Biomedical subjects

L De Gennaro

Publications and source records attributed to L De Gennaro.

At least 19 recordsLinked to original sources

PubMed2000

The spontaneous K-complex during stage 2 sleep: is it the 'forerunner' of delta waves?

The hypothesis that K-complexes (KCs) contribute to the process of synchronization leading to Slow-Wave Sleep (SWS) was evaluated by measuring their dynamic evolution across sleep cycles and before transitions to rapid eye movement (REM) or to SWS. KC density and inter-KC intervals respectively decreased and increased across the sleep cycles, revealing linear trends. Comparisons among transitions from stage 2 to SWS or to REM sleep showed a prevalence of KCs before the shift to SWS as compared to REM. Changes in KC density before the shift to SWS were fitted by a linear regression, at variance with the transition to REM sleep. Intra-night variations of KCs, paralleling the well-known decrease of slow waves across sleep cycles, and intracycle variations before shifting to SWS, both converge to indicate that KCs can be considered as the forerunner of delta waves.

Adult↗

PubMed2000

Sleep deprivation and phasic activity of REM sleep: independence of middle-ear muscle activity from rapid eye movements.

In the recovery nights after total and partial sleep deprivation there is a reduction of rapid eye movements during REM sleep as compared to baseline nights; recent evidence provided by a selective SWS deprivation study also shows that the highest percentage of variance of this reduction is explained by SWS rebound. The present study assesses whether the reduction of rapid eye movements (REMs) during the recovery night after total sleep deprivation is paralleled by a decrease of middle-ear muscle activity (MEMA), another phasic muscle activity of REM sleep. Standard polysomnography, MEMA and REMs of nine subjects were recorded for three nights (one adaptation, one baseline, one recovery); baseline and recovery night were separated by a period of 40 hours of continuous wake. Results show that, in the recovery night, sleep deprivation was effective in determining an increase of SWS amount and of the sleep efficiency index, and a decrease of stage 1, stage 2, intra-sleep wake, and NREM latencies, without affecting REM duration and latency. However, MEMA frequency during REM sleep did not diminish during these nights as compared to baseline ones, while there was a clear effect of REM frequency reduction. Results indicate an independence of phasic events of REM sleep, suggesting that the inverse relation between recovery sleep after sleep deprivation and REM frequency is not paralleled by a concomitant variation in MEMA frequency.

Adult↗

PubMed2000

A complementary relationship between wake and REM sleep in the auditory system: a pre-sleep increase of middle-ear muscle activity (MEMA) causes a decrease of MEMA during sleep.

Since some evidence has supported a complementary relationship between waking and REM-sleep eye movement (variations in frequency, amplitude, or direction of waking saccades have been found to inversely affect the corresponding parameters of rapid eye movements), the present study assessed whether this relationship can also be shown for other phasic components of REM sleep, such as middle-ear muscle activity (MEMA), as a consequence of an increase of middle-ear reflex frequency during pre-sleep wake. Ten subjects were studied in three consecutive nights (one adaptation, one baseline, one experimental). In the experimental night, subjects underwent a 2-h pure-tone (1000 Hz, 90 dB SPL) auditory stimulation and MEMA was monitored every 15 min; noise exposure during daytime was also controlled. Results show that MEMA frequency during REM sleep significantly decreased during the experimental nights compared with baseline nights, while each sleep variable as well as mean daily auditory input did not present any significant difference between baseline and experimental nights. Results suggest that the complementary relationship between wake and REM sleep is not bounded to oculomotor activity, but it may also be extended at least to middle-ear muscle phasic activity.

Acoustic Stimulation↗

PubMed2000

Psychosocial factors and male seminal parameters.

The relationships between (a) alexithymia, (b) extroversion (E), neuroticism (N), psychoticism (P), (c) coping style towards stressors, and seminal parameters, were assessed in 132 males on their first seminal fluid examination by means of a multivariate approach. They were given the TAS-20, the EPQ, and the Coping Inventory for Stressful Situations (CISS). Seminal parameters were: (1) sperm concentration; (2) total sperm count; (3) forward motility; (4) atypical forms. Multiple regressions considering quantitative parameters of seminal status as criterion showed a negative relationship with P, difficulty describing feelings (DDF), while a positive relationship was found for N, and emotion-oriented coping. A discriminant analysis also showed that P, N and DDF distinguished between two groups of normozoospermic and oligozoospermic subjects with a high probability of correct classifications. Results confirm the hypothesis that biological and psychological variables are not completely independent or randomly related in people with an impaired seminal status, although the correlations between psychosocial and biological data are not very strong.

Adaptation, Psychological↗

PubMed2000

The relationship between frequency of rapid eye movements in REM sleep and SWS rebound.

Previous studies have shown a decrease in rapid eye movement (REM) frequency during desynchronized sleep in recovery nights following total or partial sleep deprivation. This effect has been ascribed to an increase in sleep need or sleep depth consequent to sleep length manipulations. The aims of this study were to assess REM frequency variations in the recovery night after two consecutive nights of selective slow-wave sleep (SWS) deprivation, and to evaluate the relationships between REM frequency and SWS amount and auditory arousal thresholds (AAT), as an independent index of sleep depth. Ten normal males slept for six consecutive nights in the laboratory: one adaptation, two baseline, two selective SWS deprivation and one recovery night. SWS deprivation allowed us to set the SWS amount during both deprivation nights close to zero, without any shortening of total sleep time. In the ensuing recovery night a significant SWS rebound was found, accompanied by an increase in AAT. In addition, REM frequency decreased significantly compared with baseline. This effect cannot be attributed to a variation in prior sleep duration, since there was no sleep loss during the selective SWS deprivation nights. Stepwise regression also showed that the decrease in REM frequency is not correlated with the increase in AAT, the traditional index of sleep depth, but is correlated with SWS rebound.

Adult↗

PubMed2000

Time-course of sleep inertia upon awakening from nighttime sleep with different sleep homeostasis conditions.

BACKGROUND: We assessed the time-course of sleep inertia during the first 75 min after morning awakening from regular nocturnal sleep, as well as from nighttime sleep episodes with altered sleep homeostasis conditions. METHODS: Ten normal males slept for 6 nights in the laboratory: 1 adaptation (AD), 2 baseline (BSL, BSL-A), 2 selective Slow-Wave Sleep (SWS) deprivation (DEP-1, DEP-2), and 1 recovery night (REC). On morning awakening, performance was assessed by means of: a) Descending Subtraction Task (DST); b) Auditory Reaction Time task (ART); and c) Finger Tapping Task (FTT). The test battery, lasting about 13 min, was repeated for 5 times. RESULTS: In regard to DST, the Correct Response ratio (CR/NR) showed a great increase of sleep inertia on the first testing session of REC. Regarding sleep inertia time-course, a significant linear decrease across the testing sessions during the BSL-A and the DEP-2 was present, whereas a significant quadratic trend during the AD, the DEP-1 and the REC was found. On the other hand, ART performance showed a significant quadratic trend across testing sessions, while FTT performance did not show any significant variation. CONCLUSIONS: A uniform pattern of variation of time-course of sleep inertia as a function of the different sleep homeostasis conditions was not recognized. Performance accuracy (CR/NR) on the DST showed the hypothesized increasing linear trend across testing sessions only during 2 out of 6 nights, while the unexpected quadratic trend of ART performance is probably due to a fatigue effect. During sleep inertia, cognitive performance reached the baseline level about 30 min after awakening, while motor performance was still below the baseline levels 75 min after awakening. The finding that cognitive performance recovery is greater and more rapid than motor performance recovery could be very important for operational settings and in sustained operations.

Adult↗

PubMed2000

Selective slow-wave sleep deprivation and time-of-night effects on cognitive performance upon awakening.

We evaluated the effects of selective slow-wave sleep (SWS) deprivation and time-of-night factors on cognitive performance upon awakening. Ten normal men slept for 6 consecutive nights in the laboratory: 1 adaptation, 2 baseline, 2 selective SWS deprivation, and 1 recovery night. Cognitive performance was assessed by means of a Descending Subtraction Task after 2, 5, and 7.5 h of sleep. There was an almost complete selective SWS suppression during both deprivation nights, and a significant SWS rebound during the recovery sleep. Regarding cognitive performance, a progressive linear decrease of sleep inertia upon successive awakenings was found during all experimental nights except for the recovery night. In addition, a significant decrease of sleep inertia was observed upon the morning awakening of the second deprivation night for the measure of performance speed, and a significant increase of sleep inertia upon the morning awakening of the recovery night for the measure of performance accuracy. The results show that cognitive performance upon awakening is adversely affected by sleep depth and that, during the sleep-wake transition, cognitive performance accuracy is more impaired than performance speed.

Adult↗

PubMed2000

The sleep inertia phenomenon during the sleep-wake transition: theoretical and operational issues.

Sleep inertia (SI) defines a period of transitory hypovigilance, confusion, disorientation of behavior and impaired cognitive and sensory-motor performance that immediately follows awakening. SI, the cognitive and behavioral correlate of the transition from sleep to wakefulness, has been incorporated in several models of sleep and vigilance regulation. Monitoring of several physiological parameters during the awakening period clearly indicate that this transition process is very slow. On the cognitive and behavioral side, SI has relevant operational implications. SI is one of the most serious contraindications to the use of napping during quasi-continuous operations if the individual may be required to perform complex tasks immediately after sudden awakening at unpredictable times. The studies on SI modulating factors showed that SI is strongly affected by slow wave sleep amount and sleep depth, while the outcomes concerning the modulation of SI by circadian factors are not consistent. Cognitive tasks involving high attentional load seem to be much more affected by SI than simple motor ones, performance accuracy being more impaired than speed. Finally, some possible countermeasures against the detrimental effects of SI to be applied in operational settings have been provided.

Circadian Rhythm↗

PubMed1999

Auditory arousal thresholds after selective slow-wave sleep deprivation.

OBJECTIVES: The aim of this study is to assess Auditory Arousal Thresholds (AATs) three times during an undisturbed baseline night and to compare them to AATs during the recovery night that follows two consecutive nights of selective SWS deprivation. The presence of a time-of-night effect on AATs will also be assessed. METHODS: Ten male Ss slept in the laboratory for 6 consecutive nights. The first two nights were undisturbed. The 3rd night was considered as baseline. During the 4th and 5th nights, selective SWS deprivation was obtained by means of acoustic stimulation. The 6th night was a recovery. In the last 4 nights Ss were awakened three times, after 2, 5 and 7.5 h of sleep, respectively. All the awakenings were carried out from stage 2 (after at least 5 consecutive min of stage 2), by means of 1000 Hz ascending tone series. The AAT determination was based on EEG-EMG criteria: at least 10-s of clear alpha rhythm and/or a 10 s movement arousal. RESULTS: During both deprivation nights, SWS amount was close to zero. In the ensuing recovery night a significant SWS rebound was found, accompanied by a significant increase of AATs with respect to the baseline. Furthermore, there was a significant linear decrease of AATs during the night. Finally, the individual correlations between AATs and SWS amount were significant in 4 out of 10 Ss. CONCLUSIONS: These results confirm that AATs are a reliable index of sleep depth by showing that the SWS rebound following selective SWS deprivation is paralleled by a significant AAT enhancement. The experimental paradigm also allows us to claim that AATs show a decreasing linear trend during the night, having excluded any procedural bias. Finally, AATs can be directly related to SWS amount that preceded the awakening, although the individual correlations between AATs and SWS have to be considered with caution, given the high inter-subject variability and the small number of observations.

Acoustic Stimulation↗

PubMed1997

A finger-tapping task and a reaction time task as behavioral measures of the transition from wakefulness to sleep: which task interferes less with the sleep onset process.

The aim of this study was to assess whether a finger-tapping task (FTT), in which normal subjects repeatedly tap on a button while falling asleep, could be less disturbing and provide comparable information on the sleep onset period (SOP) with respect to a reaction-time task (RTT) to acoustic stimuli, in which the onset of sleep can be delayed by the arousing effect of the acoustic stimuli. Twelve subjects slept at their homes and six slept in a sleep laboratory for four consecutive nights. After one adaptation night and one baseline night, subjects were required to fall asleep in the third and fourth nights, bimanually performing either a RTT or a FTT. The results indicate that the FTT interfaces less with the SOP compared to the RTT and suggest that the FTT provides further advantages as a behavioral measure of the transition from wakefulness to sleep. In fact, the tapping task is associated with significantly shorter behavioral and polysomnographic sleep onset latencies and with a greater proportion of slow-wave sleep (SWS) during the transition from wakefulness to sleep compared with the RTT. Furthermore, correlations among subjective, behavioral, and electroencephalograph (EEG) latencies confirm the validity of the finger-tapping task as a behavioral measure of sleep onset.

Acoustic Stimulation↗

PubMed1996

Rapid eye movements density as a measure of sleep need: REM density decreases linearly with the reduction of prior sleep duration.

In the recovery nights from total and partial sleep deprivation there is a reduction of oculomotor activity during paradoxical sleep as compared to baseline nights. Aims of the present within-subjects study are to contribute in understanding the nature of the relationship between REM density and sleep need and to evaluate whether an inverse relationship exists between REM density and slow wave sleep (SWS) amount. Six healthy subjects were studied for 7 consecutive weeks with standard polysomnographic recordings. Variations in REM density were assessed in the recovery nights following a gradual sleep restriction, obtained by postponing the sleep onset time while maintaining the final awakening time constant. Results indicate that sleep curtailment decreases REM density in the ensuing recovery nights; the decrease is linearly related to the amount of sleep curtailment. The decrease in REM density parallels an increase in SWS, while no corresponding variation was found neither in the duration of paradoxical sleep nor in the latency of any other sleep stage. These results suggest that REM density could be used as a measure of sleep need.

Adult↗

PubMed1996

Left movers' advantage in heartbeat discrimination: a replication and extension.

Lateral eye movers are subjects who consistently shift their gaze either leftward or rightward while reflecting on visuospatial or verbal questions. When reliably assessed, prevalent direction of gaze can be assumed as a valid index of hemispheric asymmetry. The present study evaluated discrimination of heartbeat (HB) and of spontaneous changes of finger temperature in 24 right-handed females reliably selected as lateral movers. Results replicate and extend previous findings by showing that left movers' superiority in HB discrimination is present also in females and concerns the perception of a different vascular function, that is, peripheral finger temperature. Differences between right movers and left movers were not due to activation level during the test or to body composition.

Adult↗

PubMed1995

The complementary relationship between waking and REM sleep in the oculomotor system: an increase of rightward saccades during waking causes a decrease of rightward eye movements during REM sleep.

Since an inverse relationship between waking and REM sleep eye movements (EMs) has been found with respect to frequency, amplitude and direction of EMs, we evaluated variations in the percentages of horizontal rapid eye movements (REMs) during REM sleep after having increased rightward saccades during waking by means of a unilateral tachistoscopic visual test administered prior to sleep. In another condition subjects were given the same 4 h testing condition prior to sleep, the only difference being that they were instructed not to move their gaze; therefore only "attentional movements" were possible. This condition served as a control for the role of oculomotor activity in the complementary relationship between waking and REM sleep eye movements. The actual increase of rightward saccades during waking resulted in a significant decrease of rightward REMs. This effect has been observed only in the condition in which rightward eye movements were increased and it is specific for REMs of amplitude similar to those which were increased during waking by the lateralized test.

Adult↗

PubMed1995

Which hemisphere falls asleep first?

Behavioral tasks (reaction times to acoustic stimuli and finger tapping tasks) performed by normal subjects when sleepy or attempting to fall asleep have been used as indices of hemispheric asymmetries during the sleep onset period. Results show a stronger impairment of the left hemisphere (right hand) both in reacting to external stimuli and in sustaining endogenous motor programs. The left hemisphere seems to fall asleep earlier than the right hemisphere.

Acoustic Stimulation↗

PubMed1995

Increase of REM duration and decrease of REM latency after a prolonged test of visual attention.

Following one adaptation night, the nocturnal sleep of nine female college students was recorded for two baseline and two experimental nights. In both experimental nights, prior to sleep the subjects performed a 4 hour long visual task requiring the recognition of letters tachistoscopically presented in the right visual hemifield. In the first experimental night eye movements were permitted, while in the second subjects were allowed only covert movements of attention while keeping their gaze on a fixation point. Results show that, as a consequence of the experimental manipulation, there is an increase of REM duration and a shortening of REM latency without any concomitant significant change in REM density and in the duration and latency of the other sleep stages. The increase of REM duration was greater in the night in which only attentional "movements" were permitted (i.e., when there is a covert orienting of attention), suggesting that a load of spatial attention might have a role in increasing REM pressure.

Adult↗

PubMed1994

Prevalent direction of reflective lateral eye movements and ear asymmetries in a dichotic test of musical chords.

Subjects who consistently move their gaze either to the right or to the left while reflecting on visuo-spatial or verbal questions are usually called "lateral eye movers". This study evaluated auditory asymmetries to a dichotic test of musical chords in 23 right-handed females, selected through test-retest as reliable lateral eye movers; 12 were "left movers" (LMs) and 11 were "right movers" (RMs). During the assessment of the prevalent direction of gaze as well as during the dichotic test, the oculomotor activity was controlled through a video camera. The hypothesis was that the left ear advantage usually found with dichotic chords is enhanced in LMs and reduced in RMs, and that this effect is not due to the facilitating influence of lateral eye movements occurring during the task. Results show that: (a) left movers exhibit a marked advantage of the left ear while right movers do not exhibit any significant ear advantage; (b) despite the instruction to fix a central point, lateral movers tend to show unwarranted eye movements in their usual direction; (c) the effect of the prevalent direction of gaze on the dichotic advantage is not due to eye movements made during the dichotic test. These findings give further support to the hypothesis that the tendency to consistently shift the gaze to one side is related to hemispheric asymmetries as measured by lateralized tests.

Adult↗

PubMed1992

Reliability of a handedness performance test in right and left handed children: a research note.

A 25-item handedness performance test was administered twice, at a one-month interval, to 85 elementary school children (60 right handers and 25 left handers in two different age groups). The laterality quotient distribution for right handers was more skewed and significantly different in central tendency and shape than the left handers' distribution. Mean point-biserial item-test correlation was 0.85. The test-retest correlation coefficient for the whole group was 0.79.

Child↗

PubMed1988

Reflective lateral eye movements: individual styles, cognitive and lateralization effects.

The direction of gaze shifts following verbal and spatial questions was recorded by direct observation in two separate sessions in 80 right-handed Ss. Ocular events were stable over the sessions, and some Ss were classified reliably as lateral, vertical or bidirectional eye movers. No effect for type of question was found in lateral direction either in the general sample or in the bidirectional sample. Verbal questions elicited more downward movements than spatial questions. Less eye movements were found for spatial and for easy questions. These findings suggest a link between ocular motility and cognition independent of the lateralization issue.

Adult↗