An event-related potential study of prepotent motor activity and response inhibition deficits in schizophrenia.

Response inhibition deficits in schizophrenia (SZ) are accompanied by reduced neural activities using event-related potential (ERP) measurements. However, it remains unclear whether the reduction in inhibition-related ERPs in SZ is contingent upon prepotent motor tendencies. This study aimed to examine the relationship between ERP markers of prepotent motor activity (lateralised readiness potential, LRP) and response inhibition (P3) by collecting behavioural and EEG data from healthy control (HC) subjects and SZ patients during a modified Go/No-Go task. A trial-averaged analysis revealed that SZ patients made more commission errors in No-Go trials compared with HC subjects, although there was no significant difference in the inhibition-related P3 effect (i.e. larger P3 amplitudes in No-Go compared with Go trials) between the two groups. Subsequently, No-Go trials were sorted and median-split into bins of stronger and weaker motor tendencies. Both HC and SZ participants made more commission errors when faced with stronger motor tendencies. The LRP-sorted P3 data indicated that HC subjects exhibited larger P3 effects in response to stronger motor tendencies, whereas this trial-by-trial association between P3 and motor tendencies was absent in SZ patients. Furthermore, SZ patients displayed diminished P3 effects in No-Go trials with stronger motor tendencies but not in trials with weaker motor tendencies, relative to HC subjects. Taken together, these findings suggest that SZ patients are unable to dynamically adjust inhibition-related neural activities in response to changing inhibitory control demands and emphasise the importance of considering prepotent motor activity when investigating the neural mechanisms underlying response inhibition deficits in SZ.

The effects of pre-cue alpha and cueing strategy on age-related deficits in post-cue alpha activity and target processing during visual spatial attention.

Electroencephalography alpha-band (8-13 Hz) activity during visual spatial attention declines in normal aging. We recently reported the impacts of pre-cue baseline alpha and cueing strategy on post-cue anticipatory alpha activity and target processing in visual spatial attention (Wang et al., Cerebral Cortex, 2023). However, whether these factors affected aging effects remains unaddressed. We investigated this issue in two independent experiments (n = 114) with different cueing strategies (instructional vs. probabilistic). When median-splitting young adults (YA) by their pre-cue alpha power, we found that older adults exhibited similar pre-cue and post-cue alpha activity as YA with lower pre-cue alpha, and only YA with higher pre-cue alpha showed significant post-cue alpha activity, suggesting that diminished anticipatory alpha activity was not specific to aging but likely due to a general decrease with baseline alpha. Moreover, we found that the aging effects on cue-related event-related potentials were dependent on cueing strategy but were relatively independent of pre-cue alpha. However, age-related deficits in target-related N1 attentional modulation might depend on both pre-cue alpha and cueing strategy. By considering the impacts of pre-cue alpha and cueing strategy, our findings offer new insights into age-related deficits in anticipatory alpha activity and target processing during visual spatial attention.

The effects of pre-cue posterior alpha on post-cue alpha activity and target processing in visual spatial attention tasks with instructional and probabilistic cues.

The electroencephalography alpha-band (8-13 Hz) activity may represent a crucial neural substrate of visual spatial attention. However, factors likely contributing to alpha activity have not been adequately addressed, which impedes understanding its functional roles. We investigated whether pre-cue alpha power was associated with post-cue alpha activity in 2 independent experiments (n = 30 each) with different cueing strategies (instructional vs. probabilistic) by median-splitting subjects (between-subject) or trials (within-subject) according to pre-cue alpha. In both experiments, only subjects with higher pre-cue alpha showed significant post-cue alpha desynchronization and alpha lateralization, while whether trials had higher or lower pre-cue alpha affected post-cue alpha desynchronization but not alpha lateralization. Furthermore, significant attentional modulation of target processing indexed by N1 component was observed in subjects and trials regardless of higher or lower pre-cue alpha in the instructional cueing experiment. While in the probabilistic cueing experiment, N1 attentional modulation was only observed in higher pre-cue alpha subjects and lower pre-cue alpha trials. In summary, by demonstrating the effects of pre-cue alpha and cueing strategy on post-cue alpha activity and target processing, our results suggest the necessity of considering these 2 contributing factors when investigating the functional roles of alpha activity in visual spatial attention.

Decoding the temporal dynamics of affective scene processing.

Natural images containing affective scenes are used extensively to investigate the neural mechanisms of visual emotion processing. Functional fMRI studies have shown that these images activate a large-scale distributed brain network that encompasses areas in visual, temporal, and frontal cortices. The underlying spatial and temporal dynamics, however, remain to be better characterized. We recorded simultaneous EEG-fMRI data while participants passively viewed affective images from the International Affective Picture System (IAPS). Applying multivariate pattern analysis to decode EEG data, and representational similarity analysis to fuse EEG data with simultaneously recorded fMRI data, we found that: (1) ∼80 ms after picture onset, perceptual processing of complex visual scenes began in early visual cortex, proceeding to ventral visual cortex at ∼100 ms, (2) between ∼200 and ∼300 ms (pleasant pictures: ∼200 ms; unpleasant pictures: ∼260 ms), affect-specific neural representations began to form, supported mainly by areas in occipital and temporal cortices, and (3) affect-specific neural representations were stable, lasting up to ∼2 s, and exhibited temporally generalizable activity patterns. These results suggest that affective scene representations in the brain are formed temporally in a valence-dependent manner and may be sustained by recurrent neural interactions among distributed brain areas.

Neural mechanisms of inhibitory control deficits in obesity revealed by P3 but not N2 event-related potential component.

The lack of inhibitory control toward foods may cause unhealthy eating behavior and lead to obesity. However, previous research failed to reach consensus on the alterations in event-related potential (ERP) markers of inhibitory control, i.e., N2 and P3. We hypothesized that the ERP effects of inhibitory control reported in previous food-based Go/NoGo studies might be obscured by non-inhibitory processes associated with stimulus probability. We designed two food-based Go/NoGo tasks composed of stimuli with the same type and frequency of occurrence (60% non-foods, 20% high-calorie foods, 20% low-calorie foods), one with response inhibition toward high- and the other toward low-calorie foods. Such an experimental design allowed us to isolate neural activity associated with inhibitory control from that associated with non-inhibitory processes by constructing ERP difference waves between NoGo and Go trials with the same frequency of occurrence. Electroencephalography data were collected from 32 obese participants and 29 normal-weight controls. Obese participants showed significantly lower accuracy in NoGo trials than normal-weight controls in both tasks. ERP data suggested inhibition-related effects for P3 (P3d) but not N2 in the difference waves, and obese participants showed significantly decreased P3d amplitudes than normal-weight controls in both tasks. In addition, we found that across both groups, individuals with larger waist-to-hip ratios showed smaller P3d amplitudes in both tasks, while such correlations between body mass index and P3d amplitude were only observed in the high-calorie task. Our findings suggest that the decreased effect of P3, not N2, might reflect the neural substrate of inhibitory control deficits in obese people. Thus, P3 could serve as an important neural marker in the future development of new therapeutic strategy that aims to improve inhibitory control in obesity.

Decoding attention control and selection in visual spatial attention.

Event-related potentials (ERPs) are used extensively to investigate the neural mechanisms of attention control and selection. The univariate ERP approach, however, has left important questions inadequately answered. We addressed two questions by applying multivariate pattern classification to multichannel ERPs in two cued visual spatial attention experiments (N = 56): (a) impact of cueing strategies (instructional vs. probabilistic) on attention control and selection and (b) neural and behavioral effects of individual differences. Following cue onset, the decoding accuracy (cue left vs. cue right) began to rise above chance level earlier and remained higher in instructional cueing (~80 ms) than in probabilistic cueing (~160 ms), suggesting that unilateral attention focus leads to earlier and more distinct formation of the attention control set. A similar temporal sequence was also found for target-related processing (cued target vs. uncued target), suggesting earlier and stronger attention selection under instructional cueing. Across the two experiments: (a) individuals with higher cue-related decoding accuracy showed higher magnitude of attentional modulation of target-evoked N1 amplitude, suggesting that better formation of anticipatory attentional state leads to stronger modulation of target processing, and (b) individuals with higher target-related decoding accuracy showed faster reaction times (or larger cueing effects), suggesting that stronger selection of task-relevant information leads to better behavioral performance. Taken together, multichannel ERPs combined with machine learning decoding yields new insights into attention control and selection that complement the univariate ERP approach, and along with the univariate ERP approach, provides a more comprehensive methodology to the study of visual spatial attention.

Deciding where to attend: Large-scale network mechanisms underlying attention and intention revealed by graph-theoretic analysis.

The neural mechanisms by which intentions are transformed into actions remain poorly understood. We investigated the network mechanisms underlying spontaneous voluntary decisions about where to focus visual-spatial attention (willed attention). Graph-theoretic analysis of two independent datasets revealed that regions activated during willed attention form a set of functionally-distinct networks corresponding to the frontoparietal network, the cingulo-opercular network, and the dorsal attention network. Contrasting willed attention with instructed attention (where attention is directed by external cues), we observed that the dorsal anterior cingulate cortex was allied with the dorsal attention network in instructed attention, but shifted connectivity during willed attention to interact with the cingulo-opercular network, which then mediated communications between the frontoparietal network and the dorsal attention network. Behaviorally, greater connectivity in network hubs, including the dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and the inferior parietal lobule, was associated with faster reaction times. These results, shown to be consistent across the two independent datasets, uncover the dynamic organization of functionally-distinct networks engaged to support intentional acts.

Normal aging selectively diminishes alpha lateralization in visual spatial attention.

EEG studies of cue-induced visual alpha power (8-13 Hz) lateralization have been conducted on young adults without examining differences that may develop as a consequence of normal aging. Here, we examined age-related differences in spatial attention by comparing healthy older and younger adults. Our key finding is that cue-induced alpha power lateralization was observed in younger, but not older adults, even though both groups exhibited classic event-related potential signatures of spatial orienting. Specifically, both younger and older adults showed significant early directing-attention negativity (EDAN), anterior directing-attention negativity (ADAN), late directing-attention positivity (LDAP) and contingent negative variation (CNV). Furthermore, target-evoked sensory components were enhanced for attended relative to unattended targets in both younger and older groups. This pattern of results suggests that although older adults can successfully allocate spatial attention, they do so without the lateralization of alpha power that is commonly observed in younger adults. Taken together, our findings demonstrate that younger and older adults might engage different neural mechanisms for attentional orienting, and that alpha power lateralization during visual spatial attention is a phenomenon that diminishes during normal aging.

Willed Attentional Selection of Visual Features: An EEG Study.

Visual selective attention studies generally tend to apply cuing paradigms to instructively direct observers' attention to certain locations, features or objects. However, in real situations, attention in humans often flows spontaneously without any specific instructions. Recently, a concept named "willed attention" was raised in visuospatial attention, in which participants are free to make volitional attention decisions. Several ERP components during willed attention were found, along with a perspective that ongoing alpha activity may bias the subsequent attentional choice. However, it remains unclear whether similar neural mechanisms exist in feature- or object-based willed attention. Here, we included choice cues and instruct cues in a feature-based selective attention paradigm, allowing participants to freely choose or to be instructed to attend a color for the subsequent target detection task. Pre-cue ongoing alpha oscillations, cue-evoked potentials and target-related steady-state visual evoked potentials (SSVEPs) were simultaneously measured as markers of attentional processing. As expected, SSVEP responses were similarly modulated by attention between choice and instruct cue trials. Similar to the case of spatial attention, a willed-attention component (Willed Attention Component, WAC) was isolated during the cue-related choice period by comparing choice and instruct cues. However, pre-cue ongoing alpha oscillations did not predict the color choice (yellow vs blue), as indicated by the chance level decoding accuracy (50%). Overall, our results revealed both similarities and differences between spatial and feature-based willed attention, and thus extended the understanding toward the neural mechanisms of volitional attention.

Direct and indirect effects of error monitoring on social functioning in a cohort with high-risk and first-episode psychosis.

Error monitoring plays a key role in people's adjustment to social life. This study aimed to examine the direct (DE) and indirect effects (IDE) of error monitoring, as indicated by error-related negativity (ERN), on social functioning in a clinical cohort from high-risk (APS) to first-episode psychosis (FEP). This study recruited 100 outpatients and 49 healthy controls (HC). ERN was recorded during a modified flanker task; social functioning was evaluated using the social scale of global functioning. The path analysis was executed using the "lavaan" package. When controlling for age and education, the clinical cohort had a smaller ERN than the HC group (F1, 145 = 19.58, p < 0.001, partial η2 = 0.12, 95%CI: 0.04-0.22). ERN demonstrated no substantial direct impact on current social functioning; however, it manifested indirect influences on social functioning via the disorganization factor of the Positive and Negative Syndrome Scale, both with (standardized IDE: -0.139, p = 0.009) and without (standardized IDE: -0.087, p = 0.018) accounting for the diagnosis, defined as a dummy variable (FEP = 1 and APS = 0) and included as a covariate. These findings suggest that error monitoring, as indicated by ERN, may serve as a potential prognostic indicator of social functioning in patients with psychosis.

Impaired insight and error-monitoring deficits among outpatients with attenuated psychosis syndrome and first-episode psychosis.

We aimed to determine the relationship between electrophysiological signatures of error monitoring and clinical insight among outpatients with attenuated psychosis syndrome (APS) and first-episode psychosis (FEP). Error-related negativity (ERN), error positivity (Pe), and correct response negativity (CRN) were recorded during a modified flanker task for patients with FEP (n = 32), APS individuals (n = 58), and healthy controls (HC, n = 49). Clinical insight was measured using the Schedule of Assessment of Insight (SAI) and included awareness of illness (SAI-illness), relabeling of specific symptoms (SAI-symptoms), and treatment compliance (SAI-treatment). Compared with HC, patients with FEP showed smaller ERN (p < 0.001) and Pe (p = 0.011) amplitudes and individuals with APS showed smaller ERN amplitude (p = 0.009). No significant difference in CRN amplitude was observed among the groups. A smaller negative amplitude of ERN correlated with a lower score on SAI-symptoms (b = -0.032, 95% CI: 0.062 to -0.002, p = 0.035) and a decreased total score of SAI (b = -0.096, 95% CI: 0.182 to -0.010, p = 0.029). This links were adjusted for age, education, and diagnosis (a dummy variable with FEP = 1 and APS = 0), and was independent of positive symptoms. SAI-illness was predominantly influenced by diagnosis, whereas SAI-treatment was additionally affected by disorganized communications. Neither Pe nor CRN amplitude exhibited an association with clinical insight. Unconscious error detection, as indicated by ERN, may aid individuals at the preliminary stage of psychosis in recognizing the unusual symptoms.

Comparing the Signal-to-Noise Ratio Estimates for Event-Related Potentials: A Simulation Study.

Event-related potential (ERP) is one of the commonly used electrophysiologic measures for brain activity with millisecond time resolution, which has been widely applied to psychology and neuroscience research. Conventionally, ERP is obtained by grand-averaging EEG recordings across multiple trials to improve the signal-to-noise ratio (SNR). Reliable quantitative analysis of the amplitude or latency of ERP requires sufficient SNR. Estimating SNR thus offers a criterion for selecting the trial number in designing experiments and the ERP analysis. Unfortunately, most researchers miss assessing SNR, which leads to the reliability of the results being unchecked, particularly under a low SNR. Although a few SNR estimates for ERP have been proposed, their performances have not yet been well compared. As a result, researchers are still left without a guideline quantifying the quality of their ERP signals. An SNR estimate is considered superior if it more successfully differentiates the difference in noises. Using both simulated and actual ERP components, in this study, we aimed to compare the performances of four SNR estimates. The area under the curve (AUC) was computed from the receiver operating characteristics (ROC) curves to quantify the performances of the SNR estimates in Task I: classifying ERP and spontaneous EEG and Task II: classifying the ERP with different levels of noises. Our results showed that the SNR estimate by calculating the ratio of the highest amplitude in the ERPs to the standard deviation in the baseline time interval (SNRMaidhof) was outstanding in Task I. While the SNR estimate by dividing the mean root square of the signal by the variance of the baseline (SNRM&P) was the best SNR estimate in Task II. These results provided a guideline for assessing the quality of the ERP, excluding experimental subjects, or designing the number of required trials before the quantitative analysis.Clinical Relevance- This study provides the rules of thumb for quantifying the ERP data quality, screening the subjects and designing the number of trials in ERP experiments.

EEG correlates of anticipatory attention and target processing in children and adults during visual spatial attention.

The ability of attentional orienting has been suggested to keep developing throughout childhood. Electroencephalography (EEG) studies have shown that 6-10 year old children exhibit lateralized alpha-band (8-13 Hz) activity and event-related potentials (ERPs) that are classic markers of spatial attentional orienting in adults. However, the lack of a direct comparison of these EEG correlates between children and adults in the same experiment made it difficult to evaluate developmental effects on neural activity throughout attentional stages. This study aimed to directly compare cue-related alpha activity and ERPs for the anticipatory attention stage and target-related ERPs for the target processing stage between healthy children and adults. Participants, including 19 children (6-10 years) and 23 adults (18-34 years), successfully completed a visual spatial attention task, although children responded more slowly and less consistently than adults. Both age groups exhibited significant cue-related alpha lateralization and ERPs (EDAN, ADAN, and LDAP) during anticipatory attention and significant attentional modulation of target-related N1 during target processing. However, no significant difference was found in the magnitude of attentional modulation of these EEG correlates between children and adults. These findings suggest that the neural underpinnings of anticipatory attention and target processing during visual spatial attention could have been largely developed in 6-10 year old children.

Investigating Heritage Language Processing: Meaning Composition in Chinese Classifier-Noun Phrasal Contexts.

The aim of the present study was to investigate how Chinese-Malay bilingual speakers with Chinese as heritage language process semantic congruency effects in Chinese and how their brain activities compare to those of monolingual Chinese speakers using electroencephalography (EEG) recordings. To this end, semantic congruencies were manipulated in Chinese classifier-noun phrases, resulting in four conditions: (i) a strongly constraining/high-cloze, plausible (SP) condition, (ii) a weakly constraining/low-cloze, plausible (WP) condition, (iii) a strongly constraining/implausible (SI) condition, and (iv) a weakly constraining/implausible (WI) condition. The analysis of EEG data focused on two event-related potential components, i.e., the N400, which is known for its sensitivity to semantic fit of a target word to its context, and a post-N400 late positive complex (LPC), which is linked to semantic integration after prediction violations and retrospective, evaluative processes. We found similar N400/LPC effects in response to the manipulations of semantic congruency in the mono- and bilingual groups, with a gradient N400 pattern (WI/SI > WP > SP), a larger frontal LPC in response to WP compared to SP, SI, and WI, as well as larger centro-parietal LPCs in response to WP compared to SI and WI, and a larger centro-parietal LPC for SP compared to SI. These results suggest that, in terms of event-related potential (ERP) data, Chinese-Malay early bilingual speakers predict and integrate upcoming semantic information in Chinese classifier-noun phrase to the same extent as monolingual Chinese speakers. However, the global field power (GFP) data showed significant differences between SP and WP in the N400 and LPC time windows in bilinguals, whereas no such effects were observed in monolinguals. This finding was interpreted as showing that bilinguals differ from their monolingual peers in terms of global field power intensity of the brain by processing plausible classifier-noun pairs with different congruency effects.

Hair cortisol, social support, personality traits, and clinical course: differences in schizophrenia and bipolar disorder.

OBJECTIVE: This study aimed to investigate the differences in the relationship between hair cortisol concentration (HCC) and psychosocial stress, social support, clinical features, clinical course, and outcome in schizophrenia and bipolar disorder. METHODS: A total of 109 schizophrenia patients, 93 bipolar disorder patients and 86 healthy controls between 18 and 60 years old were enrolled in the study. Linear regression and factor analysis were employed to examine and compare the relationship between HCC and childhood trauma, the number of stressful life events, the amount of social support in the three months before the hair cortisol assessment, clinical fearures, clinical course, and outcome in schizophrenia and bipolar disorder. RESULTS: HCC is significantly associated with clinical syndromes, including depression-anxiety factor of Positive and Negative Syndrome Scale in schizophrenia patients, and thought disorder in bipolar disorder patients. However, HCC is positively related to social support and personality traits only in schizophrenia patients but not in bipolar disorder patients. Factor analysis indicates schizophrenia and bipolar disorder share a very similar but somewhat different structure in terms of HCC, psychosocial stress, social support, clinical features, clinical course, and outcome. CONCLUSION: Findings support that schizophrenia and bipolar disoder have a significant overlap in both clinical characteristics and enviromental risk factors. Aberrant HCC contributes to the complexity of clinical characteristics mainly in schizophrenia.

Conflict Processing in Schizophrenia: Dissociable neural mechanisms revealed by the N2 and frontal midline theta.

Deficits in executive control have long been regarded as one of the hallmark cognitive characteristics in people with schizophrenia (SZ), and current neurocognitive models of SZ generally regard the dysfunctional anterior cingulate cortex (ACC) as the possible neural mechanism. This however, contrasts with recent studies showing that conflict processing, a key component of executive functions that relies on ACC, remains relatively intact in SZ. The current study aimed to investigate this issue through two well-known electrophysiological signatures of conflict processing that have been suggested to originate from ACC, i.e., the N2 component of event-related potentials (ERPs) and frontal midline theta (FMθ) oscillations. We recorded 64-channel scalp electroencephalography from 29 SZ (17 women; mean age: 30.4 years) and 31 healthy control subjects (HC; 17 women; mean age: 29.1 years) performing a modified flanker task. Behavioral data revealed no significant differences in flanker conflict effects (lower accuracy and longer reaction times in incongruent trials than in congruent trials) between HC and SZ. Trial-averaged ERP and spectral analysis suggested that both N2 and FMθ were significantly impaired in SZ relative to HC. Furthermore, by sorting incongruent trials according to their reaction times within individual subjects, we found that the trial-by-trial modulation of N2 (larger amplitude and longer latency in slower trials) which was observed and localized in ACC for HC was totally absent for SZ. By contrast, the trial-by-trial modulation of FMθ (larger power in slower trials) was observed and localized in ACC for both groups, despite a smaller magnitude in SZ, which suggested that FMθ, not N2, might serve as the neural substrate of conflict processing in SZ. Taken together, our results enrich the current neurocognitive models of SZ by revealing dissociable neural responses between N2 and FMθ during conflict processing in SZ.

Effects of multi-domain cognitive training on working memory retrieval in older adults: behavioral and ERP evidence from a Chinese community study.

Working memory (WM) is a fundamental cognitive function that typically declines with age. Previous studies have shown that targeted WM training has the potential to improve WM performance in older adults. In the present study, we investigated whether a multi-domain cognitive training program that was not designed to specifically target WM could improve the behavioral performance and affect the neural activity during WM retrieval in healthy older adults. We assigned healthy older participants (70-78 years old) from a local community into a training group who completed a 3-month multi-domain cognitive training and a control group who only attended health education lectures during the same period. Behavioral and electroencephalography (EEG) data were recorded from participants while performing an untrained delayed match or non-match to category task and a control task at a pre-training baseline session and a post-training follow-up session. Behaviorally, we found that participants in the training group showed a trend toward greater WM performance gains than participants in the control group. Event-related potential (ERP) results suggest that the task-related modulation of P3 during WM retrieval was significantly enhanced at the follow-up session compared with the baseline session, and importantly, this enhancement of P3 modulation was only significant in the training group. Furthermore, no training-related effects were observed for the P2 or N2 component during WM retrieval. These results suggest that the multi-domain cognitive training program that was not designed to specifically target WM is a promising approach to improve WM performance in older adults, and that training-related gains in performance are likely mediated by an enhanced modulation of P3 which might reflect the process of WM updating.

Attention-related modulation of frontal midline theta oscillations in cingulate cortex during a spatial cueing Go/NoGo task.

Recently frontal midline theta (FMθ, 4-8 Hz) oscillations have been consistently reported and proposed as the potential neural mechanism for response inhibition, a core component of human executive functions. However, it remains unclear to what extent the increase of FMθ power during response inhibition tasks is influenced by other non-inhibitory cognitive processes that are usually required for the tasks. In this study, we examined attention-related effects on FMθ during response inhibition by revisiting the EEG data from healthy young adults (N = 30) while performing a spatial cueing Go/NoGo task (Hong et al., 2017). Such an experimental design enabled us to manipulate selective attention that was voluntarily deployed to the stimuli triggering response inhibition. Although commission error rates were low for the NoGo trials, response preparation and prepotent motor activities were qualified by observing significant contingent negative variation (CNV) and lateralized readiness potential (LRP) in both the Go and the NoGo trials. We observed an increase of FMθ power in both attended and ignored conditions of the NoGo trials compared with the Go trials, while FMθ power was significantly smaller in the ignored condition than in the attended condition. Furthermore, source localization analysis suggested cingulate cortex as the main origin for FMθ in the NoGo trials, and FMθ power differences between the attended and ignored conditions were localized in cingulate gyrus. We further provided evidence for attention-dependent FMθ generation by correlating theta source density with ERP signatures of attention (N1), response preparation (CNV), and motor activity (LRP). Overall, our findings suggest that during the Go/NoGo task, the increase of FMθ power was not purely driven by response inhibition, and part of FMθ generators in cingulate gyrus was significantly modulated by attention-related processing (possibly conflict monitoring).

Validation of a Piezoelectric Sensor Array-Based Device for Measurement of Carotid-Femoral Pulse Wave Velocity: The Philips Prototype.

BACKGROUND: Multiple piezoelectric pressure mechanotransducers topologized into an array might improve efficiency and accuracy in collecting arterial pressure waveforms for measurement of pulse wave velocity (PWV). OBJECTIVE: In the present study, we validated a piezoelectric sensor array-based prototype (Philips) against the validated and clinically widely used Complior device (Alam Medical). METHODS: We recruited 33 subjects with a wide distribution of PWV. For the validation, PWV was measured sequentially with the Complior device (four times) and the Philips prototype (three times). With the 99 paired PWV values, we investigated the agreement between the Philips prototype and the Complior device using Pearson correlation analysis and Bland-Altman plot. We also performed analysis on the determinants and reproducibility of PWV measured with both devices. RESULTS: The correlation coefficient for PWV measured with the two devices was 0.92 (p < 0.0001). Compared with the Complior device, the Philips prototype slightly overestimated PWV by 0.24 (± 2 standard deviations, ± 1.91) m/s, especially when PWV was high. The correlation coefficient between the difference and the average of the Philips and Complior measurements was 0.21 (p = 0.035). Nonetheless, they had similar determinants. Age, mean arterial pressure, and sex altogether explained 81.6 and 83.9% of the variance of PWV values measured with the Philips prototype and Complior device, respectively. When the two extremes of the three PWV values measured with the Philips prototype and the Complior device were investigated, the coefficients of variation were 8.26 and 3.26%, respectively. CONCLUSIONS: Compared with the Complior device, the Philips prototype had similar accuracy, determinants, and reproducibility in measuring PWV.

Segregating Top-Down Selective Attention from Response Inhibition in a Spatial Cueing Go/NoGo Task: An ERP and Source Localization Study.

Successfully inhibiting a prepotent response tendency requires the attentional detection of signals which cue response cancellation. Although neuroimaging studies have identified important roles of stimulus-driven processing in the attentional detection, the effects of top-down control were scarcely investigated. In this study, scalp EEG was recorded from thirty-two participants during a modified Go/NoGo task, in which a spatial-cueing approach was implemented to manipulate top-down selective attention. We observed classical event-related potential components, including N2 and P3, in the attended condition of response inhibition. While in the ignored condition of response inhibition, a smaller P3 was observed and N2 was absent. The correlation between P3 and CNV during the foreperiod suggested an inhibitory role of P3 in both conditions. Furthermore, source analysis suggested that P3 generation was mainly localized to the midcingulate cortex, and the attended condition showed increased activation relative to the ignored condition in several regions, including inferior frontal gyrus, middle frontal gyrus, precentral gyrus, insula and uncus, suggesting that these regions were involved in top-down attentional control rather than inhibitory processing. Taken together, by segregating electrophysiological correlates of top-down selective attention from those of response inhibition, our findings provide new insights in understanding the neural mechanisms of response inhibition.