Age-related changes in the brain electrical correlates of response control

About time: Ageing influences neural markers of temporal predictability

Timing abilities help organizing the temporal structure of events but are known to change systematically with age. Yet, how the neuronal signature of temporal predictability changes across the age span remains unclear. Younger (n = 21; 23.1 years) and older adults (n = 21; 68.5 years) performed an auditory oddball task, consisting of isochronous and random sound sequences. Results confirm an altered P50 response in the older compared to younger participants. P50 amplitudes differed between the isochronous and random temporal structures in younger, and for P200 in the older group. These results suggest less efficient sensory gating in older adults in both isochronous and random auditory sequences. N100 amplitudes were more negative for deviant tones. P300 amplitudes were parietally enhanced in younger, but not in older adults. In younger participants, the P50 results confirm that this component marks temporal predictability, indicating sensitive gating of temporally regular sound sequences.

Spino-cerebellar tDCS modulates N100 components of the P300 event related potential

OBJECTIVE

To evaluate the role of the cerebellum and spinal cord in cognitive processes, we assessed changes in event-related potentials (ERPs), before and after different combinations of spinal and cerebellar direct current stimulation (tDCS) in healthy subjects.

METHOD

We enrolled 37 volunteers (11 males and 26 females, aged 20-50 years), who were subsequently randomly assigned to one of four stimulation conditions: i) anodal cerebellar tDCS, with the reference electrode over the right shoulder; ii) anodal spinal tDCS, with the reference electrode over the right shoulder; iii) anodal spinal tDCS with cathodal cerebellar tDCS, and iv) sham stimulation. Stimulation intensity was set at 2 mA and delivered for 20 min. ERPs were assessed in an auditory oddball task before (T0) and 5 (T1) and 30 min (T2) after tDCS offset.

RESULTS

In condition iii, spino-cerebellar tDCS, the N100 component at T2 increased in amplitude by 60% (p = 0.019), whereas the sham stimulation left the N100 amplitude unchanged (p > 0.05).

CONCLUSION

The N100 wave reflects pre-attentive processes and correlates with arousal due to a specific stimuli and selective attention. Because spino-cerebellar tDCS induces electric fields in the brainstem, the facilitation of the N100 may be due to the modulation of the reticular formation. Regardless of the underlying mechanism, spino-cerebellar tDCS can help patients with deficits at the pre-attentive or selective attentional level.

Age Effects on Spatiotemporal Dynamics of Response Inhibition: An MEG Study

Inhibition, the ability to suppress irrelevant information, thoughts or movements, is crucial for humans to perform context-appropriate behaviors. It was suggested that declined cognitive performance in older adults might be attributed to inhibitory deficiencies. Although previous studies have shown an age-associated reduction in inhibitory ability, the understanding regarding its cortical spatiotemporal maps remained limited. Thus, we used a whole-head magnetoencephalography (MEG) to elucidate the age effects on response inhibition, and to explore the brain activation differences in high- and low-performing seniors. We recruited 22 younger and 22 older adults to participate in the visual Go/No-go task. Both behavioral performance and neuromagnetic responses to No-go stimuli were analyzed. The behavioral results showed that the older adults made more false alarm (FA) errors than the younger adults did. The MEG results showed that the seniors exhibited declined cortical activities in middle temporal gyrus (MTG) and delayed activation in MTG, prefrontal cortex (PFC) and pre-supplementary motor area (pre-SMA). Furthermore, among the older adults, more recruitment of the left PFC was found in the high-performers than in the lower-performers. In conclusion, age-related deficiencies in response inhibition were observed in both behavioral performance and neurophysiological measurement. Our results also suggested that frontal recruitment plays a compensatory role in successful inhibition.

The Effect of Aging in Inhibitory Control of Major Depressive Disorder Revealed by Event-Related Potentials

Elderly depressed patients manifest pronounced executive dysfunction compared with younger subjects with depressive disorder. Aging-related brain changes may result in executive dysfunction in geriatric depression. We investigated the neural correlates of inhibitory control processing in depressed subjects at different ages using event-related potentials (ERPs). A equiprobable visual Go/Nogo task was used in 19 young (27.4 ± 5.0 years) and 18 elderly (70.8 ± 6.9 years) depressed subjects and their age-matched healthy controls (20 young subjects, 26.2 ± 3.7 years, and 18 elderly subjects, 68.1 ± 4.8 years). The responses were based on two types of equilateral triangular figures of upright (Go) and inverted triangle (Nogo). The elderly subjects exhibited later N2 and P3 latencies, and larger Go-N2 and P3 amplitudes, compared with the younger subjects. Further, the elderly controls displayed smaller P3 in the central and parietal regions, and yielded larger Nogo-P3 amplitude in the frontal region compared with younger controls. While the young depressed patients yielded smaller P3 amplitude than the controls across frontal, central and parietal regions, elderly depressed patients yielded smaller P3 than the elderly controls only in the frontal region. Our results suggest that the inhibitory control subprocesses are differentially affected by depression and aging. The stimulus response speed and the effort intensity of inhibition control are specifically impaired in the elderly depressed patients. And the diminished amplitudes of frontal P3 in the elderly depression imply a frontal dysfunction mechanism.

Asymmetry in stimulus and response conflict processing across the adult lifespan: ERP and EMG evidence

Several studies have shown that conflict processing improves from childhood to adulthood and declines from adulthood to old age. However the neural mechanisms underlying this lifespan asymmetry were previously unexplored. We combined event-related potentials (ERPs) and electromyography (EMG) to examine lifespan changes in stimulus and response conflict processing using a modified Stroop task. We used a Stroop task that a priori dissociated stimulus and response conflict. Delayed P3b latency and increased amplitude revealed that middle age adults have a deficit in stimulus processing. Additionally a sustained P3a across frontal and central electrodes occurred only in middle age adults indicating the recruitment of frontal activity. Conversely, decreased lateralized readiness potential (LRP) amplitude and increased EMG activity in the incorrect hand in adolescents reveal protracted development of response processing into late adolescence. The N450, a measure of conflict processing, was found to be sensitive to both stimulus and response conflict. Altogether these results provide evidence for asymmetrical differences in stimulus and response conflict processing across adolescence, young adulthood and middle age.

Familiality of neural preparation and response control in childhood attention deficit-hyperactivity disorder

BACKGROUND

Patients with attention deficit-hyperactivity disorder (ADHD) exhibit difficulties in multiple attentional functions. Although high heritability rates suggest a strong genetic impact, aetiological pathways from genes and environmental factors to the ADHD phenotype are not well understood. Tracking the time course of deviant task processing using event-related electrophysiological brain activity should characterize the impact of familiality on the sequence of cognitive functions from preparation to response control in ADHD. Method Preparation and response control were assessed using behavioural and electrophysiological parameters of two versions of a cued continuous performance test with varying attentional load in boys with ADHD combined type (n = 97), their non-affected siblings (n = 27) and control children without a family history of ADHD (n = 43).

RESULTS

Children with ADHD and non-affected siblings showed more variable performance and made more omission errors than controls. The preparatory Cue-P3 and contingent negative variation (CNV) following cues were reduced in both ADHD children and their non-affected siblings compared with controls. The NoGo-P3 was diminished in ADHD compared with controls whilst non-affected siblings were located intermediate but did not differ from both other groups. No clear familiality effects were found for the Go-P3. Better task performance was further associated with higher CNV and P3 amplitudes.

CONCLUSIONS

Impairments in performance and electrophysiological parameters reflecting preparatory processes and to some extend also for inhibitory response control, especially under high attentional load, appeared to be familially driven in ADHD and may thus constitute functionally relevant endophenotypes for the disorder.

Neural correlates of attentional and executive processing in middle-age fencers

PURPOSE

Open-skill sports require high levels of visual attention and fast and flexible decision making and action execution. We evaluated whether these sports may counteract the well-known age-related declines in executive processing.

METHODS

Young and middle-age fencers and nonathletes were studied. Participants (N = 40) performed visual motor tasks while reaction times (RTs) and event-related potentials were recorded.

RESULTS

RTs were slower for the older subjects, but accuracy was not impaired. At event-related potential level, the late P3 component was delayed in older subjects, but those who participated in sports showed less delay. The RTs of middle-age and young fencers were comparable; the P1 latency of middle-age fencers was similar to that of the younger subjects; the N1 was enhanced in older, as well as younger, fencers; the N2 component of fencers had shorter latencies and larger amplitudes than nonathletes; and in no-go trials, the P3 component was enhanced in fencers independent of age.

CONCLUSIONS

Overall, the practice of open-skill sports was associated with improvement of the executive functions that are already degraded at middle age.

Differential relationships between sub-traits of BIS-11 impulsivity and executive processes: an ERP study

There is mixed evidence for a relationship between impulsivity and executive functions. Although impulsivity is heterogeneous, previous research did not examine partial relationships controlling for shared variance across sub-traits to evaluate the specificity of these associations. Eighty-five undergraduates completed the Barratt Impulsiveness Scale-11 (BIS-11) and the AX-expectancy version of the Continuous Performance Task (AX-CPT). This task engenders a conflict between two response tendencies by manipulating the frequency of specific trial types. We conducted mixed model analyses to determine the unique variance in behavioral and electrophysiological indices of relevant cognitive functions accounted for by the facets of BIS-11. Motor Impulsiveness was associated with smaller P3 across sites and conditions suggesting a general cognitive limitation not specific to the condition requiring the most inhibition, and larger N2 in some conditions indicating heightened conflict detection. Non-Planning Impulsiveness was related to smaller N2 when inhibiting a primed response and with greater P3 in some contexts. Attentional Impulsiveness appeared to be associated with an inefficient conflict detection system indicated by relatively normal engagement in trials involving the non-potent response, but relatively over engagement in the prepotent condition. Our findings suggest that sub-traits of impulsivity are differentially related to executive processes.

Hypofrontality in schizophrenic patients and its relevance for the choice of antipsychotic medication: an event-related potential study

OBJECTIVES

One of the neurobiological core features of schizophrenic illnesses is a hypo-functionality of the frontal cortex ("cerebral hypofrontality"). The two major classes of antipsychotic medication differ regarding their impact on frontal lobe function and metabolism, with a presumably more positive effect of "atypical" compared to "typical" agents. To date, neurobiological markers reliably predicting the treatment response to different antipsychotics are lacking. The present study, therefore, aimed at establishing a neurophysiological marker of frontal lobe function (NoGo-Anteriorization, NGA) as a predictor of the treatment response to first- and second-generation antipsychotics.

METHODS

Seventy-six schizophrenic patients were examined three times over a 6-week study period. Patients were treated with first- or second-generation antipsychotics, and NGA, neurocognitive performance, and symptomatology were assessed on admission as well as during two follow-up measurements.

RESULTS

Baseline NGA values significantly predicted the treatment response to typical and atypical antipsychotics; however, the direction of this prediction was dependent on the antipsychotic drug regimen. Moreover, atypical antipsychotics had a superior impact on neurocognitive performance and self-reported quality of life.

CONCLUSIONS

The NGA might be a useful tool in developing individualized treatment strategies based on pathophysiological aspects of schizophrenic illnesses that can be easily determined in clinical routine settings.

Dissociation of motor and sensory inhibition processes in normal aging

OBJECTIVE

Age-related cognitive impairments have been attributed to deficits in inhibitory processes that mediate both motor restraint and sensory filtering. However, behavioral studies have failed to show an association between tasks that measure these distinct types of inhibition. In the present study, we hypothesized neural markers reflecting each type of inhibition may reveal a relationship across inhibitory domains in older adults.

METHODS

Electroencephalography (EEG) and behavioral measures were used to explore whether there was an across-participant correlation between sensory suppression and motor inhibition. Sixteen healthy older adult participants (65-80 years) engaged in two separate experimental paradigms: a selective attention, delayed-recognition task and a stop-signal task.

RESULTS

Findings revealed no significant relationship existed between neural markers of sensory suppression (P1 amplitude; N170 latency) and markers of motor inhibition (N2 and P3 amplitude and latency) in older adults.

CONCLUSIONS

These distinct inhibitory domains are differentially impacted in normal aging, as evidenced by previous behavioral work and the current neural findings. Thus a generalized inhibitory deficit may not be a common impairment in cognitive aging.

SIGNIFICANCE

Given that some theories of cognitive aging suggest age-related failure of inhibitory mechanisms may span different modalities, the present findings contribute to an alternative view where age-related declines within each inhibitory modality are unrelated.

Targets and non-targets in the aging brain: A go/nogo event-related potential study

This study tested whether older adults show enhanced suppression of inappropriate processing of non-target information, as marked with the nogo-P3 event-related potential (ERP). Healthy younger and older adults were tested on a simple go/nogo task with visually presented numbers. Unlike in most of the previous studies, go and nogo stimuli were matched for frequency and conflict level in order to minimize the impact of task difficulty, probability monitoring, or conflict detection and resolution on the age-related ERP differences. Older adults showed slower go responses but a comparable accuracy to younger controls. The parietal go-P3 latency was also delayed with aging, while the central nogo-P3 was more pronounced in older adults than in younger controls. The amplitude of this component negatively correlated with go-RTs. In line with previous studies, this suggests that a partial response preparation to nogo events is strongly suppressed in older adults, especially faster ones.

Cognitive control in late-life depression: response inhibition deficits and dysfunction of the anterior cingulate cortex

OBJECTIVES

Geriatric depression is associated with frontolimbic functional deficits, and this frontal dysfunction may underlie the marked executive control deficits often seen in this population. The authors' goal was to assess the integrity of frontal cortical functioning in geriatric depression, while these individuals performed a standard cognitive control task. The N2 component of the event-related potential (ERP), an evoked response generated within the anterior cingulate cortex (ACC), is significantly enhanced when nondepressed individuals successfully inhibit a response, providing an excellent metric of frontal inhibitory function.

DESIGN

The authors used a variant of a demanding Go/NoGo task-switching paradigm that required participants to inhibit response execution during NoGo trials by overcoming a potent response tendency established by frequent Go trials.

PARTICIPANTS

The authors compared a cohort of depressed geriatric outpatients (N = 11) with a similarly aged group of nondepressed participants (N = 11).

MEASUREMENTS

Reaction times, accuracy, and high-density event-related potential recordings from a 64-channel electrode montage were obtained.

RESULTS

A significantly enhanced N2 to NoGo trials was observed in nondepressed elderly participants, with generators localized to the ACC. In contrast, this enhancement was strongly reduced in the depressed sample. Source analysis and topographic mapping pointed to a displacement of N2 generators toward more posterior areas of the middle frontal gyrus in depressed subjects.

CONCLUSIONS

Findings confirm previous reports of an inhibitory control deficit in depressed elderly who show significantly increased rates of commission errors (i.e., failures to inhibit responses on NoGo trials). Electrophysiologic data suggest underlying dysfunction in ACC as the basis for this deficit.

Dopamine transporter (SLC6A3) genotype impacts neurophysiological correlates of cognitive response control in an adult sample of patients with ADHD

Studies provide ample evidence for a dysfunction in dopaminergic neurotransmission in Attention-Deficit/Hyperactivity Disorder (ADHD). In that respect, a common variable number of tandem repeats (VNTR) polymorphism in the 3' untranslated region (UTR) of the dopamine transporter gene (SLC6A3) has been repeatedly associated with the disorder. Here, we examined the influence of the common 9- and 10-repeat alleles of SLC6A3 on prefrontal brain functioning and cognitive response control in a large sample of adult ADHD patients (n=161) and healthy controls (n=109). To this end, we inspected a neurophysiological marker of cognitive response control (NoGo anteriorization, NGA) elicited by means of a Go-NoGo task (continuous performance test, CPT). Within the group of ADHD patients, nine-repeat allele carriers showed significantly reduced NGA, whereas no influence of SLC6A3 genotype was observed in the control group. In contrast to previous association studies of children, the nine-repeat-not the 10-repeat-allele was associated with functional impairments in our sample of adult ADHD patients. Our findings confirm a significant effect of the SLC6A3 genotype on the neurophysiological correlates of cognitive response control in ADHD, and indicate that still to-be-identified age-related factors are important variables modulating the effect of genetic factors on endophenotypes.

Reduced NoGo-anteriorisation during continuous performance test in deletion syndrome 22q11.2

Deletion syndrome 22q11.2 (DS22q11.2) is a high-risk factor for psychiatric disorders. Alterations in brain morphology and function including the anterior cingulate cortex (ACC) are suggested to underlie the increased psychiatric disposition. We assessed response-inhibition in patients with DS22q11.2 (n=13) and healthy controls (n=13) matched for age, sex, and handedness by means of a Go-NoGo-Task during recording of a multi-channel electroencephalography (EEG). Analysis of event-related potentials (P300) resulted in an aberrant topographical pattern and NoGo-anteriorisation (NGA) as a parameter of medial prefrontal function was significantly reduced in patients with DS22q11.2 compared to controls. Differences in IQ between groups did not account for the findings. Source localization analysis (LORETA) revealed diminished left temporal brain activation during the Go-condition, but no altered ACC activation in DS22q11 during the NoGo-condition. Despite recent reports of structural alterations of the ACC in DS22q11.2 our findings suggest that response-inhibition mediated by the ACC is not impaired in DS22q11.2.

Alpha Brain Oscillations and Inhibitory Control

A major challenge for developmental cognitive neuroscience is to understand how changes in cognitive functions related to aging are associated with changes in the neuronal information processing architecture. Previous studies on EEG event-related brain oscillations suggest functional changes in alpha-bands with age during sensory and memory tasks. Specifically, the topographical distribution of both single-trial lower and upper alpha magnitude and the corresponding phase coherence is altered in elderly persons. Thus, alpha oscillations, associated not only with sensory, but also with sensorimotor functions, may be altered with age. Compensatory mechanisms, possibly reflected in increased frontal alpha synchronization, may thereby be of profound relevance. The present study investigates age-related differences in the modulation of alpha oscillatory activity related to sensory and sensorimotor functions, including response preparation, execution, and inhibition. EEG was recorded while 10 young and 10 elderly persons performed a visual evoked potential (VEP), a cued stimulus response (S-R), and a cued visual Go/NoGo task. Early event-related synchronization (ERS, 0–250 ms) and late event-related desynchronization (ERD, 200–600 ms) of single-trial lower and upper alpha was analyzed using poststimulus amplitude enhancement and intertrial phase coherence measures. The results show comparable modulations of lower (8–10 Hz) and upper (10–15 Hz) alpha activity in young and elderly related to the sensory and different forms of motor response processing. Specifically, reduced early lower alpha ERS as well as late upper alpha ERD at central locations characterized response inhibition processing in both age groups. We discuss the counterintuitive hypothesis that reduced efficacy of some basal neural inhibitory mechanisms enables older observers to perform better than or comparable to younger observers on some visual tasks, and conclude that alterations in alpha oscillatory networks with age may depend on the stimuli applied.

Changes in the neural bases of emotion regulation associated with clinical improvement in children with behavior problems

Children's behavior problems may stem from ineffective cortical mechanisms for regulating negative emotions, and the success of interventions may depend on their impact on such mechanisms. We examined neurophysiological markers associated with emotion regulation in children comorbid for externalizing and internalizing problems before and after treatment. We hypothesized that treatment success would correspond with reduced ventral prefrontal activation, and increased dorsomedial prefrontal activation, at the time point of an event-related potential (ERP) associated with inhibitory control. Twenty-seven 8- to 12-year-old children (with usable data) were tested before and after a 14-week community-based treatment program and assessed as to improvement status. Fifteen 8- to 12-year-olds from the normal population (with usable data) were tested over the same interval. All children completed an emotion-induction go/no-go task while fitted with a 128-channel electrode net at each test session. ERP amplitudes, and estimates of cortical activation in prefrontal regions of interest, were measured at the peak of the "inhibitory" N2 and compared between improvers, nonimprovers, and nonclinical children. ERP amplitudes showed no group differences. However, improvers showed an overall reduction in ventral prefrontal activation from pretreatment to posttreatment, bringing them in line with nonclinical children, whereas ventral activation remained high for nonimprovers. Both improvers and nonimprovers showed high dorsal activation relative to nonclinical children. Supplementary analyses indicated that only ventral prefrontal regions, and only within the N2 time window, showed decreased activity from pre- to posttreatment, suggesting changes in regulatory processes rather than in overall emotional arousal. These cortically mediated changes may permit a reduction in the overengaged, rigid style of emotion regulation characteristic of children with behavior problems.

Impulsiveness and ERP components in a Go/Nogo task

Impulsiveness has been linked to fast guesses and premature responses in reaction time tasks like the Eriksen flanker task or the Go/Nogo task. In the present study, healthy subjects without history of DSM-IV Axis I or II psychopathology were examined. Impulsiveness was determined by calculating individual reaction times (as a function of general response speed) in order to split the entire group (n = 26) in a subgroup with a more controlled response style (low impulsiveness [LI] group; n = 13) and a subgroup with a more impulsive response style (high impulsiveness [HI] group; n = 13). Subjects performed a Go/Nogo task while a multi-channel EEG was recorded. Two event-related potentials (ERP) were of special interest: the Nogo-N2 and -P3 component. HI subjects had significantly reduced (less positive) Nogo-P3 amplitudes compared to LI subjects whereas groups did not differ with regard to the Nogo-N2. These results corroborate previous findings of reduced Nogo-P3 amplitudes in samples with enhanced levels of impulsiveness. Moreover, present data suggest that there is a broader range of impulsiveness even in healthy subjects which might mask or pronounce between-group differences in clinical studies. Therefore, different levels of impulsiveness in control groups should be carefully taken into account in further ERP studies.

Consensus paper of the WFSBP Task Force on Biological Markers: biological markers in depression

Biological markers for depression are of great interest to aid in elucidating the causes of major depression. We assess currently available biological markers to query their validity for aiding in the diagnosis of major depression. We specifically focus on neurotrophic factors, serotonergic markers, biochemical markers, immunological markers, neuroimaging, neurophysiological findings, and neuropsychological markers. We delineate the most robust biological markers of major depression. These include decreased platelet imipramine binding, decreased 5-HT1A receptor expression, increase of soluble interleukin-2 receptor and interleukin-6 in serum, decreased brain-derived neurotrophic factor in serum, hypocholesterolemia, low blood folate levels, and impaired suppression of the dexamethasone suppression test. To date, however, none of these markers are sufficiently specific to contribute to the diagnosis of major depression. Thus, with regard to new diagnostic manuals such as DSM-V and ICD-11 which are currently assessing whether biological markers may be included in diagnostic criteria, no biological markers for major depression are currently available for inclusion in the diagnostic criteria.

Improvement of prefrontal brain function in endogenous psychoses under atypical antipsychotic treatment

Typical and atypical antipsychotics are thought to exert their effects on different neurotransmitter pathways with specific action of atypical compounds on the prefrontal cortex, but studies directly investigating the effect of those drugs on neurophysiological measures of prefrontal brain function are sparse. We therefore investigated the influence of different antipsychotics on an electrophysiological marker of prefrontal brain function (NoGo anteriorization, NGA) and neuropsychological test scores. For this purpose, 38 patients with endogenous psychoses were investigated at the beginning of a stationary psychiatric treatment and at a 6-week-follow-up. Patients were treated with typical or atypical antipsychotics, or a combination of both. They underwent psychopathological diagnostic and neuropsychological testing, as well as electrophysiological investigations during a Continuous Performance Test. The results indicate that typical and atypical antipsychotics differentially affected the development of the NGA over the course of the treatment, typical antipsychotics tending to result in decreased values at follow-up, and atypical antipsychotics stabilizing, or increasing this parameter. Performance in tests of frontal lobe function generally declined under typical antipsychotics and improved with atypical compounds, changes in Stroop interference correlated with changes in the NGA. We conclude that typical and atypical antipsychotics differ regarding their effect on prefrontal brain function in schizophrenia, atypical neuroleptics often showing a more favorable impact than conventional antipsychotics on respective parameters.

Electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder

In this study, we have attempted to determine the electrophysiological correlates of behavioral response inhibition in patients with obsessive-compulsive disorder (OCD). To evaluate response inhibition ability, we have used the Go/NoGo task and measured N2 and P3 event-related potential (ERP) components. Both the OCD and control groups exhibited greater and more frontally distributed N2 and P3 amplitudes in the NoGo condition compared to what we observed in the Go condition. However, the patients with OCD also manifested reduced NoGo-N2 and Go-N2 amplitudes at the frontocentral electrode sites compared to the controls. In addition, the NoGo-N2 amplitudes were more posteriorly distributed in patients with OCD than in controls. The NoGo-N2 amplitudes and latencies measured at the central sites were also negatively correlated with the obsession score on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). The OCD and control groups were comparable with regard to Go-P3 and NoGo-P3 amplitude and latencies. Our findings suggest dysfunctions in frontal regions mediating response inhibition in OCD, consistent with the involvement of response inhibition in the pathophysiology of this disorder. In addition, NoGo-N2 seems to result in more accurate response inhibition measurements in patients with OCD than does NoGo-P3.

Event-related potential measures of emotion regulation in early childhood

Emotion regulation in adults may be mediated by frontal cortical activities that adjust attention in response to challenging emotions. We examined event-related potentials across emotional conditions to assess normative patterns and individual differences in cortical mechanisms of emotion regulation in 4-6-year-olds. The children viewed pictures of angry, neutral, and happy faces during a Go/No-go task. Angry faces generated the greatest (frontocentral) N2 amplitudes and fastest N2 latencies, and happy faces produced the smallest amplitudes and slowest latencies. Frontal electrodes showed larger N2s to angry faces in the Go condition. The P3b was also largest for angry faces. More fearful children showed faster latency N2s to angry faces. These results are interpreted in terms of early-developing mechanisms for regulating anxiety and processing emotional information.

A Developmental Investigation of Stop-Signal Inhibition

Abstract. The present study examined the development of response inhibition in the stop-signal task across child (8-13 years), young-adult (18-22 years), and middle-aged adult (29-47 years) groups through a dissociation of low- and higher-frequency ERP activity. Fifty-one subjects (n = 17 in each group) performed the stop-signal task, which consisted of a visual choice reaction time (RT) task and auditory stop-signals, while EEG was recorded. The original EEG data (0.01-30 Hz) was subsequently filtered to separate slow-wave (0.01-2 Hz) and residual (2-30 Hz) activity. Performance findings revealed that stop-signal reaction time (SSRT) decreased from the child to young-adult group and then showed a small increase in the middle-aged adult group. Original ERPs revealed decreasing N1 and N2 amplitudes and increasing P2 and P3 amplitudes across the scalp with increasing age for successful-stop trials. These developmental effects did not occur in the residual waveforms after removal of slow-wave activity. For failed-stop trials, a response-locked negative component, identified as the error-negativity (Ne), showed an age-related decrease in amplitude across the scalp in the residual, but not the original, waveform. The error-positivity (Pe) increased in amplitude with age in the original data, but this was accounted for by a positive slow-wave (PSW). Together, the findings suggest that underlying slow-wave activity accounts for a large number of developmental effects in the traditionally quantified ERP components, but may also obscure effects occurring in residual activity. These findings highlight the importance of dissociating low- and higher-frequency ERP activity in developmental research.

The development of stop-signal and Go/Nogo response inhibition in children aged 7–12 years: Performance and event-related potential indices

The present study examined the development of response inhibition during the Stop-signal and Go/Nogo tasks in children using performance and ERP measures. Twenty-four children aged 7 to 12 years completed both tasks, each with an auditory Nogo/Stop-signal presented on 30% of trials. On average, response inhibition was more difficult in the Stop-signal than Go/Nogo task. Response inhibition performance did not develop significantly across the age range, while response execution varied significantly in a task dependent manner (Go/Nogo: increasing accuracy and reducing response variability with age; Stop-signal: reducing Go mean reaction time and response variability with age). The N1, P2, N2 and P3 components showed different scalp distributions, with N1 and P2 peaking earlier, and P3 later, in Nogo compared to Stop stimuli. N2 and P3 amplitude were positively correlated with successful inhibition probability in the Go/Nogo task only. N2 amplitude and latency to both Nogo and successful Stop stimuli decreased linearly with age, but not in the frontal regions. N1 and P3 amplitude in the parietal region increased with age for Stop-signals. An age-related reduction in P3 latency to Nogo stimuli correlated significantly with reduced RT and variability in Go responding, indicating a relationship between efficient Nogo and Go processing. Together the behavioural and ERP results suggest little development of the response inhibition process as measured via the Stop-signal and Go/Nogo tasks across the 7 to 12 year age range, while response execution processes develop substantially.

DTNBP1 (dysbindin) gene variants modulate prefrontal brain function in healthy individuals

DTNBP1 (dysbindin) is one of the several putative schizophrenia genes supported by association, neuroanatomical, and cellular studies. These suggest an involvement of DTNBP1 in the prefrontal cortex and cognitive functions mediated by interaction with neurotransmitter systems, in particular glutamate. The influence of DTNBP1 gene variation on prefrontal brain function at the systemic neurophysiological level, though, has not been characterized. The NoGo-anteriorization (NGA) as an event-related potential (ERP) measure elicited during the continuous performance test (CPT) has been established as a valid neurophysiological parameter for prefrontal brain function in healthy individuals and patients with schizophrenias. In the present study, we therefore investigated the influence of eight dysbindin gene variants on the NGA as a marker of prefrontal brain function in 48 healthy individuals. Two DTNBP1 polymorphisms previously linked to schizophrenia (P1765 and P1320) were found associated with changes in the NGA. Post hoc analysis showing an influence of genetic variation at these loci on the Go centroid and frontal amplitudes suggest that this might be due to modification of the execution of motor processes by the prefrontal cortex. This is the first report on a role of DTNBP1 gene variation for prefrontal brain function at a systemic neurophysiological level in healthy humans. Future studies will have to address the relevance of this observation for patients with schizophrenias.

Comparative analysis of event-related potentials during Go/NoGo and CPT: Decomposition of electrophysiological markers of response inhibition and sustained attention

Neuropsychological tests target specific cognitive functions; however, numerous cognitive subcomponents are involved in each test. The aim of this study was to decompose the components of two frontal executive function tests, Go/NoGo (GNG) and cued continuous performance task (CPT), by analyzing event-related potentials (ERPs) of 24 subjects both in time and time-frequency domains. In the time domain, P1, N1, P2, N2 and P3 peak amplitudes and latencies and mean amplitudes of 100 ms time windows of the post-P3 time period were measured. For GNG, the N1 amplitude and for both GNG and CPT N2 amplitudes were significantly higher in the NoGo condition compared with the Go condition. P3 had a central maximum in the NoGo conditions of both paradigms in contrast to a parietal maximum in the Go conditions. All peaks except P1 and mean amplitudes of the post-P3 period were more positive in CPT compared to those of GNG. N1, N2 and P3 latencies were longer for the NoGo condition than the Go condition in the CPT. In time-frequency analyses, the NoGo condition evoked higher theta coefficients than the Go condition, whereas the CPT and GNG paradigms differed mainly in the delta band. These results suggest that theta component reflects response inhibition in both GNG and CPT, whereas delta component reflects the more demanding sustained attention requirement of the CPT. The latency prolongation observed with the NoGo condition of the CPT paradigm was thought to be due to perseverance/inhibition conflict enhanced by the primer stimuli in CPT.

On the relation of movement-related potentials to the go/no-go effect on P3

According to Simson et al. [Simson, R., Vaughan, H.G., Jr., Ritter, W., 1977. The scalp topography of potentials in auditory and visual go/nogo tasks. Electroencephalography and Clinical Neurophysiology 43, 864-875], the difference between no-go P3 and go-P3 (the go/no-go effect) is due to overlap of P3 onto the return of the preceding contingent negative variation (CNV) in no-go trials and onto the continuing CNV in go trials. Similarly, according to Kok [Kok, A., 1986. Effects of degradation of visual stimuli on components of the event-related potential (ERP) in go/nogo reaction tasks. Biological Psychology 23, 21-38], the go/no-go effect is due to movement-related negative potentials, in particular contralateral negativity, adding with P3 in go trials. To investigate these notions, we studied how CNV, go-P3 and no-go P3 are lateralized at fronto-central sites when the side of the response varies across trials, comparing these effects between hand movements and eye movements and delineating them more precisely for hand movements with multichannel recordings. The go/no-go effect was larger and contralaterally lateralized with hand movements than with eye movements. Dipole analysis dissected its components into a large contribution of the medial cingulate gyrus, into activity of motor areas contralateral to the cued hand and a left-frontal source. Motor-related portions of the effect seemed to build upon and extend motor-related components included in CNV. Results provide support for the notion that the go/no-go effect is related to movement-related potentials. We suggest that go-P3 and no-go P3 are characterized by addition and reduction of motor-related activation to the core P3.

Neurophysiological Correlates of Emotion Regulation in Children and Adolescents

Psychologists consider emotion regulation a critical developmental acquisition. Yet, there has been very little research on the neural underpinnings of emotion regulation across childhood and adolescence. We selected two ERP components associated with inhibitory control—the frontal N2 and frontal P3. We recorded these components before, during, and after a negative emotion induction, and compared their amplitude, latency, and source localization over age. Fifty-eight children 5–16 years of age engaged in a simple go/no-go procedure in which points for successful performance earned a valued prize. The temporary loss of all points triggered negative emotions, as confirmed by self-report scales. Both the frontal N2 and frontal P3 decreased in amplitude and latency with age, consistent with the hypothesis of increasing cortical efficiency. Amplitudes were also greater following the emotion induction, only for adolescents for the N2 but across the age span for the frontal P3, suggesting different but overlapping profiles of emotion-related control mechanisms. No-go N2 amplitudes were greater than go N2 amplitudes following the emotion induction at all ages, suggesting a consistent effect of negative emotion on mechanisms of response inhibition. No-go P3 amplitudes were also greater than go P3 amplitudes and they decreased with age, whereas go P3 amplitudes remained low. Finally, source modeling indicated a developmental decline in central-posterior midline activity paralleled by increasing activity in frontal midline regions suggestive of the anterior cingulate cortex. Negative emotion induction corresponded with an additional right ventral prefrontal or temporal generator beginning in middle childhood.

Age effect on far field potentials from the brain stem after transcutaneous vagus nerve stimulation

Recently, a new electrophysiological method for the assessment of vagus nerve function in the brainstem has been proposed in healthy participants. Before this procedure may be applied to patients with neurodegenerative diseases, its feasibility in elderly healthy participants and a possible age effect on the measurement have to be investigated. The vagus sensory evoked potentials (VSEP) after transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve have been assessed in healthy younger and elderly participants. VSEP measured as far field potentials probably originating in vagus nuclei in the brainstem were recorded in 20 of 22 younger as well as in 39 of 43 elderly healthy participants. Latencies were significantly longer in the elderly as compared to the younger participants, while no clear age effects on amplitudes were identified. These results indicate that the assessment of VSEP is feasible also in elderly healthy participants. This is a prerequisite for testing this method in elderly patients with neurodegenerative diseases like Alzheimer and Parkinson disease as a noninvasive tool to detect an affection of the brainstem nuclei of the vagus nerve early in their course.

Diminished prefrontal brain function in adults with psychopathology in childhood related to attention deficit hyperactivity disorder

The aim of the present study was to investigate prefrontal brain function and cognitive response control in patients with personality disorders who either suffered or did not suffer from psychopathology related to attention deficit hyperactivity disorder (ADHD) during childhood. For this purpose, 36 psychiatric out-patients with personality disorders--24 of whom showed ADHD-related psychopathology during childhood assessed by the German short form of the Wender Utah Rating Scale--and 24 healthy controls were investigated electrophysiologically by means of a cued Go-NoGo task (Continuous Performance Test). Topographical analyses were conducted to individually quantify the NoGo anteriorisation (NGA), a neurophysiological correlate of prefrontal response control that has been suggested to reflect activation of the anterior cingulate cortex. ADHD patients exhibited a significantly reduced mean NGA and diminished amplitudes of the Global Field Power, as well as a reduced increase of fronto-central P300 amplitudes, in NoGo-trials compared with the healthy controls, whereas patients with personality disorders alone did not differ from the control group in any of the electrophysiological parameters. The results indicate that ADHD-related psychopathology is associated with prefrontal brain dysfunction, probably related to processes of response inhibition and/or cognitive response control.

Event-related potentials for response inhibition in Parkinson's disease

This study investigated inhibitory function in patients with Parkinson's disease (PD) by recording event-related brain potentials (ERPs) during a Go/NoGo task. Fourteen healthy volunteers and 13 patients with PD without dementia performed a cued continuous performance test that included Go and NoGo trials. The peak latency, amplitude, and topographic distributions of the ERPs to Go and NoGo stimuli were analyzed. Cognitive function was evaluated using the Wisconsin Card Sorting Test (WCST), Kana Pick-out Test, and Verbal Fluency Test (VFT). Performances in the WCST and VFT were significantly impaired in the PD group as compared with the control group. The PD group had significantly higher rates of omission and commission errors during the ERP task. The ERP study found no differences in the latency and amplitude of the Go-P3 between the two groups. By contrast, the NoGo-P3 latency was significantly longer in the PD group than in the control group. The amplitudes of the NoGo-P3 and NoGo-N2 were also significantly smaller in the PD group than in the control group. The NoGo-P3 latency was significantly correlated with the Kana Pick-out Test and VFT scores. The NoGo-P3 amplitude was significantly correlated with the WCST and VFT scores, as well as with the number of commission errors. There were no significant correlations between the cognitive function tests and either the Go-P3 or NoGo-N2 measures. The behavioral and ERP data suggest that there is selective impairment of inhibitory function in PD and that this deficit may be related to impaired inhibitory executive function in the frontal lobe.

Electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task

OBJECTIVE

The aim was to verify the occurrence of proposed electrophysiological correlates of attention, inhibition, sensitivity and bias in a continuous performance task and to support their functional interpretation by using a manipulation intended to enhance subjects' response bias.

METHODS

Electroencephalographic activity was recorded during administration of a transformed version of the AX continuous performance task in which cues signaled response alternatives.

RESULTS

The previously reported parietal P3, NoGo-N2, NoGo-P3 and contingent negative variation were replicated. Besides, the frontal selection positivity and the lateralized readiness potential were demonstrated. With increasing Go-probability, the parietal P3 to the cue increased without changes in other cue-related correlates. In addition, reaction times decreased, non-parametric measures of sensitivity and bias decreased, the NoGo-N2 increased, and the parietal Go-P3 decreased.

CONCLUSIONS

The proposed electrophysiological correlates were identified. Sub-threshold LRPs suggested a central inhibition mechanism. Cue-related correlates revealed that anticipation of a high-probability Go-stimulus involves attention rather than bias. This implies that the increased NoGo-N2 reflected an increase in conflict rather than an increase in inhibition.

SIGNIFICANCE

Electrophysiological measures can greatly enhance our understanding of normal and abnormal information processing during continuous performance and related tasks.

The NoGo P300 'anteriorization' effect and response inhibition

OBJECTIVE

The P300 event-related potential shows anterior P300 increases on NoGo tasks (target stimulus=withhold response) relative to Go tasks (target stimulus=commit response). This 'NoGo anteriorization' has been hypothesized to reflect response inhibition. However, silent-count tasks show similar P300 anteriorization. The P300 anteriorization on silent-count tasks relative to Go tasks cannot reflect inhibition-related processes, and questions the degree to which anteriorization observed on NoGo trials can be ascribed to response inhibition. Comparison of anteriorization between the silent-count and NoGo tasks is thus essential. P300 topography on NoGo and silent-count tasks has not been previously compared.

METHODS

P300 on Go, NoGo, and silent-count auditory oddball tasks were compared. If the NoGo P300 anteriorization reflects response inhibitory processes, the NoGo P300 should be larger anteriorly than the Go P300 (overt responses) and the silent-count P300s (covert responses). If anteriorization primarily reflects negative voltage Go task motor activity that reduces the normal frontal P300 amplitude, then the Go task P300 should be smaller than both the NoGo and silent-count P300s, which should not differ from one another.

RESULTS

The Go task elicited a bilaterally reduced frontal P300 and asymmetrical frontal P300 relative to both the NoGo and silent-count tasks. The NoGo task P300 and silent-count task P300 showed similar amplitude and topography. P300 and slow wave on the NoGo task were not asymmetrical.

CONCLUSIONS

The increased frontal P300 in NoGo tasks cannot be attributed solely to a positive-going inhibitory process, but likely reflects negative voltage response execution processes on Go trials. However, the alternative explanation that memory-related processes increase the silent-count P300 anteriorly to the same degree as NoGo inhibitory processes cannot be ruled out.

Visual information processing in dyslexic children

OBJECTIVE

Several studies presented evidence for magnocellular deficits in dyslexics both in behavioural as well as in electrophysiological data of local electrode sites. We investigated two well-known paradigms (motion-onset and random-dot-kinematogram) with regard to global electrophysiological parameters.

METHODS

Twenty-one-channel event-related potentials (ERPs) of 16 dyslectic and 15 control children were analyzed with reference-independent methods. For each paradigm quasi stable microstates were identified by means of a data-driven segmentation procedure and compared between both groups.

RESULTS

Differences in global ERP responses between dyslexic and control children could be found for rapid moving gratings but not for the dot coherence.

CONCLUSIONS

Dyslexic children seem to have some highly specific visual deficits in processing moving stimuli. These deficits can be related to the magnocellular system.

Developmental differences in behavioral and event-related brain responses associated with response preparation and inhibition in a go/nogo task

The present study investigated developmental trends in response inhibition and preparation by studying behavior and event-related brain activity in a cued go/nogo task, administered to nine-year-old children and young adults. Hits, false alarms, inattention, and impulsivity scores and ERP measures of inhibition (fronto-central nogo-N2 and P3), target selection (parietal go-nogo P3 difference), and response preparation (contingent negative variation; CNV) were collected. Higher false alarm and impulsivity scores and the absence of the fronto-central nogo P3 all suggest a developmental lag in response inhibition in children. A developmental lag in sustained attention processes was suggested by worse target detection and larger parietal target/nontarget P3 effects in children. Cue orientation and response preparation processes were respectively measured by early and late CNV activity. Children displayed smaller early CNV amplitudes at fronto-central locations, but mature late CNV. The smaller early CNV activity might indicate inefficient cue-orientation processes caused by incomplete frontal lobe development.

Brain electrical dysfunction of the anterior cingulate in schizophrenic patients

The anterior cingulate cortex (ACC) is a key region within the human prefrontal cortex that has been shown to be dysfunctional in schizophrenic patients. Supporting evidence for this notion has been collected with neuroimaging methods during various cognitive activation tasks. Recently, electrophysiological ACC activity has been demonstrated by means of a three-dimensional source location with low resolution electromagnetic tomography (LORETA) in the event-related potentials elicited during the NoGo condition of the Continuous Performance Test (CPT) as compared to its Go condition. Thirty-one schizophrenic patients and 31 age- and gender-matched healthy volunteers were investigated with this newly developed electrophysiological method. LORETA analysis revealed a significantly diminished brain electrical activity in the ACC of schizophrenic patients as compared to controls during the NoGo condition of the CPT. This result supports the assumption of a functional deficit of the ACC during this cognitive task as a central feature in schizophrenias and, thereby, specifies the general concept of hypofrontality. Moreover, this investigation underscores the value of sophisticated electrophysiological methods in combination with unambiguously designed mental tasks for the evaluation of the pathophysiological processes underlying schizophrenic diseases.

Inhibition-Related ERP Components: Variation with Modality, Age, and Time-on-Task

Abstract In Go/Nogo tasks, the ERP after Nogo stimuli generally reveals a negativity (Nogo-)N2 and a subsequent positivity (Nogo-)P3 over fronto-central scalp regions. These components are probably related to different subprocesses serving response inhibition, namely, modality-specific and general inhibition, respectively. In the present study we investigate whether aging or prolonged work (“time-on-task”) have an effect on N2 and P3. Twelve young and 12 elderly subjects performed simple Go/Nogo tasks to visual or auditory letter stimuli. Reaction times were longer after visual than after auditory stimuli, and longer in the elderly than in the young. The ERP results reveal a slight impairment of modality-specific inhibition (N2) in the elderly after visual, but not after auditory, stimuli. General inhibition (P3) was delayed in the elderly for both modalities, as was Go-P3 and RT. Hence, it appears that the response slowing of the elderly is the result of a slowing of the decision process whether to respond or to inhibit. Moreover, age appears to affect both aspects of inhibition in a different manner. No effects of time-on-task were found, which suggests that the inhibitory processes are fairly robust against mental fatigue.

Electrophysiological correlates for response inhibition in a Go/NoGo task

OBJECTIVE

Event-related brain potentials (ERPs) during a Go/NoGo task were investigated to elucidate the electrophysiological basis for executive and inhibitory control of responses.

METHODS

We studied Go/NoGo ERPs in 13 healthy subjects during a modified continuous performance test using high-density electroencephalogram (EEG) recording. We measured peak latency, amplitude, and topographic distribution of the components, and analyzed the neural sources using low-resolution electromagnetic tomography.

RESULTS

There were no differences between the Go and NoGo conditions in the latency, amplitude, scalp topography, or the electrical source localization of the P1 and N1 components. The N2 component was seen only in the NoGo ERP, and its source was located in the right lateral orbitofrontal and cingulate cortex. The NoGo-P3 component had larger amplitude and longer latency, and was more anteriorly localized than Go-P3; Go-P3 was located mainly in the medial part of the parietal cortex, whereas the NoGo-P3 activity was observed in the left lateral orbitofrontal cortex.

CONCLUSIONS

These results suggest that the lateral orbitofrontal and anterior cingulate areas play critical roles in the inhibitory control of behavior and that both hemispheres are involved in inhibitory cognitive function.

Cognitive response control in writer's cramp

Disturbances of the motor and sensory system as well as an alteration of the preparation of movements have been reported to play a role in the pathogenesis of dystonias. However, it is unclear whether higher aspects of cortical - like cognitive - functions are also involved. Recently, the NoGo-anteriorization (NGA) elicited with a visual continuous performance test (CPT) during recording of a 21-channel electroencephalogram has been proposed as an electrophysiological standard-index for cognitive response control. The NGA consists of a more anterior location of the positive area of the brain electrical field associated with the inhibition (NoGo-condition) compared with that of the execution (Go-condition) of a prepared motor response in the CPT. This response control paradigm was applied in 16 patients with writer's cramp (WC) and 14 age matched healthy controls. Topographical analysis of the associated event-related potentials revealed a significant (P < 0.05) NGA effect for both patients and controls. Moreover, patients with WC showed a significantly higher global field power value (P < 0.05) in the Go-condition and a significantly higher difference-amplitude (P < 0.05) in the NoGo-condition. A source location analysis with the low resolution electromagnetic tomography (LORETA) method demonstrated a hypoactivity for the Go-condition in the parietal cortex of the right hemisphere and a hyperactivity in the NoGo-condition in the left parietal cortex in patients with WC compared with healthy controls. These results indicate an altered response control in patients with WC in widespread cortical brain areas and therefore support the hypothesis that the pathogenesis of WC is not restricted to a pure sensory-motor dysfunction.

Electrophysiological signs of reduced prefrontal response control in schizophrenic patients

The prefrontal cortex is considered as a brain region important in the etiopathogenesis of schizophrenic disorders. Based on converging results from different research areas, the prefrontal cortex is regarded as the anatomical and functional representation of response control under physiological conditions. In previous studies, a robust electrophysiological marker for the investigation of response control in healthy control subjects was validated. This parameter was termed NoGo anteriorisation and consists of a more anterior peak of the event-related potentials during the inhibition of a prepared motor response (NoGo condition within the Continuous Performance Test) than during its execution (Go condition). The present study investigated these brain electrical correlates of response control in 19 schizophrenic patients and 19 age- and sex-matched healthy subjects. Compared to control subjects, the event-related potentials in schizophrenic patients were located more anterior in the Go condition and, as a trend, more posterior in the NoGo condition. The NoGo anteriorisation was strongly reduced in the schizophrenic group. On a qualitative level, the NoGo anteriorisation was present in all control subjects, but not in eight of the 19 patients. The results were interpreted as an indication of a disturbed prefrontal response control in schizophrenic patients. Further studies will clarify whether this method may be useful as a global test of hypofrontality in different groups of chronic schizophrenias, or as a quantifiable measure of an affected response control system, especially in catatonic subgroups.