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Background A compelling hypothesis about attention-deficit/hyperactivity disorder (ADHD) etiopathogenesis is that the ADHD phenotype reflects a delay in cortical maturation. Slow-wave activity (SWA) of non-rapid eye movement (NREM) sleep electroencephalogram (EEG) is an electrophysiological index of sleep intensity reflecting cortical maturation. Available data on ADHD and SWA are conflicting, and developmental differences, or the effect of pharmacological treatment, are relatively unknown. Methods We examined, in samples (M age = 16.4, SD  = 1.2), of ever-medicated adolescents at risk for ADHD (n = 18; 72% boys), medication-naïve adolescents at risk for ADHD (n = 15, 67% boys), and adolescents not at risk for ADHD (n = 31, 61% boys) matched for chronological age and controlling for non-ADHD pharmacotherapy, whether ADHD pharmacotherapy modulates the association between NREM SWA and ADHD risk in home sleep. Results Findings indicated medication-naïve adolescents at risk for ADHD exhibited greater first sleep cycle and entire night NREM SWA than both ever-medicated adolescents at risk for ADHD and adolescents not at risk for ADHD and no difference between ever-medicated, at-risk adolescents, and not at-risk adolescents. Conclusions Results support atypical cortical maturation in medication-naïve adolescents at risk for ADHD that appears to be normalized by ADHD pharmacotherapy in ever-medicated adolescents at risk for ADHD. Greater NREM SWA may reflect a compensatory mechanism in middle-later adolescents at risk for ADHD that normalizes an earlier occurring developmental delay. [ABSTRACT FROM AUTHOR]

Sleep spindles are major oscillatory components of Non‐Rapid Eye Movement (NREM) sleep, reflecting hyperpolarization‐rebound sequences of thalamocortical neurons. Reports suggest a link between sleep spindles and several forms of high‐frequency oscillations which are considered as expressions of pathological off‐line neural plasticity in the central nervous system. Here we investigated the relationship between thalamic sleep spindles and ripples in the anterior and mediodorsal nuclei (ANT and MD) of epilepsy patients. Whole‐night LFP from the ANT and MD were co‐registered with scalp EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing a Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles were present in the human ANT and MD and roughly, 20% of them were associated with ripples. Ripple‐associated thalamic sleep spindles were characterized by longer duration and exceeded pure spindles in terms of spindle power as indicated by time‐frequency analysis. Furthermore, ripple amplitude was modulated by the phase of sleep spindles within both thalamic nuclei. No signs of pathological processes were correlated with measures of ripple and spindle association, furthermore, the density of ripple‐associated sleep spindles in the ANT showed a positive correlation with verbal comprehension. Our findings indicate the involvement of the human thalamus in coalescent spindle‐ripple oscillations of NREM sleep. Significance Statement: Thalamo‐cortical loops are associated with sensory processing, memory formation and executive functions, many of which are tightly related to sleep state‐dependent neural oscillations, such as sleep spindles. It was proposed that sleep‐related epileptic transformation of normal neurological networks interferes with sleep‐related synaptic homeostasis, neural plasticity and cognitive functioning. We had a unique opportunity to investigate the association between thalamic sleep spindles and ripples, and their associations with intellectual ability within two higher‐order thalamic nuclei in human subjects, the anterior thalamic and mediodorsal thalamic nuclei. Our findings indicate the involvement of the human thalamus in sleep‐spindle‐related activity. [ABSTRACT FROM AUTHOR]

Summary: Homeostatic and circadian processes play a pivotal role in determining sleep structure, timing, and quality. In sharp contrast with the wide accessibility of the electroencephalogram (EEG) index of sleep homeostasis, an electrophysiological measure of the circadian modulation of sleep is still unavailable. Evidence suggests that sleep‐spindle frequencies decelerate during biological night. In order to test the feasibility of measuring this marker in common polysomnographic protocols, the Budapest‐Munich database of sleep records (N = 251 healthy subjects, 122 females, age range: 4–69 years), as well as an afternoon nap sleep record database (N = 112 healthy subjects, 30 females, age range: 18–30 years) were analysed by the individual adjustment method of sleep‐spindle analysis. Slow and fast sleep‐spindle frequencies were characterised by U‐shaped overnight dynamics, with highest values in the first and the fourth‐to‐fifth sleep cycle and the lowest values in the middle of the sleeping period (cycles two to three). Age‐related attenuation of sleep‐spindle deceleration was evident. Estimated phases of the nadirs in sleep‐spindle frequencies were advanced in children as compared to other age groups. Additionally, nap sleep spindles were faster than night sleep spindles (0.57 and 0.39 Hz difference for slow and fast types, respectively). The fine frequency resolution analysis of sleep spindles is a feasible method of measuring the assumed circadian modulation of sleep. Moreover, age‐related attenuation of circadian sleep modulation might be measurable by assessing the overnight dynamics in sleep‐spindle frequency. Phase of the minimal sleep‐spindle frequency is a putative biomarker of chronotype. [ABSTRACT FROM AUTHOR]

People with normal hearing can usually follow one of the several concurrent speakers. Speech tempo affects both the separation of concurrent speech streams and information extraction from them. The current study varied the tempo of two concurrent speech streams to investigate these processes in a multi‐talker situation. Listeners performed a target‐detection and a content‐tracking task, while target‐related ERPs and functional brain networks sensitive to speech tempo were extracted from the EEG signal. At slower than normal speech tempo, building the two streams required longer processing times, and possibly the utilization of higher‐order, for example, syntactic and semantic cues. The observed longer reaction times and higher connectivity strength in a theta band network associated with frontal control over auditory/speech processing are compatible with this notion. With increasing tempo, target detection performance decreased and the N2b and the P3b amplitudes increased. These data suggest an increased need for strictly allocating target‐detection‐related resources at higher tempo. This was also reflected by the observed increase in the strength of gamma‐band networks within and between frontal, temporal, and cingular areas. At the fastest tested speech tempo, there was a sharp drop in recognition memory performance, while target detection performance increased compared to the normal speech tempo. This was accompanied by a significant increase in the strength of a low alpha network associated with the suppression of task‐irrelevant speech. These results suggest that participants prioritized the immediate target detection task over the continuous content tracking, likely due to some capacity limit reached the fastest speech tempo. Our results add a new perspective on extracting and storing information from a target speech stream in the presence of a concurrent speech. Behavioral, ERP, and functional connectivity data from the current study showed that speech processing is affected by the tempo of speech in a multi‐talker situation. At slower speech tempos segregating the two speech streams and selection of the target stream required more processing capacity/effort, whereas, at higher speech tempos, processes related to target detection and the suppression of information interfering with this task became prominent. [ABSTRACT FROM AUTHOR]

Although atypical theta and alpha activity may be biomarkers of attention-deficit/hyperactivity disorder (ADHD) outcomes such as atypical affective processing and attention, the exact nature of the relations of these characteristics is unknown. We examined in age- and sex-matched adolescents ( N = 132; M age = 14.944, years, SD = .802) with and without ADHD, whether resting state (RS) theta and alpha power or theta and alpha event-related synchronization (ERS) during affect regulation (1) differ between adolescents with and without ADHD; (2) are differentially associated with event-related potential (ERP) and parent- and self-report measures of affective processing and inattention, given ADHD status and sex, and (3) are differentially lateralized, given ADHD status and sex. Adolescents with ADHD exhibited lower RS frontal-midline alpha power than adolescents without ADHD. In adolescents with ADHD, right parietal theta ERS was positively associated with the ERP measure of elaborate affective/motivational processing and right parietal RS alpha power was negatively associated with self-reported positive affectivity. In adolescents without ADHD, associations were nonsignificant. There was no disassociation of theta and alpha activity with affective processing and inattention. Consistent with clinical impressions, the between-group difference in frontal-midline theta ERS was more marked in boys than girls.