Biomedical subjects

S Niemcewicz

Publications and source records attributed to S Niemcewicz.

6 recordsLinked to original sources

PubMed2001

Event-related current density in primary insomnia.

Using Low Resolution Electromagnetic Tomography (LORETA), event-related current density was investigated in 14 patients with primary insomnia and 14 controls matched for age, gender and education level. All subjects were rated on the Athens Insomnia Scale, the Hyperarousal Scale, the Hamilton Depression Rating Scale and the Beck Depression Inventory. They also completed the Selective Reminding Test and the Continuous Attention Test. Only minor elevations on depression scales were found in patients. The Continuous Attention Test did not reveal any between group differences. However, insomniacs required more trials before all the Selective Reminding Test items were learned. Insomniacs showed less event-related current density in orbitofrontal, medial prefrontal and anterior cingulate cortex, i.e. brain regions of relevance for cognition and affect. Earliest group differences appeared in the P1 time range and then were observed at the N1, N2 and P3 stages of stimulus processing. These stimulus processing differences correlated most consistently with severity of insomnia. Neuropsychological impairment correlated most strongly with less current density in Brodmann area 10.

Adult↗

PubMed2000

Severity of insomnia correlates with cognitive impairment.

INTRODUCTION AND METHODS: Cognitive deficits in insomnia have been already reported (5), however, a correlation between cognitive impairment and severity of insomnia was not as yet studied. Sixteen not medicated patients with primary insomnia according to DSM-IV (4), 7 men an 9 women, of mean age 40.8 year, were compared to 16 controls, matched according to age, sex and education. Standard polysomnographic data (PSG) were recorded. The next day all the subjects completed Athens Insomnia Scale (AIS) (7), Hyperarousal Scale (HS) (6), Hamilton Depression Rating Scale (HAM-D), Beck Depression Inventory (BDI), Multiple Sleep Latency Test (MSLT) (3), Continuous Attention Test (CAT) with simple reaction time (RT) (8) and Selective Reminding Test (SRT) (2). RESULTS AND DISCUSSION: The psychophysiological differences between patients and controls are shown in Table I. HAM-D and BDI scores were elevated in patients, although none of the patients met clinical criteria of depression. Insomniacs did not differ in the immediate recall, but the number of repetitions necessary to learn all the items of SRT was greater in patients. Insomniacs usually complain of poor performance, however, learning impairment has not been documented in insomnia. Degree of the learning impairment correlated with insomnia score (Fig. 1). Cognitive deficit cannot be due to a daytime sleepiness because sleep latency in all MSLT sessions was not shorter in insomniacs. No correlations between results of SRT and standard PSG parameters were found, in accordance with the thesis that subjective feeling of nonrestorative sleep and other accompanying deficits are only symptoms of an underlying 24-hour disorder (1).

Adult↗

PubMed1999

High resolution study of sleep spindles.

OBJECTIVE: Universal high-resolution time-frequency parameterization of sleep EEG structures. METHODS: A new algorithm called Matching Pursuit was used for the decomposition of sleep EEG into waveforms chosen from a large and redundant set of functions. As a result all signal structures were parameterized in terms of their frequency, time occurrence, time span and energy. Slow wave activity and sleep spindles were identified according to neurophysiological criteria and various distributions describing their time evolution, topographical and frequency characteristics were constructed. RESULTS: Two types of sleep spindles of different topological and spectral properties were identified. High time-frequency resolution made possible separation of superimposed spindles. Cross-correlation between high- and low-frequency components of superimposed spindles revealed a fixed time-delay between them, the high-frequency component preceding the low-frequency one. CONCLUSION: The results of our study suggest that processes of generation of both types of sleep spindles are weakly coupled.

Adult↗

PubMed1996

Analysis of complexity of EEG during sleep.

New multichannel descriptors of EEG activity: complexity (omega), total power (zeta) and generalized frequency (phi) were applied to whole night sleep analysis in 11 healthy subjects. The values of omega and phi decreased systematically from waking to slow wave sleep, and increased systematically in consecutive NREM-REM sleep cycles. The changes of zeta were opposite to omega and phi. These descriptors may be an alternative approach to the EEG sleep analysis.

Adult↗

PubMed1996

Interhemispheric differences of sleep EEG complexity.

Complexity of EEG (omega), a global measure reflecting degree of spatial synchronization, was computed for whole night recordings of sleep EEG of 10 healthy volunteers, 9 males and 1 female (age 21-53) and 6 depressive patients, 5 males and 1 female (age 23-64). Sleep was scored visually in 20 s epochs, omega was calculated in 2.5 s segments and the median from 8 segments (20 s) was calculated. omega was calculated for the whole field of 21 electrodes and for the left and right hemisphere separately (2 x 8 electrodes). Measure of global power (sigma) and generalized frequency (phi) were also computed for the same data. In healthy subjects the complexity was higher over the right hemisphere during waking, and the difference shifted to higher complexity over the left hemisphere in slow wave sleep (F = 5.15, df1 = 4, df2 = 6856, P < 0.0005). The opposite trend was found in depressives (F = 10.51, df1 = 4, df2 = 3960, P < 0.0001).

Adult↗

PubMedDate not supplied

[Psychophysiological correlates of primary insomnia].

Psychophysiological differences between 16 patients with primary insomnia, 7 men and 9 women, of mean age 40.8 years, and 16 controls, matched according to age, sex and education, were studied. Insomniacs differed from controls in the following results: their motor activity level was higher during night, sleep efficiency was lower and complexity in slow wave sleep was higher. The Hyperarousal Scale score was higher in insomniacs and it correlated with severity of insomnia in Athens Insomnia Scale. Sleep latency in MSLT was not shorter in patients group. Reaction time was shorter, moreover, the number of presentations necessary to memorize all items of Selective Reminding Test was greater in these patients. Degree of the learning disturbance correlated with the Athens Insomnia Scale score. No correlations were found between Selective Reminding Test and standard polysomnographic parameters. To sum up, the hypothesis on 24-hour hyperarousal in primary insomnia has been confirmed and learning impairment has been documented in the present study, independent of standard polysomnographic parameters.

Adult↗