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An auditory novelty-oddball task, which is known to evoke a P3 event-related potential (ERP) in a target condition and a novelty-P3 ERP in response to task-irrelevant unique environmental sounds, was repeatedly applied to healthy participants (n=14) on two separate recording sessions, 7 days apart. Both target-P3 and novelty-P3 were internally consistent and test–retest reliable. Interestingly, novelty-P3 amplitude declined from the first to the second half of each recording session, whereas no systematic alteration between both sessions occurred. The target-P3 showed the opposite pattern, i.e. a reduced amplitude from the first to the second session, but no systematic change within each session. These findings suggest that novelty-P3 amplitude changes reflect habituation, whereas target-P3 session effects may indicate the adjusted amount of processing resources invested into the task. In general, the results support the interpretation of the novelty-P3 as indicating automatic, bottom–up related aspects of attention, whereas the target-P3, in the present paradigm, seems to reflect voluntary, top–down related aspects of attention. [Copyright &y& Elsevier]

Postlingually deaf Cochlear Implant (CI) users show better lip reading skills compared to normal hearing individuals even after several years of CI experience. A neuronal component of this enhanced performance could be cortical cross-modal reorganization of the auditory cortex. A higher auditory cortex activity in response to visual stimuli in CI users has been related to better face recognition as well as enhanced lip reading performance. On the other hand, a residual pattern of cross-modal cortical reorganization in experienced CI users may limit auditory speech perception. To what extend these changes are deprivation-induced or related to sensory recovery is still debated. Evidence for a deprivation-induced onset of reorganization comes from recent studies with individuals showing only a moderate hearing loss. However, the amount of sensory deprivation that is required for the initiation of cortical reorganization remains poorly understood. Investigations with normal hearing, moderately and severely hearing-impaired individuals (CI users) are therefore needed to better understand the role of cross-modal reorganization for auditory rehabilitation. [ABSTRACT FROM AUTHOR]

Background Motor imagery (MI) training, in particular in combination with EEG-based neurofeedback (MI-NF), has been suggested as a potential add-on therapy for rehabilitation of upper limb motor impairments after stroke. Most MI-NF implementations are based on the event-related desynchronization (ERD) in the 8–30 Hz frequency range that is typically observed over sensorimotor areas during motor execution and imagination. The amplitude and consistency of the ERD depends, among other things, on brain structure and function during motor imagery (e.g., Halder et al., 2013; Zich et al., 2015 ). Because the vast majority of the research on MI-NF has been conducted with young healthy individuals, it is unclear to what degree changes regarding the relationship between MI-induced ERD, MI-induced functional magnetic resonance imaging (fMRI) activation and brain structure in stroke patients are due to normal aging and the stroke, respectively. Objectives (1) to investigate in healthy older adults (>45 years) associations of MI-induced ERD, MI-induced fMRI activation and diffusion tensor imaging (DTI) measures, and (2) to investigate differences in these measures between chronic stroke patients and healthy older adults matched for age and gender. Methods We included 12 chronic stroke patients with residual upper limb motor impairment (mean age 61.5 years – range 49–75 years; 3 females) and 17 healthy older adults (mean age 60.4 years – range 48–77 years; 9 females). All participants completed a 3T MRI session and a 96-electrode EEG session. The MRI session included a high-resolution anatomical scan, DTI, and fMRI during rest, motor execution and kinesthetic MI of repeated hand opening and closing. The EEG session consisted of three blocks: motor execution, kinesthetic MI and kinesthetic MI with real-time EEG-based visual feedback, all with the same hand movement as during fMRI. Each patient also completed a motor assessment consisting of the upper limb section of the Fugl-Mayer Assessment and the Modified Ashworth Scale. Results We will present preliminary results regarding the correlations of ERD and fMRI activation related to motor execution and imagination. Moreover, we will present the results of a replication of the analysis of Halder et al. (2013) that for young healthy adults indicated a significant association between MI-induced ERD and white matter integrity (fractional anisotropy) in subcortical structures. [ABSTRACT FROM AUTHOR]

Motor imagery (MI) supported by neurofeedback has been suggested as a promising add-on therapy to facilitate motor recovery after stroke. Though the main target group for such an intervention are elderly patients, research so far is largely focused on young, healthy adults. We therefore examined in two experiments the influence of age on the neural correlates of motor imagery (MI) in a real-time electroencephalogram (EEG) neurofeedback framework. In a first experiment MI-induced activity was studied in MI and neurofeedback naïve young ( N = 39; 18–30 years) and elderly ( N = 36; >55 years) healthy adults. MI was supported by EEG feedback, and feedback was based on features extracted from the mu and beta frequency bands. Electromyogram (EMG) data were recorded concurrently to control for executed movements. During MI the group of older participants was characterized by a significantly reduced lateralization of EEG event-related desynchronization (ERD), mainly due to stronger ipsilateral ERD, and, in consequence, reduced classification accuracies. EEG-based neurofeedback resulted in a task-related activity increase irrespective of age. Aim of the second experiment was to replicate and validate these results. To this end, EEG was combined with simultaneous functional near-infrared spectroscopy (fNIRS). MI-induced activity was studied in a new sample of MI and neurofeedback naïve young ( N = 19; 18–30 years) and elderly ( N = 18; >55 years) healthy adults. As before, MI was supported by EEG feedback based on features extracted from mu and beta frequency bands and EMG data were recorded concurrently to control for executed movements. The observation of a reduced lateralization due to stronger ipsilateral ERD could be replicated. Furthermore, fNIRS deoxygenated haemoglobin concentration changes confirmed this less lateralized pattern in the elderly. For both age groups the EEG-based neurofeedback resulted in a task-related increase in ERD and fNIRS activity. The reduction of lateralized brain activity during MI in the elderly is in good agreement with previous research showing similar age-related changes during MI and other cognitive tasks. This finding is in line with the general view that compensatory processes are recruited to counteract neurodegenerative changes during healthy ageing. However, these age-related changes did not compromise the responsiveness to neurofeedback. We therefore conclude that the potential benefit of a neurofeedback supported modulation of brain activity is preserved in the elderly. [ABSTRACT FROM AUTHOR]

Background. Spontaneous very low frequency oscillations (VLFO: <0.2 Hz) in functional magnetic-resonance imaging are proposed to identify a default-mode network of resting brain activity. Activity in this network has been related to lapses of attention during goal-directed tasks and may provide a basis for ADHD. This study assessed the relation between scalp-recorded EEG VLFO at rest and ADHD. Methods. 13 young adults with high- and 11 with low self-ratings of ADHD participated. Direct current EEG was recorded during a five minute rest session and was retested after approximately 1 week. Results. A consistent and temporally stable pattern of VLFOs was observed across specific scalp regions in low-ADHD participants. High-ADHD participants had less VLFO power across these locations, especially where inattention self-ratings were high. Inattention was not related to VLFO power in other locations. Discussion. Initial evidence is provided for a pattern of VLFOs at rest which is associated with inattention symptoms. [ABSTRACT FROM AUTHOR]

Mental training, including motor observation and motor imagery, has awakened much academic interest. The presumed functional equivalence of motor imagery and motor execution has given hope that mental training could be used for motor rehabilitation after a stroke. Results obtained from randomized controlled trials have shown mixed results. Approximately half of the studies demonstrate positive effects of motor imagery training but the rest do not show an additional benefit. Possible reasons why motor imagery training has so far not become established as a robust therapeutic approach are discussed in detail. Moreover, more recent approaches, such as neurofeedback-based motor imagery or closed-loop systems are presented and the potential importance for motor learning and rehabilitation after a stroke is discussed. [ABSTRACT FROM AUTHOR]

Objectives: The goal of this study was to investigate the effects of auditory deprivation (untreated hearing loss) and auditory stimulation (treated hearing loss) on different levels of speech processing using behavioral and electrophysiological measures. Material and methods: A between-groups design with three groups of older participants was used: (1) participants with a pure-tone average hearing loss of <25 dB HL from 500 to 4000 Hz, (2) participants with mild-to-moderately- severe sensorineural hearing loss but no hearing aid experience, and (3) participants with mild-to-moderately-severe sensorineural hearing loss and at least 2 years of hearing aid experience. In terms of behavioral measurements, speech detection thresholds (SDT), speech recognition thresholds (SRT), and speech comprehension scores (SCS) were measured. In terms of electrophysiological measurements (EEG), speech evoked N100, P300, N400 and Late Positive Complex (LPC) responses were measured. The N100 and P300 responses were evoked using an active oddball paradigm, while the N400 and LPC responses were evoked using audio-visual (bimodal) and audio-only (unimodal) test paradigms. All measurements were performed in the free field in the presence of stationary speech-shaped noise. All hearing-impaired participants were fitted with hearing aids to ensure audibility. Results: Regarding the behavioral measurements, the SDT are expected to be similar across the three groups, while for the SRT and SCS the group with untreated hearing loss is expected to show poorer results. Regarding the electrophysiological measurements, the N100 responses are expected to be similar across the three groups, while for the P300, N400 and LPC responses the group with untreated hearing loss is expected to show smaller amplitudes. No group differences in terms of mean latencies are expected. Conclusions: The hypothesized group differences in the behavioral and electrophysiological measures of discrimination and comprehension would be indicative of changes in cortical speech processing due to (lack of) hearing aid treatment. [ABSTRACT FROM AUTHOR]

Objective This study characterized thalamo-cortical communication by assessing the effect of context-dependent modulation on the very early somatosensory evoked high-frequency oscillations (HF oscillations). Methods We applied electrical stimuli to the median nerve together with an auditory oddball paradigm, presenting standard and deviant target tones representing differential cognitive contexts to the constantly repeated electrical stimulation. Median nerve stimulation without auditory stimulation served as unimodal control. Results A model consisting of one subcortical (near thalamus) and two cortical (Brodmann areas 1 and 3b) dipolar sources explained the measured HF oscillations. Both at subcortical and the cortical levels HF oscillations were significantly smaller during bimodal (somatosensory plus auditory) than unimodal (somatosensory only) stimulation. A delay differential equation model was developed to investigate interactions within the 3-node thalamo-cortical network. Importantly, a significant change in the eigenfrequency of Brodmann area 3b was related to the context-dependent modulation, while there was no change in the network coupling. Conclusion This model strongly suggests cortico-thalamic feedback from both cortical Brodmann areas 1 and 3b to the thalamus. With the 3-node network model, thalamo-cortical feedback could be described. Significance Frequency encoding plays an important role in contextual modulation in the somatosensory thalamo-cortical network. [ABSTRACT FROM AUTHOR]

Interpersonal behavioral synchrony is defined as the temporal coordination of action between two or more individuals. Humans tend to synchronize their movements during repetitive movement tasks such as walking. Mobile EEG technology now allows us to examine how this happens during gait. 18 participants equipped with foot accelerometers and mobile EEG walked with an experimenter in three conditions: With their view of the experimenter blocked, walking naturally, and trying to synchronize their steps with the experimenter. The experimenter walked following a headphone metronome to keep their steps consistent for all conditions. Step behavior and synchronization between the experimenter and participant were compared between conditions. Additionally, event-related spectral perturbations (ERSPs) were time-warped to the gait cycle in order to analyze alpha-mu (7.5-12.5 Hz) and beta (16-32 Hz) rhythms over the whole gait cycle. Step synchronization was significantly higher in the synchrony condition than in the natural condition. Likewise regarding ERSPs, right parietal channel (C4, C6, CP4, CP6) alpha-mu and central channel (C1, Cz, C2) beta power were suppressed from baseline in the walking synchrony condition compared to the natural walking condition. The natural and blocked conditions were not found to be significantly different in behavioral or spectral comparisons. Our results are compatible with the view that intentional synchronization employs systems associated with social interaction as well as the central motor system. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: To date, the anesthesia-induced blockade of nociceptive inputs is insufficiently reflected by commercially available electroencephalographic depth-of-anesthesia monitors. The aim of the current study was to evaluate the potential of somatosensory (SSEP) and intracutaneous pain evoked (iSEP) potentials during remifentanil and propofol anesthesia as electroencephalographic indicators of the nociceptive blockade. METHODS: Ten healthy men were investigated in a double-blind crossover design during three sessions with remifentanil, propofol, and placebo administration. All dosages were increased in a step-by-step mode. SSEP and iSEP recordings were performed followed by subjective pain ratings and measurement of level of sedation (modified Observer's Assessment of Alertness and Sedation Scale). Changes from baseline in evoked potential components, pain ratings, and sedation scale were assessed by Bonferroni-Holms-corrected Wilcoxon tests. RESULTS: Pain ratings were significantly reduced by remifentanil. Sedation scale was significantly reduced by propofol. Early SSEP components were not affected by medication. The amplitudes of the long latency SSEP components increased significantly with remifentanil, decreased with propofol, and did not change with placebo. The amplitudes of long latency components of the iSEP decreased significantly with both remifentanil and propofol and did not change with placebo. CONCLUSION: Long latency components of the SSEP are differently affected by remifentanil and propofol administration. Further studies are needed to clarify whether they can serve as a specific indicator of the nociceptive blockade during anesthesia. [ABSTRACT FROM AUTHOR]

Chronic hemiparesis of an upper limp following stroke has been related to an over-involvement of the ipsilateral hemisphere that inhibits use of the affected limb. Interventions helping to shift back this altered lateralization have been suggested to positively affect upper limp functional recovery. One such intervention is the combination of motor imagery (MI) supported by EEG neurofeedback. However, cortical reorganization requires highly intensive practice. In this feasibility study this was achieved by implementing a mobile EEG neurofeedback system. The training regime consisted of 14 MI sessions over a time course of 4 weeks. Three chronic stroke patients practiced MI neurofeedback using kinaesthetic imagination of a power grip of either the affected or the unaffected hand. Neurofeedback was based on features extracted from the 8-30 Hz frequency range. MI training was conducted at the patients’ home using a fully mobile 24-channel EEG system. Before and after the training, motor functions were assessed using a modified version of the Fugl-Meyer Assessment (FMA) and the modified Motor Assessment Scale (MAS). Moreover, pre- and post-training 96-channel EEG recordings were performed for MI and movement execution (ME) of the power grip task that was used for the MI neurofeedback training. Event-related desynchronization (ERD) in the 8–30 Hz frequency range was extracted offline for a region of interest analysis. Analysis focused on contra- and ipsilateral ERD and on the lateralization of ERD, defined as the difference between contralateral and ipsilateral ERD. All patients remained motivated throughout the training and completed the training regime. During MI and ME with the unaffected hand, patients showed stronger contralateral than ipsilateral activity in both the pre- and the post-training sessions. For the affected hand, MI and ME were however associated with stronger ipsilateral than contralateral activity. Changes were observed over the course of training, that, on a descriptive level, suggest a reduction of the altered lateralization for the affected hand in all three patients during MI. Furthermore, for one patient a significant improvement in the FMA score was observed, which paralleled the changes in MI and ME induced ERD. This study demonstrates that home-based MI neurofeedback training is feasible and allows for highly intensive training regimes. The observations made are in line with the notion of an over-involvement of the ipsilateral hemisphere during activities of the affected limb. The described changes of lateralization with MI neurofeedback training encourage continuing this line of research with larger sample sizes and matched healthy controls, to see if home-based MI neurofeedback training can indeed help to shift MI- and ME-related activation towards the expected lateralization patterns. [ABSTRACT FROM AUTHOR]