Frontal Electrode Sites Research Articles

Cortical brain potentials in response to lower limb proprioceptive stimuli in young adults with probable developmental coordination disorder

BackgroundProprioceptive deficits have been shown to underlie motor problems in individuals with a probable developmental coordination disorder (pDCD). Behavioral studies have employed response times to passive limb movement to evaluate proprioceptive function in individuals with pDCD. However, the underlying neural mechanisms involved in the cortical processing of proprioceptive input and its corresponding motor response are unclear. To address this issue, this study aims to investigate neuropsychological and neurophysiological performances using event-related potentials (ERP) on proprioceptive-motor tasks in young adults with pDCD. MethodsFrom a total of 149 young adults screened using the Bruininks-Oseretsky Test of Motor Proficiency 2nd Edition Complete Form (BOT-2), 12 individuals with pDCD were identified (mean age ± SD: 20.50 ± 1.08 years) along with 12 age- and sex-matched controls (mean age ± SD: 20.75 ± 1.05 years). Participants placed their dominant foot on a passive ankle motion apparatus that plantarflexed the ankle at a constant velocity of 22°/s for a total of 75 trials in each proprioceptive condition. With vision occluded, participants had to press the trigger button held by the dominant hand when they sensed the passive motion of the ankle (voluntary response, VR), or purely receive the movement without a voluntary response (non-voluntary response, NVR). Behavioral performances [i.e., mean movement detection time (MDTmean), the standard deviation of the movement detection time (MDTSD)] and ERP indices (i.e., N1, P3 amplitude, and latency) related to ankle kinesthetic stimuli were obtained to determine the proprioceptive-motor function. ResultsThe results showed that young adults with pDCD exhibited longer MDTmean (p < 0.001) and MDTSD (p = 0.002) compared to their controls. Electrophysiological indices measured at frontal and central electrode sites, showed that young adults with pDCD exhibited significantly smaller N1 (p = 0.019) and P3 amplitudes (p = 0.032) during VR and NVR conditions. Notably, correlation analysis revealed a significant negative relationship between MDTmean and N1 (r = 0.62, p < 0.001) and P3 amplitudes (r = − 0.55, p = 0.005) in the VR condition in young adults with and without pDCD. ConclusionsThis study sheds light on the central brain mechanisms underlying proprioceptive-motor deficits in young adults with pDCD. The combined analysis of behavioral and ERP data suggests that longer MDTmean and larger MDTSD in young adults with pDCD are associated with weaker proprioceptive afferent inflow shown by decreased N1 amplitude to the frontal and parietal cortices. Such degraded proprioceptive signals are followed by reduced P3 amplitude, suggesting that young adults with pDCD allocate fewer neural resources to modulate motor processes with regard to proprioceptive stimuli. These findings contribute to a better understanding of the neurophysiological basis of proprioceptive-motor deficits in pDCD and may inform the development of targeted sensorimotor interventions.

Effects of Single-Session Practice Structure on Motor Skill Acquisition and Alpha and Beta EEG Oscillations

Background: Although it is known that practicing a motor skill updates the associated internal model, it is still unclear as to how cortical oscillations linked with the motor skill change under differing practice schedules. The current study investigated α- and β-power changes associated with motor skill acquisition. Objectives: Firstly, we investigated the behavioral effects of practice on motor learning and retention during repetitive (RP) and variable (VP) practice schedules on an anticipation timing task. Secondly, we investigated changes in cortical α (10 - 13 Hz) and β (15 - 30 Hz) event-related synchronization and desynchronization (ERS/ERD) under RP and VP during early (EP) and late (LP) stages of practice. Methods: To investigate the behavioral effects of practice on learning and retention, participants were pretested, post-tested at 5 min (retention), and tested twice at 30 min (one for longer retention, one for transfer to a novel velocity). To investigate electroencephalography (EEG) α and β power changes, data were collected from electrode sites T7, T8, C3, C4, CP3, CP4, FCz, AFz, and Pz. Results: Based on a 2 × 4 (practice group × test block) ANOVA, results indicated a significant learning effect for both group participants, with VP participants performing better on the 30-min transfer test. To investigate EEG α and β power changes, data were analyzed using separate, 2 × 2 repeated measures ANOVA (group [RP and VP] × practice trial blocks [EP and LP]). Power analyses revealed (1) attenuated α ERD at T7 (cognitive/verbal rehearsal), C3 (motor cortex), CP3, CP4, and FCz (pooled data representing premotor cortices), and AFz (frontal cortex and attentional processes) during LP, with greater changes observed in premotor activity (PMA), T7, and AFz electrode sites in RP participants. β frequency analysis, using beta modulation depth (BMD), revealed that participants in both groups had increased BMD at premotor, motor, and frontal electrode sites at LP, with RP participants exhibiting greater changes. Conclusions: Results are in accordance with previous research indicating that practicing under a VP schedule leads to superior motor skill transfer than practicing under an RP schedule. Moreover, lesser changes in α ERD along and lower BMD observed in VP participants might be responsible for a more adaptable and flexible motor program, allowing for greater skill retention and transfer in individuals practicing under VP conditions.

Inhibitory control deficits in patients with mesial temporal lobe epilepsy: an event-related potential analysis based on Go/NoGo task.

Neuropsychiatric comorbidities are common among patients with mesial temporal lobe epilepsy (MTLE). One of these comorbidities, impulsivity, can significantly impact the quality of life and prognosis. However, there have been few studies of impulsivity in these patients, and the existing findings are inconsistent. The present study investigates impulsivity in MTLE patients from the perspective of inhibitory control and its underlying processes using event-related potentials (ERPs) initiated using a Go/NoGo task. A total of 25 MTLE patients and 25 age-, gender-, and education-matched healthy controls (HCs) completed an unequal visual Go/NoGo task. Different waveforms as well as behavioral measures were analyzed between Go and NoGo conditions (N2d and P3d). Impulsivity was also assessed using self -rating scales, and clinical variables that may be related to ERPs were explored. Compared with HCs, MTLE patients exhibited significantly longer reaction time (RT) (p = 0.002) and lower P3d especially at the frontal electrode sites (p = 0.001). In the MTLE group, the seizure frequency (p = 0.045) and seizure types (p < 0.001) were correlated with the P3d amplitude. A self-rated impulsivity assessment revealed that MTLE patients had higher non-planning (p = 0.017) and total scores (p = 0.019) on the BIS-11 as well as higher DI (p = 0.010) and lower FI (p = 0.007) on the DII. The findings demonstrate that the presence of inhibitory control deficits in patients with MTLE are characterized by deficits in the late stage of inhibition control, namely the motor inhibition stage. This study improves our understanding of impulsivity in MTLE patients and suggests that ERPs may constitute a sensitive means of detecting this trait.

Immature event-related alpha dynamics in children compared with the young adults during inhibition shown by day-night stroop task.

Inhibitory control develops gradually from infancy to childhood and improves further during adolescence as the brain matures. Related previous studies showed the indispensable role of task-related alpha power during inhibition both in children and young adults. Nonetheless, none of the studies have been able to investigate the direct differences in brain responses between children and young adults when confronted with a stimulus that should be inhibited. Because, unlike event-related designs, task-related designs involve continuous tasks over a certain period, which precludes the possibility of making such a comparison. Accordingly, by employing event-related design, the present study first time in the literature, aimed to analyze the event-related alpha phase locking and event-related alpha synchronization/ desynchronization to differentiate the inhibitory processes in children compared to young adults. Twenty children between the ages of 6 to 7 years and 20 healthy young adult subjects between the ages of 18 to 30 years were included in the study. Day-night Stroop task was applied to all subjects during 18-channel EEG recordings. Event-related time-frequency analysis was performed with the complex Morlet Wavelet Transform for the alpha frequency band (8-13 Hz). Event related spectral perturbation (ERSP) in three different time windows (0-200 ms, 200-400 ms, 400-600 ms) and Event-related phase locking in the early time window (0-400 ms) was calculated. The children had increased alpha power in early and late time windows but decreased alpha phase locking in the early time windows compared to young adults. There were also topological differences between groups; while young adults had increased alpha phase-locking in frontal and parietal electrode sites, children had increased occipital alpha power and phase locking. The shift in event-related alpha power observed from posterior to anterior regions with age may suggest a progressive maturation of the frontal areas involved in inhibitory processes from childhood to adulthood. The results of the present study showed that children and young adults had different EEG oscillatory dynamics during inhibitory processes at alpha frequency range.

Electroencephalography spectral coherence analysis during cycle ergometry in low- and high-tolerant individuals.

The main objective of this study was to further understanding of the patterns of spectral connectivity during exercise in low- and high-tolerant individuals. Thirty-nine healthy individuals (i.e., 17 low- and 22 high-tolerant participants) took part in the present study. A state-of-the-art portable electroencephalography system was used to measure the brain's electrical activity during an incremental exercise test performed until the point of volitional exhaustion on a cycle ergometer. Spectral coherence was used to explore the patterns of connectivity in the frontal, central, and parietal regions of the brain. Physiological, perceptual, and affective responses were assessed throughout the exercise bout. The spontaneous eyeblink rate was also calculated prior to commencement and upon completion of the exercise trial as an indirect assessment of the dopaminergic system. The present findings indicate that high-tolerant individuals reported lower levels of perceived activation, especially during the preliminary stages of the exercise test. Participants in the high-tolerance group also reported greater levels of remembered pleasure upon completion of the exercise test. The data also revealed that high-tolerant individuals exhibited increased connectivity of theta waves between frontal, central, and parietal electrode sites and increased connectivity of beta waves, primarily within the parietal cortex. Correlational analysis indicated the possibility that low- and high-tolerant individuals make use of different neural networks to process and regulate their psychophysiological state during exercise-related situations. This strategy could potentially represent a conscious decision to downregulate affective arousal and facilitate the neural control of working muscles during situations of physical stress.

Effects of Healthy Aging and Gender on the Electrophysiological Correlates of Semantic Sentence Comprehension: The Development of Dutch Normative Data.

The clinical use of event-related potentials in patients with language disorders is increasingly acknowledged. For this purpose, normative data should be available. Within this context, healthy aging and gender effects on the electrophysiological correlates of semantic sentence comprehension were investigated. One hundred and ten healthy subjects (55 men and 55 women), divided among three age groups (young, middle aged, and elderly), performed a semantic sentence congruity task in the visual modality during electroencephalographic recording. The early visual complex was affected by increasing age as shown by smaller P2 amplitudes in the elderly compared to the young. Moreover, the N400 effect in the elderly was smaller than in the young and was delayed compared to latency measures in both middle-aged and young subjects. The topography of age-related amplitude changes of the N400 effect appeared to be gender specific. The late positive complex effect was increased at frontal electrode sites from middle age on, but this was not statistically significant. No gender effects were detected regarding the early P1, N1, and P2, or the late positive complex effect. Especially aging effects were found during semantic sentence comprehension, and this from the level of perceptual processing on. Normative data are now available for clinical use.

What naturalistic stimuli tell us about pronoun resolution in real-time processing.

Studies on pronoun resolution have mostly utilized short texts consisting of a context and a target sentence. In the current study we presented participants with nine chapters of an audio book while recording their EEG to investigate the real-time resolution of personal and demonstrative pronouns in a more naturalistic setting. The annotation of the features of the pronouns and their antecedents registered a surprising pattern: demonstrative pronouns showed an interpretive preference for subject/agent antecedents, although they are described to have an anti-subject or anti-agent preference. Given the presence of perspectival centers in the audio book, this however confirmed proposals that demonstrative pronouns are sensitive to perspectival centers. The ERP results revealed a biphasic N400-Late Positivity pattern at posterior electrodes for the demonstrative pronoun relative to the personal pronoun, thereby confirming previous findings with highly controlled stimuli. We take the observed N400 for the demonstrative pronoun as an indication for more demanding processing costs that occur due to the relative unexpectedness of this referential expression. The Late Positivity is taken to reflect the consequences of attentional reorientation: since the demonstrative pronoun indicates a possible shift in the discourse structure, it induces updating of the discourse structure. In addition to the biphasic pattern, the data showed an enhanced positivity at frontal electrode sites for the demonstrative pronoun relative to the personal pronoun. We suggest that this frontal positivity reflects self-relevant engagement and identification with the perspective holder. Our study suggests that by using naturalistic stimuli, we get one step closer to understanding the implementation of language processing in the brain during real life language processing.

Habituation of the stress response multiplex to repeated cold pressor exposure.

Humans show remarkable habituation to aversive events as reflected by changes of both subjective report and objective measures of stress. Although much experimental human research focuses on the effects of stress, relatively little is known about the cascade of physiological and neural responses that contribute to stress habituation. The cold pressor test (CPT) is a common method for inducing acute stress in human participants in the laboratory; however, there are gaps in our understanding of the global state changes resulting from this stress-induction technique and how these responses change over multiple exposures. Here, we measure the stress response to repeated CPT exposures using an extensive suite of physiologic measures and state-of-the-art analysis techniques. In two separate sessions on different days, participants underwent five 90 s CPT exposures of both feet and five warm water control exposures, while electrocardiography (ECG), impedance cardiography, continuous blood pressure, pupillometry, scalp electroencephalography (EEG), salivary cortisol and self-reported pain assessments were recorded. A diverse array of adaptive responses are reported that vary in their temporal dynamics within each exposure as well as habituation across repeated exposures. During cold-water exposure there was a cascade of changes across several cardiovascular measures (elevated heart rate (HR), cardiac output (CO) and Mean Arterial Pressure (MAP) and reduced left ventricular ejection time (LVET), stroke volume (SV) and high-frequency heart rate variability (HF)). Increased pupil dilation was observed, as was increased power in low-frequency bands (delta and theta) across frontal EEG electrode sites. Several cardiovascular measures also habituated over repeated cold-water exposures (HR, MAP, CO, SV, LVET) as did pupil dilation and alpha frequency activity across the scalp. Anticipation of cold water induced stress effects in the time-period immediately prior to exposure, indexed by increased pupil size and cortical disinhibition in the alpha and beta frequency bands across central scalp sites. These results provide comprehensive insight into the evolution of a diverse array of stress responses to an acute noxious stressor, and how these responses adaptively contribute to stress habituation.

Increased resting-state alpha coherence and impaired inhibition control in young smokers.

Exposure to nicotine is the first cause of entirely preventable death killing, which is commonly initiated in adolescence. Previous studies revealed the changes of electroencephalography (EEG) and inhibition control in smokers. However, little is known about the specific link between alpha coherence during the resting state and inhibition control ability in young smokers. The present study aimed to investigate inter-hemispherical and frontal-parietal alpha coherence changes and assessed the relationships between alpha coherence and inhibition control in young smokers. We collected resting-state EEG data from 23 young smokers and 24 healthy controls. Inhibition control ability was assessed by a Go/NoGo task. Compared to healthy controls, young smokers exhibited increased inter-hemispherical and frontal-parietal alpha coherence. Furthermore, young smokers committed more NoGo errors in the Go/NogGo task. It is noteworthy that alpha coherence at the frontal electrode sites was positively correlated with NoGo errors in healthy controls, whereas inverse correlations were observed in young smokers. Our findings suggested that alterations of alpha coherence may provide support to the earlier nicotine-dependence-related research findings, which may help us to understand the neuropathology of inhibitory control in young smokers.

Neural basis of implicit motor sequence learning: Modulation of cortical power.

Implicit sequence learning describes the acquisition of serially ordered movements and sequentially structured cognitive information, that occurs without awareness. Theta, alpha and beta cortical oscillations are present during implicit motor sequence learning, but their role in this process is unclear. The current study addressed this gap in the literature. A total of 50 healthy adults aged between 19 and 37 years participated in the study. Implicit motor sequence learning was examined using the Serial Reaction Time task where participants unknowingly repeat a sequence of finger movements in response to a visual stimulus. Sequence learning was examined by comparing reaction times and oscillatory power between sequence trials and a set of control trials comprising random stimulus presentations. Electroencephalography was recorded as participants completed the task. Analyses of the behavioral data revealed participants learnt the sequence. Analyses of oscillatory activity, using permutation testing, revealed sequence learning was associated with a decrease in theta band (4-7Hz) power recorded over frontal and central electrode sites. Sequence learning effects were not observed in the alpha (7-12 Hz) or beta bands (12-20 Hz). Even though alpha and beta power modulations have long been associated with executing a motor response, it seems theta power is a correlate of sequence learning in the manual domain. Theta power modulations on the serial reaction time task may reflect disengagement of attentional resources, either promoting or occurring as a consequence of implicit motor sequence learning.

Individual differences in slow wave sleep architecture relate to variation in white matter microstructure across adulthood.

Sleep plays a key role in supporting brain function and resilience to brain decline. It is well known that sleep changes substantially with aging and that aging is associated with deterioration of brain structure. In this study, we sought to characterize the relationship between slow wave slope (SWslope)—a key marker of sleep architecture and an indirect proxy of sleep quality—and microstructure of white matter pathways in healthy adults with no sleep complaints. Participants were 12 young (24–27 years) and 12 older (50–79 years) adults. Sleep was assessed with nocturnal electroencephalography (EEG) and the Pittsburgh Sleep Quality Index (PSQI). White matter integrity was assessed using tract-based spatial statistics (TBSS) on tensor-based metrics such as Fractional Anisotropy (FA) and Mean Diffusivity (MD). Global PSQI score did not differ between younger (n = 11) and older (n = 11) adults (U = 50, p = 0.505), but EEG revealed that younger adults had a steeper SWslope at both frontal electrode sites (F3: U = 2, p < 0.001, F4: U = 4, p < 0.001, n = 12 younger, 10 older). There were widespread correlations between various diffusion tensor-based metrics of white matter integrity and sleep SWslope, over and above effects of age (n = 11 younger, 9 older). This was particularly evident for the corpus callosum, corona radiata, superior longitudinal fasciculus, internal and external capsule. This indicates that reduced sleep slow waves may be associated with widespread white matter deterioration. Future studies should investigate whether interventions targeted at improving sleep architecture also impact on decline in white matter microstructure in older adults.

A Prospective Randomized Controlled Trial: Alternative Approach to EEG Application to Reduce Electrode-induced Skin Injury among Ambulatory EEG Patients

ABSTRACT Ambulatory electroencephalography (AEEG) is a technique of continuous EEG recording of patients in their natural setting, outside the controlled environment of the hospital. Electrode-induced skin injury is a common complication of prolonged EEG monitoring. This randomized study aimed to investigate the performance of two methods of electrode application in reducing electrode-induced skin injury among patients undergoing 4-day AEEG monitoring. A randomized interventional study was conducted from November 2020 to May 2021 in the Neurosciences Ambulatory Care Unit at a metropolitan hospital in Sydney, Australia. We enrolled patients into two groups: i) Group 1 (standard protocol group) received Ten20 Conductive PasteTM with Tensive® adhesive gel as the primary approach to electrode application and ii) Group 2 (intervention group) received Ten20 Conductive PasteTM with Tensive® adhesive gel and hydrogel electrodes on hairless locations as the primary approach to electrode application. A total of 79 patients participated in this study. The group that received the addition of hydrogel electrodes (Group 2) performed better than the standard protocol group on electrode site inflammation for the frontal region, particularly FP1, FP2, F8, and the ground electrode sites. EEG quality and self-reports of patient comfort and mood did not differ significantly between the two groups. The addition of hydrogel electrodes using a Ten20 Conductive PasteTM with a Tensive® adhesive gel protocol results in reduced inflammation at frontal lobe and ground electrode sites.

Unpleasant Odors Affect Alerting Attention in Young Men: An Event-Related Potential Study Using the Attention Network Test

Attention to unpleasant odors is crucial for human safety because they may signal danger; however, whether odor concentration also plays a role remains debated. Here, we explored the effects of two concentrations of pleasant and unpleasant odors on the attention network, comprising the alerting, orienting, and executive control networks. Behavioral responses were examined using the Attention Network Test, while electrophysiological responses were examined by assessing N1 and N2 amplitudes in 30 young men. We found that irrespective of odor concentration, an unpleasant odor induced larger cue-related N1 and N2 amplitudes in the alerting and executive control networks at occipital and frontal electrode sites and that was only paralleled by a reduced behavioral response time of cue-related trails in the alerting network. Thus, our results do not provide supporting evidence for a concentration-dependent effect, but they do suggest that more attentional resources are allocated to alerting-relevant stimuli to improve behavioral response times to a potential threat in young men.

P143 Sleep-dependent declarative memory consolidation and NREM sleep EEG oscillations in older adults with obstructive sleep apnea

Abstract Objectives To compare overnight declarative memory consolidation and NREM sleep EEG oscillations in older adults with OSA to an age-matched control group, and to assess the quantitative sleep EEG features as correlates of memory consolidation. Methods 46 participants (24 without OSA and 22 patients with OSA) were recruited. Participants completed a word-paired associates declarative memory task before and after an 8-hour sleep opportunity with full polysomnography. Power spectral analysis was performed on all-night EEG recorded at frontal and central electrode sites. We calculated slow wave activity (slow oscillations absolute power 0.25–1 Hz; and delta EEG power (0.5–4.5 Hz) in NREM sleep. Slow spindle density (11–13 Hz, events p/min) and fast spindle density (13–16 Hz, events p/min) in stage N2 was derived using an automated spindle detection algorithm. Results Patients with OSA showed no significant differences in overnight memory recall and recognition compared to individuals without OSA. The OSA group showed reduced slow spindle density at the central region and fast spindle density at the frontal region relative to controls. No differences were observed in SWA. Within group correlations showed slow and fast spindle density were correlated to percent recognition in the control group. Conclusion Older adults with OSA had deficits in slow and fast sleep spindles compared to controls. OSA patients showed preserved sleep-dependent declarative memory consolidation despite sleep fragmentation and intermittent hypoxemia. Sleep spindles were positively correlated with overnight memory consolidation in controls but not OSA patients. Targeted interventions to boost spindles may enhance memory consolidation in older adults.

Early ERP Evidence for Children's and Adult's Sensitivity to Scalar Implicatures Triggered by Existential Quantifiers (Some).

How quickly do children and adults interpret scalar lexical items in speech processing? The current study examined interpretation of the scalar terms some vs. all in contexts where either the stronger (some = not all) or the weaker interpretation was permissible (some allows all). Children and adults showed increased negative deflections in brain activity following the word some in some-infelicitous versus some-felicitous contexts. This effect was found as early as 100 ms across central electrode sites (in children), and 300–500 ms across left frontal, fronto-central, and centro-parietal electrode sites (in children and adults). These results strongly suggest that young children (aged between 3 and 4 years) as well as adults quickly have access to the contextually appropriate interpretation of scalar terms.

Novelty processing depends on medial temporal lobe structures

ObjectivesThe goal of the present study was to identify the role of the medial temporal lobe (MTL) in the detection and later processing of novelty. MethodsTwenty-one epilepsy patients with unilateral MTL resection (10 left-sided; 11 right-sided) and 26 matched healthy controls performed an adapted visual novelty oddball task. In this task two streams of stimuli were presented on the left and right of fixation while the patients’ electroencephalogram was measured. The participants had to respond to infrequent target stimuli, while ignoring frequent standard, and infrequent novel stimuli that were presented to the left or right, appearing either contra- or ipsilateral to the patients’ resections. ResultsNovelty detection, as indexed by the N2 ERP component elicited by novels, was reduced by the MTL resections, as evidenced by a smaller N2 for patients than healthy controls. Later processing of novels, as indexed by the novelty P3 ERP component, was reduced for novels presented contra- versus ipsilateral to the resected side. Moreover, at a frontal electrode site, the N2-P3 complex showed reduced novelty processing in patients with MTL resections compared to healthy controls.The ERP differences were specific for the novel stimuli, as target processing, as indexed by the P3b, was unaffected in the patients: No P3b differences were found between targets presented ipsi- or contralaterally to the resected side, nor between patients and healthy controls. ConclusionsThe current results suggest that MTL structures play a role in novelty processing. In contrast, target processing was unaffected by MTL resections.

Psychological and psychophysiological mechanisms underlying the effects of meditation during moderate-intensity exercise

ABSTRACT The present experiment sought to further understanding of the psychological and psychophysiological mechanisms underlying the effects of a single session of audio-guided meditation during moderate-intensity cycling exercise. Twenty-four healthy participants were recruited. A portable EEG device was employed to investigate the cerebral responses associated with the effects of meditation on exercise. Psychological measures were administered at three timepoints during the exercise bout. Two experimental conditions (endurance meditation [EM] and catastrophic meditation [CM]) and a control condition (CO) were administered. Participants were asked to exercise for 8 min (2 min of warm-up performed at 20% below the first ventilatory threshold + 6 min of exercise performed at the first ventilatory threshold) at 60 rpm. The EEG signal from frontal electrode sites was decomposed using Morlet Complex Wavelets, and event-related perturbation was calculated to investigate changes in beta frequency associated with the cycling phase. The results indicate that EM was sufficiently potent to ameliorate exertion and enhance affect to a greater degree than CO and CM. The neural mechanisms underlying the effects of EM appear to be associated with increased beta activity in the right frontal regions. The results of this study also indicate that exertional fatigue can be modulated through an alternative route that is not reliant upon the use of dissociative thoughts and does not require motivation to be up-regulated.

Effects of Age on Cortical Tracking of Word-Level Features of Continuous Competing Speech.

Speech-in-noise comprehension difficulties are common among the elderly population, yet traditional objective measures of speech perception are largely insensitive to this deficit, particularly in the absence of clinical hearing loss. In recent years, a growing body of research in young normal-hearing adults has demonstrated that high-level features related to speech semantics and lexical predictability elicit strong centro-parietal negativity in the EEG signal around 400 ms following the word onset. Here we investigate effects of age on cortical tracking of these word-level features within a two-talker speech mixture, and their relationship with self-reported difficulties with speech-in-noise understanding. While undergoing EEG recordings, younger and older adult participants listened to a continuous narrative story in the presence of a distractor story. We then utilized forward encoding models to estimate cortical tracking of four speech features: (1) word onsets, (2) “semantic” dissimilarity of each word relative to the preceding context, (3) lexical surprisal for each word, and (4) overall word audibility. Our results revealed robust tracking of all features for attended speech, with surprisal and word audibility showing significantly stronger contributions to neural activity than dissimilarity. Additionally, older adults exhibited significantly stronger tracking of word-level features than younger adults, especially over frontal electrode sites, potentially reflecting increased listening effort. Finally, neuro-behavioral analyses revealed trends of a negative relationship between subjective speech-in-noise perception difficulties and the model goodness-of-fit for attended speech, as well as a positive relationship between task performance and the goodness-of-fit, indicating behavioral relevance of these measures. Together, our results demonstrate the utility of modeling cortical responses to multi-talker speech using complex, word-level features and the potential for their use to study changes in speech processing due to aging and hearing loss.

Assessing Neural Oscillations during Erotic and Negative Emotional Pictures Viewing: An Event-Related Potential Study

The present study was designed to determine whether or not there are components of the ERPs that discriminate the erotic and negative pictures during affective picture processing. Participants viewed erotic, negative and neutral pictures form the International Affective Picture System (IAPS). Eighteen right-handed volunteer students from North-Eastern University participated in the experiment. Electrode from the frontal site (F3 and F4), C3 and C4 (central electrodes), P3 andP4 (parietal electrodes) and O1 and O2 (occipital electrodes) were averaged with the stimuli type and brain hemisphere. The change in spectral power of the brain signal and its main spectral bands of theta (3-7.5 Hz), Alpha (7.5-13 Hz) and Beta (13-25 Hz) were analyzed. Erotic stimuli showed ERP components deflected more negatively at the frontal electrode site than the negative picture stimuli during the time window of 200-300 ms whereas the negative valence stimuli processing reflected a positively twisted amplitude at the time window of 120-300 ms. The erotic and negative valence emotional picture stimuli show a significant difference in the spectral power of theta, alpha and beta frequency bands for the left vs. right hemisphere and frontal vs. occipital sites. Nonetheless, the time-frequency plots show us those emotionally valence visual stimuli triggered an increase of alpha band (7.5-13 Hz).

Multisensory expectations about dynamic visual objects facilitates early sensory processing of congruent sounds

In everyday life, visual objects are often accompanied by sounds, yet little is known about how information in one sense may influence the processing of information in another sense. We examined how dynamic visual input – an object moving continuously across the visual field – influences early auditory processing of a sound that is either congruent with the object’s motion, and thus likely perceived as being part of the visual object, or incongruent with the object’s motion. We recorded EEG activity from 31 neurotypical adults who passively viewed a red ball that appeared either on the far left or right edge of the display and continuously traversed along the horizontal midline to make contact and bounce off the opposite edge. For multisensory trials, a tone accompanied the visual input the moment the ball made contact with the opposite edge (AV-synchronous), or the sound occurred 450ms before contact (AV-asynchronous). We also included audio-only and visual-only trials. Our main analysis focused on the auditory-evoked event-related potential (ERP) measured at frontal electrode sites and revealed reliable differences in the amplitude and latency of the N1-P2 auditory complex (all p’s < 0.003). Follow-up pairwise comparisons showed a reduced N1-amplitude for the AV-synchronous condition relative to the AV-asynchronous and audio-only conditions, and a delayed latency for the AV-asynchronous condition relative to the AV-synchronous and audio-only conditions. P2-peak analyses revealed greater amplitude for the audio-only relative to the AV-synchronous and AV-asynchronous and delayed latency toward AV-asynchronous relative to AV-synchronous and audio-only conditions. Overall, these results show that audio-visual synchrony elicited a faster and attenuated early auditory response relative to asynchronous or auditory-only events. This suggests that dynamic visual stimuli can help generate expectations about the timing of auditory events, which then facilitates the processing of auditory information that matches these expectations.