1,721,063 research outputs found
REDUCTION OF OCULAR MOTILITY FOLLOWING VISUOSPATIAL QUESTIONS - A TEST OF THE VISUAL INTERFERENCE HYPOTHESIS
No full textStudies in which lateral eye movements (LEMs) were used as
indices of differential hemispheric activation during cognitive
processing have found a greater proportion of ‘stares’ following
visuo-spatial questions than following verbal questions.
This phenomenon was explained by a visual interference
hypothesis (VIH): assuming that solving spatial questions involves
visual imagery, and that visual stimuli may interfere
with internally generated visual images, interference can be
limited by suppressing eye movements (EMS). No support to
the VIH came from investigations predicting a greater proportion
of stares in visually enriched environments. However
assuming that the ‘gating out’ of visual inputs during the
processing ofvisuo-spatial questions is a well-established habit,
experimental manipulation of the visual environment may be
ineffective in modifying the rate of stares. Based on the VIH,
we tested a different prediction: instances in which spatial
questions are followed by an EM should be characterized by
longer reflection latencies (RL).
Data from 32 female Ss. tested in a LEMs experiment
confirmed that RLs for spatial questions followed by an EM
are significantly longer CM= 10.33”) than those followed by
stares (M = 6.34”). Since this could be due to the fact that
EMS might have a greater probability of occurring in longer
time intervals, analysis was repeated with a 2” cut off for
EMS. The effect of interference was confirmed, RL for questions
followed by an EM being equal to 8.05” and for those
followed by stares being equal to 5.10”.
Further analyses for verbal questions will reveal whether
the interference effect is specific to visuo-spatial processing
La direzione dei movimenti oculari come indice di asimmetrie emisferiche durante il sonno REM.
No full textThe hypothesis of right hemisphere predominance in REM sleep and of an increase in left activity throughout the night have been tested by analyzing the distribution of vertical and of horizontal rapid eye movements (REMs) to the right and to the left during the first and the last REM periods in 5 right-handed subjects. Neither the expected superiority of REMs to the left nor variations along the REM periods were found. For vertical eye movements our data suggest a superiority of upward movements during REM. In waking some empirical evidences suggest a relationship between upward eye movements and right hemisphere functioning although to date no hemispheric model can explain it
Quality of sleep and P300 amplitude in primary insomniacs
No full textThe hyperarousal hypothesis of primary insomnia (e.g. [1]) yelded controversial results (e.g. [2]) which could depend on the weakness of the assumption which consider insomniac’s high arousal level as a stable individual characteristic. Since there is a wide variability in bad and good nights of sleep, a low arousal level could be present following the good nights of sleep. This view is consistent with results of a recent study that showed higher P300 amplitude in insomniacs only following a bad night [3]. The aim of the present study is to replicate previous results and to extend the finding, recording also a presleep measure of cortical arousal.
Methods: seven primary insomniacs and seven healthy age matched controls took part in the study for 1 week, during which they were actigraphically monitored. At their homes, each day, before and after sleep, subjects filled in a questionnaire diary and their P300 ERP (oddball paradigm) was recorded through portable equipment (Evo-Quick, Micromed, Italy). For each subject diary and actigraphic data were used for identifying the worse (N–) and the best (N+) sleep quality night in the week. N– was defined as the night with the lowest Sleep Efficiency Index and the N+ the one with the highest SEI. The mean amplitudes of the P300 from FZ, CZ and PZ were submitted to a MANOVA considering NIGHT (N– vs. N+), GROUP (insomniacs vs. controls) and TIME of day (presleep vs. postsleep) as factors. As a control, means of sleep parameters (i.e. SOL, WASO and SEI) of the selected nights were submitted to different factorial ANOVAs with NIGHT and GROUP as factors.
Results: MANOVA On P300 amplitude shows a significant GROUP X NIGHT interaction [R Rao (3.10) = 4.56; <0.0293]. Post hoc LSD Test indicates that in insomniacs P300 amplitude recorded from FZ is significantly higher (P < 0.05) compared to controls, but this difference is shown only with the occurrence of the N–, independently by the TIME of day. Control ANOVAs on sleep parameters showed significant NIGHT effects indicating that IES is significantly lower (F1.10 = 6.79; P < 0.05) and WASO is significantly higher (F1.10 = 12.12; P < 0.01) in the N– compared to the N+. Conclusion: Insomniacs showed a higher cortical arousal with respect to controls but only with the occurrence of a bad night of sleep. These results agree with the previous study and are consistent with the hyperarousal hypothesis but confirm that the level of cortical arousal is also related to the quality of sleep. Hyperarousal is not a stable trait in primary insoniacs but varies as a function of sleep quality.
References
[1] Bonnet, M.H., Arand, D.L. Hyperarousal and insomnia. Sleep Med. Rev., 1997, 1: 97–108.
[2] Lichstein, L., Wilson, N., Noe, S., Aguillard, R., Bellur, S. Daytime sleepiness in Insomnia: behavioral, biological and subjective indices. Sleep, 1994, 17: 693–702.
[3] Devoto, A., Violani, C., Lucidi, F:, Lombardo, C. P300 amplitude in subjects with primary insomnia is modulated by their sleep quality. J. Psyc. Res., 2003, 54: 3–10
Proposed synonymy of Sylvia cantillans moltonii Orlando, 1937, with Sylvia cantillans subalpina Temminck, 1820
No full textVolume: 127Start Page: 107End Page: 11
ULTRADIAN VARIATIONS IN A LATERALIZED LETTERS RECOGNITION AND POINTS ENUMERATION TASK - NON-STATIONARITY, STABILITY AND INDIVIDUAL-DIFFERENCES
No full textIntroduction
Broughton (1975) hypothesized that the 90 minute
Basic Rest Activity Cycle (BRAC) is associated with
an alternation in the relative efficiency of the cerebral
hemispheres. Investigations testing daytime ultradian
rhythms in cognitive performance with non-lateralized
verbal and spatial tasks (Klein and Armitage, 1979;
Kripke, Fleck, Mullaney dz Levy, 1983 ; Armitage,
Moffitt, Hoffman & Pigeau, 1985) yielded contrasting
results.
In order to have a more direct evaluation of hemispheric
functioning, the present study assessed performance
in a letters recognition (LR) and in points
enumeration (PE) task, in which stimuli were laterally
presented to the left and to the right visual hemifields
(LVHF and RHVF) (Bertini, Violani, Zoccolotti, Altomare,
Doricchi & Evangelisti, 1985). Furthermore
morning V.S. afternoon statiomniety, stability of ultradian
variations in two different days and modulating
effects by individual characteristics were assessed.
Methods
Ten right-handed subjects (5 males and 5 females),
were individually tested on the two lateralized tasks
(LR and PE) in a soundproof chamber at 15’ intervals
from 10.00 am to 6.00 p.m. The same procedure was
repeated the following day. For each day of each
subject 8 hour time series of lateralized performance
scores in LR and PE tasks were constructed and
submitted to power spectra analysis centered at 48,24,
16..6 cycles/day (c/d) frequenciesIn order to evaluate
morning-afternoon stationariety each time series was
divided in two 4 hour series.
Results
Anovas were carried out on power spectra of the
performance scores for each task in each hemifield. In
order to assess the significance of the variance explained
by the ultradian frequencies, the power spectra
at the BRAC frequency (16 c/d, corresponding to a 90
minute period) at the two adjacent frequencies (12 c/d
and 24 c/d) and the mean power at all other frequencies
considered, were computed andconsidered as levels of
the factor “Frequency”. Three-way 2x2x4 (SEX x
SESSION x FREQUENCY) anovas failed to reveal
any main effect or interactions involving the factor
“FREQUENCY”. Four-way 2x2x2x4 (SEX x SESSION
x PART OF DAY x FREQUENCY) on power
spectra of the 4h. time series revealed a significant
PART OF DAY x FREQUENCY interaction F(3,24)=
4.68; p=.Oll for LVHF performance in the LR task,
indicating that, in the morning, power was greater in
the 16 c/d band (a 90 minute period), while in the
afternoon it was greater in the 12 c/d band ( a 120
minute period). A significant SEX x PART OF DAY x
FREQUENCY interaction [F(3,24)=6.31; p=.OO2] was
found for RVHF in the PE task, indicating that only in
males there were more power in the 16 c/d band in the
morning and in the 12 c/d band during the afternoon.
Anovas including “group factor” based on mean individual
differences in Morning-Evening Type, EPI
neuroticism, sleep quality and dream recall assessed on
a 7 days morning diary, failed to show any modulating
effects on the power spectra.
Conclusion
Considering the entire 8 hour time series no ultradian
16 c/d (a 90 minute period) rhythm was found in
cognitive performances in lateralized verbal and spatial
tasks. But considering the part of day (momingafternoon),
a significant 16 c/d rhythm was shown in
the morning. This phenomenon concerns the nondominant
hemisphere for verbal functions in the LR
task and, at least for males, the non-dominant hemisphere
for spatial functions in the PE task. This
ultradian rhythm is stable over two successive experimental
sessions and doe
Sleep and migraine: an actigraphic study
No full textThe aim of the study was to evaluate sleep of children with migraine during the interictal period and the modifications of sleep which precede, are concomitant with, or follow migraine attacks. Eighteen patients with migraine without aura were compared with a group of 17 healthy age-matched children. Sleep parameters were monitored for two full weeks by means of actigraphs and self-report diaries. Headache diaries were also filled out in order to evaluate the occurrence and the characteristics of migraine attacks. Fifty-seven attacks were recorded during the monitoring period. During the interictal period, sleep parameters of children suffering from migraine did not differ from those of controls; only sleep onset latency was slightly prolonged in the migraine group. Timing of the attack affected nocturnal motor activity which presented the lowest values on the night preceding the attack, indicating a decrease in cortical activation during sleep preceding migraine attacks. Further studies should clarify if the observed reduction in nocturnal motor activity close to the attack is related to neurotransmitter imbalance
- …
