Age,physical fitness,and attention: P3a and P3b

The influence of age and fitness on the neuroelectric correlates of attentional orienting and processing during stimulus discrimination were investigated. Younger and older adult participants completed a maximal aerobic exercise test and were separated into higher‐ and lower‐fit groups according to their cardiorespiratory fitness. Task performance and event‐related potential measures were obtained during two‐ and three‐stimulus oddball tasks. Results indicated that fitness may ameliorate or protect against cognitive aging for simple stimulus discriminations. Increases in task difficulty indicated that fitness may not be sufficient to overcome age‐related deficits in stimulus discrimination. Further, fitness did not influence attentional orienting. The findings suggest that fitness‐related changes in cognitive function may originate from other attentional mechanisms. Theoretical implications are discussed.     

Neuroelectric indices of goal maintenance following a single bout of physical activity

Previous event-related brain potential (ERP) investigations have demonstrated that single bouts of physical activity have transient benefits to aspects of cognitive control. However, this line of research has yet to explore goal maintenance. ERPs were collected using a within-participants design with young-adults following 30-min of both moderate walking and a non-exercise control session. Participants completed three conditions of an AX-continuous performance task (AX-CPT) that targeted goal maintenance processes, which were placed under greater cognitive demand when contexts were conflicting, as indexed by modulation of the N2 and P3 components. Following exercise, individuals exhibited increased accuracy for target trials, and P3 amplitude was greater at midline-parietal sites for both target trials and non-target trials. These results suggest that a single bout of aerobic exercise may facilitate goal maintenance processes and enable individuals to better inhibit extraneous neural activity to allocate greater attentional resources towards the updating and revision of goal representations.     

The effect of acute treadmill walking on cognitive control and academic achievement in preadolescent children

The effect of an acute bout of moderate treadmill walking on behavioral and neuroelectric indexes of the cognitive control of attention and applied aspects of cognition involved in school-based academic performance were assessed. A within-subjects design included 20 preadolescent participants (age=9.5±0.5 years; eight female) to assess exercise-induced changes in performance during a modified flanker task and the Wide Range Achievement Test 3. The resting session consisted of cognitive testing followed by a cardiorespiratory fitness assessment to determine aerobic fitness. The exercise session consisted of 20 min of walking on a motor-driven treadmill at 60% of estimated maximum heart rate followed by cognitive testing once heart rate returned to within 10% of pre-exercise levels. Results indicated an improvement in response accuracy, larger P3 amplitude, and better performance on the academic achievement test following aerobic exercise relative to the resting session. Collectively, these findings indicate that single, acute bouts of moderately-intense aerobic exercise (i.e. walking) may improve the cognitive control of attention in preadolescent children, and further support the use of moderate acute exercise as a contributing factor for increasing attention and academic performance. These data suggest that single bouts of exercise affect specific underlying processes that support cognitive health and may be necessary for effective functioning across the lifespan.     

Comparison of the acute effects of high‐intensity interval training and continuous aerobic walking on inhibitory control

The purpose of this study was to investigate the effects of a single bout of high‐intensity interval training (HIIT) and continuous aerobic exercise (CAE) on inhibitory control. The P3 component of the stimulus‐locked ERP was collected in 64 young adults during a modified flanker task following 20 min of seated rest, 20 min of CAE, and 9 min of HIIT on separate days in counterbalanced order. Participants exhibited shorter overall reaction time following CAE and HIIT compared to seated rest. Response accuracy improved following HIIT in the task condition requiring greater inhibitory control compared to seated rest and CAE. P3 amplitude was larger following CAE compared to seated rest and HIIT. Decreased P3 amplitude and latency were observed following HIIT compared to seated rest. The current results replicated previous findings indicating the beneficial effect of acute CAE on behavioral and neuroelectric indices of inhibitory control. With a smaller duration and volume of exercise, a single bout of HIIT resulted in additional improvements in inhibitory control, paralleled by a smaller and more efficient P3 component. In sum, the current study demonstrated that CAE and HIIT differentially facilitate inhibitory control and its underlying neuroelectric activation, and that HIIT may be a time‐efficient approach for enhancing cognitive health.     

Acute cardiovascular exercise and executive control function.

Acute cardiovascular exercise effects on cognitive function were examined using an executive control task by comparing neuroelectric and behavioral performance at baseline with post-exercise in 20 undergraduates. A within-subjects design was used to assess the P3 component of an event-related brain potential (ERP) and behavioral performance using a task that varied the amount of executive control required. The baseline session involved participation on the Eriksen flankers task followed by a graded maximal exercise test to measure cardiovascular fitness. The exercise session consisted of a 30-min acute bout of exercise on a treadmill followed by the Eriksen flankers task after heart rate returned to within 10% of pre-exercise levels. Across midline recordings sites, results indicated larger P3 amplitude following acute exercise compared to baseline. Shorter P3 latency was observed during the baseline Eriksen flankers task for the neutral compared to the incompatible condition; an effect not found following the acute bout of exercise. These findings suggest that acute bouts of cardiovascular exercise affect neuroelectric processes underlying executive control through the increased allocation of neuroelectric resources and through changes in cognitive processing and stimulus classification speed.     

Does a single session of Attentional Bias Modification influence early neural mechanisms of spatial attention? An ERP study

A relatively new cognitive‐affective training procedure, the Attentional Bias Modification (ABM) technique, is thought to decrease biases in the allocation of attention toward negative emotional stimuli. In two studies, we tested in samples of healthy students whether a single session of ABM has an influence on early orienting of spatial attention as indexed by the N2pc. Replicating previous studies, we found an occipitotemporal N2pc (180–300 ms) contralateral to angry versus neutral facial expressions, indicating that threatening faces automatically draw attention in early stages of stimulus processing. However, this N2pc effect did not significantly change during the ABM training session. Our results therefore indicate that a single session of ABM does not affect early attentional orienting. ABM effects reported in prior research may therefore have been mediated by later cognitive‐affective mechanisms.     

The uniqueness of social attention revisited: working memory load interferes with endogenous but not social orienting

It is well known that perceived eye gaze direction influences attentional orienting. However, it still remains unclear whether social orienting involves exogenous or endogenous attentional control. To address this issue, we examined if social orienting and endogenous orienting were differentially modulated by working memory load, which is known to interfere with endogenous but not exogenous attention. To do so, we manipulated eye direction as either spatially counterpredictive in Experiment 1 or spatially predictive in Experiment 2 while participants performed a cueing task either in isolation or under working memory load. We found that when social attention and endogenous attention diverged spatially in Experiment 1, social orienting elicited by gaze direction remained intact while endogenous orienting elicited by the cue’s predictive meaning was suppressed under working memory load, suggesting independence between social orienting and endogenous orienting. Indeed, a comparison between the sum of isolated social orienting and endogenous orienting magnitudes from Experiment 1 relative to their combined measure from Experiment 2 confirmed that social attention and endogenous attention operated in parallel. Together, our data show that social orienting is independent from endogenous orienting and further suggest that paying attention to social information might involve either exogenous or unique attentional mechanisms.     

Neurophysiological mechanisms in the emotional modulation of attention: the interplay between threat sensitivity and attentional control

Processing task-irrelevant emotional information may compromise attention performance, particularly among those showing elevated threat sensitivity. If threat-sensitive individuals are able to recruit attentional control to inhibit emotional processing, however, they may show few decrements in attention performance. To examine this hypothesis, attention performance was measured in three domains--alerting, orienting, and executive attention. Task-irrelevant fearful, sad, and happy faces were presented for 50 ms before each trial of the attention task to create a mildly competitive emotional context. Electroencephalographic recordings were made from 64 scalp electrodes to generate event-related potentials (ERPs) to the faces. Participants reporting high threat sensitivity showed enhanced ERPs thought to reflect emotional processing (P200) and attentional control (P100 and N200). Enhanced N200 following fearful faces was linked to sustained and even slightly improved executive attention performance (reduced conflict interference) among high threat-sensitive individuals, but with decrements in executive attention among low threat-sensitive individuals. Results are discussed in terms of cognitive processing efficiency and the balance between threat sensitivity and attentional control in relation to executive attention performance. Results may have implications for understanding automatic and voluntary attentional biases related to anxiety.     

The role of somatic threat feature detectors in the attentional bias toward pain: Effects of spatial attention

Our previous work suggests that somatic threat feature detectors indexed by a pain‐evoked midlatency negative scalp potential play an important role in the attentional bias toward pain. In these studies the somatic threat feature detectors facilitated the shift in attention to a somatic threat when attention was focused on another stimulus modality but not when it was focused on another spatial location. This experiment used the Posner cuing paradigm to investigate possible explanations for this discrepancy. The results demonstrate that the different somatic threat effects observed in previous modal and spatial cuing studies are not due to attentional set. Rather, this discrepancy may be related to differences in contingent attention capture. This study also verifies earlier findings suggesting that some of the pain‐related P2 component generators are involved in stimulus‐driven shifts in spatial attention toward task‐relevant stimuli.     

Acute exercise has a general facilitative effect on cognitive function: A combined ERP temporal dynamics and BDNF study

This study examined whether acute moderate intensity exercise results in a general or selective improvement in cognitive function. In addition, multiple stimulus‐locked ERP components and serum BDNF levels were assessed to investigate potential neurobiological mechanisms underlying acute exercise effects on select aspects of cognitive performance. Thirty young adults were recruited and participated in exercise and reading control sessions in a counterbalanced order. Following treatments, the Stroop task was administrated, and N1, N2, P3, and N450 components of the ERP waveform were recorded and analyzed. Additionally, blood samples were withdrawn immediately following exercise or rest conditions prior to administration of the Stroop task. Acute exercise facilitated response times for both Stroop congruent and incongruent task conditions, with a similar magnitude of improvement. Larger P3 and reduced N450 amplitudes as well as decreased N450 latency were observed following exercise, but no effects on N1 and N2 components were found. This dose of exercise also did not influence serum BDNF levels. These findings suggest that moderate intensity acute exercise results in a generalized rather than selective improvement in cognition. The facilitation may be related to an increase in attentional or neural resource allocation and conflict detection processes reflected by longer latency endogenous components (P3, N450), but is not influenced by earlier sensory and monitoring processes revealed by earlier ERP components or by serum levels of BDNF.     

Effect of working memory load on electrophysiological markers of visuospatial orienting in a spatial cueing task simulating a traffic situation

Visuospatial attentional orienting has typically been studied in abstract tasks with low ecological validity. However, real‐life tasks such as driving require allocation of working memory (WM) resources to several subtasks over and above orienting in a complex sensory environment. The aims of this study were twofold: firstly, to establish whether electrophysiological signatures of attentional orienting commonly observed under simplified task conditions generalize to a more naturalistic task situation with realistic‐looking stimuli, and, secondly, to assess how these signatures are affected by increased WM load under such conditions. Sixteen healthy participants performed a dual task consisting of a spatial cueing paradigm and a concurrent verbal memory task that simulated aspects of an actual traffic situation. Behaviorally, we observed a load‐induced detriment of sensitivity to targets. In the EEG, we replicated orienting‐related alpha lateralization, the lateralized ERPs ADAN, EDAN, and LDAP, and the P1‐N1 attention effect. When WM load was high (i.e., WM resources were reduced), lateralization of oscillatory activity in the lower alpha band was delayed. In the ERPs, we found that ADAN was also delayed, while EDAN was absent. Later ERP correlates were unaffected by load. Our results show that the findings in highly controlled artificial tasks can be generalized to spatial orienting in ecologically more valid tasks, and further suggest that the initiation of spatial orienting is delayed when WM demands of an unrelated secondary task are high.     

Attenuation of protective effect against eccentric exercise-induced muscle damage.

A single bout of eccentric exercise confers a long-lasting protective effect against subsequent bouts of the same exercise. This study investigated how the protective effect was lessened when the interval between the initial and secondary exercise bouts was increased from 4 to 12 weeks. Thirty young men performed two bouts of 12 maximal eccentric actions of the elbow flexors of the nondominant arm separated by either 4 (n = 9), 8 (n = 10), or 12 (n = 11) weeks. Maximal isometric strength, flexed and relaxed elbow joint angles, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase (CK), and myoglobin (Mb) were measured before, immediately after, and for 4 days after exercise. Changes in criterion measures were compared between bouts for each group and among groups by two-way repeated-measures ANOVA. There were no significant differences among groups in the changes in all measures following the first bout. Significantly (p < 0.05) smaller responses in all measures were observed after the second bout as compared with first bout for the 4 and 8 weeks, but only in strength, muscle soreness, CK, and Mb for the 12 weeks. It was concluded that some aspects of the protective effect were attenuated after 8 weeks, and the factors responsible for the effect vary among the measures.     

Sweating responses to a sustained static exercise is dependent on thermal load in humans

The purpose of this project was to test the hypothesis that internal temperature modulates the sweating response to sustained handgrip exercise. Ten healthy male subjects immersed their legs in 43 degrees C water for 30-40 min at an ambient temperatures of 30 degrees C and a relative humidity of 50%. Sweating responses to 50% maximal voluntary contraction isometric handgrip exercise (IH) were measured following the onset of sweating (i.e. following slight increases in internal temperature), and after more pronounced increases in internal temperature. Oesophageal temperature (Tes) was significantly lower during the first bout of exercise (37.54 +/- 0.07 degrees C) relative to the second bout (37.84 +/- 0.12 degrees C; P < 0.05). However, the increase in mean sweating rate (SR) from both the chest and forearm (non-glabrous skin) was significantly greater during the first IH bout relative to the second bout (P < 0.05). Increases in mean arterial blood pressure and palm SR (glabrous skin) did not differ significantly between exercise bouts, while heart rate and rating of perceived effort were significantly greater during the second bout of IH. As Tes and mean skin temperature did not change during either bout of exercise, the changes in SR from non-glabrous skin between the bouts of IH were likely because of non-thermal factors. These data suggest that sweating responses from non-glabrous skin during IH vary depending on the magnitude of thermal input as indicated by differing internal temperatures between bouts of IH. Moreover, these data suggest that the contribution of non-thermal factors in governing sweating from non-glabrous skin may be greatest when internal temperature is moderate (37.54 degrees C), but has less of an effect after greater elevations in internal temperature (i.e. 37.84 degrees C).     

Emotional face processing and attention performance in three domains: neurophysiological mechanisms and moderating effects of trait anxiety.

The rapid processing of emotional information adaptively regulates the allocation of attention, but may also divert resources away from attention performance, particularly for those showing elevated anxiety. The temporal organization of rapid emotional processing and its implications for attention performance, however, remain unclear. Participants were 18 healthy adults (12 females) who reported on trait anxiety. Tasks-irrelevant fearful, sad, and neutral faces were presented for 50 ms prior to each trial of a cued attention task measuring alerting, orienting, and executive attention. Electroencephalographic recordings were made from 64 scalp electrodes to generate event-related potentials (ERPs) to faces. Emotional face type and trait anxiety modulated ERP responses at three early stages around 200 ms, 250 ms, and 320 ms. Although behavioral findings showed enhanced orienting and executive attention following presentation of fearful and sad faces, the degree to which these faces modulated ERP responses, particularly around 250 ms, interfered with orienting and executive attention in the high trait anxiety group, and enhanced alerting in the low trait anxiety group. Results are discussed in terms of mechanisms in the emotional capture of attention and implications for understanding attentional processes in anxiety.     

Top-down and bottom-up attentional guidance: investigating the role of the dorsal and ventral parietal cortices

Recent neuroimaging studies suggest that the superior parietal lobule (SPL) of the human cortex mediates goal-directed attentional orienting, while the temporo-parietal junction (TPJ) mediates stimulus-driven attentional orienting. Here, we investigated these brain-behavior correspondences by examining the performance of patients with an attentional deficit following a right hemisphere lesion. Patients completed two tasks, one sensitive to stimulus-driven attentional orienting and the other to goal-directed attentional orienting. Based on the behavioral profiles obtained on each task, patients were assigned to different groups and their lesion overlap explored. Patients who exhibited difficulties with goal-directed attentional orienting and showed concurrent “hyper-capture” presented with lesion overlap centered over superior portions of the parietal lobule with spared inferior portions of the parietal lobule. Patients who performed normally on the goal-directed orienting task, while remaining abnormally immune to attentional capture, presented with lesion overlap centered over the inferior portions of the parietal lobule but spared superior parietal lobule. The findings from this study clearly suggest that (a) SPL and TPJ are anatomical regions that are recruited for the purposes of top-down and bottom-up orienting, respectively, and that damage to SPL and TPJ leads to disorders of top-down and bottom-up orienting, and (b) albeit dissociable, top-down and bottom-up orienting (and, by extension, SPL and TPJ) are not entirely independent mechanisms.     

Muscle damage responses of the elbow flexors to four maximal eccentric exercise bouts performed every 4 weeks

Since little is known about the repeated bout effect of more than two eccentric exercise bouts, this study compared muscle damage responses among four exercise bouts. Fifteen young (21.8 ± 1.9 years) men performed four bouts of 30 maximal isokinetic eccentric contractions of the elbow flexors every 4 weeks. Maximal voluntary elbow flexion isometric and concentric strength, range of motion at the elbow joint (ROM), upper arm circumference, blood markers of muscle damage, and muscle soreness were measured before and up to 120 h following each bout. Changes in all measures following the second to fourth bouts were significantly (P < 0.05) smaller than those after the first bout. The decreases in strength and ROM immediately after the fourth bout were significantly (P < 0.05) smaller than other bouts. It is concluded that the first bout confers the greatest adaptation, but further adaptation is induced when the exercise is repeated more than three times.     

Differential influences of exercise intensity on information processing in the central nervous system

The influence of exercise intensity on information processing in the central nervous system was investigated using P300 and no-go P300 event-related potentials. Twelve subjects (22–33 years) performed a go/no-go reaction time task in a control condition, and again after high-, medium-, and low-intensity pedaling exercises. Compared to the control condition, P300 amplitude decreased after high-intensity pedaling exercise and increased after medium-intensity pedaling exercise. There was no change after low-intensity pedaling exercise. These results suggested that the amount of attentional resources devoted to a given task decreased after high-intensity exercise and increased after medium-intensity exercise. The findings also suggest that changes in P300 amplitude are an inverted U-shaped behavior of differences in exercise intensity. In addition, no-go P300 amplitude showed the same changes as P300 amplitude at different exercise intensities. This indicates that differences in exercise intensity influenced not only the intensity of processing the requirement for a go response, but also processing of the need for a no-go response. It is concluded that differences in exercise intensity influenced information processing in the CNS.     

Attentional processes in children with ADHD: An event-related potential study using the attention network test

A variety of event-related potential (ERP) based studies have shown differences in neuronal processes underlying attention, inhibition and error processing in children with attention-deficit/hyperactivity disorder (ADHD) compared to controls. However, so far there are no studies that have compared children with ADHD and typically developing (TD) children regarding effects in ERP components associated with the attention network test (ANT). The ANT allows to differentiate between three particular aspects of attention: alerting, orienting, conflict.Twenty-five children with ADHD and 19 TD children (comparable with respect to age, sex, and IQ) performed the ANT while ERPs were recorded. Based on DSM-IV, the group of children with ADHD was divided in an inattentive (ADHDin, n = 10) and a combined (ADHDcom, n = 15) subgroup.On the performance level, the ADHD group showed a significantly higher variability of reaction times. Concerning ERP measures, smaller cue-P3 amplitudes were found in the ADHD group indicating that children with ADHD allocate less attentional resources for cue processing. In addition, the target-P3 in ADHD showed smaller amplitudes. Subgroup analysis revealed reduced cue-P3 amplitudes in both subgroups and reduced target-P3 amplitudes in ADHDin compared to TD children. Except for a higher alerting score in ADHD after correction for cue-P3 group differences, performance data revealed no group differences specific for the three attention networks. No group differences related to the attention networks were observed at the ERP level.Our results suggest that deviant attentional processing in children with ADHD is only partly related to ANT-specific effects. Findings are compatible with the model of a suboptimal energetic state regulation in ADHD. Furthermore, our results suggest that deviant cue processing in ADHD and related differences in task modulations should be accounted for in data analysis.     

Electrical microstimulation of primate posterior parietal cortex initiates orienting and alerting components of covert attention

The posterior parietal cortex (PPC) is implicated in the control of visuospatial orienting, including both overt saccadic eye movements and covert shifts of attention (i.e., attention to a location other than at visual fixation). Some studies have suggested that the attentional system is part of the premotor processing in the brain, while others suggest they are separate. Here, we test how the PPC controls covert attention shifts in the absence of executed eye movements. Electrical microstimulation was applied to the right PPC while monkeys performed a spatial, cued target detection task, in which they were not allowed to move their gaze. At high currents, contralateral saccades were evoked. With currents below the thresholds for eliciting saccades, microstimulation produced a purely attentional shift (as indexed by decreased target reaction time) when a cue and target were presented in the contralateral visual field. This suggests that microstimulation can move attention specifically in the absence of any overt movements of the eyes or limbs. In addition, there was a reduction in reaction times in trials that did not evoke attentional orienting, suggesting a more general alerting effect of microstimulation These data provide direct evidence that the PPC may be a source of both attentional modulation of neuronal responses and saccadic eye movements to peripheral visual stimuli.     

The N2pc component and its links to attention shifts and spatially selective visual processing

The N2pc component has recently become a popular tool in attention research. To investigate whether this component exclusively reflects attentional target selection or also prior stages in attentional processing (covert orienting, target-unspecific spatial attention), a spatial cuing procedure was combined with a visual search task. In some blocks, informative cues indicated the side of upcoming singleton targets that were present on most trials among uniform distractors. In other blocks, cues were spatially uninformative, and no preparatory shifts of attention were possible. The N2pc in response to targets was unaffected by this manipulation, showing that this component is not associated with attention shifts. Following informative cues, an attenuated N2pc was elicited by uniform nontarget arrays, suggesting that the N2pc may also reflect spatially specific processing of stimulus features at task-relevant locations prior to target selection.