Showing papers on "Delta wave published in 2003"

Communication between neocortex and hippocampus during sleep in rodents

Abstract: Both neocortical and hippocampal networks organize the firing patterns of their neurons by prominent oscillations during sleep, but the functional role of these rhythms is not well understood. Here, we show a robust correlation of neuronal discharges between the somatosensory cortex and hippocampus on both slow and fine time scales in the mouse and rat. Neuronal bursts in deep cortical layers, associated with sleep spindles and delta waves/slow rhythm, effectively triggered hippocampal discharges related to fast (ripple) oscillations. We hypothesize that oscillation-mediated temporal links coordinate specific information transfer between neocortical and hippocampal cell assemblies. Such a neocortical–hippocampal interplay may be important for memory consolidation.

Prefrontal cortex: links between low frequency delta EEG in sleep and neuropsychological performance in healthy, older people.

Abstract: Low frequency (< 1 Hz) delta EEG in sleep is of increasing interest as it indicates cortical reorganization, especially in the prefrontal cortex (PFC). Other research shows that delta power in sleep is positively linked to waking cerebral metabolic rate. Such findings suggest that < 1 Hz activity may reflect waking performance at neuropsychological tests specific to the PFC. We investigated this unexplored area. Sleep EEGs (Fp1-F3, Fp2-F4, O1-P3, O2-P4) were recorded in 24 healthy 61-75-year-olds. We found significant associations between 0.5-1.0 Hz power from the left frontal EEG channel, in the first non-REM period, and performance at tasks more specific to the left PFC (e.g., nonverbal planning and verbal fluency). This association was absent from the posterior channels. Neither age nor response times were confounding factors. This potential sleep EEG marker for PFC neuropsychological function in healthy, older people also points to further uses of the sleep EEG in understanding the role of sleep.

Sleep and circadian rhythm disturbances in patients with delayed sleep phase syndrome.

Abstract: Study objectives The objective of this study was to clarify sleep characteristics and pathophysiology in patients with delayed sleep phase syndrome (DSPS), which is a major circadian rhythm sleep disorder subtype. Design Polysomnography was performed for 2 consecutive nights and core body temperature was sampled for 7 consecutive days, including the polysomnography study period, in all subjects. Findings were compared and statistically analyzed between patients with DSPS and matched controls. Setting Sleep disorders unit in National Center Hospital. Participants 11 DSPS patients and 11 age-matched healthy volunteers. Interventions N/A. Measurements and results Sleep latency, total sleep time, wakefulness after sleep-onset, and the amount and percentage of Stage 1 sleep were greater in DSPS patients than in volunteers. Sleep efficiency and the amount and percentage of slow wave sleep were lower in DSPS patients than in volunteers. Compared with the healthy volunteers, DSPS patients showed a decreased number and different temporal distribution of high-voltage and low-frequency delta waves. The time of minimum body temperature appeared earlier in the sleep phase for the patients than for the volunteers. Significant correlation was found between the amount of slow wave sleep and the time from sleep onset to minimum body temperature and between the amount and percentage of slow wave sleep and time from minimum body temperature to sleep offset. Conclusions Disturbances were found in the sleep structure of patients with DSPS, and these disturbances were related to the discrepancy between patients and controls in the phase relationship difference between sleep and core body temperature rhythms.

EEG patterns in 10 extreme premature neonates with normal neurological outcome: qualitative and quantitative data.

Abstract: The aim of this prospective study was to describe and quantify EEG patterns in 10 very premature infants (24 weeks 2 days– 26 weeks 4 days GA) without neonatal neurological pathology and with a normal outcome at 3 years of age for nine of them. EEG and eye movements were recorded in the first 5 days of life. All tracings were discontinuous; EEG inactivity ( 50 μV and to 197 s when >15 μV. High voltage delta waves (0.5 Hz; up to 330 μV), either smooth or superimposed with 7–12 Hz rhythms, were the most typical and frequent figures, mainly in temporal (mean number 257.2±73.3) and occipital (237.7±65.8 per hour recording) areas. In temporal areas, they appeared mainly in clusters; more often unilateral than bilateral (P<0.05). Occipital delta waves were as often bilateral and synchronous as unilateral. The two distinct frontal delta waves were significantly less numerous than other delta waves (P<0.05). Bursts of hypersynchronous high voltage delta waves and of diffuse sharp theta waves were less numerous than other waves (P<0.01). Considering periods with or without eye movements, the mean percentage and the mean longest period of EEG activity (≤50 μV) were significantly greater (P<0.01) when eye movements were present, indicating a rough sleep state differentiation as early as 25 weeks CA. These EEG patterns are qualitatively and quantitatively reproducible. They constitute standards of normality and a basis for the determination of neurological prognosis.

Amplitude spectral analysis of maturational changes of delta waves in preterm infants.

Abstract: The aim of this study is to clarify the usefulness of amplitude spectral analysis for an evaluation of maturational changes of delta activities in preterm infants. We chose each ten healthy infants without complications who were 29–30, 31–32, and 33–34 weeks of post-conceptional age (PCA) at electroencephalogram (EEG) recordings. Fast Fourier transform algorithm was applied for amplitude spectral analysis. The analyzed data were divided into four frequency bands; D1 0.53–1, D2 1–2, D3 2–3, and D4 3–4 Hz. The average amplitude of six segments with high voltage slow waves was calculated in each frequency band. A significant reduction of the amplitude along with PCA was present in all leads in D1 band. On the other hand, a significant negative correlation with PCA was observed only in the occipital leads in D2, D3 or D4 bands. In conclusion, maturational EEG changes assessed by amplitude spectral analysis were prominent in the occipital areas, and in the frequency less than 1 Hz.

EEG patterns in 10 extreme premature neonates with normal neurological outcome: qualitative and quantitative data

Abstract: The aim of this prospective study was to describe and quantify EEG patterns in 10 very premature infants (24 weeks 2 days– 26 weeks 4 days GA) without neonatal neurological pathology and with a normal outcome at 3 years of age for nine of them. EEG and eye movements were recorded in the first 5 days of life. All tracings were discontinuous; EEG inactivity (, 15 mV) never exceeded 1 min, representing 45.3% of total recording time. The EEG bursts, mainly synchronous, could last up to 83 s when . 50 mV and to 197 s when . 15 mV. High voltage delta waves (0.5 Hz; up to 330 mV), either smooth or superimposed with 7 – 12 Hz rhythms, were the most typical and frequent figures, mainly in temporal (mean number 257.2 ^ 73.3) and occipital (237.7 ^ 65.8 per hour recording) areas. In temporal areas, they appeared mainly in clusters; more often unilateral than bilateral (P , 0:05). Occipital delta waves were as often bilateral and synchronous as unilateral. The two distinct frontal delta waves were significantly less numerous than other delta waves (P , 0:05). Bursts of hypersynchronous high voltage delta waves and of diffuse sharp theta waves were less numerous than other waves (P , 0:01). Considering periods with or without eye movements, the mean percentage and the mean longest period of EEG activity (#50 mV) were significantly greater (P , 0:01) when eye movements were present, indicating a rough sleep state differentiation as early as 25 weeks CA. These EEG patterns are qualitatively and quantitatively reproducible. They constitute standards of normality and a basis for the determination of neurological prognosis. q 2003 Elsevier Science B.V. All rights reserved.