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BackgroundA newly developed fetal movement acceleration measurement recorder has made it possible to count gross movements for hours. The purpose of this study was to determine the normal reference values for such movements.MethodsOne hundred and six pregnant women recorded fetal movements by themselves when they slept at home weekly from 28 weeks to term. The normal reference values were determined based on the data that could be recorded for more than 4 h per night.ResultsA total of 2,458 h of data from 385 recordings from 64 women was available. The median ratio of 10-s periods in which fetal movements occurred to the total time interval was 17% at 28 gestational weeks, decreasing to ∼6% at term. The number of fetal movements was 74 times/h, decreasing to 29 times at term. The number, the mean, and the longest durations of periods with no fetal movement, meaning no fetal movements were found for more than 5 min, were 1.56 times/h, 7.95 and 14.25 min, respectively, at 28 weeks, and increasing to 2.54 times, and 9.63 and 19.67 min, respectively, at term.ConclusionsThis study provides normal reference values for gross fetal movement count using the fetal movement acceleration measurement recorder.

To study brain mechanisms of memory scan, we have measured event-related potentials (ERPs) during the execution of a Sternberg task concerned with movement directions of random dot patterns (RDPs). Five healthy male subjects participated in the experiment. Event-related potentials were recorded at 20 electrode positions over the entire head. A prominent positive ERP component peaking at 380–390 ms known as P300 was observed in the parietal region after the presentation of the probe moving random dot pattern, whereas the P300 was not observed after the presentation of a control stationary RDP. On the other hand, a positive ERP component peaking at 127 ms was commonly observed in the occipital region after the presentation of both moving and control stationary RDPs. These findings suggest that P300 may reflect cortical activities related to the memory scan of movement directions of RDP.

STUDY OBJECTIVES Cyclic alternating pattern (CAP) is frequently followed by changes in heart rate (HR) and blood pressure (BP), but the sequential associations between CAP and autonomic nerve activity have not been studied. The study aimed to reveal the precise changes in heart rate variability (HRV) during phase A of the CAP cycle. DESIGN Polysomnography was recorded according to the CAP Atlas (Terzano, 2002), and BP and electrocardiogram were simultaneously recorded. The complex demodulation method was used for analysis of HRV and evaluation of autonomic nerve activity. SETTING Academic sleep laboratory. PARTICIPANTS Ten healthy males. MEASUREMENTS AND RESULTS The increase in HR (median [first quartile - third quartile]) for each subtype was as follows: A1, 0.64 (-0.30 to 1.69), A2, 1.44 (0.02 to 3.79), and A3, 6.24 (2.53 to 10.76) bpm (A1 vs. A2 P < 0.001, A1 vs. A3 P < 0.001, A2 vs. A3 P < 0.001). The increase in BP for each subtype was as follows: A1, 1.23 (-2.04 to 5.75), A2, 1.76 (-1.46 to 9.32), and A3, 12.51 (4.75 to 19.94) mm Hg (A1 vs. A2 P = 0.249, A1 vs. A3 P < 0.001, A2 vs. A3 P < 0.001). In all of phase A, the peak values for HR and BP appeared at 4.2 (3.5 to 5.4) and 8.4 (7.0 to 10.3) seconds, respectively, after the onset of phase A. The area under the curve for low-frequency and high-frequency amplitude significantly increased after the onset of CAP phase A (P < 0.001) and was higher in the order of subtype A3, A2, and A1 (P < 0.001). CONCLUSIONS All phase A subtypes were accompanied with increased heart rate variability, and the largest heart rate variability was seen in subtype A3, while a tendency for less heart rate variability was seen in subtype A1.

Background The gender-specific influences of various confounding factors, including apnea, age, BMI, and cigarette consumption, on the function of the parasympathetic nerve system (PNS) during sleep in OSA patients has never been investigated. Methods One hundred ninety-seven males and 63 females with OSA were subjected to full PSG examinations including assessment of R-R intervals (RRIs) during an overnight ECG. The PNS-derived modulatory effect on the RRIs and the variability of this effect were quantified during REM and NREM using instantaneous time-frequency analysis with complex demodulation. The spectral domain with the maximum instantaneous amplitude in the high-frequency band between 0.15 and 0.4 Hz was defined as the main HF peak and used as a surrogate marker of PNS discharge. Based on density-spectrum-array maps of the main HF peaks (HF-DSA map), shifts in the central frequency of the main HF peak over time were continuously observed. When the main HF peaks on the HF-DSA maps maintained the same central frequency for more than 20 sec or 5 min, the PNS functions were considered to be “stable” or “very stable”, respectively. Results Apneas enhanced PNS-derived cardiac-modulation during REM in males, but more importantly, they made PNS-function unstable during both REM and NREM in males and during NREM in females. Aging blunted the PNS-derived cardiac-modulation during both REM and NREM regardless of gender, but aging had no impact on the stability of PNS-function. BMI blunted PNS-eliciting cardiac-modulation during REM in males and during NREM in both males and females. BMI made the PNS unstable during REM in females. Neither height nor cigarette consumption influenced any PNS-related parameter. Conclusions The PNS-derived cardiac-modulation was generally inhibited by aging and obesity, in which the effect of obesity was gender-specific. The PNS instability at nighttime was mainly induced by apneas but by obesity particularly during REM in females.

Kappa-rhythm appears at the highest amplitude on a bipolar T3-T4 derivation and its frequency range is 7-10 Hz. When a contra-lateral earlobe is used as a reference, the kappa-rhythm causes serious problems in assessing drowsiness. Assessment of drowsiness using contra- and ipsi-lateral earlobes as references in 129 subjects who showed kappa-rhythm was compared. Drowsiness could be assessed properly in only 26% of subjects using the contra-lateral earlobe and in 90% of subjects using the ipsi-lateral earlobe. These results suggest that the ear on the ipsi-lateral earlobe should be used as a reference in subjects who show kappa-rhythm.