20 research outputs found
Arousal-state modulation in children with AD/HD
No full textObjective: To investigate the effect of arousal-state modulation, via manipulation of stimulus event-rate,on response inhibition in children with Attention-Deficit/Hyperactivity disorder (AD/HD) using behaviouraland ERP measures.Methods: Eighteen children with AD/HD, aged 7–14 years, and 18 age-and sex-matched controls performeda cued visual Go/Nogo task (70% Go) with stimuli presented at fast, medium and slow event-rates.Task performance and ERPs to Warning, Go and Nogo stimuli, as well as preparation between the S1–S2interval, were examined for group differences.Results: AD/HD subjects displayed poorer response inhibition during the fast condition, accompanied bya reduced Nogo P3. Group differences during the fast rate extended to Warning cues, with the AD/HDgroup showing ERP evidence of atypical orienting/preparation, as indexed by the early and late CNV,and early sensory/attentive processing prior to S2.Conclusions: Although deficient response inhibition has been proposed as the core deficit in AD/HD, theresults of the present study highlight the key role of energetic factors. Furthermore, group differencesfound to cues suggest that this effect extends to the processing of task-irrelevant stimuli.Significance: This was the first ERP Go/Nogo task investigation using three event-rates, and the resultssupport the theory that state factors may contribute to response inhibition deficits in AD/HD
Short-term training in the Go/Nogo task: behavioural and neural changes depend on task demands
No full textNeural activity underlying executive functions is subject to modulation as a result of increasing cognitive demands and practice. In the present study, we examined these modulatory effects by varying task difficulty, as manipulated by reaction time deadline (RTD), on inhibitory control during a single Go/Nogo training session (8 blocks; 70% Go). Sixty adults were randomly assigned to one of three task difficulty conditions: High (n=20), Medium (n=20) and Low (n=20), with RTDs of 300, 500 or 1000ms, respectively. Task performance, Event-related potentials (ERPs) and task-related arousal (indexed by skin conductance level) were examined for training effects. Results indicated that improvements in behavioural Go/Nogo proficiency were optimised during conditions of moderate rather than low or high inhibitory demands. An across-session increase in task-related arousal did not differ between conditions, indicating a generalised increase in the mobilisation of mental resources with time-on-task. In contrast, training-related changes in ERPs were dependent on task demands such that the Low task difficulty condition showed an enhanced centroparietal Nogo P2, while a training-induced augmentation in the Nogo>Go P3 effect was greater in the High than Medium condition. The High condition also showed the greatest reduction in the Nogo N1. Although further research is needed in this area, these findings implicate the potential key role of task difficulty in training inhibitory control and suggest that practice-related changes are reflected by qualitative changes in brain activity
Spontaneous activity in the waiting brain: a marker of impulsive choice in attention-deficit/hyperactivity disorder?
No full textBackground: spontaneous very low frequency oscillations (VLFO), seen in the resting brain, are attenuated when individuals are working on attention demanding tasks or waiting for rewards ( Hsu et al., 2013). Individuals with attention-deficit/hyperactivity disorder (ADHD) display excess VLFO when working on attention tasks. They also have difficulty waiting for rewards. Here we examined the waiting brain signature in ADHD and its association with impulsive choice.Methods: DC-EEG from 21 children with ADHD and 21 controls (9–15 years) were collected under four conditions: (i) resting; (ii) choosing to wait; (iii) being “forced” to wait; and (iv) working on a reaction time task. A questionnaire measured two components of impulsive choice.Results: significant VLFO reductions were observed in controls within anterior brain regions in both working and waiting conditions. Individuals with ADHD showed VLFO attenuation while working but to a reduced level and none at all when waiting. A closer inspection revealed an increase of VLFO activity in temporal regions during waiting. Excess VLFO activity during waiting was associated with parents’ ratings of temporal discounting and delay aversion.Conclusions: the results highlight the potential role for waiting-related spontaneous neural activity in the pathophysiology of impulsive decision-making of ADH
Varying task difficulty in the Go/Nogo task: the effects of inhibitory control, arousal, and perceived effort on ERP components
No full textSimilar to other executive functions, inhibitory control is thought to be a dynamic process that can be influenced by variations in task difficulty. However, little is known about how different task parameters alter inhibitory performance and processing as a task becomes more difficult. The aim of this study was to investigate the influence of varying task difficulty, via manipulation of reaction time deadline (RTD), on measures of inhibitory control, perceived effort, and task-related arousal (indexed by skin conductance level). Sixty adults completed a visual Go/Nogo task (70% Go) after being randomly assigned to one of three task difficulty conditions: High, Medium and Low, with RTDs of 300, 500 or 1000ms, respectively. Results revealed incremental increases in Go/Nogo errors and greater perceived effort with increasing difficulty. No condition differences were found for arousal, but the amplitude of the Nogo N2 increased and peaked earlier with increasing task difficulty. In contrast, the Nogo P3 effect was reduced in the High condition compared to the Low and Medium conditions. Finally, the amplitude of N1 and P2 showed differential effects, with Nogo N1 increasing with task difficulty, while the Nogo P2 decreased. This study provides valuable baseline behavioural and ERP data for appropriately manipulating difficulty (via RTD) in Go/Nogo tasks - highlighting the potential key role of not only the N2 and P3, but also the N1 and P2 components for task performance
The role of configurality in the Thatcher illusion: an ERP study
No full textThe Thatcher illusion (Thompson in Perception, 9, 483-484, 1980) is often explained as resulting from recognising a distortion of configural information when 'Thatcherised' faces are upright but not when inverted. However, recent behavioural studies suggest that there is an absence of perceptual configurality in upright Thatcherised faces (Donnelly et al. in Attention, Perception & Psychophysics, 74, 1475-1487, 2012) and both perceptual and decisional sources of configurality in behavioural tasks with Thatcherised stimuli (Mestry, Menneer et al. in Frontiers in Psychology, 3, 456, 2012). To examine sources linked to the behavioural experience of the illusion, we studied inversion and Thatcherisation of faces (comparing across conditions in which no features, the eyes, the mouth, or both features were Thatcherised) on a set of event-related potential (ERP) components. Effects of inversion were found at the N170, P2 and P3b. Effects of eye condition were restricted to the N170 generated in the right hemisphere. Critically, an interaction of orientation and eye Thatcherisation was found for the P3b amplitude. Results from an individual with acquired prosopagnosia who can discriminate Thatcherised from typical faces but cannot categorise them or perceive the illusion (Mestry, Donnelly et al. in Neuropsychologia, 50, 3410-3418, 2012) only differed from typical participants at the P3b component. Findings suggest the P3b links most directly to the experience of the illusion. Overall, the study showed evidence consistent with both perceptual and decisional sources and the need to consider both in relation to configurality
Impacts of inversion and Thatcherisation on face processing: mapping between ERP and GRT
No full textPrior work on the Thatcher illusion (Cornes et al., 2011; Mestry et al., 2012) has indicated both perceptual and decisional components of the illusion. We provide evidence of neural correlates associated with independent influences of inversion and level of feature manipulation (Thatcherisation) in the Thatcher illusion. We also provide an account of how ERP results can be interpreted within the configural processing framework defined by general recognition theory (GRT). We conducted a study examining inversion and the level of Thatcherisation (typical face, eyes Thatcherised, mouth Thatcherised, or both features Thatcherised) on a set of event-related components (the P1, N170, P2 and P3b) that have previously been considered in relation to the Thatcher illusion. Results reveal three independent effects: (1) inversion effects leading to increased amplitude for inverted faces at the N170 and P2 in the occipito-parietal area; (2) a reduction in N170 amplitude with level of Thatcherisation in the right hemisphere; and (3) inversion effects leading to increased amplitude for inverted faces at P3b in the centro-parietal area. This study reveals effects of Thatcherisation that are independent from effects of inversion in the ERP data. These effects can also be mapped to perceptual and decisional measures of configurality revealed in behavioural data using GRT (Mestry et al., 2012). We suggest the Thatcherisation effect at N170 may relate to violations of perceptual independence, the inversion effect across N170 and P2 may relate to violations of perceptual separability, and the inversion effect at P3b may relate to violations of decisional separability. Thus, we suggest a possible role for ERP data in providing a source of converging evidence for inferences regarding the role of perceptual and decisional factors in configurality
The late positive potential: a neural marker of the regulation of emotion-based approach-avoidance actions?
No full textThe ability to regulate our emotional responses is crucial to effective functioning in daily life. Whilst there has been extensive study of the brain potentials related to valenced stimuli, the neural basis of the ability to regulate actions elicited by these remains to be clarified. To address this, 40 volunteers undertook an approach-avoidance paradigm. In the congruent condition, participants approached pleasant and avoided unpleasant stimuli. In the incongruent condition, the opposite was the case, requiring the regulation of natural emotional response tendencies. Both behavioural and electrophysiological indices of emotional regulation were recorded. Congruency effects were observed at both the behavioural and electrophysiological level. Reaction times were faster and the LPP larger, when performing emotionally congruous relative to incongruous actions. Moreover, neural and behavioural effects were correlated. The current results suggest that the LPP congruency effect can be considered a neural marker of individual differences in emotion-driven action tendencies. We discuss whether this reflects emotion regulation, effort allocation, or correct mapping of stimulus response tendencies
Atypical neural responses to vocal anger in attention-deficit/hyperactivity disorder
No full textBackgroundDeficits in facial emotion processing, reported in attention-deficit/hyperactivity disorder (ADHD), have been linked to both early perceptual and later attentional components of event-related potentials (ERPs). However, the neural underpinnings of vocal emotion processing deficits in ADHD have yet to be characterised. Here, we report the first ERP study of vocal affective prosody processing in ADHD.MethodsEvent-related potentials of 6–11-year-old children with ADHD (n = 25) and typically developing controls (n = 25) were recorded as they completed a task measuring recognition of vocal prosodic stimuli (angry, happy and neutral). Audiometric assessments were conducted to screen for hearing impairments.ResultsChildren with ADHD were less accurate than controls at recognising vocal anger. Relative to controls, they displayed enhanced N100 and attenuated P300 components to vocal anger. The P300 effect was reduced, but remained significant, after controlling for N100 effects by rebaselining. Only the N100 effect was significant when children with ADHD and comorbid conduct disorder (n = 10) were excluded.ConclusionThis study provides the first evidence linking ADHD to atypical neural activity during the early perceptual stages of vocal anger processing. These effects may reflect preattentive hyper-vigilance to vocal anger in ADHD
“Can waiting awaken the resting brain?” a comparison of waiting- and cognitive task-induced attenuation of very low frequency neural oscillations
No full textThe default mode network (DMN) is characterised by coherent very low frequency (VLF) neural oscillations in the resting brain. The attenuation of this activity has been demonstrated following the transition from rest to performance of a broad range of cognitive goal-directed tasks. Whether the activity of resting state VLF oscillations is attenuated during non-cognitive goal-directed tasks such as waiting for rewarding outcomes is not known. This study examined the VLF EEG power from resting to performance of attention demanding task and two types of goal-directed waiting tasks. The association between the attenuation of VLF EEG power and Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms was examined.Direct current EEG (DC-EEG) data was collected from 32 healthy young adults (half high and half low ADHD symptom scorers) during (i) a rest state, (ii) while performing a cognitive demanding reaction time task (2CRT), and (iii) while undertaking each of two different goal-directed waiting conditions: “forced-to-wait (FW)” and “choose-to-wait (CW)” tasks. The spatial distribution of VLF EEG power across scalp was similar to that seen in previous resting VLF EEG studies. Significant rest-to-task attenuation of VLF EEG power occurred during the 2CRT and the CW task, but not during the FW task. The association between self-ratings of ADHD symptoms and waiting-induced attenuation was not significant.This study suggests VLF EEG power attenuation that occurs following rest to task transition is not simply determined by changes in cognitive load. The goal-directed nature of a task, its motivated nature and/or the involvement of effortful attention may also contribute. Future studies should explore the attenuation of resting state VLF oscillations during waiting and impulsive choice
The moderating effect of self-reported state and trait anxiety on the late positive potential to emotional faces in 6-11-year-old children
No full textIntroduction: The emergence of anxiety during childhood is accompanied by the development of attentional biases to threat. However, the neural mechanisms underlying these biases are poorly understood. In addition, previous research has not examined whether state and trait anxiety are independently associated with threat-related biases. Methods: We compared ERP waveforms during the processing of emotional faces in a population sample of 58 6-11-year-olds who completed self-reported measures of trait and state anxiety and depression. Results: The results showed that the P1 was larger to angry than neutral faces in the left hemisphere, though early components (P1, N170) were not strongly associated with child anxiety or depression. In contrast, Late Positive Potential (LPP) amplitudes to angry (vs. neutral) faces were significantly and positively associated with symptoms of anxiety/depression. In addition, the difference between LPPs for angry (vs. neutral) faces was independently associated with state and trait anxiety symptoms. Discussion: The results showed that neural responses to facial emotion in children with elevated symptoms of anxiety and depression were most evident at later processing stages characterized as evaluative and effortful. The findings support cognitive models of threat perception in anxiety and indicate that trait elements of anxiety and more transitory fluctuations in anxious affect are important in understanding individual variation in the neural response to threat in late childhood.</p
