Physical Activity Shapes Brain Structure, Function, and the Computational Mechanisms of Cognitive Control

Perceptual decision-making performance depends on several cognitive and neural processes. Here, we fit Ratcliff's diffusion model to accuracy data and reaction-time distributions from one numerical and one verbal two-choice perceptual-decision task to deconstruct these performance measures into the rate of evidence accumulation (i.e., drift rate), response criterion setting (i.e., boundary separation), and peripheral aspects of performance (i.e., nondecision time). These theoretical processes are then related to individual differences in brain activation by means of multiple regression. The sample consisted of 24 younger and 15 older adults performing the task in fMRI before and after 100 daily 1-hr behavioral training sessions in a multitude of cognitive tasks. Results showed that individual differences in boundary separation were related to striatal activity, whereas differences in drift rate were related to activity in the inferior parietal lobe. These associations were not significantly modified by adult age or perceptual expertise. We conclude that the striatum is involved in regulating response thresholds, whereas the inferior parietal lobe might represent decision-making evidence related to letters and numbers.

Decades of research show that people from adverse environments tend to score lower on cognitive tasks. These findings have been associated with deficits in various cognitive abilities, which has led to the proliferation of deficit models. These models emphasize the negative effects of chronic stress on social and cognitive development. More recently, research has started to focus on the ways in which adversity exposure may lead to adaptations specific cognitive abilities and strategies. Such adaptations could potentially lead to enhancements in abilities that are useful for solving the unique challenges posed by adverse environments, such as threat detection. A better integration of deficit and adaptation perspectives is important both for basic science and the development of interventions. Despite their importance, deficit and adaptation perspectives are not well-integrated. This dissertation argues that one reason for this might be that research from both perspectives tends to focus on raw performance measures, such as response times and accuracy. However, these measures have two important limitations. First, performance on EF tasks is not just influenced by specific EF abilities, but also by other cognitive processes, such as response caution. Second, performance on EF tasks is additionally influenced by general processes that shape performance across multiple cognitive tasks. These limitations hinder our understanding of how adversity shapes cognitive abilities. To address the first limitation, this dissertation uses Drift Diffusion Modeling (DDM). The DDM explains response times and accuracy on tasks that require binary decision-making as a combination of (1) the speed with which someone accumulates information (Drift rate), (2) the amount of information someone needs before making a decision (Boundary separation), and (3) the speed of non-decisional processes, such as stimulus encoding and respons execution (Non-decision time). By applying DDM to empirical task data, we can obtain participant-level estimates of these three cognitive processes. To address the second limitation, this dissertation uses structural equation modeling. This technique allows us to investigate the extent to which performance on EF tasks is shaped by task-specific processes versus task-general processes. This dissertation shows that adversity researchers may overestimate the association between adversity and specific EF abilities. We find that negative associations between adversity and drift rates are mostly driven by general processing speed. After correcting for general factors, we find little to no evidence for associations between adversity and specific EF abilities. Finally, we show that people with more adversity exposure sometimes use different strategies compared to people with less adversity exposure. These findings show that researchers should account for the fact that performance on EF tasks cannot be explained by specific EF abilities alone. Instead, they should tease apart the distinct cognitive processes that affect performance to better understand how adversity shapes cognitive development. Ideally, studies would include two or more tasks per EF ability in order to estimate abilities on a latent level. Cognitive modeling can be a valuable technique for the next generation of adversity researchers.

Background: Visual hallucinations (VH) are a common symptom in dementia with Lewy bodies (DLB); however, their cognitive underpinnings remain unclear. Hallucinations have been related to cognitive slowing in DLB and may arise due to impaired sensory input, dysregulation in top-down influences over perception, or an imbalance between the two, resulting in false visual inferences. Methods: Here we employed a drift diffusion model yielding estimates of perceptual encoding time, decision threshold, and drift rate of evidence accumulation to (i) investigate the nature of DLB-related slowing of responses and (ii) their relationship to visuospatial performance and visual hallucinations. The EZ drift diffusion model was fitted to mean reaction time (RT), accuracy and RT variance from two-choice reaction time (CRT) tasks and data were compared between groups of mild cognitive impairment (MCI-LB) LB patients (n = 49) and healthy older adults (n = 25). Results: No difference was detected in drift rate between patients and controls, but MCI-LB patients showed slower non-decision times and boundary separation values than control participants. Furthermore, non-decision time was negatively correlated with visuospatial performance in MCI-LB, and score on visual hallucinations inventory. However, only boundary separation was related to clinical incidence of visual hallucinations. Conclusions: These results suggest that a primary impairment in perceptual encoding may contribute to the visuospatial performance, however a more cautious response strategy may be related to visual hallucinations in Lewy body disease. Interestingly, MCI-LB patients showed no impairment in information processing ability, suggesting that, when perceptual encoding was successful, patients were able to normally process information, potentially explaining the variability of hallucination incidence.

The present study hypothesized that simple, everyday physical activity (EPA) would decline with advancing age; that women would have a more favorable EPA profile than would men; and that EPA would have a survival benefit. Community-dwelling participants (aged 80-98 years, n = 198) wore mechanical actigraphs in order for EPA to be assessed. Individuals were classified as active, inactive, and sedentary based on their level of EPA exhibited over a substantial part of the day. Survival status was available at approximately 2 years. Mean EPA scores decreased with advancing age and, in contrast to men, women in their early eighties appeared to be protected from declining EPA. This partially supported the hypothesis that women would have a more favorable EPA profile. What is most important is that mean EPA scores predicted mortality. Moreover, when compared with their less sedentary counterparts, sedentary adults were more than three times as likely to be deceased 2 years later. Researchers need to conduct new trials to determine whether or how physical activity is associated with mortality.

Introduction. Cardiorespiratory endurance, also known as aerobic fitness or maximal aerobic power, represents the overall capacity of the cardiovascular and respiratory systems to sustain prolonged strenuous exercise. It is typically quantified as maximal oxygen uptake (VO2max) through direct gas analysis. Materials and methods. This cross-sectional observational study was conducted in the Department of Physiology, SMS Medical College, Jaipur, India. Forty apparently healthy male participants (20 athletes and 20 sedentary individuals) aged 18-25 years were recruited using convenience sampling. Maximal aerobic capacity (VO2max) was assessed scientifically and consistently in the laboratory by directly analyzing gases involved in pulmonary ventilation during a progressive exercise stress test on a bicycle ergometer using RAMP protocols. Oxygen saturation was measured via pulse oximetry. Results. The mean VO2max for male athletes was 54.44 ± 7.67 mL/kg/min, significantly higher than that for sedentary male individuals (47.99 ± 5.85 mL/kg/min; p = 0.003). Mean oxygen saturation was 97.14 ± 0.72% for athletes and 96.90 ± 1.33% for sedentary individuals, a non-significant difference (p = 0.685). A weak negative correlation was observed between VO2max and oxygen saturation in sedentary male individuals (r = -0.540, p = 0.014), but not in male athletes (r = -0.118, p = 0.620). Daily physical activity, as measured by the Global Physical Activity Questionnaire (GPAQ), showed a negligible positive correlation with VO2max in both groups, which was not statistically significant. Conclusion. Male athletes demonstrated significantly higher VO2max compared to sedentary male individuals. While oxygen saturation did not differ significantly between groups, a weak negative correlation between VO2max and oxygen saturation was noted in sedentary individuals. Daily physical activity, as assessed by GPAQ, was not significantly correlated with VO2max in either group. These findings underscore the importance of regular athletic training for enhancing cardiorespiratory fitness.

Connections of the parietal lobe

The aim was to explore everyday physical activity (PA) and leisure-time PA in youth and adults with cerebral palsy (CP) including perceived cardiorespiratory exertion. A questionnaire covering everyday and leisure-time PA was answered by 159 persons, mean age 36 years. During morning hygiene, 18% perceived moderate and 4% vigorous exertion, during breakfast 9% perceived moderate and 3% vigorous exertion and during transportation 9% perceived moderate and 5% vigorous exertion. Fifty-seven percent of the participants had some leisure-time PA, of which 14% reached the general recommended level of “at least moderate” and 9% the level of “vigorous” exertion. Total assistance during leisure-time PA was reported by 48%. The number of individuals who reached the levels of leisure-time PA recommended for the general population to receive health benefits and increased aerobic capacity, was low. Everyday and leisure-time PA were not added together because the participation in everyday routines may have been a treatment goal. Limitations of the study were the difficulties to estimate received assistance and the high number of proxy answers. With respect to the participants’ capabilities, we suggest suitable tools exploring both PA habits and intensity of activity in various severities of CP.

Background: In nondemented aging, higher levels of everyday physical activity (EPA) and mobility performance are associated with better executive function (EF) trajectories. However, these associations may be moderated by both sex and Alzheimer’s disease (AD) genetic risk. Objectives: In a longitudinal study, we investigate sex differences in (a) EPA and mobility effects on EF performance (level) and change (slope) and (b) AD genetic risk moderation of these associations. Methods: The longitudinal design included nondemented adults (n = 532, mean age = 70.4 years, range 53–95) from the Victoria Longitudinal Study. Using structural equation analyses on an EF latent variable, we tested (a) sex moderation and (b) interactive effects of sex and APOE on observed EPA-EF and mobility-EF performance and change relationships. Results: First, we observed independent sex effects for the EPA-EF and mobility-EF predictions. Whereas EPA had a significant effect on EF performance and change only for females, mobility had a significant effect for both sexes. Notably, males with lower mobility levels experienced steeper EF decline than females with lower mobility levels. Second, we observed significant sex × APOE interaction effects. The combination of lower genetic risk and higher EPA benefitted females but not males. In contrast, lower genetic risk and higher mobility benefited both sexes, although male APOE no-risk carriers with lower mobility levels had EF decline patterns that were similar to APOE risk carriers. Conclusions: Longitudinal analyses across a broad band of aging show that sex moderates the effects of both EPA and mobility on EF performance and change. Notably, this moderation occurs differentially across the AD genetic risk status. These results point to a precision health approach to observational and interventional research in which effects of physical activity and mobility on EF trajectories and dementia are examined in the personalized and interactive context of sex and AD risk.

Chronic alcohol-use disorders (AUDs) have been shown to interact with normal age-related volume loss to exacerbate brain atrophy with increasing age. However, chronic cigarette smoking, a highly co-morbid condition in AUD and its influence on age-related brain atrophy have not been evaluated. We performed 1.5 T quantitative magnetic resonance imaging in non-smoking controls [non-smoking light drinking controls (nsCONs); n = 54], smoking light drinking controls (sCONs, n = 34), and one-week abstinent, treatment-seeking alcohol-dependent (ALC) non-smokers (nsALCs, n = 35) and smokers (sALCs, n = 43), to evaluate the independent and interactive effects of alcohol dependence and chronic smoking on regional cortical and subcortical brain volumes, emphasizing the brain reward/executive oversight system (BREOS). The nsCONs and sALCs showed greater age-related volume losses than the nsALCs in the dorsal prefrontal cortex (DPFC), total cortical BREOS, superior parietal lobule and putamen. The nsALCs and sALCs demonstrated smaller volumes than the nsCONs in most cortical region of interests (ROIs). The sCONs had smaller volumes than the nsCONs in the DPFC, insula, inferior parietal lobule, temporal pole/parahippocampal region and all global cortical measures. The nsALCs and sALCs had smaller volumes than the sCONs in the DPFC, superior temporal gyrus, inferior and superior parietal lobules, precuneus and all global cortical measures. Volume differences between the nsALCs and sALCs were observed only in the putamen. Alcohol consumption measures were not related to volumes in any ROI for ALC; smoking severity measures were related to corpus callosum volume in the sCONs and sALCs. The findings indicate that consideration of smoking status is necessary for a better understanding of the factors contributing to regional brain atrophy in AUD.

Exploring Avenues for Raising HDL Cholesterol

Evidence-accumulation models are a useful tool for investigating the cognitive processes that give rise to behavioural data patterns in reaction times (RTs) and error rates. In their simplest form, evidence-accumulation models include three parameters: The average rate of evidence accumulation over time (drift rate) and the amount of evidence that needs to be accumulated before a response becomes selected (boundary) both characterise the response-selection process; a third parameter summarises all processes before and after the response-selection process (non-decision time). Researchers often compute experimental effects as simple difference scores between two within-subject conditions and such difference scores can also be computed on model parameters. In the present paper, we report spurious correlations between such model parameter difference scores, both in empirical data and in computer simulations. The most pronounced spurious effect is a negative correlation between boundary difference and non-decision difference, which amounts to r = - .70 or larger. In the simulations, we only observed this spurious negative correlation when either (a) there was no true difference in model parameters between simulated experimental conditions, or (b) only drift rate was manipulated between simulated experimental conditions; when a true difference existed in boundary separation, non-decision time, or all three main parameters, the correlation disappeared. We suggest that care should be taken when using evidence-accumulation model difference scores for correlational approaches because the parameter difference scores can correlate in the absence of any true inter-individual differences at the population level.

The flanker task is a widely used measure of cognitive control abilities. Drift-diffusion modeling of flanker task behavior can yield separable parameters of cognitive control-related subprocesses, but the parameters' psychometrics are not well-established. We examined the reliability and validity of four behavioral measures: (1) raw accuracy, (2) reaction time (RT) interference, (3) NIH Toolbox flanker score, and (4) two drift-diffusion model (DDM) parameters-drift rate and boundary separation-capturing evidence accumulation efficiency and speed-accuracy trade-off, respectively. Participants from two independent studies - one cross-sectional (N = 381) and one with three timepoints (N = 83) - completed the flanker task while electroencephalography data were collected. Across both studies, drift rate and boundary separation demonstrated comparable split-half and test-retest reliability to accuracy, RT interference, and NIH Toolbox flanker score, but better incremental convergent validity with psychophysiological measures (i.e., the error-related negativity; ERN) and neuropsychological measures of cognitive control than the other behavioral indices. Greater drift rate (i.e., faster and more accurate responses) to congruent and incongruent stimuli, and smaller boundary separation to incongruent stimuli were related to 1) larger ERN amplitudes (in both studies) and 2) faster and more accurate inhibition and set-shifting over and above raw accuracy, reaction time, and NIH Toolbox flanker scores (in Study 1). Computational models, such as DDM, can parse behavioral performance into subprocesses that exhibit comparable reliability to other scoring approaches, but more meaningful relationships with other measures of cognitive control. The application of these computational models may be applied to existing data and enhance the identification of cognitive control deficits in psychiatric disorders.

Problematic short-form video users (PSVU) usually exhibit deficits in inhibitory control, which has been attributed to an imbalance between the goal-directed and habitual systems. However, the cognitive processes underlying this association remain unclear. From an information-processing perspective, this study employed the drift–diffusion model (DDM) to examine the link between inhibitory control deficits and a dual-system imbalance in PSVU. Thirty PSVU and twenty-eight matched controls completed a go/no-go task and a contingency degradation task. DDM was applied to model latent information-processing mechanisms from go/no-go performance. Habitual tendencies were assessed using ratio scores across contingency degradation conditions. Compared with healthy counterparts, PSVU showed a higher false-alarm rate and lower boundary separation in the go/no-go task. No significant group differences were found in other DDM parameters. In the contingency degradation task, PSVU showed a stubborn ratio score during action-outcome congruence transitions, which correlated positively with the boundary separation index. These findings suggest that, rather than abnormal information accumulation processes or response bias, inhibitory control deficits in PSVU arise from a more impulsive decision-making pattern, associated with insensitivity to task-setting changes. The study provided novel implications for intervention in behavioral addictions.

Generative models of decision now permeate all subfields of psychology, cognitive, and clinical neuroscience. To successfully investigate decision mechanisms from behavior, it is necessary to assume the presence of delays prior and after the decision process itself. However, directly observing this "non-decision time (NDT)" from behavior long appeared beyond reach, the field mainly relying on models to estimate it. Here, we propose a biological definition of decision that includes perceptual discrimination and action selection, and in turn, explicitly equates NDT with the minimum sensorimotor delay, or "deadtime." We show how this delay is directly observable in behavioral data, without modeling assumptions, using the visual interference approach. We apply this approach to 11 novel and archival data sets from humans and monkeys gathered from multiple labs. We validate the method by showing that visual properties (brightness, color, size) consistently affect empirically measured visuomotor deadtime (VMDT), as predicted by neurophysiology. We then show that endogenous factors (strategic slowing, attention) do not affect VMDT. Therefore, VMDT consistently satisfies widespread selective influence assumptions, in contrast to NDT parameters from model fits. Last, contrasting empirically observed VMDT with NDT estimates from the EZ, drift diffusion, and linear ballistic accumulator models, we conclude that NDT parameters from these models are unlikely to consistently reflect visuomotor delays, neither at a group level nor for individual differences, in contrast to a widely held assumption. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

The importance of a physically active lifestyle as a preventive measure for maintaining bone mass is often stressed. The aim of this study was to evaluate the effect of everyday physical activity on bone mass from young adulthood to old age in 75-year-old women. Bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry technique in total body, hip (femoral neck and trochanter), and spine (LII-LIV) in a population-based cohort of 995 women, all 75 years old. Each woman responded to a questionnaire giving an estimate of the previous and present physical activity level at work and leisure time from youth and up to the present age of 75 years. No correlations were found between the different estimates of physical activity level and BMD. In a multiple regression analysis the different estimates of physical activity level did not have any combined effect on BMD in any of the skeletal regions measured; neither did the physical activity, previous or present, differ when the subgroup of women with a BMD in the highest quintile at all sites was compared with women with a BMD in the lowest quintile. The activity level in the various areas of life did not correlate to each other indicating that few women had chosen a generally active vs non-active lifestyle. A hypothetical positive effect on bone by one activity could therefore be diminished by another. The answer alternatives were mostly not normally distributed, which could also affect the results, making it difficult to identify women with extremely high or low physical activity level. In conclusion, the results from this study of randomly selected elderly women cannot confirm an effect of previous and present everyday physical activity on bone mass. Neither was it possible to find an effect of physical activity in those women with the highest BMD at all sites, suggesting that other factors are of greater importance for maintaining bone mass in elderly women.