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[Display omitted] • Persons with CP underwent MEG during an arrow-based Flanker task. • Reaction time was used to assess motor performance. • Cognitive interference of cortical oscillations moderated the reaction time. • Changes in cortical oscillations reflects top-down control over motor system in CP. Emerging evidence indicates that aberrations in sensorimotor cortical oscillations likely play a key role in uncharacteristic motor actions seen in cerebral palsy. This interpretation is largely centered on the assumption that the aberrant cortical oscillations primarily reflect the motor aspects, with less consideration of possible higher-order cognitive connections. To directly probe this view, we examined the impact of cognitive interference on the sensorimotor cortical oscillations seen in persons with cerebral palsy using magnetoencephalography. Persons with cerebral palsy (N = 26, 9–47 years old) and controls (N = 46, 11–49 years) underwent magnetoencephalographic imaging while completing an arrow-based version of the Eriksen flanker task. Structural equation modeling was used to evaluate the relationship between the extent of interference generated by the flanker task and the strength of the sensorimotor cortical oscillations and motor performance. Our results indicated that the impact of cognitive interference on beta and gamma oscillations moderated the interference effect on reaction times in persons with cerebral palsy, above and beyond that seen in controls. Overall, these findings suggest that alterations in sensorimotor oscillatory activity in those with cerebral palsy at least partly reflects top-down control influences on the motor system. Thus, suppression of distracting stimuli should be a consideration when evaluating altered motor actions in cerebral palsy. [ABSTRACT FROM AUTHOR]

• Learning of a complex motor skill was evaluated using archery training as a model. • EEG was recorded during three training sessions. • Lateralization shifts in the theta, alpha and beta band were evaluated in source space. • Theta shift to the left (dominant) hemisphere were significantly related to performance improvement. • Effects were observed especially in fronto-parietal areas. An intrinsic characteristic of the motor system is the preference of one side of the body. Lateralization is found in motor behavior and in the structural and functional correlates of cortical motor networks. While genetic factors have been elucidated as mechanisms leading to such asymmetries, findings in motor learning and experience from clinical experience demonstrate considerable additional plasticity during the lifespan. If and how functional lateralization develops in short timeframes during training of motor skills involving both sides of the body is still largely unclear. In the present exploratory study, we investigate lateralization of theta-, alpha- and beta-band oscillations during training of an ecologically valid skill – archery. We relate lateralization shift to performance improvement and elucidate the underlying cortical areas. To this end, healthy participants without any previous experience in archery underwent intensive training with 100 shots on each of three days. 64-channel electroencephalography was recorded simultaneously during the individual shots. We found that a central-parietal theta lateralization shift to the left immediately before the shot was associated with performance improvement. Lateralization of alpha or beta did not yield a significant association. Importantly, areas of maximum activation were not identical with areas showing the strongest associations with performance improvement. These data suggest that learning a complex bimanual motor skill is associated with a shift of theta-band oscillations to the left in central-parietal areas. The relationship with performance improvement may reflect increased cortical efficiency of task-relevant processing. [ABSTRACT FROM AUTHOR]

• Online beta-tACS impaired phonological task accuracy relative to sham stimulation. • There was no significant difference between online alpha- and beta-tACS. • Beta-tACS caused significantly stronger eye flickering sensations. • There are no correlations between eye flickering sensations and number of errors. • The inclusion of a control frequency is crucial to test for frequency specificity. The left posterior inferior frontal gyrus in the prefrontal cortex is a key region for phonological aspects of language processing. A previous study has shown that alpha-tACS over the prefrontal cortex applied before task processing facilitated phonological decision-making and increased task-related theta power. However, it is unclear how alpha-tACS affects phonological processing when applied directly during the task. Moreover, the frequency specificity of this effect is also unclear since the majority of neurostimulation studies tested a single frequency only. The present study addressed the question whether and how 10 Hz online tACS affects phonological decisions. To this end, 24 healthy participants received tACS at 10 Hz or 16.18 Hz (control frequency) or sham stimulation over the left prefrontal cortex during task processing in three sessions. As an unexpected finding, 16.18 Hz significantly impaired task accuracy relative to sham stimulation, without affecting response speed. There was no significant difference in phonological task performance between 10 Hz and 16.18 Hz tACS or between 10 Hz and sham stimulation. Our results support the functional relevance of the left prefrontal cortex for phonological decisions and suggest that online beta-tACS may modulate language comprehension. [ABSTRACT FROM AUTHOR]

• The organization of resting state EEG networks dynamically fluctuates in a frequency-specific way. • The interplay of local and global information processing efficiency fluctuates frequency-specific. • Frequency-specific network characteristics in resting state are important to consider. Functional connectivity in EEG resting-state is not stable but fluctuates considerably. The aim of this study was to investigate how efficient information flows through a network, i.e. how resting-state EEG networks are organized and whether this organization it also subject to fluctuations. Differences of the network organization (small-worldness), degree of clustered connectivity, and path length as an indicator of how information is integrated into the network across time was compared between theta, alpha and beta bands. We show robust differences in network organization (small-worldness) between frequency bands. Fluctuations in network organization were larger in the theta, compared to the alpha and beta frequency. Variation in network organization and not the frequency of fluctuations differs between frequency bands. Furthermore, the degree of clustered connectivity and its modulation across time is the same across frequency bands, but the path length revealed the same modulatory pattern as the small-world metric. It is therefore the interplay of local processing efficiency and global information processing efficiency in the brain that fluctuates in a frequency-specific way. Properties of how information can be integrated is subject to fluctuations in a frequency-specific way in the resting-state. The possible relevance of these resting-state EEG properties is discussed including its clinical relevance. [ABSTRACT FROM AUTHOR]

It is well established that the primary motor cortex (M1) plays a significant role in motor learning in healthy humans. It is unclear, however, whether mechanisms of motor learning include M1 oscillatory activity. In this study, we aimed to test whether M1 oscillations, entrained by transcranial Alternating Current Stimulation (tACS) at motor resonant frequencies, have any effect on motor acquisition and retention during a rapid learning task, as assessed by kinematic analysis. We also tested whether the stimulation influenced the corticospinal excitability changes after motor learning. Sixteen healthy subjects were enrolled in the study. Participants performed the motor learning task in three experimental conditions: sham-tACS (baseline), β-tACS and γ-tACS. Corticospinal excitability was assessed with single-pulse TMS before the motor learning task and 5, 15, and 30 min thereafter. Motor retention was tested 30 min after the motor learning task. During training, acceleration of the practiced movement improved in the baseline condition and the enhanced performance was retained when tested 30 min later. The β-tACS delivered during training inhibited the acquisition of the motor learning task. Conversely, the γ-tACS slightly improved the acceleration of the practiced movement during training but it reduced motor retention. At the end of training, corticospinal excitability had similarly increased in the three sessions. The results are compatible with the hypothesis that entrainment of the two major motor resonant rhythms through tACS over M1 has different effects on motor learning in healthy humans. The effects, however, were unrelated to corticospinal excitability changes. • β-tACS delivered during training inhibits the acquisition of a motor learning task. • γ-tACS slightly improved the acceleration of the practiced movement during training. • Neither β nor γ tACS influenced practice-related corticospinal excitability changes. • The effects of tACS on motor behavior were unrelated to corticospinal excitability changes. [ABSTRACT FROM AUTHOR]

Oscillatory activity is a prominent characteristic of the olfactory system. We previously demonstrated that beta and gamma oscillations occurrence in the olfactory bulb (OB) is modulated by the physical properties of the odorant. However, it remains unknown whether such odor-related modulation of oscillatory patterns is maintained in the piriform cortex (PC) and whether those patterns are similar between the anterior PC (aPC) and posterior PC (pPC). The present study was designed to analyze how different odorant molecular features can affect the local field potential (LFP) oscillatory signals in both the aPC and the pPC in anesthetized rats. As reported in the OB, three oscillatory patterns were observed: standard pattern (gamma + beta), gamma-only and beta-only patterns. These patterns occurred with significantly different probabilities in the two PC areas. We observed that odor identity has a strong influence on the probability of occurrence of LFP beta and gamma oscillatory activity in the aPC. Thus, some odor coding mechanisms observed in the OB are retained in the aPC. By contrast, probability of occurrence of different oscillatory patterns is homogeneous in the pPC with beta-only pattern being the most prevalent one for all the different odor families. Overall, our results confirmed the functional heterogeneity of the PC with its anterior part tightly coupled with the OB and mainly encoding odorant features whereas its posterior part activity is not correlated with odorant features but probably more involved in associative and multi-sensory encoding functions. • Odor-evoked oscillatory patterns in anterior vs. posterior piriform cortex significantly differ. • Odor-evoked oscillatory patterns correlate with odorant molecular features in anterior but not in posterior piriform cortex. • Data strengthen the hypothesis of functional piriform cortex heterogeneity along its antero-posterior axis. [ABSTRACT FROM AUTHOR]

Highlights • Motor learning capacity significantly increased after 70-Hz tACS. • Endogenous oscillatory beta activities were modulated after 70-Hz tACS. • Changes in beta activity and improvement in motor learning were correlated. • 70-Hz tACS may increase motor learning capacity by modulating beta activity. Abstract Motor function can be modulated by transcranial alternating current stimulation (tACS) in alpha, beta, and high-gamma frequencies. However, few studies have investigated tACS-induced behavioral changes in combination with endogenous oscillatory neural activity in detail. Herein, we investigated the effect of tACS on motor learning capacity and endogenous oscillatory neural activity. Fifty-two healthy volunteers were randomly assigned to four stimulation groups (10 Hz, 20 Hz, 70 Hz, or sham) and performed a visually cued button press motor learning task before and after tACS, which was delivered at the left primary motor area. Oscillatory neural activities during the motor learning task were measured using magnetoencephalography (MEG). Following tACS, the capacity for motor learning was significantly increased for 70 Hz tACS compared to sham stimulation. Oscillation analysis revealed a significant increase in beta-band power after 70-Hz tACS but not in the other stimulation groups. Our finding that capacity for motor learning and endogenous oscillatory beta activity were modulated in parallel after 70-Hz tACS suggests that 70-Hz tACS may increase the motor learning capacity by cross-modulating beta oscillatory activity. Because high gamma and beta oscillatory activity have been shown to reflect the activity of excitatory and inhibitory interneuron, our results may derive from the modulation of excitatory and inhibitory interneurons in M1 by 70-Hz tACS. [ABSTRACT FROM AUTHOR]

Down syndrome (DS) results from the triplication of genes located on human chromosome 21 (Hsa21). Though many cognitive and behavioral impairments are associated with DS, sleep disturbances remain poorly understood despite being a reported phenotype in approximately 60% of individuals diagnosed with DS. In this study, sleep and electroencephalography (EEG) oscillations were recorded from aged (12–14 mos.) Dp(16)1Yey/+ mice (Dp16), a mouse model of DS. We observed disrupted sleep demonstrated by increased activity during the dark phase and increased time awake at the expense of NREM sleep compared to wild-type mice. In addition, we found that Dp16 mice display significant differences in relative EEG power distribution among oscillation frequencies in both sleep and awake states. These results in Dp16 mice are consistent with sleep disturbances found in individuals with DS, and the abnormal EEG oscillations in aged Dp16 mice suggest a potential role for GABAergic activity in these sleep and EEG abnormalities. These sleep and EEG data reflect underlying differences in neuronal activity at the network level and thus are causative agents rather than merely symptoms of DS. [ABSTRACT FROM AUTHOR]

Numerous clinical investigations have reported that children with cerebral palsy (CP) have tactile discrimination deficits that likely limit their ability to plan and manipulate objects. Despite this clinical awareness, we still have a substantial knowledge gap in our understanding of the neurological basis for these tactile discrimination deficits. Previously, we have shown that children with CP have aberrant theta–alpha (4–14 Hz) oscillations in the somatosensory cortices following tactile stimulation of the foot. In this investigation, we evaluated if these aberrant theta–alpha oscillations also extend to the hand. Magnetoencephalography was used to evaluate event-related changes in the theta–alpha and beta (18–34 Hz) somatosensory cortical oscillations in groups of children with CP and typically developing (TD) children following tactile stimulation of their hands. Our results showed that the somatosensory theta–alpha oscillations were relatively intact in children with CP, which is in contrast to our previous results for foot tactile stimulations. We suspect that these inter-study differences may be related to the higher probability that the neural tracts serving the lower extremities are damaged in children with CP, compared to those serving the upper extremities. This inference is plausible since the participating children with CP had Manual Ability Classification System (MACS) levels between I and II. In contrast to the theta–alpha results, children with CP did exhibit a sharp increase in beta activity during the same time period, which was not observed in TD children. This suggests that children with CP still have deficits in the computational aspect of somatosensory processing. [ABSTRACT FROM AUTHOR]

Abstract: The importance and diversity of calcium signaling in the brain is mirrored by the expression of a multitude of voltage-activated calcium channel (CaV) isoforms. Whereas the overall distributions of α1 subunits are well established, the expression patterns of distinct channel isoforms in specific brain regions and neurons, as well as those of the auxiliary β and α2δ subunits are still incompletely characterized. Further it is unknown whether neuronal differentiation and activity induce changes of CaV subunit composition. Here we combined absolute and relative quantitative TaqMan reverse transcription PCR (RT-PCR) to analyze mRNA expression of all high voltage-activated CaV α1 subunits and all β and α2δ subunits. This allowed for the first time the direct comparison of complete CaV expression profiles of mouse cortex, hippocampus, cerebellum, and cultured hippocampal neurons. All brain regions expressed characteristic profiles of the full set of isoforms, except CaV1.1 and CaV1.4. In cortex development was accompanied by a general down regulation of α1 and α2δ subunits and a shift from β1/β3 to β2/β4. The most abundant CaV isoforms in cerebellum were CaV2.1, β4, and α2δ-2, and in hippocampus CaV2.3, β2, and α2δ-1. Interestingly, cultured hippocampal neurons also expressed the same CaV complement as adult hippocampus. During differentiation specific CaV isoforms experienced up- or down-regulation; however blocking electrical activity did not affect CaV expression patterns. Correlation analysis of α1, β and α2δ subunit expression throughout all examined preparations revealed a strong preference of CaV2.1 for β4 and α2δ-2 and vice versa, whereas the other α1 isoforms were non-selectively expressed together with each of the other β and α2δ isoforms. Together our results revealed a remarkably stable overall Ca2+ channel complement as well as tissue specific differences in expression levels. Developmental changes are likely determined by an intrinsic program and not regulated by changes in neuronal activity. [Copyright &y& Elsevier]

Abstract: This laboratory, using post-mitotic rat brain neurons as a model system, has been testing the hypothesis that the inherited DNA repair potential would have profound influence on the aging process of the individual. It has been found that both single and double strand breaks in DNA accumulate in neurons with age. Since base excision repair (BER) is the pathway to effect repair of the type of DNA damage that is likely to occur in neurons, model oligo duplexes were used to assess the BER pathway. Both extension of a primer and one or four nucleotide gap repair are markedly reduced in aging neurons as compared with the young. The extension activity could be restored by supplementing the neuronal extracts with pure DNA polymerase β (pol β) while the restoration of gap repair needed the addition of both pol β and DNA ligase. It thus appears that both pol β and DNA ligase are deficient in aging neurons. We have also established a system to study the non-homologous end joining (NHEJ) mode of DNA repair in neurons. The end joining of cohesive but not of blunt or non-matching ends, is reduced with age and attempts to identify the limiting factor(s) in this case have been unsuccessful so far. These results are reviewed vis-à-vis the existing literature. [Copyright &y& Elsevier]