Biomedical subjects

Charles H Hillman

Publications and source records attributed to Charles H Hillman.

12 recordsLinked to original sources

PubMed2006

Neuroelectric and behavioral indices of interference control during acute cycling.

OBJECTIVE: This study examined the effects of in-task, moderate-intensity aerobic exercise on neuroelectric and behavioral indices of interference control, one component of executive control. METHODS: Forty-one participants completed a V O(2) max test to determine maximal heart rate (HR). On a separate day, event-related brain potentials and task performance were measured during the counterbalanced conditions of upright cycling at 60% of maximal HR and rest while performing congruent and incongruent trials of a flanker task. RESULTS: Exercise resulted in reduced response accuracy for incongruent trials relative to rest; an effect not found for congruent trials. Decreased N1 amplitude was observed during exercise at parietal sites and globally for N2. Exercise also resulted in increased amplitude for the P2 at frontal and central sites, and for the P3 at frontal and lateral sites. Further, longer N2 and P3 latencies were observed during exercise relative to rest. CONCLUSION: These findings suggest that the need to allocate attentional resources toward the large-scale bodily movements inherent in exercise may relate to inefficiency of neural resource allocation, resulting in decreased interference control. SIGNIFICANCE: These data indicate general and selective exercise-induced decrements in cognitive processing while performing acute aerobic exercise.

Adult↗

PubMed2006

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.

Aged↗

PubMed2006

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.

Adolescent↗

PubMed2006

Neurobiology of exercise.

Voluntary physical activity and exercise training can favorably influence brain plasticity by facilitating neurogenerative, neuroadaptive, and neuroprotective processes. At least some of the processes are mediated by neurotrophic factors. Motor skill training and regular exercise enhance executive functions of cognition and some types of learning, including motor learning in the spinal cord. These adaptations in the central nervous system have implications for the prevention and treatment of obesity, cancer, depression, the decline in cognition associated with aging, and neurological disorders such as Parkinson's disease, Alzheimer's dementia, ischemic stroke, and head and spinal cord injury. Chronic voluntary physical activity also attenuates neural responses to stress in brain circuits responsible for regulating peripheral sympathetic activity, suggesting constraint on sympathetic responses to stress that could plausibly contribute to reductions in clinical disorders such as hypertension, heart failure, oxidative stress, and suppression of immunity. Mechanisms explaining these adaptations are not as yet known, but metabolic and neurochemical pathways among skeletal muscle, the spinal cord, and the brain offer plausible, testable mechanisms that might help explain effects of physical activity and exercise on the central nervous system.

Adaptation, Physiological↗

PubMed2005

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.

Adolescent↗

PubMed2005

Postural and eye-blink indices of the defensive startle reflex.

Postural and eye-blink reactions to acoustic startle probes were examined in 24 volunteers, who completed two blocked conditions (baseline, startle). A postural reaction during the startle condition demonstrated a reflexive movement in the anterior-posterior direction, which was not observed during the baseline condition. This reflexive response was positively associated with the eye-blink reflex, such that larger blink magnitude related to greater posterior movement. These findings were not observed for postural movements in the medial-lateral direction. The results suggest that a measurable postural reaction may be observed following a startling acoustic stimulus, which may reflect generalized bodily flexion associated with a preparatory behavioral response.

Acoustic Stimulation↗

PubMed2005

Influences of age on emotional reactivity during picture processing.

We compared emotional reactivity to affective pictures for 32 older (60-71 years) and 34 younger (18-23 years) adults. We collected the startle-blink reflex, N1 and P3 components of the probe-evoked event-related brain potential, corrugator electromyogram, heart rate, and self-report measures of pleasure and arousal. Self-report findings indicated that older, compared with younger, adults reported greater overall pleasure and arousal. Older adults also exhibited decreased N1 and P3 amplitude, corrugator activity, and heart rate deceleration compared with younger adults. The startle-blink reflex revealed that older adults exhibited increased startle-blink magnitude compared with younger adults during unpleasant pictures, with no age differences observed for pleasant and neutral contents. These age differences suggest that older adults have differential reactivity to affective picture viewing, and they indicate that age-related changes in emotion are not unitary across response systems.

Adolescent↗

PubMed2005

Aerobic fitness and neurocognitive function in healthy preadolescent children.

PURPOSE: We investigated the relationship between age, aerobic fitness, and cognitive function by comparing high- and low-fit preadolescent children and adults. METHOD: Twenty-four children (mean age = 9.6 yr) and 27 adults (mean age = 19.3 yr) were grouped according to their fitness (high, low) such that four approximately equal groups were compared. Fitness was assessed using the Fitnessgram test, and cognitive function was measured by neuroelectric and behavioral responses to a stimulus discrimination task. RESULTS: Adults exhibited greater P3 amplitude at Cz and Pz sites, and decreased amplitude at the Oz site compared with children. High-fit children had greater P3 amplitude compared with low-fit children and high- and low-fit adults. Further, adults had faster P3 latency compared with children, and high-fit participants had faster P3 latency compared with low-fit participants at the Oz site. Adults exhibited faster reaction time than children; however, fitness interacted with age such that high-fit children had faster reaction time than low-fit children. CONCLUSION: These findings suggest that fitness was positively associated with neuroelectric indices of attention and working memory, and response speed in children. Fitness was also associated with cognitive processing speed, but these findings were not age-specific. These data indicate that fitness may be related to better cognitive functioning in preadolescents and have implications for increasing cognitive health in children and adults.

Adult↗

PubMed2004

Emotion and motivated behavior: postural adjustments to affective picture viewing.

Thirty-six participants (18 female, 18 male) viewed affective pictures to investigate the coupling between emotional reactions and motivated behavior. Framed within the biphasic theory of emotion, the three systems approach was employed by collecting measures of subjective report, expressive physiology, and motivated behavior. Postural adjustments associated with viewing affective pictures were measured. Results indicated sex-differences for postural responses to unpleasant pictures; an effect not found for pleasant and neutral picture contents. Females exhibited increased postural movement in the posterior direction, and males exhibited increased movement in the anterior direction, for unpleasant pictures. Subjective report of valence and arousal using the self-assessment manikin (SAM), and the startle eye-blink reflex were collected during a separate session, which replicated previous picture-viewing research. Specifically, participants rated pleasant pictures higher in valence and exhibited smaller startle responses compared to unpleasant pictures. Females also reported lower valence ratings compared to males across all picture contents. These findings extend our knowledge of motivated engagement with affective stimuli and indicate that postural responses may provide insight into sex-related differences in withdrawal behavior.

Adolescent↗

PubMed2004

Physical activity and executive control: implications for increased cognitive health during older adulthood.

Electrocortical and behavioral responses of low, moderate, and high physically active older adults were compared with a younger control group on neutral and incompatible conditions of a flankers task. Compared to younger adults, high and moderate active older adults exhibited increased event-related potentials component P3 amplitude for the incompatible condition at the frontal electrode site. For the neutral condition, only low active older adults exhibited decreased amplitude at the central-parietal site, compared to younger adults. P3 latency revealed the longest latencies for low active older adults, followed by moderate active, high active, and younger adults, respectively. Reaction time (RT) data revealed that younger adults exhibited faster RT compared to all three older groups. Results suggest that physical activity may improve executive control function in older adults by affecting the distribution of P3 amplitude, which has been related to memory and attentional processes, and by decreasing P3 latency, which relates to the speed of cognitive processing.

Aged↗

PubMed2003

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.

Adult↗

PubMed2002

The relationship of age and cardiovascular fitness to cognitive and motor processes.

Older and younger aerobically trained and sedentary adults participated in an S1-S2-S3 paradigm designed to elicit event-related potential (ERP) and behavioral responses to determine the influence of cardiovascular fitness on cognitive and motor processes. The paradigm provided warning (S1) as to the difficulty level of an upcoming decision task (S2). Participants had to decide the taller of two bars on presentation of S2 but hold their response until S3, to which they indicated their choice motorically. Results revealed age-related differences for ERP measures as older participants showed increased amplitude of the stimulus preceding negativity (SPN) prior to S2, and longer latencies and equipotentiality of P3 in response to S2. Fitness effects were also observed for the contingent negative variation (CNV) with decreased amplitude for fit relative to sedentary individuals. Age interacted with fitness for P3 latency to S2 as older sedentary individuals showed the longest latency followed by older fit and both younger groups. No significant group differences were observed for reaction time (RT) to S3. Therefore, physical fitness is associated with attenuation of cognitive decline in older individuals and greater economy of motor preparation for both young and older participants.

Adolescent↗