessing vigilance through a brief pencil and paper letter cancellation task (LCT): effects of one night of sleep deprivation and of the time of day.

Behavioural effects of the lack of sleep in normal subjects have been investigated mostly by experimenter-paced choice reaction times in prolonged stimulus detection tasks. However, length and procedure complexity of these tasks limit their use in research on larger numbers of subjects. The aim of the present study was to assess the effectiveness of a brief subject-paced pencil and paper performance task, i.e. letter cancellation task (LCT) in revealing the effects of one night of sleep deprivation. In addition, the authors evaluated sleep loss and time of day effects on six Visual Analogue Scales (VAS) measuring subjective activation-deactivation. Results show that a LCT is sensitive in revealing the effects of time of day and of 24 h of sleep deprivation. Effects of sleep deprivation were also revealed by VAS data. Sleepiness, tiredness and energy scales on the VAS were also affected by time of day. Despite the sensitivity of both the LCT and VAS, there was little correspondence between performance and subjective measures.

Adult↗
PubMedDate not supplied

Visual search performance across 40 h of continuous wakefulness: Measures of speed and accuracy and relation with oculomotor performance.

The aim of the study was to estimate the sensitivity of a brief self-paced visual search task to increased levels of sleepiness as a consequence of 40 h of sleep deprivation. Time-of-day effects on this task, on subjective sleepiness and on oculomotor performance changes, were also assessed. Eight normal subjects slept for three nights in the laboratory (adaptation, baseline, recovery). Baseline and recovery nights were separated by a period of 40 h of continuous wakefulness, during which subjects were tested every 2 h from 10:00 to 22:00 h on both days preceding and following the sleep deprivation night, as well as from 24:00 to 08:00 h during the deprivation period. At the same time, subjects filled in a visual analogue sleepiness scale and the Stanford Sleepiness Scale (SSS). As regards cognitive performance, significant effects were found on speed measures, while accuracy was not affected. The number of explored rows was higher after the baseline night than after the sleepless night, and showed a consistent time-of-day trend. Omissions ratio (OR), false positives ratio (FPR) and hits ratio (HR) did not show any significant effect. Subjective ratings of sleepiness varied according to speed measures, being affected by sleep deprivation and time of day. Since similar effects were found with an oculomotor task, detrended functions for all variables across the 40 h of continuous wakefulness were calculated. A circadian effect was found, in which speed measures seem to be more affected than accuracy ones in both visual search and oculomotor tasks. It is concluded that 40 h of prolonged wakefulness significantly impairs performance in a brief cognitive visual search task. Such a performance worsening is evident on speed, but not on accuracy indices, and is strictly related to the deterioration of oculomotor performance, indicating a clear circadian effect.

Adult↗
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↗