P3 topographical change with task familiarization and task complexity

Neural mechanisms of Chinese character recognition, updating, and maintenance in the N-back task

Using the N-back task, we investigated how memory load influences the neural activity of the Chinese character cognitive subprocess (recognition, updating, and maintenance) in Mainland Chinese speakers. Twenty-seven participants completed the Chinese character N-back paradigm while having their event-related potentials recorded. The study employed time and frequency domain analyses of EEG data. Results showed that accuracy decreased and response times increased with larger N values. For ERPs, N2pc and P300 amplitudes decreased and SW amplitude increased with larger N values. For time frequency analyses, the desynchronization of alpha oscillations decreased after stimulus onset, but the synchronization of alpha oscillations increased during the maintenance phase. The results suggest that greater memory load is related to a decrease in cognitive resources during updating and an increase in cognitive resources during information maintenance. The results of a behavioral-ERP data structural equation model analysis showed that the ERP indicators in the maintenance phase predicted behavioral performance.

Group analysis and classification of working memory task conditions using electroencephalogram cortical currents during an n-back task

Electroencephalographic studies of working memory have demonstrated cortical activity and oscillatory representations without clarifying how the stored information is retained in the brain. To address this gap, we measured scalp electroencephalography data, while participants performed a modified n-back working memory task. We calculated the current intensities from the estimated cortical currents by introducing a statistical map generated using Neurosynth as prior information. Group analysis of the cortical current level revealed that the current amplitudes and power spectra were significantly different between the modified n-back and delayed match-to-sample conditions. Additionally, we classified information on the working memory task conditions using the amplitudes and power spectra of the currents during the encoding and retention periods. Our results indicate that the representation of executive control over memory retention may be mediated through both persistent neural activity and oscillatory representations in the beta and gamma bands over multiple cortical regions that contribute to visual working memory functions.

Long-term practice of intuitive inquiry meditation modulates EEG dynamics during self-schema processing

Objective

Intuitive inquiry meditation is a unique form of Buddhist Zen/Chan practice in which individuals actively and intuitively utilize the cognitive functions to cultivate doubt and explore the concept of the self. This event-related potential (ERP) study aimed to investigate the neural correlates by which long-term practice of intuitive inquiry meditation induces flexibility in self-schema processing, highlighting the role of doubt and belief processes in this exploration.

Methods

Twenty experienced and eighteen beginner meditators in intuitive inquiry meditation were recruited for this ERP study. The interactions of doubt and belief processes with concepts of the self and Buddha were investigated. A 128-channel electroencephalography (EEG) system was used to collect EEG data. The ERP data were processed and analyzed using EEGLAB.

Results

The data showed a double dissociation between beginners and experienced meditators (monks) in the concepts of the self and Buddha: intuitive inquiry meditation reduced the brain activity of beginners when viewing Buddha image but not when viewing a picture of themselves. However, in experienced meditators, intuitive inquiry meditation reduced brain activity when they viewed images of themselves but not when they viewed Buddha image. Further event-related spectral perturbation (ERSP) analysis revealed that experienced meditators had a greater theta spectral power and higher intertrial coherence (ITC), indicating that they could more flexibly modulate ongoing cognitive processes than beginner meditators.

Conclusion

Intuitive inquiry meditation could help beginner meditators detach from the concept of Buddha but not from that of the self. However, in experienced meditators, the opposite was true. ERSP analysis showed that only experienced meditators exhibited significant alterations in brain activity dynamics during intuitive inquiry meditation, which might enable these practitioners to become spontaneously detached from the concept of the self. These findings revealed the neural mechanism by which long-term practice of intuitive inquiry meditation can influence the doubting process and its effect on self-schema processing.

Effects of attention bias modification for anxiety: Neurophysiological indices and moderation by symptom severity

OBJECTIVE

Attention bias modification (ABM) aims to decrease anxiety symptom severity through the reduction of threat-related attention bias (AB). Individual differences in treatment response and poor measurement reliability of AB have called its clinical promise into question. The current study examined whether individual differences in anxiety severity at baseline moderated treatment response, and employed both behavioral and neurophysiological metrics of AB.

METHODS

Participants (N = 99) were randomly assigned to four weeks of ABM or placebo control training (PT). Self-reported anxiety symptom severity, and AB metrics and ERPs generated during the dot probe task were collected at baseline (Time 1), one-week post-intervention (Time 5), and at a three-month follow-up (Time 6).

RESULTS

ABM, relative to PT, reduced ERPs indexing attention discrimination (N170) and increased ERPs indexing salience tracking (P3). Increases in P3 were associated with ABM-related reductions in anxiety. Anxiety severity was reduced following ABM, but only among those with higher baseline anxiety symptom severity.

CONCLUSIONS

ABM effectively reduced symptom severity among those with higher levels of anxiety, and modulated neurophysiological indices of AB.

SIGNIFICANCE

Results provide evidence for attention-relevant ERPs as outcomes of ABM treatment responsivity and suggest that ABM may be most beneficial for those with more severe anxiety symptoms.

Cardiorespiratory fitness is associated with sustained neurocognitive function during a prolonged inhibitory control task in young adults: An ERP study

Although beneficial associations between cardiorespiratory fitness and cognitive function have been established, whether cardiorespiratory fitness is related to behavioral and neuroelectric indices of performance during a prolonged inhibitory control task remains unknown. Young adults, categorized into High and Low Fitness groups, completed a 60-min Stroop task, while the N1 and P3 components of event-related potentials were measured. The results showed that the High Fitness group demonstrated shorter response times, regardless of the Stroop task congruency or time-on-task, than Low Fitness group. The High Fitness group also exhibited larger P3 amplitudes than the Low Fitness group, but no differences in N1 amplitudes were observed. These findings suggest that cardiorespiratory fitness during young adulthood has beneficial effects on task performance and attention allocation during an inhibitory control task, and these benefits can be sustained for 60 min.

Updating Emotional Stimuli in Heroin Abstainers' Working Memory: An Event-Related Potential Investigation

BACKGROUND

It is well-documented that heroin users demonstrate aberrant emotion-processing abilities. However, the mechanism by which heroin users process emotional information after it has captured their attention and entered their working memory is unclear.

OBJECTIVES

A modified emotional 2-back task was used to examine whether heroin abstainers demonstrate specific bias patterns in updating emotional stimuli in their working memory.

METHODS

In total, 26 male heroin abstainers and 29 healthy controls were asked to identify whether the current picture was the same as a picture that had appeared two trials earlier, while behavioral data and electroencephalogram data were collected.

RESULTS

Contrary to predictions, the heroin abstainers and healthy controls demonstrated a similar pattern of P300 activity in response to emotional stimuli with no between-group differences in accuracy or reaction time. More specifically, the P300 amplitudes were larger for negative pictures than for positive and neutral pictures. Surprisingly, we found larger P300 amplitudes at Fz electrodes than at Cz and Pz electrodes in the control group, whereas there was no significant difference at midline electrodes in the heroin abstainers.

CONCLUSIONS/IMPORTANCE

Although subtle differences may exist in attentional engagement toward incoming emotional stimulus between two groups, the similar P300 pattern may indicate partial preservation of emotional working memory capacity associated with adaptive emotion regulation in heroin abstainers. These results deepen our understanding of the emotion regulation impairments associated with chronic drug use.

Economical Assessment of Working Memory and Response Inhibition in ADHD Using a Combined n-back/Nogo Paradigm: An ERP Study

The development of cognitive interventions in attention-deficit/hyperactivity disorder (ADHD) often requires the assessment of multiple cognitive functions. However, experimental settings consisting of various tasks are particularly strenuous for patients and can thus result in poor data quality. For the economical assessment of working memory and response inhibition, this study aims to validate a combined n-back/nogo paradigm by comparing it to single task versions and to demonstrate its applicability for ADHD research. Twenty-five healthy individuals and 34 ADHD patients between 9 and 16 years participated in this event-related potential (ERP) study. Healthy controls underwent single task versions of a 2-back working memory task and a go/nogo response inhibition task as well as the introduced combined 2-back/nogo task. This combined task demonstrated a comparable ERP structure for working memory and response inhibition aspects as single task versions. Behaviorally, higher working memory performance during the combined paradigm indicated lower task difficulty, while high correlations between combined and single task versions still indicated valid working memory measures. For response inhibition performance, different task versions resulted in similar outcomes. The application of the combined n-back/nogo paradigm in ADHD patients revealed the expected working memory and response inhibition deficits, increased omission errors, reaction times, and standard deviation of reaction time, as well as diminished n-back P3 and nogo P3 amplitudes. We conclude that the combined n-back/nogo task is an effective paradigm for the economical assessment of working memory and response inhibition deficits in ADHD on a behavioral and neurophysiological level.

Modality Effects on Lexical Encoding and Memory Representations of Spoken Words

OBJECTIVES

The present study investigated presentation modality differences in lexical encoding and working memory representations of spoken words of older, hearing-impaired adults. Two experiments were undertaken: a memory-scanning experiment and a stimulus gating experiment. The primary objective of experiment 1 was to determine whether memory encoding and retrieval and scanning speeds are different for easily identifiable words presented in auditory-visual (AV), auditory-only (AO), and visual-only (VO) modalities. The primary objective of experiment 2 was to determine if memory encoding and retrieval speed differences observed in experiment 1 could be attributed to the early availability of AV speech information compared with AO or VO conditions.

DESIGN

Twenty-six adults over age 60 years with bilateral mild to moderate sensorineural hearing loss participated in experiment 1, and 24 adults who took part in experiment 1 participated in experiment 2. An item recognition reaction-time paradigm (memory-scanning) was used in experiment 1 to measure (1) lexical encoding speed, that is, the speed at which an easily identifiable word was recognized and placed into working memory, and (2) retrieval speed, that is, the speed at which words were retrieved from memory and compared with similarly encoded words (memory scanning) presented in AV, AO, and VO modalities. Experiment 2 used a time-gated word identification task to test whether the time course of stimulus information available to participants predicted the modality-related memory encoding and retrieval speed results from experiment 1.

RESULTS

The results of experiment 1 revealed significant differences among the modalities with respect to both memory encoding and retrieval speed, with AV fastest and VO slowest. These differences motivated an examination of the time course of stimulus information available as a function of modality. Results from experiment 2 indicated the encoding and retrieval speed advantages for AV and AO words compared with VO words were mostly driven by the time course of stimulus information. The AV advantage seen in encoding and retrieval speeds is likely due to a combination of robust stimulus information available to the listener earlier in time and lower attentional demands compared with AO or VO encoding and retrieval.

CONCLUSIONS

Significant modality differences in lexical encoding and memory retrieval speeds were observed across modalities. The memory scanning speed advantage observed for AV compared with AO or VO modalities was strongly related to the time course of stimulus information. In contrast, lexical encoding and retrieval speeds for VO words could not be explained by the time-course of stimulus information alone. Working memory processes for the VO modality may be impacted by greater attentional demands and less information availability compared with the AV and AO modalities. Overall, these results support the hypothesis that the presentation modality for speech inputs (AV, AO, or VO) affects how older adult listeners with hearing loss encode, remember, and retrieve what they hear.

Moderate Cardiovascular Exercise Speeds Up Neural Markers of Stimulus Evaluation During Attentional Control Processes

Moderate intensity cardiovascular exercise appears to provide a low-cost "intervention" on neurocognitive processes such as attentional control, yet the effects vary depending, for example, on cognitive task, time of testing, or exercise intensity. However, while a number of studies show that brief bouts of acute exercise can modulate behavioral indices of cognitive control, relatively few studies have attempted to identify the brain activity associated with these changes immediately following exercise. Here, we tested 11 young adults in a crossover design with a Flanker task at rest and immediately (within 2-3 minutes) following 20 minutes of acute exercise at 60% of the individual VO2max. In order to prevent delayed exercise effects that might confound or dilute immediate effects, a short version of the Flanker task (8 minutes) was chosen and an EEG was recorded simultaneously. The N2 and P3 ERP components were analyzed in addition to accuracy and response time. The N2 reflects conflict resolution, and the P3 has been linked to stimulus evaluation processes. No effect of exercise was found for behavioral data but P3 peak latencies were shorter following exercise as compared to rest. The N2 amplitude data suggest that exercise seems to prevent a decline in resources of attentional control over time. These data indicate that acute exercise, at a moderate intensity level, speeds up neural processing of attentional control by modulating stimulus evaluation processes immediately following exercise and that exercise helps maintain a steady level of neurocognitive resources.

Disentangling specific inhibitory versus general decision-making processes during sleep deprivation using a Go/NoGo ERP paradigm

This study used a Go/NoGo ERP paradigm in which Go and NoGo stimuli occurred rarely and equally often in an attempt to determine if sleep deprivation has a general effect on decision-making or a more specific effect on inhibition. A Go/NoGo task was administered six times to eleven participants during 36 h of sleep deprivation and once again post recovery sleep. In the Go condition, the participant was asked to respond to the rare stimulus. In the separate NoGo condition, the participant was asked to withhold the response to the rare stimulus. ERPs were recorded to the rare stimuli. The NoGo P3 should be attenuated if sleep loss mainly affects inhibitory processes. Both Go and NoGo P3 should be attenuated if sleep loss affects general detection processes. During sleep loss, accuracy decreased for both tasks. RT also gradually increased for the Go task. Performance during the NoGo task was more complex and was better accounted by a speed-accuracy trade-off. Overall, findings indicate that sleep deprivation did not have specific effects on inhibition. However, the amplitude of the Go P3 occurred as early as 12 h after waking and might reflect an effect of task repetition rather than true sleep deprivation. In contrast, the NoGo P3 amplitude was not significantly reduced until after 24 and 36 h of wakefulness, suggesting a true sleep deprivation effect. Both Go and NoGo P3 post recovery sleep did not return to baseline levels, possibly due to residual sleep inertia.

Investigating Established EEG Parameter During Real-World Driving

In real life, behavior is influenced by dynamically changing contextual factors and is rarely limited to simple tasks and binary choices. For a meaningful interpretation of brain dynamics underlying more natural cognitive processing in active humans, ecologically valid test scenarios are essential. To understand whether brain dynamics in restricted artificial lab settings reflect the neural activity in complex natural environments, we systematically tested the auditory event-related P300 in both settings. We developed an integrative approach comprising an initial P300-study in a highly controlled laboratory set-up and a subsequent validation within a realistic driving scenario. Using a simulated dialog with a speech-based input system, increased P300 amplitudes reflected processing of infrequent and incorrect auditory feedback events in both the laboratory setting and the real world setup. Environmental noise and movement-related activity in the car driving scenario led to higher data rejection rates but revealed comparable theta and alpha frequency band pattern. Our results demonstrate the possibility to investigate cognitive functions like context updating in highly artifact prone driving scenarios and encourage the consideration of more realistic task settings in prospective brain imaging approaches.

Alcohol affects the P3 component of an adaptive stop signal task ERP

BACKGROUND

The P3 component of the event-related potential (ERP) has been particularly useful in alcohol research for identifying endophenotypes of alcohol-use disorder (AUD) risk in sober subjects. However, practice and/or fatigue reduce P3 amplitude, limiting the ability to ascertain acute and adaptive effects of alcohol exposure. Here, we report acute alcohol effects on P3 amplitude and latency using an adaptive stop signal task (aSST).

METHODS

One hundred forty-eight non-dependent moderate to heavy social drinkers, ages 21 to 27, participated in two single-blind, alcohol or placebo, counterbalanced sessions approximately 1 week apart. During each session, subjects performed an adaptive stop signal task (aSST) at 1) baseline, 2) upon reaching the target 60 mg/dL breath alcohol concentration or at the equivalent time during the placebo session, and 3) approximately 135 min later while the breath alcohol concentration was clamped. Here, we report on differences between baseline and first subsequent measurements across the experimental sessions. During each aSST run, the stop signal delay (SSD, the time between stop and go signals) adjusted trial-by-trial, based on the subject's performance.

RESULTS

The aSST reliably generated a STOP P3 component that did not change significantly with repeated task performance. The pre-infusion SSD distribution was bimodal, with mean values several hundred msec apart (FAST: 153 msec and SLOW: 390 msec). This suggested different response strategies: FAST SSD favoring "going" over "stopping", and SLOW SSD favoring "stopping" over "going". Exposure to alcohol at 60 mg/dL differentially affected the amplitude and latency of the STOP P3 according to SSD group. Alcohol significantly reduced P3 amplitude in the SLOW SSD compared to the FAST SSD group, but significantly increased P3 latency in the FAST SSD compared to the SLOW SSD group.

CONCLUSIONS

The aSST is a robust and sensitive task for detecting alcohol-induced changes in inhibition behavior as measured by the P3 component in a within-subject design. Alcohol was associated with P3 component changes, which varied by SSD group, suggesting a differential effect as a function of task strategy. Overall, the data support the potential utility of the aSST in the detection of alcohol response-related AUD risk.

(Don't) Mind the effort: Effects of contextual interference on ERP indicators of motor preparation

Motor learning is associated with a decrease in frontal control-related brain activity and increase of central and parietal motor-related activity. Contextual interference (CI), manipulated typically by blocked versus randomized training schedules, affects motor learning, resulting in inferior performance during training but in superior performance during retention and transfer. The CI effect is often explained by increased processing demands under high CI training. Consistently, in the motor preparation phase, the activity of control- and attention-related brain areas is increased under high CI. Here, we investigated the effect of CI on learning-related changes in ERPs during motor preparation. Participants learned throwing at virtual targets and were tested for retention in the target condition 1 week later. The frontal P3 component decreased with learning during the first session and across sessions. In addition, there was a trend for a stronger reduction of P3 during retention after high CI training. Both initial and late contingent negative variation (iCNV and lCNV) amplitudes decreased with learning and showed a significantly stronger reduction under high CI. We conclude that CI modulates the interplay of cognitive and motor processes in the preparatory phase of motor learning and that a stronger involvement of cognitive processes during high CI training accounts for differential effects of CI on ERP indicators of motor preparation during retention.

The Auditory-Visual Speech Benefit on Working Memory in Older Adults with Hearing Impairment

This study examined the effect of auditory-visual (AV) speech stimuli on working memory in older adults with poorer-hearing (PH) in comparison to age- and education-matched older adults with better hearing (BH). Participants completed a working memory n-back task (0- to 2-back) in which sequences of digits were presented in visual-only (i.e., speech-reading), auditory-only (A-only), and AV conditions. Auditory event-related potentials (ERP) were collected to assess the relationship between perceptual and working memory processing. The behavioral results showed that both groups were faster in the AV condition in comparison to the unisensory conditions. The ERP data showed perceptual facilitation in the AV condition, in the form of reduced amplitudes and latencies of the auditory N1 and/or P1 components, in the PH group. Furthermore, a working memory ERP component, the P3, peaked earlier for both groups in the AV condition compared to the A-only condition. In general, the PH group showed a more robust AV benefit; however, the BH group showed a dose-response relationship between perceptual facilitation and working memory improvement, especially for facilitation of processing speed. Two measures, reaction time and P3 amplitude, suggested that the presence of visual speech cues may have helped the PH group to counteract the demanding auditory processing, to the level that no group differences were evident during the AV modality despite lower performance during the A-only condition. Overall, this study provides support for the theory of an integrated perceptual-cognitive system. The practical significance of these findings is also discussed.

Tai Chi and meditation-plus-exercise benefit neural substrates of executive function: a cross-sectional, controlled study

BACKGROUND

We report the first controlled study of Tai Chi effects on the P300 event-related potential, a neuroelectric index of human executive function. Tai Chi is a form of exercise and moving meditation. Exercise and meditation have been associated with enhanced executive function. This cross-sectional, controlled study utilized the P300 event-related potential (ERP) to compare executive network neural function between self-selected long-term Tai Chi, meditation, aerobic fitness, and sedentary groups. We hypothesized that because Tai Chi requires moderate aerobic and mental exertion, this group would show similar or better executive neural function compared to meditation and aerobic exercise groups. We predicted all health training groups would outperform sedentary controls.

METHODS

Fifty-four volunteers (Tai Chi, n=10; meditation, n=16; aerobic exercise, n=16; sedentary, n=12) were tested with the Rockport 1-mile walk (estimated VO2 Max), a well-validated measure of aerobic capacity, and an ecologically valid visuo-spatial, randomized, alternating runs Task Switch test during dense-array electroencephalographic (EEG) recording.

RESULTS

Only Tai Chi and meditation plus exercise groups demonstrated larger P3b ERP switch trial amplitudes compared to sedentary controls.

CONCLUSIONS

Our results suggest long-term Tai Chi practice, and meditation plus exercise may benefit the neural substrates of executive function.

The relationship between P3 amplitude and working memory performance differs in young and older adults

While some elderly show deteriorations in cognitive performance, others achieve performance levels comparable to young adults. To examine whether age-related changes in brain activity varied with working memory performance efficiency, we recorded electroencephalography (EEG) from young and older healthy adults during performance on an n-back task with two loads (0- and 1-back) and two versions (identity and integrated). Young adults showed a typical P3 amplitude pattern with a parietal-maximum. Compared to young adults, the P3 amplitude of older adults was characterized by frontal hyperactivity coupled with posterior hypoactivity. Moreover, P3 amplitude in young and older adults varied with working memory performance efficiency. Among young adults, more efficient performance correlated with a larger P3 amplitude at parietal sites. In contrast, a higher P3 amplitude at midline electrode sites in older adults correlated with less efficient performance. Particularly, the enhanced frontal midline EEG activity in older adults during working memory performance seems to reflect inefficient use of neural resources due to frontal lobe dysfunction.

The Association Between Physical Activity and Attentional Control in Younger and Older Middle-Aged Adults

This study investigates the association between physical activity level and attentional control in a group of younger and older middle-aged adults (MA). Participants performed a Flanker task; two types of conflict were analyzed: response and perceptual conflict. For perceptual conflict, behavioral findings suggest that, irrespective of age, physical activity is positively associated with attentional control. For response conflicts, only highly active younger MA showed better attentional control, indicated by increased amplitudes of the event related potential N2 and reduced interference costs by distracting information. Physical activity did not modulate P3 amplitudes. The findings are discussed with respect to physical activity as functional approach to maintain cognitive functioning across the lifespan.

Electrophysiological indices of altered working memory processes in long-term ecstasy users

OBJECTIVE

The aim of this study was to determine the effect of light long-term ecstasy consumption on verbal short-term and working memory and to identify the cognitive processes contributing to task performance.

METHOD

Electroencephalogram was recorded while ecstasy users (N = 11), polydrug users (N = 13), and non-users (N = 13) completed forward and backward serial recognition tasks designed to engage verbal short-term memory and verbal working memory, respectively.

RESULTS

All three groups displayed significantly lower digit-backward span than digit-forward span with ecstasy users displaying the greatest difference. The parietally distributed P3b was significantly smaller in the digits backward task than in the digits forward task in non-ecstasy-using controls. Ecstasy users did not show the reduced P3b component in the backward task that was seen in both non-ecstasy-using control groups.

CONCLUSIONS

Ecstasy users' performance was suppressed more by the concurrent processing demands of the working memory task than that of the non-ecstasy-using controls. Non-ecstasy-using controls showed differential event-related potential wave forms in the short-term and working memory tasks, and this pattern was not seen in the ecstasy users. This is consistent with a reduction in the cognitive resources allocated to processing in working memory in ecstasy users.

Neural plasticity in response to attention training in anxiety

BACKGROUND

Behavioral studies show that attention training can alter threat bias, influence vulnerability to stress and reduce clinical anxiety symptoms. The aim of this study was to examine which cognitive functions of attention processing are modulated by attention training, and how a priori anxiety interacts with the attention training procedure. Specifically, we expected modulation in the P1/N1 event-related potential (ERP) complex if early spatial attention was to be affected by training and modulation in later ERP components (P2, N2, P3) had training affected top-down attentional processes.

METHOD

Thirty anxious and 30 non-anxious adults performed a modified probe detection task. Electroencephalograms (EEGs) were recorded throughout for later ERP analyses. Half the participants in each anxiety group were randomly assigned to undergo a training procedure designed to divert their attention away from threat and the other half received placebo training.

RESULTS

Anxious participants who were trained to avoid threat showed a linear reduction in response time (RT) to targets replacing neutral faces with the progression of training. This change in RT was not observed among non-anxious participants or among anxious participants who were exposed to placebo training. Following training, the anxious participants who were trained to avoid threat showed a reduction in P2 and P3 mean amplitudes and an enhancement in N2 mean amplitude.

CONCLUSIONS

Attention training affects anxious participants whereas non-anxious participants seem not to respond to it. The ERP data suggest that attention training modulates top-down processes of attention control rather than processes of early attention orienting.

I-NET: interactive neuro-educational technology to accelerate skill learning

The learning of a novel task currently rely heavily on conventional classroom instruction with qualitative assessment and observation. Introduction of individualized tutorials with integrated neuroscience-based evaluation techniques could significantly accelerate skill acquisition and provide quantitative evidence of successful training. We have created a suite of adaptive and interactive neuro-educational technologies (I-NET) to increase the pace and efficiency of skill learning. It covers four major themes: 1) Integration of brain monitoring into paced instructional tutorials, 2) Identifying psychophysiological characteristics of expertise using a model population, 3) Developing sensor-based feedback to accelerate novice-to-expert transition, 4) Identifying neurocognitive factors that are predictive of skill acquisition to allow early triage and interventions. We selected rifle marksmanship training as the field of application. Rifle marksmanship is a core skill for the Army and Marine Corps and it involves a combination of classroom instructional learning and field practice involving instantiation of a well-defined set of sensory, motor and cognitive skills. The instrumentation that incorporates the I-NET technologies is called the Adaptive Peak Performance Trainer (APPT). Preliminary analysis of pilot study data for performance data from a novice population that used this device revealed an improved learning trajectory.

Regulation of cognitive resources during sustained attention and working memory in 10-year-olds and adults

We examined differences between 10-year-olds and young adults in resource recruitment and regulation during tasks of sustained attention and spatial working memory. We administered participants spatial 0- and 1-back tasks and used pupillary dilation as a measure of resource recruitment. Repeated administration of 0-back led to smaller pupillary dilations and greater response time (RT) variability, revealing a vigilance decrement. Effects of repeated administration of 0-back and differences between 0- and 1-back in d' and RTs were similar between ages. Results further suggested that the children may not have been as effective as adults in extracting frequency information. Thus, on simple tasks of sustained attention and working memory, children recruit resources in a manner similar to adults. Finally, d' was correlated with RT variability on both tasks at both ages, highlighting the role of attentional fluctuations on both tasks.

Error-related electrocortical responses in 10-year-old children and young adults

Recent anatomical and electrophysiological evidence suggests that the anterior cingulate cortex (ACC) is relatively late to mature. This brain region appears to be critical for monitoring, evaluating, and adjusting ongoing behaviors. This monitoring elicits characteristic ERP components including the error-related negativity (ERN), error positivity (Pe) and correct-related negativity (CRN), with the ERN clearly relating to activation of the ACC; however, little attention has been paid to the examination of these ERP components in children. The present study examined developmental differences in the ERN, Pe, and CRN in normal 10-year-old children and young adults in a standard visual flanker task. We found that children had smaller ERNs than adults, with no between-group differences on the Pe, and some ambiguity concerning the CRN. Results provide electrophysiological support either for late maturation of the ACC or late involvement of the ACC in response monitoring. Results also suggest that there is some functional independence of response-monitoring ERP components. Error-related ERPs may be a useful tool in studying the development of this brain region and its role in behavior in normal and atypical development.

Working memory deficits in multiple sclerosis: comparison between the n-back task and the Paced Auditory Serial Addition Test

Working memory (WM) deficits are common in multiple sclerosis (MS). The Paced Auditory Serial Addition Test (PASAT) is used frequently to measure WM in clinical settings. The n-back paradigm is used often in experimental studies of WM. One unique component of the n-back task is that it provides a measure of reaction time (RT), an additional behavioral index of processing speed and task difficulty. Despite the use of both tasks to measure WM, their common variance has not been documented. We tested 32 MS patients and 20 controls; performance measures were obtained for both tasks. Compared with controls, MS patients generally had poorer performance on both the PASAT and n-back task. MS patients also had slower RTs on the n-back than controls and showed more slowing than controls as a function of WM load. Correlational analyses showed a high correspondence between performance measures on the PASAT and n-back. Principal components analysis pointed to a common feature of the PASAT, n-back, and specific other neuropsychological measures, that is, processing speed. Although the PASAT and n-back were shown to have a significant amount of shared variance, each test has specific advantages and disadvantages for use in clinical populations.

P3 amplitude and time-on-task effects in distractible adolescents

OBJECTIVE

The aim of our study was to examine the role of brain activity related to stimulus evaluation processes in distractibility by analyzing the P3 event-related potential.

METHODS

We studied the P3 response to target stimuli at the beginning, in the middle, and at the end of a two-tone auditory oddball task in easily distractible (n = 16) and non-distractible (n = 16) adolescents.

RESULTS

Easily distractible adolescents showed enhanced frontal and reduced parietal P3 amplitude across the blocks relative to non-distractible adolescents. Also, the usual decline in P3 amplitude at the end of the task was significantly larger in distractible than in non-distractible adolescents.

CONCLUSIONS

These results suggests that the P3 effects are not limited to the neuropsychiatric disorders, and that increased distractibility may be characterized by reduced amount of resources allocated to the task with continued testing.

SIGNIFICANCE

The results of this study contribute to elucidation of the functional basis of distractibility.

Eliminating the P300 rebound in short oddball paradigms

In short oddball paradigms, the P3 (or P300) amplitude often shows a curvilinear "rebound" pattern, such that an initial drop during the first few trials is followed by an increase in later trials. While the initial attenuation has been attributed to habituation, no explanation has been offered for the later increase. Our hypothesis was that this curvilinear pattern is due to anticipation of the end of each fixed-length block. In study 1, a series of 16 short, fixed-length auditory oddball tests (with six targets each) replicated the rebound effect. In study 2, a further set of 16 variable-length blocks (7-10 targets) eliminated the rebound, and the P300 amplitude decreased linearly as expected. Results are interpreted in light of various constructs related to the P3: habituation, attentional salience, and updating in working memory.

Syntactic processing with aging: an event-related potential study

To assess age-related changes in simple syntactic processing with normal aging, event-related brain potentials (ERPs) elicited by grammatical number violations as individuals read sentences for comprehension were analyzed. Violations were found to elicit a P600 of equal amplitude and latency regardless of an individual's age. Instead, advancing age was associated with a change in the scalp distribution of the P600 effect, being less asymmetric and more frontal (though still with a parietal maximum) in older than younger adults. Our results thus show that the brain's response to simple syntactic violations, unlike those reported for simple binary categorizations and simple semantic violations, is neither slowed nor diminished in amplitude by age. At the same time, the brain's processing of these grammatical number violations did engage at least somewhat different brain regions as a function of age, suggesting a qualitative change rather than any simple quantitative change in speed of processing.

Charting the maturation of the frontal lobe: An electrophysiological strategy

Tracking the functional development of specific regions of the prefrontal cortex in children using event-related potentials (ERPs) is challenging for both technical and conceptual reasons. In this paper we outline our strategy for studying frontal lobe development and present preliminary results from children aged 7-17 years and young adults using ERPs functionally associated with anterior cingulate and prefrontal cortex, especially the orbitofrontal, ventral, and medial portions. Our analysis of contingent negative variation, error-related negativity, and novelty P300 data show that the ERPs associated with these regions are still maturing into late adolescence, and that their amplitude has significant correlations with behavioral capacities.

Electrophysiological response during source memory decisions in older and younger adults

We recorded event-related potentials (ERPs) as individuals made source monitoring decisions in a paradigm in which the influence of item familiarity and goal relevance could be separately evaluated. Younger and older adults read a list of words and subsequently distinguished these words from foils in a running recognition test in which some foils were repeated after a lag of 6 items, creating familiar lures. Behaviorally, older and younger adults performed equally well in the recognition of study words and the rejection of singly presented foils. However, older adults were more likely to respond to the familiar lures as though they had come from the study list, thus producing the expected group difference in source-monitoring error. For younger adults the ERPs elicited by the targeted study words were maximal at posterior sites and significantly greater than those elicited by either familiar lures or foils. Older adults generated far less differentiated ERP waveforms but with a markedly greater amplitude at frontal sites. We interpret this frontal maximum in the context of poorer source monitoring as suggesting that older adults are more dependent on controlled processes to make discriminations that seem to occur much earlier and more automatically for younger adults.