Biology subjects

Crawford, J. L.

Publications and source records attributed to Crawford, J. L..

6 recordsLinked to original sources

bioRxiv2026

Caudate dopamine predicts cognitive effort decisions both in the lab and daily life

Making choices about whether and when to engage cognitive effort is a common feature of human everyday experience with important consequences for academic, career, and health outcomes. Yet, despite its importance, little is understood about the neurochemical mechanisms that underlie individual differences in the willingness to engage in cognitively effortful activities. To examine this question, we employed a multi-modal neuroimaging approach in which participants performed the Cognitive Effort Discounting paradigm (Cog-ED) while simultaneous PET-fMRI was acquired. We assessed both individual differences in dopamine-D2 receptor availability and brain activity during decision-making. In addition, the same participants performed a parametric working memory task (N-Back) and reported the cognitive effort associated with their daily life activities through a seven-day Ecological Momentary Assessment (EMA) protocol. The findings suggest a central role for caudate dopamine-D2 receptors in modulating cognitive effort-related motivation. People with higher caudate dopamine-D2 receptor availability had better working memory function, heightened sensitivity to effort costs, and greater modulation of brain activity during effort valuation. These laboratory findings also translated directly to daily life: higher levels of caudate dopamine-D2 receptors were associated with greater engagement in cognitively effortful activities. Together, the results suggest that how individuals determine the motivational value of cognitively effortful activities strongly depends on the dopamine system.

neuroscience↗

bioRxiv2022

Plant architecture is correlated with variation in cannabinoid concentration and biomass production in Cannabis sativa

Cannabis sativa is cultivated for multiple uses including the production of cannabinoids. In developing improved production systems for high-cannabinoid cultivars, scientists and cultivators must consider the optimization of complex and interacting sets of morphological, phenological, and biochemical traits, which have historically been shaped by natural and anthropogenic selection. Determining factors that modulate cannabinoid variation within and among genotypes is fundamental to developing efficient production systems and understanding the ecological significance of cannabinoids. Thirty-two high-cannabinoid hemp cultivars were characterized for traits including flowering date and shoot-tip cannabinoid concentration. Additionally, a set of plant architecture traits, as well as wet, dry, and stripped inflorescence biomass were measured at harvest. One plant per plot was partitioned post-harvest to quantify intra-plant variation in inflorescence biomass production and cannabinoid concentration. Some cultivars showed intra-plant variation in cannabinoid concentration, while many had a consistent concentration regardless of canopy position. There was both intra- and inter-cultivar variation in architecture that correlated with intra-plant distribution of inflorescence biomass, and concentration of cannabinoids sampled from various positions within a plant. These relationships among morphological and biochemical traits will inform future decisions by cultivators, regulators, and plant breeders as well as our broader understanding of intra-plant variation of specialized biochemicals. HighlightIn-season hemp plant architecture measurements can predict post-harvest traits related to the distribution of biomass and concentration of cannabinoids.

plant biology↗

bioRxiv2021

Multivariate associations between dopamine receptor availability and risky investment decision making across adulthood

Pharmacological manipulations have revealed that enhancing dopamine increases financial risk taking across adulthood. However, it is unclear whether baseline individual differences in dopamine function, assessed using PET imaging, are related to performance on risky financial decision making tasks. Here, thirty-five healthy adults completed an incentive-compatible learning-based risky investment decision task and a PET scan at rest using [11C]FLB457 to assess dopamine D2-like receptor availability. In the task, participants made choices between a safe asset (bond) and a risky asset (stock) with either an expected value less than the bond ("bad stock") or expected value greater than the bond ("good stock"). Five measures of behavioral performance (choice inflexibility, risk seeking, suboptimal investment) and beliefs (absolute error, optimism) were extracted from the task data and average non-displaceable dopamine D2-like binding potential was extracted from four brain regions of interest (midbrain, amygdala, anterior cingulate, insula) from the PET imaging data. Given the presence of multiple independent and dependent variables, we used canonical correlation analysis (CCA) to evaluate multivariate associations between learning-based decision making and dopamine function controlling for age. Decomposition of the first dimension (r = .76) revealed that the strongest associations were between measures of choice inflexibility, incorrect choice, optimism, amygdala binding potential, and age. Follow-up univariate analyses revealed that amygdala binding potential and age were both independently associated with choice inflexibility. The findings reveal latent associations between baseline neural and behavioral measures suggesting that individual differences in dopamine function may be associated with learning-based financial risk taking in healthy adults.

neuroscience↗

bioRxiv2020

Dorsal Anterior Cingulate Cortex Encodes the Subjective Motivational Value of Cognitive Task Performance

Humans can seamlessly combine value signals from diverse motivational incentives, yet it is not well-understood how these signals are "bundled" in the brain to modulate cognitive control. The dorsal anterior cingulate cortex (dACC) is theorized to integrate motivational value dimensions in the service of goal-directed action, though this hypothesis has yet to receive rigorous confirmation. In the present study, we examined the role of human dACC in motivational incentive integration. Healthy young adult men and women were scanned with fMRI while engaged in an experimental paradigm that quantifies the combined effects of liquid (e.g., juice, neutral, saltwater) and monetary incentives on cognitive task performance. Monetary incentives modulated trial-by-trial dACC activation, whereas block-related effects of liquid incentives on dACC activity were observed. When bundled together, incentive-related dACC modulation predicted fluctuations in both cognitive performance and self-report motivation ratings. Statistical mediation analyses suggest that dACC encoded the incentives in terms of their integrated subjective motivational value, and that this value signal was most proximally associated with task performance. Finally, we confirmed that these incentive integration effects were selectively present in dACC. Together, the results support an account in which dACC integrates motivational signals to compute the expected value of goal-directed cognitive control. Significance StatementHow are primary and secondary incentives integrated in the brain to influence goal-directed behavior? Using an innovative experimental fMRI paradigm that combines motivational incentives that have historically been studied independently between species (e.g., monetary rewards for humans, food rewards for animals), we examine the relationship between incentive motivational value and cognitive control allocation. We find evidence that the integrated incentive motivational value of combined incentives is encoded in human dorsal anterior cingulate cortex (dACC). Further, self-reported motivational shifts mediated the effects of incentive-modulated dACC activity on task performance, revealing convergence in how self-reported and experimentally-induced motivation are encoded in the human brain. Our findings may inform future translational studies examining affective/motivational and cognitive impairments in psychopathology (e.g., anxiety, depression, addiction).

neuroscience↗

bioRxiv2018

Reliability of the correlative triad among aging, dopamine D2-like receptor availability, and cognition

The evidence that dopamine function mediates the association between aging and cognition is one of the most cited findings in the cognitive neuroscience of aging. However, few and relatively small studies have directly examined these associations. Here we examined correlations among adult age, dopamine D2-like receptor (D2R) availability, and cognition in two cross-sectional studies of healthy human adults. Participants completed a short cognitive test battery and, on a separate day, a PET scan with either the high-affinity D2R tracer [18F]Fallypride (Study 1) or [11C]FLB457 (Study 2). Digit span, a measure of short-term memory maintenance and working memory, was the only cognitive test for which dopamine D2R availability partially mediated the age effect on cognition. In Study 1, age was negatively correlated with digit span. Striatal D2R availability was positively correlated with digit span controlling for age. The age effect on digit span was smaller when controlling for striatal D2R availability. Although other cognitive measures used here have individually been associated with age and D2R availability in prior studies, we found no consistent evidence for significant associations between low D2R availability and low cognitive performance on these measures. These results at best only partially supported the correlative triad of age, dopamine D2R availability, and cognition. While a wealth of other research in human and non-human animals demonstrates that dopamine makes critical contributions to cognition, the present studies suggest caution in interpreting PET findings as evidence that dopamine D2R loss is a primary cause of broad age-related declines in fluid cognition.

neuroscience↗

bioRxiv2018

Individual differences in dopamine are associated with reward discounting in clinical groups but not in healthy adults

Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N=144 males and females across 3 samples) and one meta-analytic (Study 2: N=307 across 12 samples), we sought to characterize associations between individual differences in DA and time, probability, and physical effort discounting in human adults. Study 1 demonstrated that individual differences in DA D2-like receptors were not associated with time or probability discounting of monetary rewards in healthy humans, and associations with physical effort discounting were inconsistent across adults of different ages. Meta-analytic results for temporal discounting corroborated our empirical finding for minimal effect of DA measures on discounting in healthy individuals, but suggested that associations between individual differences in DA and reward discounting depend on clinical features. Addictions were characterized by negative correlations between DA and discounting but other clinical conditions like Parkinsons Disease, obesity, and ADHD were characterized by positive correlations between DA and discounting. Together the results suggest that trait differences in discounting in healthy adults do not appear to be strongly associated with individual differences in D2-like receptors. The difference in meta-analytic correlation effects between healthy controls and individuals with psychopathology suggests that individual difference findings related to DA and reward discounting in clinical samples may not be reliably generalized to healthy controls, and vice-versa.\n\nSignificance StatementDecisions to forgo large rewards for smaller ones due to increasing time delays, uncertainty, or physical effort have been linked to differences in dopamine (DA) function, which is disrupted in some forms of psychopathology. It remains unclear whether alterations in DA function associated with psychopathology also extend to explaining associations between DA function and decision making in healthy individuals. We show that individual differences in dopamine D2 receptor availability are not consistently related to monetary discounting of time, probability, or physical effort in healthy individuals across a broad age range. By contrast, we suggest that psychopathology accounts for observed inconsistencies in the relationship between measures of dopamine function and reward discounting behavior.

neuroscience↗