Cardiovascular fitness and executive control during task-switching: An ERP study

Cardiovascular fitness recently has been linked to executive control function in older adults. The present study examined the relationship between cardiovascular fitness and executive control in young adults using event-related potentials (ERPs). Participants completed a two-part experiment. In part one, a graded exercise test (GXT) was administered using a cycle ergometer to obtain VO(2)max, a measure of maximal oxygen uptake. High-fit participants had VO(2)max measures at or above the 70th percentile based on age and sex, and low-fit participants had VO(2)max measures at or below the 30th percentile. In part two, a task-switching paradigm was used to investigate executive control. Task-switching trials produced slower response times and greater amplitude for both the P3a and P3b components of the ERP relative to a non-switch trial block. No ERP components varied as a function of fitness group. These findings, combined with results from previous research, suggest that the relationship between greater cardiovascular fitness and better cognitive function emerges after early adulthood.     

The effects of covert attention and stimulus complexity on the P3 response during an auditory continuous performance task.

This study examined the effects of motor responding and stimulus complexity on the event-related potential (ERP) P3 amplitude and latency during an auditory continuous performance task (A-CPT). Subjects were presented with undegraded and degraded syllables during two experimental conditions. In the motor attention (MA) condition participants performed a button press to target syllables. In the covert attention (CA) condition, participants listened for target syllables without responding. The ERP P3 amplitude for targets during MA and CA showed the expected anterior-to-posterior scalp topography, with the greatest amplitude at Pz. Although amplitudes across all scalp sites were greater for MA than CA target P3 responses, both MA and CA targets had greater P3 amplitudes than the P3 for the nontarget syllables (NT). There was no effect of stimulus complexity (degraded vs. undegraded) on P3 amplitude. However, stimulus complexity did affect P3 latency. Degraded syllables elicited longer P3 latency than undegraded syllables for both the MA and CA conditions. The amplitude and topography findings show that when stimulus probability is controlled through the use of a CPT paradigm, a reliable P3 component is present even when the task does not require a motor response to target stimuli.     

A cross-sectional examination of age and physical activity on performance and event-related brain potentials in a task switching paradigm.

Younger and older physically active and sedentary adults participated in a task switching paradigm in which they performed a task repeatedly or switched between two different tasks, while measures of response speed, response accuracy, P3 amplitude, and P3 latency were recorded. Overall, response times were faster and midline P3 amplitudes were larger for the active than for the sedentary participants. P3 latencies discriminated between active and sedentary individuals on trials in which multiple task sets were maintained in memory and task switches occurred unpredictably but not in blocks of trials in which a single task was repeatedly performed. Results are discussed in terms of the specificity and generality of physical activity effects on cognition.     

P300, N400, aerobic fitness, and maximal aerobic exercise

Electrophysiological effects of aerobic fitness and maximal aerobic exercise were investigated by comparing P300 and N400 before and after a maximal cycling test. Event-related potentials (ERPs) were obtained from 20 students divided into two matched groups defined by their aerobic fitness level (cyclists vs. sedentary subjects). The session of postexercise ERPs was performed immediately after body temperature and heart rate returned to preexercise values. At rest, no significant differences were observed in ERP parameters between cyclists and sedentary subjects. This finding argued against the hypothesis that ERP modifications may be directly assumed by aerobic fitness level. The postexercise session of ERPs showed a significant P300 amplitude increase and a significant P300 latency decrease in all subjects. Similarly, N400 effect increased significantly after the maximal exercise in all subjects. ERP changes were of the same magnitude in the two groups. The present study argues for a general arousing effect of maximal aerobic exercise, independently of the aerobic fitness level.     

An ERP study of age‐related differences in the central cost of interlimb coordination

The study investigated event‐related EEG potentials during concurrent performance of interlimb coordination and visual oddball tasks by younger and older adults. Coordination task difficulty was equated between age groups by allowing participants to perform the task at self‐determined frequencies. The amplitude of the P3b component of the event‐related potentials (ERPs) elicited by visual task targets showed a different pattern across midline sites (Fz, Cz, Pz) for younger and older adults. While younger adults showed a parietal maximum, P3b amplitudes in older adults did not differ across midline site, with lower amplitudes at central and parietal sites than younger adults but higher amplitude at the frontal site. Younger adults also had significantly shorter P3b latency than older adults. The results suggest that older adults may rely more on cognitive control of their movements than younger adults.     

六周虚拟现实运动对大学生认知能力影响的事件相关电位测评

评价虚拟现实运动对人体认知能力的影响.随机招募30名健康大学生,实验组(20人)利用爱动运动王Ⅱ进行六周的虚拟现实运动(伸展运动、射箭运动与平衡运动),每次30 min,每周三次.对照组(10人)正常作息.采用德国BP公司生产的32导Brain Vision Analyzer分别测量受试者实验前和六周实验结束后安静状态下的事件相关电位(event-related potential,ERP) P300,选用改良版的Flanker刺激范式.采用SPSS15.0 for windows对数据分别进行描述性统计和推断性统计分析.六周前后组内配对t检验显示,实验组额叶区(F3、F4)和中央区(C3)电极点在一致性刺激时(S1和S2)ERP P300潜伏期较实验前显著延长(P<0.05),额叶区表现更为显著.实验组中顶区(P3)S1刺激下ERP P300波幅较实验前显著增加(P<0.05).对照组和实验组其他电极点和其他刺激方式下未见有显著性改变(P>0.05).六周虚拟现实运动(伸展运动、射箭运动与平衡运动)对大学生认知能力有一定的选择性影响,体现于ERP P300潜伏期和波幅指标显著性改变仅出现在特定的脑区和刺激方式.P300潜伏期改变只出现于额叶区和中央区,P300波幅改变只出现在顶区,且上述改变仅发生在一致性刺激的条件下.这些选择性改变应是对该运动方式的适应性改变.     

Event-related potential index of age-related differences in memory processes in adults with Down syndrome

A major goal of aging research is to identify early markers of age-related cognitive decline. Persons with Down syndrome (DS) experience accelerated aging and high risks for dementia, making them a valuable albeit understudied model for testing such markers. This study examined event-related potential (ERP) indices of visual memory in younger (19–25 years) and older (35–40 years) adults with DS using a passive viewing paradigm that did not require memorization or behavioral responses. ERPs were recorded in response to unfamiliar urban and nature scenes, with some images presented once and others repeated multiple times. Within 600 to 900 milliseconds after stimulus onset, repeated stimuli elicited more positive amplitudes in younger participants, indicating stimilus recognition. ERPs of older adults did not show such increases, suggesting reduced memory functioning. ERP indices were unrelated to participants' intellectual functioning, but did correlate with age and caregiver-reported lethargy/withdrawal behaviors. Passive ERP measures of memory processes are sensitive to early stages of cognitive decline in DS and are promising markers of cognitive risk for future aging studies.     

Age and physical activity influences on action monitoring during task switching

Behavioral and neuroelectric indices of action monitoring were compared for 53 high and low physically active older (60-71 years) and younger (18-21 years) adults during a task-switching paradigm in which they performed a task repeatedly or switched between two different tasks. The error-related negativity (ERN) of a response-locked event-related brain potential (ERP) and behavioral measures of response speed and accuracy were measured during the heterogeneous condition (switching randomly between two tasks) of the switch task. Results indicated that older adults exhibited a greater relative slowing in RT during heterogeneous blocks and smaller ERN amplitude compared to younger adults. Additionally, physical activity differences revealed a relatively smaller global switch cost for physically active older adults and decreased ERN amplitude, as well as increased post-error response slowing for older and younger physically active participants, compared to their less physically active counterparts. The findings suggest that both age and physical activity participation influence behavioral and neuroelectric indices of action monitoring and provide further evidence for the beneficial effects of physical activity on executive control.     

The relation of aerobic fitness to neuroelectric indices of cognitive and motor task preparation

The relation of aerobic fitness to task preparation was examined in a sample of young adults separated into higher‐ and lower‐fit groups according to their maximal oxygen consumption. Participants performed a modified Sternberg working memory task under speed and accuracy instructions while measures of task performance and contingent negative variation (CNV) were collected. Analyses revealed no significant fitness differences between groups on task performance measures. However, frontal CNV amplitude was significantly larger for lower‐fit participants compared to higher‐fit participants during the speed instructions, an effect not found for the accuracy instructions. These results suggest that lower‐fit individuals may rely to a greater extent on cognitive control processes to respond under speeded conditions, whereas higher‐fit individuals may maintain a more constant level of control irrespective of the task instructions.     

Electrocortical correlates of intra-subject variability in reaction times: average and single-trial analyses

Intra-subject variability of reaction times (ISV), generally considered secondary to measures of central tendency, has become increasingly important for cognitive neuroscience. Event-related potential (ERP) research suggests an inverse relationship between ISV and P3b amplitude; however ERP methods’ reliance on averaged waveforms may be unsuitable for studying ISV due to potentially distorting effects of latency jitter. The present study investigates the neural bases of ISV through single-trial analysis of P3bs in groups with low and high ISV, using Infomax-rotated principal components analysis of ERP data. Results indicate that while latency jitter contributes to the reduced P3b amplitude seen in average ERPs of high ISV participants, group differences in amplitude survive the use of single-trial methods that are robust to such distortions. A decoupling of P3b and RT was also seen in the high ISV group. The results are discussed in the context of the P3b's dimensionality, and its possible catecholaminergic underpinnings.     

Age‐related changes in ERP correlates of visuospatial and motor processes

Although previous ERP studies have demonstrated slowing of visuospatial and motor processes with age, such studies frequently included only young and elderly participants, and lacked information about age‐related changes across the adult lifespan. The present research used a Simon task with two irrelevant dimensions (position and direction of an arrow) to study visuospatial (N2 posterior contralateral, N2pc) and motor (response‐locked lateralized readiness potential, LRP‐r) processes in young, middle‐aged, and elderly adults. The reaction time and motor execution stage (LRP‐r) increased gradually with age, while visuospatial processes (N2pc latency) were similarly delayed in the older groups. No age‐related increase in interference was observed, probably related to a delay in processing the symbolic meaning of the direction in older groups, which was consistent with age‐related differences in distributional analyses and N2pc amplitude modulations.     

P300 amplitude age reductions are not caused by latency jitter

Studies of the event-related potentials (ERPs) P3a/P3b have given insights into age effects on cognitive processes in the brain, and it has been established that latency increases and amplitude decreases with age. However, if latency jitter, that is, variation in single trial latencies, is larger in elderly than in younger participants, this may create an artificial age-amplitude correlation. The aim of this article is to test whether correction for latency jitter affects the P3a/P3b age correlations. One hundred thirty-three healthy adults (20-88 years old) went through a 3-stimuli visual oddball paradigm. Latency jitter was corrected by use of a Maximum Likelihood Estimation method. The results showed that corrections for latency jitter did not significantly affect the correlations between P3a/P3b and age. It is concluded that previous reports of amplitude reduction as a function of age seem to be valid regardless of whether latency jitter correction has been applied.     

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.     

Age-related frontoparietal changes during the control of bottom-up and top-down attention: an ERP study

We investigated age-related changes in frontal and parietal scalp event-related potential (ERP) activity during bottom-up and top-down attention. Younger and older participants were presented with arrays constructed to induce either automatic “pop-out” (bottom-up) or effortful “search” (top-down) behavior. Reaction times (RTs) increased and accuracy decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. The latency of the P300 elicited by the visual search array was shorter in both conditions in the younger than in the older adults. Pop-out target detection was associated with greater activity at parietal than at prefrontal locations in younger participants and with a more equipotential prefrontal-parietal distribution in older adults. Search target detection was associated with greater activity at prefrontal than at parietal locations in older relative to younger participants. Thus, aging was associated with a more prefrontal P300 scalp distribution during the control of bottom-up and top-down attention. Early latency extrastriate potentials were enhanced and N2-posterior-contralateral (N2pc) was reduced in the older group, supporting the idea that the frontal enhancements may be due to a compensation for disinhibition and distraction in the older adults. Taken together these findings provide evidence that younger and older adults recruit different frontal-parietal networks during top-down and bottom-up attention, with older adults increasing their recruitment of a more frontally distributed network in both of these types of attention. This work is in accord with previous neuroimaging findings suggesting that older adults recruit more frontal activity in the service of a variety of tasks than younger adults.     

Aging,physical activity,and cognitive processing: an examination of P300

Physical activity appears to attenuate the decline of cognitive function typically observed in older men and women. The P300 component of the event-related potential (ERP) is particularly affected by aging and allows for basic neurobiological assessment of cognitive function. Three aspects of the P300 component (i.e. latency, amplitude, and area under the curve (AUC)), elicited by an oddball task, were derived to assess cognitive function in young and older participants (N=73) who were further classified as high- and low-active. The low-active elderly participants exhibited larger AUC values than those observed in all other groups which were undifferentiated. That is, the high-active elderly and the young participants exhibited smaller AUC values than the low-active older group. In conclusion, higher levels of physical activity in the elderly may be associated with a reduction in the neural resources allocated in response to simple cognitive challenge. This interpretation is consistent with the concept of psychomotor efficiency proposed by Hatfield and Hillman [The psychophysiology of sport: a mechanistic understanding of the psychology of superior performance. In: Singer RN, Hausenbias HA, Janelle CM, editors. Handbook of sport psychology. 2nd ed. New York: Wiley; 2001, p. 362-88].     

Independent processing of visual stimulus changes in ventral and dorsal stream features indexed by an early positive difference in event-related brain potentials.

In event-related brain potential (ERP) studies of brain activity using a visual S1-S2 matching task, change stimuli elicit a posterior positive component with a latency of 100-200 ms. To elucidate the hierarchical organization of the processing of a visual stimulus change based on multiple stimulus features, ERPs were recorded in 12 participants performing an S1-S2 matching task with stimuli defined by color (mediated by the ventral stream) and motion direction (mediated by the dorsal stream). Each trial consisted of two sequentially presented stimuli (S1-S2), where S2 was either (1) the same as S1 (i.e., no change), (2) different from S1 in color only (color change), (3) different in motion direction only (motion direction change), or (4) different in both color and motion direction (color-motion direction change). These trials were presented in random order with equal probability, and the participants were asked to respond to one of these trials in separate blocks. Relative to the no-change stimulus, the three types of change stimuli elicited posterior positivities. The scalp-topography of change positivities differed according to the feature changed. In addition, the amplitude and scalp-topography of change positivities in response to a conjunction change were the respective sums of those in response to changes in the corresponding single features. These results suggest that the change detection system reflected by the change positivity is separate for each feature dimension, and these operate independently.     

Overcoming limitations of the ERP method with Residue Iteration Decomposition (RIDE): A demonstration in go/no‐go experiments

The usefulness of the event‐related potential (ERP) method can be compromised by violations of the underlying assumptions, for example, confounding variations of latency and amplitude of ERP components within and between conditions. Here we show how the ERP subtraction method might yield misleading information due to latency variability of ERP components. We propose a solution to this problem by correcting for latency variability using Residue Iteration Decomposition (RIDE), demonstrated with data from representative go/no‐go experiments. The overlap of N2 and P3 components in go/no‐go data gives rise to spurious topographical localization of the no‐go–N2 component. RIDE decomposes N2 and P3 based on their latency variability. The decomposition restored the N2 topography by removing the contamination from latency‐variable late components. The RIDE‐derived N2 and P3 give a clearer insight about their functional relevance in the go/no‐go paradigm.     

P300 event-related potential heritability in monozygotic and dizygotic twins

The present study examined the heritability of the P3 waveform and the N1, P2, and N2 components by assessing the visual event-related potential (ERP) of 30 monozygotic (MZ) and 34 dizygotic (DZ) twin pairs. Electroencephalogram activity was recorded from Pz, P3, and P4 scalp sites while individuals performed a reaction time task involving two conditions differing in difficulty. Genetic modeling indicated substantial genetic influence on P3 amplitude, P3 latency, and manual reaction time for the difficult condition. No significant heritability was found for the latency of P3 or manual reaction time for the easy condition, but P3 amplitude was heritable for this condition. The amplitude of the early components (N1, P2, and N2) was heritable, but no significant genetic influences were found for the latency of these components. Compared with the DZ twins, the greater similarity of the MZ pairs on the event-related potential measures was not due to their greater similarity in either head dimensions or mental ability, despite the facts that IQ scores were weakly correlated with P3 and N2 amplitude and that amplitude and latency were related to some measures of head size. These findings suggest that P3 amplitude and the amplitude of earlier ERP components are under partial genetic control, supporting the notion that these ERP components could perhaps be used to identify genetic risk for psychopathology.     

正常人的视觉事件相关电位研究

本文利用三种视觉符号编排的刺激序列，记录了９５名正常人的视觉ＥＲＰ，报道了Ｆｚ、Ｐｚ点Ｎ２、Ｐ３波幅和潜伏期的正常值及Ｎ２、Ｐ３的影响因素。结果表明：该刺激序列可引出清晰、稳定的ＥＲＰ波形；Ｐ３波幅与任务和部位有关，靶Ｐ３波幅大于非靶Ｐ３，靶Ｐ３于Ｐｚ点波幅大于Ｆｚ，非靶Ｐ３在Ｆｚ、Ｐｚ点间波幅无明显差异；Ｎ２波幅与任务无关，靶与非靶之间Ｎ２波幅无差异，而与部位有关，Ｆｚ点波幅大于Ｐｚ点；Ｎ２、Ｐ３受年龄的影响．中老年人Ｎ２、Ｐ３潜伏期长于青年人，而波幅中老年人较青年人低。     

Older adults display diminished error processing and response in a continuous tracking task

Advancing age is often accompanied by a decline in motor control that results in a decreased ability to successfully perform motor tasks. While there are multiple factors that contribute to age‐related deficits in motor control, one unexplored possibility is that age‐related deficits in our ability to evaluate motor output result in an increase in motor errors. In line with this, previous work from our laboratory demonstrated that motor errors evoked an error‐related negativity (ERN)—a component of the human ERP associated with error evaluation originating within the human medial‐frontal cortex. In the present study, we examined whether or not deficits in the medial‐frontal error evaluation system contribute to age‐related deficits in motor control. Two groups of participants (young, old) performed a computer‐based tracking task that paralleled driving while EEG data were recorded. Our results show that older adults committed more behavioral errors than young adults during performance of the tracking task. An analysis of our ERP data revealed that the amplitude of the ERN was reduced in older adults relative to young adults following motor errors. Our results make an important extension from previous work demonstrating age‐related reductions in the ERN during performance of cognitive tasks. Importantly, our results imply the possibility of understanding motor deficits in older age.