Resting and Initial Beta Amplitudes Predict Learning Ability in Beta/Theta Ratio Neurofeedback Training in Healthy Young Adults.

Neurofeedback (NF) training has been proved beneficial in cognitive and behavioral performance improvement in healthy individuals. Unfortunately, the NF learning ability shows large individual difference and in a number of NF studies there are even some non-learners who cannot successfully self-regulate their brain activity by NF. This study aimed to find out the neurophysiological predictor of the learning ability in up-regulating beta-1 (15-18 Hz)/theta (4-7 Hz) ratio (BTR) training in healthy young adults. Eighteen volunteers finished five training sessions in successive 5 days. We found that low beta (12-15 Hz) amplitude in a 1-min eyes-open resting baseline measured before training and the beta-1 amplitude in the first training block with 4.5-min duration could predict the BTR learning ability across sessions. The results provide a low cost, convenient and easy way to predict the learning ability in up-regulating BTR training, and would be helpful in avoiding potential frustration and adjusting training protocol for the participants with poor learning ability.

Dynamic peripheral visual performance relates to alpha activity in soccer players.

Many studies have demonstrated the relationship between the alpha activity and the central visual ability, in which the visual ability is usually assessed through static stimuli. Besides static circumstance, however in the real environment there are often dynamic changes and the peripheral visual ability in a dynamic environment (i.e., dynamic peripheral visual ability) is important for all people. So far, no work has reported whether there is a relationship between the dynamic peripheral visual ability and the alpha activity. Thus, the objective of this study was to investigate their relationship. Sixty-two soccer players performed a newly designed peripheral vision task in which the visual stimuli were dynamic, while their EEG signals were recorded from Cz, O1, and O2 locations. The relationship between the dynamic peripheral visual performance and the alpha activity was examined by the percentage-bend correlation test. The results indicated no significant correlation between the dynamic peripheral visual performance and the alpha amplitudes in the eyes-open and eyes-closed resting condition. However, it was not the case for the alpha activity during the peripheral vision task: the dynamic peripheral visual performance showed significant positive inter-individual correlations with the amplitudes in the alpha band (8-12 Hz) and the individual alpha band (IAB) during the peripheral vision task. A potential application of this finding is to improve the dynamic peripheral visual performance by up-regulating alpha activity using neuromodulation techniques.

The cyclic alternating pattern demonstrates increased sleep instability and correlates with fatigue and sleepiness in adults with upper airway resistance syndrome.

OBJECTIVE: To clarify the relationship between sleep instability and subjective complaints in patients with upper airway resistance syndrome (UARS). METHODS: Thirty subjects (15 women) with UARS and 30 age- and sex-matched controls in a prospective, single-blind, case-control study. Blinded cyclic alternating pattern (CAP) electroencephalogram analysis and scales of fatigue and sleepiness were completed. ANALYSIS: Mann-Whitney U tests for independent, nonparametric variables between groups and chi2 tests for nonparametric variables with defined standard values. RESULTS: Patients with UARS had significantly more complaints of fatigue and sleepiness, compared with controls, demonstrated on their Fatigue Severity Scale (P < 0.001) and Epworth Sleepiness Scale (P < 0.001). By design, the mean apnea-hypopnea index was normal in both groups, whereas the respiratory disturbance index was greater in patients with UARS than in those without (14.5 +/- 3.0 vs 9 +/- 5.2, respectively [P < 0.001]). CAP analysis demonstrated abnormal non-rapid eye movement sleep with abnormally increased CAP rate, electroencephalogram arousals, A2 index, and A3 index. Decreased A1 index in controls was consistent with their more normal progression of sleep. CAP rate correlated with both the Epworth Sleepiness Scale (r = 0.38, P < 0.01) and the Fatigue Severity Scale (r = 0.51, P < 0.0001), and there was a positive trend between the Fatigue Severity Scale and phase A2 index (r = 0.29, P < 0.05). CONCLUSION: Compared with age- and sex-matched controls, patients with UARS have higher electroencephalogram arousal indexes and important non-rapid eye movement sleep disturbances that correlate with subjective symptoms of sleepiness and fatigue. These disturbances are identifiable with sensitive measures such as CAP analysis but not with traditional diagnostic scoring systems.

Sleepwalking, a disorder of NREM sleep instability.

BACKGROUND AND PURPOSE: Thirty-two chronic sleepwalkers who were part of a larger, previously reported sleepwalking group all achieved control of sleepwalking after undergoing treatment for an associated sleep disorder. In the current study, all records were blindly scored to perform a cyclic alternating pattern (CAP) analysis. PATIENTS AND METHODS: Thirty-two young adult chronic sleepwalkers had polysomnography (PSG) on initial nights without sleepwalking events, as did age-matched normal controls and patients with mild sleep-disordered breathing (SDB). More than 90% of these patients with mild SDB had upper airway resistance syndrome (UARS). Ten randomly selected PSGs for sleepwalkers and matched controls also had quantitative electroencephalographic (EEG) analysis using Fast Fourier Transformation (FFT) with determination of delta power for each non-rapid eye movement (NREM)-REM sleep cycle. RESULTS: Compared to normal controls, an investigation of CAP in sleepwalkers demonstrated the presence of an abnormal CAP rate with a decrease in phase A1 and an increase in phases A2 and A3 on non-sleepwalking nights. The results of CAP analysis in sleepwalkers were similar to those obtained in age-matched UARS patients. Furthermore, the analysis of the first four NREM-REM sleep cycles reconfirmed the presence of an important decrease in delta power in sleep cycles 1 and 2 during a non-sleepwalking night in sleepwalkers compared to normal controls. CONCLUSIONS: The presence of both 'hypersynchronous slow delta' and 'burst of delta waves' have been reported in sleepwalkers, but their significance is controversial. These EEG patterns are similar to phase A1 (and possibly A2) of the CAP. Proper analysis of the sleep EEG of sleepwalkers should integrate CAP analysis. Sleepwalkers on a non-sleepwalking night present instability of NREM sleep, as demonstrated by this analysis. This instability is similar to the one noted in UARS patients. Subtle sleep disorders associated with chronic sleepwalking constitute the unstable NREM sleep background on which sleepwalking events occur. A subtle associated sleep disorder should be systematically searched for and treated in the presence of sleepwalking with abnormal CAP.

Non-REM-sleep instability in recurrent sleepwalking in pre-pubertal children.

BACKGROUND AND PURPOSE: We questioned whether or not the sleep of pre-pubertal children with recurrent sleepwalking was different from that recorded in normal children. PATIENTS AND METHODS: Twelve pre-pubertal chronic sleepwalkers were compared to age- and gender-matched normal children. All children had a clinical evaluation covering pediatric, sleep, neuropsychiatric and otolaryngological fields. Two standardized sleep questionnaires were administered, and a minimum of two successive polysomnograms were performed with monitoring of sleep electroencephalographic (EEG) and cardiorespiratory variables. The research investigations were performed on nights without sleepwalking to search for the presence of other sleep disorders, including upper airway resistance syndrome (UARS). Sleep was scored using standard atlases, but it was also evaluated for the cyclic alternating pattern (CAP) rate. RESULTS: All sleepwalkers presented with either obstructive sleep apnea (n=2) or UARS (n=10). Compared to normal children, sleepwalkers had shorter total sleep time but no significant change in wake after sleep onset when considering all arousals > 3 s. CAP analysis showed a significantly higher CAP rate than in controls. CONCLUSIONS: Chronic sleepwalkers have instability of non-rapid eye movement (NREM) sleep detectable only by the calculation of CAP rate. Instability of NREM sleep was seen even on nights without sleepwalking and is probably related to the presence of the associated sleep disorders. We hypothesize that chronic NREM-sleep instability is a risk factor for occurrence of sleepwalking when further sleep disruption is triggered by external events.