Analysis of EEG characteristic at early stages of depression using method of independent components

Independent Component Analysis (ICA) was used for 19-channel resting EEG analysis 111 patients at early stages of depressive disorder and 526 age-matched healthy subjects. Comparison of independent components power spectra in depressed patients and healthy subjects in two states: Eyes closed and Eyes open, has revealed significant differences between groups for three frequency bands: Theta (4-7.5 Hz), Alpha (7.5-14 Hz), and Beta (14-20 Hz). Increased power of alpha and theta activity in depressed patients at parietal and occipital sites may be caused by decreased cortical activation of these regions. Diffuse enhancement of beta activity level can correlate with anxiety symptoms which take an important place in clinical picture of depressive disorder at early stages. Using of ICA method for comparison of spectral characteristics of EEG in groups of patients with different brain pathology and healthy subjects gives a possibility to localize more precisely the discovered differences as compare to traditional analysis of EEG spectra.     

From Lab to Field Conditions: A Pilot Study on EEG Methodology in Applied Sports Sciences

Although neurophysiological aspects have become more important in sports and exercise sciences in the last years, it was not possible to measure cortical activity during performance outside a laboratory due to equipment limits or movement artifacts in particular. With this pilot study we want to investigate whether Electroencephalography (EEG) data obtained in a laboratory golf putting performance differ from a suitable putting task under field conditions. Therefore, parameters of the working memory (frontal Theta and parietal Alpha 2 power) were recorded during these two conditions. Statistical calculations demonstrated a significant difference only for Theta power at F4 regarding the two putting conditions “field” and “laboratory”. These findings support the idea that brain activity patterns obtained under laboratory conditions are comparable but not equivalent to those obtained under field conditions. Additionally, we were able to show that the EEG methodology seems to be a reliable tool to observe brain activity under field conditions in a golf putting task. However, considering the still existing problems of movement artifacts during EEG measurements, eligible sports and exercises are limited to those being relatively motionless during execution. Further studies are needed to confirm these pilot results.     

Donepezil impairs memory in healthy older subjects: behavioural, EEG and simultaneous EEG/fMRI biomarkers

Rising life expectancies coupled with an increasing awareness of age-related cognitive decline have led to the unwarranted use of psychopharmaceuticals, including acetylcholinesterase inhibitors (AChEIs), by significant numbers of healthy older individuals. This trend has developed despite very limited data regarding the effectiveness of such drugs on non-clinical groups and recent work indicates that AChEIs can have negative cognitive effects in healthy populations. For the first time, we use a combination of EEG and simultaneous EEG/fMRI to examine the effects of a commonly prescribed AChEI (donepezil) on cognition in healthy older participants. The short- and long-term impact of donepezil was assessed using two double-blind, placebo-controlled trials. In both cases, we utilised cognitive (paired associates learning (CPAL)) and electrophysiological measures (resting EEG power) that have demonstrated high-sensitivity to age-related cognitive decline. Experiment 1 tested the effects of 5 mg/per day dosage on cognitive and EEG markers at 6-hour, 2-week and 4-week follow-ups. In experiment 2, the same markers were further scrutinised using simultaneous EEG/fMRI after a single 5 mg dose. Experiment 1 found significant negative effects of donepezil on CPAL and resting Alpha and Beta band power. Experiment 2 replicated these results and found additional drug-related increases in the Delta band. EEG/fMRI analyses revealed that these oscillatory differences were associated with activity differences in the left hippocampus (Delta), right frontal-parietal network (Alpha), and default-mode network (Beta). We demonstrate the utility of simple cognitive and EEG measures in evaluating drug responses after acute and chronic donepezil administration. The presentation of previously established markers of age-related cognitive decline indicates that AChEIs can impair cognitive function in healthy older individuals. To our knowledge this is the first study to identify the precise neuroanatomical origins of EEG drug markers using simultaneous EEG/fMRI. The results of this study may be useful for evaluating novel drugs for cognitive enhancement.     

急性高原低氧环境对不同情绪状态脑电功率的影响

目的:探讨急性高原低氧环境对不同情绪状态脑电功率的影响。方法:本研究为双因素多水平试验设计(氧气环境2个水平!情绪类型4个水平)。通过编写情绪图片诱导12名年龄在20～25岁之间的男性被试产生四类不同情绪:低效价低唤醒(LVLA)、高效价低唤醒(HVLA)、低效价高唤醒(LVHA)、高效价高唤醒(HVHA),分别近似于沮丧、轻松、恐惧、快乐四类情绪,并使用Brain Products 32导脑电采集设备采集不同情绪状态下的脑电信号;次日,采用常压低氧舱模拟4 300 m的高原低氧环境,同一批被试在低氧10 h后使用相同试验范式采集脑电信号。对采集来的脑电信号进行功率谱分析(FFT),同时对额叶(F3\Fz\F4)脑电的五个频段(delta、theta、alpha、beta、gamma)进行两因素重复测量方差分析。结果:功率谱分析发现:急性低氧前后,四类情绪状态下alpha波的全脑分布差异主要集中在额叶、顶叶及部分颞叶; HVLA情绪状态下alpha波全脑分布差异最小。两因素重复测量方差分析结果发现:(1)delta、beta频段功率受氧气环境影响显著(P<0.05),低氧环境下功...     

The Neural Dynamics of Conflict Adaptation within a Look-to-Do Transition

Background

For optimal performance in conflict situations, conflict adaptation (conflict detection and adjustment) is necessary. However, the neural dynamics of conflict adaptation is still unclear.

Methods

In the present study, behavioral and electroencephalography (EEG) data were recorded from seventeen healthy participants during performance of a color-word Stroop task with a novel look-to-do transition. Within this transition, participants looked at the Stroop stimuli but no responses were required in the ‘look’ trials; or made manual responses to the Stroop stimuli in the ‘do’ trials.

Results

In the ‘look’ trials, the amplitude modulation of N450 occurred exclusively in the right-frontal region. Subsequently, the amplitude modulation of sustained potential (SP) emerged in the posterior parietal and right-frontal regions. A significantly positive correlation between the modulation of reconfiguration in the ‘look’ trials and the behavioral conflict adaptation in the ‘do’ trials was observed. Specially, a stronger information flow from right-frontal region to posterior parietal region in the beta band was observed for incongruent condition than for congruent condition. In the ‘do’ trials, the conflict of ‘look’ trials enhanced the amplitude modulations of N450 in the right-frontal and posterior parietal regions, but decreased the amplitude modulations of SP in these regions. Uniquely, a stronger information flow from centro-parietal region to right-frontal region in the theta band was observed for iI condition than for cI condition.

Conclusion

All these findings showed that top-down conflict adaptation is implemented by: (1) enhancing the sensitivity to conflict detection and the adaptation to conflict resolution; (2) modulating the effective connectivity between parietal region and right-frontal region.     

Placebo-Suggestion Modulates Conflict Resolution in the Stroop Task

Here, we ask whether placebo-suggestion (without any form of hypnotic induction) can modulate the resolution of cognitive conflict. Naïve participants performed a Stroop Task while wearing an EEG cap described as a “brain wave” machine. In Experiment 1, participants were made to believe that the EEG cap would either enhance or decrease their color perception and performance on the Stroop task. In Experiment 2, participants were explicitly asked to imagine that their color perception and performance would be enhanced or decreased (non-hypnotic imaginative suggestion). We observed effects of placebo-suggestion on Stroop interference on accuracy: interference was decreased with positive suggestion and increased with negative suggestion compared to baseline. Intra-individual variability was also increased under negative suggestion compared to baseline. Compliance with the instruction to imagine a modulation of performance, on the other hand, did not influence accuracy and only had a negative impact on response latencies and on intra-individual variability, especially in the congruent condition of the Stroop Task. Taken together, these results demonstrate that expectations induced by a placebo-suggestion can modulate our ability to resolve cognitive conflict, either facilitating or impairing response accuracy depending on the suggestion’s contents. Our results also demonstrate a dissociation between placebo-suggestion and non-hypnotic imaginative suggestion.     

Infant Auditory Processing and Event-related Brain Oscillations

Rapid auditory processing and acoustic change detection abilities play a critical role in allowing human infants to efficiently process the fine spectral and temporal changes that are characteristic of human language. These abilities lay the foundation for effective language acquisition; allowing infants to hone in on the sounds of their native language. Invasive procedures in animals and scalp-recorded potentials from human adults suggest that simultaneous, rhythmic activity (oscillations) between and within brain regions are fundamental to sensory development; determining the resolution with which incoming stimuli are parsed. At this time, little is known about oscillatory dynamics in human infant development. However, animal neurophysiology and adult EEG data provide the basis for a strong hypothesis that rapid auditory processing in infants is mediated by oscillatory synchrony in discrete frequency bands. In order to investigate this, 128-channel, high-density EEG responses of 4-month old infants to frequency change in tone pairs, presented in two rate conditions (Rapid: 70 msec ISI and Control: 300 msec ISI) were examined. To determine the frequency band and magnitude of activity, auditory evoked response averages were first co-registered with age-appropriate brain templates. Next, the principal components of the response were identified and localized using a two-dipole model of brain activity. Single-trial analysis of oscillatory power showed a robust index of frequency change processing in bursts of Theta band (3 - 8 Hz) activity in both right and left auditory cortices, with left activation more prominent in the Rapid condition. These methods have produced data that are not only some of the first reported evoked oscillations analyses in infants, but are also, importantly, the product of a well-established method of recording and analyzing clean, meticulously collected, infant EEG and ERPs. In this article, we describe our method for infant EEG net application, recording, dynamic brain response analysis, and representative results.     

The Genesis of the EEG and its Relation to Electromagnetic Radiation

The dominant frequencies in the human electroencephlogram (EEG) are 8–13 Hz (Alpha), 4–7 Hz (Theta), less than 4 Hz (Delta), and greater than 13 Hz (Beta). The conventional explanation of the mechanism for these dominant rhythms involves the effect of electrical activity i n the thalamus on the cortical synaptic potentials that are recorded in an EEG (1,2). Although electrical activity in the thalamus is of prime importance in determining what is recorded Ly the EEG, it is not known why the dominant rhythms recorded are of those specific frequencies. These dominant frequencies may be related through evolution to some aspect of the environment. This paper is devoted to a consideration of the possible relation between the brain's electrical activity and external electromagnetic fields.     

Resolving emotional conflict: a role for the rostral anterior cingulate cortex in modulating activity in the amygdala

Effective mental functioning requires that cognition be protected from emotional conflict due to interference by task-irrelevant emotionally salient stimuli. The neural mechanisms by which the brain detects and resolves emotional conflict are still largely unknown, however. Drawing on the classic Stroop conflict task, we developed a protocol that allowed us to dissociate the generation and monitoring of emotional conflict from its resolution. Using functional magnetic resonance imaging (fMRI), we find that activity in the amygdala and dorsomedial and dorsolateral prefrontal cortices reflects the amount of emotional conflict. By contrast, the resolution of emotional conflict is associated with activation of the rostral anterior cingulate cortex. Activation of the rostral cingulate is predicted by the amount of previous-trial conflict-related neural activity and is accompanied by a simultaneous and correlated reduction of amygdalar activity. These data suggest that emotional conflict is resolved through top-down inhibition of amygdalar activity by the rostral cingulate cortex.     

Cerebral Correlates of Abnormal Emotion Conflict Processing in Euthymic Bipolar Patients: A Functional MRI Study

Background

Patients with bipolar disorder experience cognitive and emotional impairment that may persist even during the euthymic state of the disease. These persistent symptoms in bipolar patients (BP) may be characterized by disturbances of emotion regulation and related fronto-limbic brain circuitry. The present study aims to investigate the modulation of fronto-limbic activity and connectivity in BP by the processing of emotional conflict.

Methods

Fourteen euthymic BP and 13 matched healthy subjects (HS) underwent functional magnetic resonance imaging (fMRI) while performing a word-face emotional Stroop task designed to dissociate the monitoring/generation of emotional conflict from its resolution. Functional connectivity was determined by means of psychophysiological interaction (PPI) approach.

Results

Relative to HS, BP were slower to process incongruent stimuli, reflecting higher amount of behavioral interference during emotional Stroop. Furthermore, BP showed decreased activation of the right dorsolateral prefrontal cortex (DLPFC) during the monitoring and a lack of bilateral amygdala deactivation during the resolution of the emotional conflict. In addition, during conflict monitoring, BP showed abnormal positive connectivity between the right DLPFC and several regions of the default mode network.

Conclusions

Overall, our results highlighted dysfunctional processing of the emotion conflict in euthymic BP that may be subtended by abnormal activity and connectivity of the DLPFC during the conflict monitoring, which, in turn, leads to failure of amygdala deactivation during the resolution of the conflict. Emotional dysregulation in BP may be underpinned by a lack of top-down cognitive control and a difficulty to focus on the task due to persistent self-oriented attention.     

Reflection of the emotion manifestation in effects of evoked EEG synchronization and desynchronization

Event-related desynchronization (ERD) and synchronization (ERS) in response to neutral, positive and negative emotional IAPS stimuli were measured in narrow theta, alpha-1, alpha-2 and alpha-3 frequency bands in 22 healthy Ss. A high resolution 62-channel EEG was recorded while subjects viewed a sequence of pictures. The effects of valence discrimination related to hemispheric asymmetries are associated with increased theta and alpha-3 synchronization. Theta ERS revealed a significant valence by hemisphere interaction for anterior temporal leads in the time window of 100-700 ms after stimulus onset indicating a relatively greater right hemisphere ERS for negative and a left hemisphere ERS for positive stimuli in comparison to neutral those. In the alpha-3 band, negative stimuli induced a left hemisphere ERS increase (F7 site) in the time window of 800-1200 ms not observed for neutral and positive stimuli. The results obtained along with the earlier observations on EEG correlates of affective processing challenge the notion that effective anterior hemispheric asymmetries are reflected mainly in the wide alpha frequency band.     

High Resolution Topography of Age-Related Changes in Non-Rapid Eye Movement Sleep Electroencephalography

Sleeping brain activity reflects brain anatomy and physiology. The aim of this study was to use high density (256 channel) electroencephalography (EEG) during sleep to characterize topographic changes in sleep EEG power across normal aging, with high spatial resolution. Sleep was evaluated in 92 healthy adults aged 18–65 years old using full polysomnography and high density EEG. After artifact removal, spectral power density was calculated for standard frequency bands for all channels, averaged across the NREM periods of the first 3 sleep cycles. To quantify topographic changes with age, maps were generated of the Pearson’s coefficient of the correlation between power and age at each electrode. Significant correlations were determined by statistical non-parametric mapping. Absolute slow wave power declined significantly with increasing age across the entire scalp, whereas declines in theta and sigma power were significant only in frontal regions. Power in fast spindle frequencies declined significantly with increasing age frontally, whereas absolute power of slow spindle frequencies showed no significant change with age. When EEG power was normalized across the scalp, a left centro-parietal region showed significantly less age-related decline in power than the rest of the scalp. This partial preservation was particularly significant in the slow wave and sigma bands. The effect of age on sleep EEG varies substantially by region and frequency band. This non-uniformity should inform the design of future investigations of aging and sleep. This study provides normative data on the effect of age on sleep EEG topography, and provides a basis from which to explore the mechanisms of normal aging as well as neurodegenerative disorders for which age is a risk factor.     

Evidence of neurotoxicity of ecstasy: sustained effects on electroencephalographic activity in polydrug users

Objective

According to previous EEG reports of indicative disturbances in Alpha and Beta activities, a systematic search for distinct EEG abnormalities in a broader population of Ecstasy users may especially corroborate the presumed specific neurotoxicity of Ecstasy in humans.

Methods

105 poly-drug consumers with former Ecstasy use and 41 persons with comparable drug history without Ecstasy use, and 11 drug naives were investigated for EEG features. Conventional EEG derivations of 19 electrodes according to the 10-20-system were conducted. Besides standard EEG bands, quantitative EEG analyses of 1-Hz-subdivided power ranges of Alpha, Theta and Beta bands have been considered.

Results

Ecstasy users with medium and high cumulative Ecstasy doses revealed an increase in Theta and lower Alpha activities, significant increases in Beta activities, and a reduction of background activity. Ecstasy users with low cumulative Ecstasy doses showed a significant Alpha activity at 11 Hz. Interestingly, the spectral power of low frequencies in medium and high Ecstasy users was already significantly increased in the early phase of EEG recording. Statistical analyses suggested the main effect of Ecstasy to EEG results.

Conclusions

Our data from a major sample of Ecstasy users support previous data revealing alterations of EEG frequency spectrum due rather to neurotoxic effects of Ecstasy on serotonergic systems in more detail. Accordingly, our data may be in line with the observation of attentional and memory impairments in Ecstasy users with moderate to high misuse. Despite the methodological problem of polydrug use also in our approach, our EEG results may be indicative of the neuropathophysiological background of the reported memory and attentional deficits in Ecstasy abusers. Overall, our findings may suggest the usefulness of EEG in diagnostic approaches in assessing neurotoxic sequela of this common drug abuse.     

Age-Related Changes in Electroencephalographic Signal Complexity

The study of active and healthy aging is a primary focus for social and neuroscientific communities. Here, we move a step forward in assessing electrophysiological neuronal activity changes in the brain with healthy aging. To this end, electroencephalographic (EEG) resting state activity was acquired in 40 healthy subjects (age 16–85). We evaluated Fractal Dimension (FD) according to the Higuchi algorithm, a measure which quantifies the presence of statistical similarity at different scales in temporal fluctuations of EEG signals. Our results showed that FD increases from age twenty to age fifty and then decreases. The curve that best fits the changes in FD values across age over the whole sample is a parabola, with the vertex located around age fifty. Moreover, FD changes are site specific, with interhemispheric FD asymmetry being pronounced in elderly individuals in the frontal and central regions. The present results indicate that fractal dimension well describes the modulations of brain activity with age. Since fractal dimension has been proposed to be related to the complexity of the signal dynamics, our data demonstrate that the complexity of neuronal electric activity changes across the life span of an individual, with a steady increase during young adulthood and a decrease in the elderly population.     

Neuromodulating Attention and Mind-Wandering Processes with a Single Session Real Time EEG

Our minds are continuously alternating between external attention (EA) and mind wandering (MW). An appropriate balance between EA and MW is important for promoting efficient perceptual processing, executive functioning, decision-making, auto-biographical memory, and creativity. There is evidence that EA processes are associated with increased activity in high-frequency EEG bands (e.g., SMR), contrasting with the dominance of low-frequency bands during MW (e.g., Theta). The aim of the present study was to test the effects of two distinct single session real-time EEG (rtEEG) protocols (SMR up-training/Theta down-training—SMR?Theta?; Theta up-training/SMR down-training—Theta?SMR?) on EA and MW processes. Thirty healthy volunteers were randomly assigned to one of two rtEEG training protocols (SMR?Theta?; Theta?SMR?). Before and after the rtEEG training, participants completed the attention network task (ANT) along with several MW measures. Both training protocols were effective in increasing SMR (SMR?Theta?) and theta (Theta?SMR?) amplitudes but not in decreasing the amplitude of down-trained bands. There were no significant effects of the rtEEG training in either EA or MW measures. However, there was a significant positive correlation between post-training SMR increases and the use of deliberate MW (rather than spontaneous) strategies. Additionally, for the Theta?SMR? protocol, increase in post-training Theta amplitude was significantly associated with a decreased efficiency in the orientation network.     

完全睡眠剥夺对大脑注意网络冲突效应和脑电样本熵的影响*

目的: 本研究分析睡眠剥夺对个体选择性注意网络冲突效应和脑电样本熵的影响,探讨睡眠剥夺对大脑注意网络的影响。方法: 25名健康受试者参与36 h完全睡眠剥夺试验。试验于当天9:00开始,于次日21:00结束,试验采用自身前后对照设计。受试者在睡眠剥夺前后分别完成注意网络任务,同步采集受试者的脑电图。用脑电样本熵算法分析脑电图的delta、theta、alpha、beta和gamma频率段的脑电复杂度并对比各频段脑电样本熵在睡眠剥夺前、后的变化。结果: 同睡眠剥夺前比较,睡眠剥夺后与受试者的注意网络冲突效应密切相关的反应时显著下降(P＜0.01),正确率显著增加(P＜0.01)。脑电样本熵分析发现在beta频率段,与注意网络冲突控制相关的脑电样本熵值在睡眠剥夺后明显增大(P＜0.01)。其余脑电频率段脑电样本熵未发现显著差异。结论: 表明完全睡眠剥夺后大脑的注意网络冲突效应降低,表明睡眠剥夺后执行冲突控制能力的下降。     

Parental generalized EEG alpha activity predisposes to spike wave discharges in offspring

Familial and twin studies have shown that the individual variability of the normal human electroencephalogram (EEG) is largely genetically determined. In epileptology, these genetic parameters of the EEG background activity are almost totally neglected. The aim of the present study has been to investigate whether a special genetic type of background activity might be related to the pathogenesis of epilepsy. EEG recordings of parents of 257 epileptic children were evaluated retrospectively. Some 156 healthy adults served as controls. Special attention was paid to alpha activity extending to the frontal region, both in bipolar and in referential recordings (Alpha I). Alpha I was found significantly more often in parents of children with primary generalized epilepsy (18%) compared with parents of children with focal epilepsy (8%) or controls (9%). In a second step, parental EEGs of children with different EEG patterns associated with epilepsy were studied. Alpha I was found significantly more often in parents of children with focal sharp waves and generalized spikes and waves (26%) than in parents of probands with focal sharp waves without additional generalized spikes and waves (8%) or in controls (9%). Parents of probands with theta rhythms and spikes and waves had alpha I significantly more often (18%) than parents of probands with theta rhythms without additional spikes and waves (8%) or controls (9%). The findings reveal a clear correlation between the type of EEG background activity in parents and the EEG characteristics in their children, thus pointing to common mechanisms.     

Transitions from Wakefulness to Sleep at Different Times of Day: Old vs. Young Subjects

In order to assess age effects upon the daytime level of alertness, both subjective and objective measures of alertness were obtained in 19 healthy elderly males (mean age 65 years) and 19 healthy young males (mean age 21 years). Subjects were recorded during a Multiple Sleep Latency Test (MSLT), administered at 5 different times of day (9 a.m., 12 a.m., 3 p.m., 6 p.m., 9 p.m.). Before each test, subjects filled out an alertness questionnaire. During the entire 20 minutes of each test electroencephalographic (EEG) recordings were made and transformed into 40 averaged spectra, one for each 30 s epoch. For the delta, theta, alpha, sigma and beta bands of the EEG 6 consecutive values were averaged to obtain 1 value per 3 minutes. On the basis of the visually guided detection of the first spindle, sleep onset was determined. The elderly subjects obtained a higher overall level of subjective alertness than the young subjects. No age effect was observed for sleep latency, which followed a U-shaped diurnal trend. Overall, the mean relative EEG energy values followed a diurnal trend that was the reverse of that for sleep latency. The mean relative delta EEG energy gradually increased, and the mean relative alpha EEG energy gradually decreased across the MSLT. For the young subjects the respective ranges of variation of these EEG bands were very similar, while for the elderly subjects the range of variation of the alpha values was less than half of that for the delta band. Apparently, alpha EEG activity during the wake-sleep transition does not simply covary with delta EEG activity. Moreover, age appears to have a significant effect upon the dynamics of alpha EEG activity during the wake-sleep transition.     

Testing the Benefits of Neurofeedback on Selective Attention Measured Through Dichotic Listening

The electrophysiological changes after a single session of neurofeedback training (↑SMR/↓Theta) and its effects on executive attention during a dichotic listening test with forced attentional procedures were measured in a sample of 20 healthy women. A pre–post moment test double blind design, with the inclusion of a group receiving sham neurofeedback, allowed for minimization of alien influences. The interaction of Moment × Group was significant, indicating an enhancement of SMR band after the real neurofeedback. The dichotic listening scores were correlated with the amplitude of Beta band in baseline conditions. The performance on the forced left attentional condition in dichotic listening was significantly improved and correlated positively with the post-training enhancement of the SMR band. The sham neurofeedback group also improved DL scores, so a clear affirmation about the benefits of neurofeedback training over cognitive performance could not be unambiguously established. It is concluded that the protocol showed a good independence and acceptable trainability in modifying the EEG results, but there was limited interpretability regarding cognitive outcomes.     

Neural Congruency Effects in the Multi-Source Interference Task Vanish in Healthy Youth after Controlling for Conditional Differences in Mean RT

According to the conflict monitoring model of cognitive control, reaction time (RT) in distracter interference tasks (e.g., the Stroop task) is a more precise index of response conflict than stimulus congruency (incongruent vs. congruent). The model therefore predicts that RT should be a reliable predictor of activity in regions of the posterior medial frontal cortex (pMFC) that are posited to detect response conflict. In particular, pMFC activity should be (a) greater in slow-RT than in fast-RT trials within a given task condition (e.g., congruent) and (b) equivalent in RT-matched trials from different conditions (i.e., congruent and incongruent trials). Both of these effects have been observed in functional magnetic resonance imaging (MRI) studies of adults. However, neither effect was observed in a recent study of healthy youth, suggesting that (a) the model does not accurately describe the relationship between RT and pMFC activity in this population or (b) the recent study was characterized by high variability due to a relatively small sample size. To distinguish between these possibilities, we asked a relatively large group of healthy youth (n = 28) to perform a distracter interference task - the multi-source interference task (MSIT) - while we recorded their brain activity with functional MRI. In this relatively large sample, both of the model’s predictions were confirmed. We conclude that the model accurately describes the relationship between pMFC activity and RT in healthy youth, but that additional research is needed to determine whether processes unrelated to response conflict contribute to this relationship.