Matthew B. Pontifex

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.

A neuroimaging investigation of the association between aerobic fitness, hippocampal volume, and memory performance in preadolescent children

Because children are becoming overweight, unhealthy, and unfit, understanding the neurocognitive benefits of an active lifestyle in childhood has important public health and educational implications. Animal research has indicated that aerobic exercise is related to increased cell proliferation and survival in the hippocampus as well as enhanced hippocampal-dependent learning and memory. Recent evidence extends this relationship to elderly humans by suggesting that high aerobic fitness levels in older adults are associated with increased hippocampal volume and superior memory performance. The present study aimed to further extend the link between fitness, hippocampal volume, and memory to a sample of preadolescent children. To this end, magnetic resonance imaging was employed to investigate whether higher- and lower-fit 9- and 10-year-old children showed differences in hippocampal volume and if the differences were related to performance on an item and relational memory task. Relational but not item memory is primarily supported by the hippocampus. Consistent with predictions, higher-fit children showed greater bilateral hippocampal volumes and superior relational memory task performance compared to lower-fit children. Hippocampal volume was also positively associated with performance on the relational but not the item memory task. Furthermore, bilateral hippocampal volume was found to mediate the relationship between fitness level (VO(2) max) and relational memory. No relationship between aerobic fitness, nucleus accumbens volume, and memory was reported, which strengthens the hypothesized specific effect of fitness on the hippocampus. The findings are the first to indicate that aerobic fitness may relate to the structure and function of the preadolescent human brain.

Aerobic Fitness and Cognitive Development: Event-Related Brain Potential and Task Performance Indices of Executive Control in Preadolescent Children

The relationship between aerobic fitness and executive control was assessed in 38 higher- and lower-fit children (M-sub(age) = 9.4 years), grouped according to their performance on a field test of aerobic capacity. Participants performed a flanker task requiring variable amounts of executive control while event-related brain potential responses and task performance were assessed. Results indicated that higher-fit children performed more accurately across conditions of the flanker task and following commission errors when compared to lower-fit children, whereas no group differences were observed for reaction time. Neuroelectric data indicated that P3 amplitude was larger for higher- compared to lower-fit children across conditions of the flanker task, and higher-fit children exhibited reduced error-related negativity amplitude and increased error positivity amplitude compared to lower-fit children. The data suggest that fitness is associated with better cognitive performance on an executive control task through increased cognitive control, resulting in greater allocation of attentional resources during stimulus encoding and a subsequent reduction in conflict during response selection. The findings differ from those observed in adult populations by indicating a general rather than a selective relationship between aerobic fitness and cognition.

Cardiorespiratory fitness and the flexible modulation of cognitive control in preadolescent children

The influence of cardiorespiratory fitness on the modulation of cognitive control was assessed in preadolescent children separated into higher- and lower-fit groups. Participants completed compatible and incompatible stimulus–response conditions of a modified flanker task, consisting of congruent and incongruent arrays, while ERPs and task performance were concurrently measured. Findings revealed decreased response accuracy for lower- relative to higher-fit participants with a selectively larger deficit in response to the incompatible stimulus–response condition, requiring the greatest amount of cognitive control. In contrast, higher-fit participants maintained response accuracy across stimulus–response compatibility conditions. Neuroelectric measures indicated that higher-fit, relative to lower-fit, participants exhibited global increases in P3 amplitude and shorter P3 latency, as well as greater modulation of P3 amplitude between the compatible and incompatible stimulus–response conditions. Similarly, higher-fit participants exhibited smaller error-related negativity (ERN) amplitudes in the compatible condition, and greater modulation of the ERN between the compatible and incompatible conditions, relative to lower-fit participants who exhibited large ERN amplitudes across both conditions. These findings suggest that lower-fit children may have more difficulty than higher-fit children in the flexible modulation of cognitive control processes to meet task demands.

Effects of the FITKids Randomized Controlled Trial on Executive Control and Brain Function

OBJECTIVE: To assess the effect of a physical activity (PA) intervention on brain and behavioral indices of executive control in preadolescent children. METHODS: Two hundred twenty-one children (7–9 years) were randomly assigned to a 9-month afterschool PA program or a wait-list control. In addition to changes in fitness (maximal oxygen consumption), electrical activity in the brain (P3-ERP) and behavioral measures (accuracy, reaction time) of executive control were collected by using tasks that modulated attentional inhibition and cognitive flexibility. RESULTS: Fitness improved more among intervention participants from pretest to posttest compared with the wait-list control (1.3 mL/kg per minute, 95% confidence interval [CI]: 0.3 to 2.4; d = 0.34 for group difference in pre-to-post change score). Intervention participants exhibited greater improvements from pretest to posttest in inhibition (3.2%, 95% CI: 0.0 to 6.5; d = 0.27) and cognitive flexibility (4.8%, 95% CI: 1.1 to 8.4; d = 0.35 for group difference in pre-to-post change score) compared with control. Only the intervention group increased attentional resources from pretest to posttest during tasks requiring increased inhibition (1.4 µV, 95% CI: 0.3 to 2.6; d = 0.34) and cognitive flexibility (1.5 µV, 95% CI: 0.6 to 2.5; d = 0.43). Finally, improvements in brain function on the inhibition task (r = 0.22) and performance on the flexibility task correlated with intervention attendance (r = 0.24). CONCLUSIONS: The intervention enhanced cognitive performance and brain function during tasks requiring greater executive control. These findings demonstrate a causal effect of a PA program on executive control, and provide support for PA for improving childhood cognition and brain health.

Basal Ganglia Volume Is Associated with Aerobic Fitness in Preadolescent Children

The present investigation is the first to explore the association between childhood aerobic fitness and basal ganglia structure and function. Rodent research has revealed that exercise influences the striatum by increasing dopamine signaling and angiogenesis. In children, higher aerobic fitness levels are associated with greater hippocampal volumes, superior performance on tasks of attentional and interference control, and elevated event-related brain potential indices of executive function. The present study used magnetic resonance imaging to investigate if higher-fit and lower-fit 9- and 10-year-old children exhibited differential volumes of other subcortical brain regions, specifically the basal ganglia involved in attentional control. The relationship between aerobic fitness, dorsal and ventral striatum volumes and performance on an attention and inhibition Eriksen flanker task was also examined. The results indicated that higher-fit children showed superior flanker task performance compared to lower-fit children. Higher-fit children also showed greater volumes of the dorsal striatum, and dorsal striatum volume was negatively associated with behavioral interference. The results support the claim that the dorsal striatum is involved in cognitive control and response resolution and that these cognitive processes vary as a function of aerobic fitness. No relationship was found between aerobic fitness, the volume of the ventral striatum and flanker performance. The findings suggest that increased childhood aerobic fitness is associated with greater dorsal striatal volumes and that this is related to enhanced cognitive control. Because children are becoming increasingly overweight, unhealthy and unfit, understanding the neurocognitive benefits of an active lifestyle during childhood has important public health and educational implications.

Physical Activity and Cognitive Function in a Cross-Section of Younger and Older Community-Dwelling Individuals

Previous reports have indicated a small, positive relationship between physical activity and cognition. However, the majority of research has focused on older adults, with few studies examining this relationship during earlier periods of the life span. This study examined the relationship of physical activity to cognition in a cross-section of 241 community-dwelling individuals 15-71 years of age with a task requiring variable amounts of executive control. Data were analyzed with multiple regression, which controlled for age, sex, and IQ. Participants reported their physical activity behavior and were tested for reaction time (RT) and response accuracy on congruent and incongruent conditions of a flanker task, which manipulates interference control. After controlling for confounding variables, an age-related slowing of RT was observed during both congruent and incongruent flanker conditions. However, physical activity was associated with faster RT during these conditions, regardless of age. Response accuracy findings indicated that increased physical activity was associated with better performance only during the incongruent condition for the older cohort. Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults.

The effect of acute aerobic and resistance exercise on working memory

PURPOSE The goal of this investigation was to assess the influence of acute bouts of aerobic versus resistance exercise on the executive control of working memory. METHODS Twenty-one young adult participants completed a cardiorespiratory fitness test and maximal strength tests. On subsequent days, task performance measures of reaction time (RT) and accuracy were collected while participants completed a modified Sternberg working memory task before the start of, immediately after, and 30 min after an intervention consisting of 30 min of either resistance or aerobic exercise and a seated rest control. RESULTS Findings indicated shorter RT immediately and 30 min after acute aerobic exercise relative to the preexercise baseline with no such effects observed after resistance exercise or seated rest. Further, in the aerobic condition, a larger reduction in RT from the baseline occurred during task conditions requiring increased working memory capacity. Again, no effect was observed in the resistance exercise or the seated rest conditions. CONCLUSION These data extend the current knowledge base by indicating that acute exercise-induced changes in cognition are disproportionately related to executive control and may be specific to the aerobic exercise domain.

The effects of an afterschool physical activity program on working memory in preadolescent children

The present study examined the effects of a 9-month randomized control physical activity intervention aimed at improving cardiorespiratory fitness on changes in working memory performance in preadolescent children relative to a waitlist control group. Participants performed a modified Sternberg task, which manipulated working memory demands based on encoding set sizes, while task performance and the contingent negative variation (CNV) event-related brain potential were measured. Analyses revealed that the physical activity intervention led to increases in cardiorespiratory fitness and improved Sternberg task performance. Further, the beneficial effects of the physical activity intervention were greater for a task condition requiring greater working memory demands. In addition, the intervention group exhibited larger initial CNV at the frontal electrode site, relative to the waitlist group at post-test; an effect not observed during the pre-test. These results indicate that increases in cardiorespiratory fitness are associated with improvements in the cognitive control of working memory in preadolescent children.

A Review of the Relation of Aerobic Fitness and Physical Activity to Brain Structure and Function in Children

A growing number of schools have increasingly de-emphasized the importance of providing physical activity opportunities during the school day, despite emerging research that illustrates the deleterious relationship between low levels of aerobic fitness and neurocognition in children. Accordingly, a brief review of studies that link fitness-related differences in brain structure and brain function to cognitive abilities is provided herein. Overall, the extant literature suggests that childhood aerobic fitness is associated with higher levels of cognition and differences in regional brain structure and function. Indeed, it has recently been found that aerobic fitness level even predicts cognition over time. Given the paucity of work in this area, several avenues for future investigations are also highlighted.