Biology subjects

Darcey, V. L.

Publications and source records attributed to Darcey, V. L..

5 recordsLinked to original sources

bioRxiv2026

When does post-ingestive dopamine signaling occur in humans?

The post-ingestive dopamine response is an integral determinant of subsequent eating behavior in animals yet measurement of the post-ingestive response to nutrients in humans has been elusive when assessed in the early post-ingestive period (30 minutes postprandially). We conducted secondary analysis comparing dopamine D2 receptor binding potential (D2BP) measured using [18F]fallypride positron emission tomography in two inpatient controlled feeding cohorts consuming standardized diet (50% carbohydrate; 35% fat; 15% protein) with similar characteristics and procedures but differing in time since last meal: confirmed overnight fast (n=57; 66.7% female; BMI 29.6{+/-}7.6 kg/m2; 31.9{+/-}7.2 years old) and 2-hours after a standardized meal reflecting 20% of energy requirements (n=43; 48.8% female; BMI 28.8{+/-}7.8 kg/m2, 31.3{+/-}7.7 years old). Compared to the fasted cohort, the 2-hour postprandial cohort exhibited significantly reduced whole striatal D2BP (p<0.0001) as well as in clusters in insular cortex, prefrontal cortex which remained after adjustment for age, sex, and insulin sensitivity. Voxelwise comparisons of the relationship between D2BP and BMI in the fasted and fed cohorts reveals clusters within dorsolateral and ventral striatum where dopamine level is dependent on postprandial state and adiposity. Given the similarities between protocol procedures and participant characteristics, our results suggest that the post-ingestive dopamine response to nutrients may be prominent in the extended post-ingestive period and warrant investigation within-subject.

neuroscience↗

bioRxiv2022

Restriction of dietary fat, but not carbohydrate, alters brain reward circuitry in adults with obesity

Weight loss diets often target restriction of dietary fat or carbohydrate, macronutrients that are sensed via distinct gut-brain pathways and differentially affect peripheral hormones and metabolism. However, the effects of such diet changes on human brain are unclear. We investigated whether selective isocaloric reductions in dietary fat or carbohydrate altered dopamine D2/3 receptor binding potential (D2BP) and neural activity in brain reward regions in response to visual food cues in 17 inpatient adults with obesity as compared to a eucaloric baseline diet. On the fifth day of dietary fat restriction, but not carbohydrate restriction, both D2BP and neural activity to food cues were decreased in brain reward regions. After the reduced fat diet, ad libitum intake shifted towards foods high in both fat and carbohydrates. These results suggest that dietary fat restriction increases tonic dopamine in brain reward regions and affects food choice in ways that may hamper diet adherence.

neuroscience↗

bioRxiv2020

Risk-related decision making evokes distinct brain activation patterns in reward evaluation regions in substance use naïve versus non-naïve adolescents

Identifying brain and behavioral precursors to substance use (SU) may guide interventions that delay initiation in youth at risk for SU disorders (SUD). Heightened reward-sensitivity and risk-taking may confer risk for SUD. In a longitudinal, prospective study, we characterized behavioral and neural profiles associated with reward-sensitivity and risk-taking in substance-naive adolescents, examining whether they differed as a function of SU initiation at 18- and 36-months follow-up. Adolescents (N=70; 11.1-14.0 years) completed a reward-related decision-making task (Wheel of Fortune (WOF)) while undergoing functional MRI. Measures of reward sensitivity (Behavioral Inhibition System-Behavioral Approach System; BIS-BAS), impulsive decision-making (delay discounting task), and SUD risk (Drug Use Screening Inventory, Revised (DUSI-R)) were collected at baseline. Baseline metrics were compared for youth who did (SI; n=27) and did not (SN; n=43) initiate SU at follow-up. While groups displayed similar discounting and risk taking behavior, SI youth showed more variable patterns of activation in left insular cortex during high-risk selections, and left anterior cingulate cortex in response to rewarded outcomes. SI participants scored higher on the DUSI-R and BAS subscales. Results suggest differences in brain regions critical in the development and experience of SUDs may precede SU and serve as a biomarker for SUD risk.

neuroscience↗

bioRxiv2019

Altered cortical development and psychiatric symptom risk in adolescents exposed to maternal stress in utero

ObjectiveMaternal exposure to stress during pregnancy is associated with increased risk for cognitive and behavioral sequelae in offspring. Animal research demonstrates exposure to stress during gestation has effects on brain structure. In humans, however, little is known about the enduring effects of in utero exposure to maternal stress on brain morphology. We examine whether maternal report of stressful events during pregnancy is associated with brain structure and behavior in adolescents. MethodWe compare gray matter morphometry of typically-developing early adolescents (11-14 years of age, mean 12.7) based on presence/absence of maternal report of stressful event(s) during pregnancy: prenatal stress (PS; n=28), no prenatal stress (NS; n=55). The Drug Use Survey Index Revised (DUSI-R) assessed adolescent risk for problematic behaviors. Exclusionary criteria included pre-term birth, low birth weight, and maternal substance use during pregnancy. Groups were equivalent for demographic (age, sex, IQ, SES, race/ethnicity), and birth measures (weight, length). ResultsCompared to NS peers, adolescents in the PS group exhibited increased gray matter volume in bilateral posterior parietal cortex (PPC): bilateral intraparietal sulcus, left superior parietal lobule and inferior parietal lobule. Additionally, the PS group displayed greater risk for psychiatric symptoms and family system dysfunction, as assessed via DUSI-R subscales. ConclusionThis study provides evidence for the enduring neurodevelopmental effects of exposure to maternal stress while in utero, suggesting the dynamic alterations in brain structure that occur during the adolescent critical period may unmask the latent effects of gestational stress on brain morphology and increase subsequent risk for psychiatric symptomatology.

neuroscience↗

bioRxiv2018

Dietary long-chain omega-3 fatty acids are related to impulse control and anterior cingulate function in adolescents

Impulse control, an emergent function modulated by the prefrontal cortex (PFC), helps to dampen risky behaviors during adolescence. Influences on PFC maturation during this period may contribute to variations in impulse control. Availability of omega-3 fatty acids, an essential dietary nutrient integral to neuronal structure and function, may be one such influence. This study examined whether intake of energy-adjusted long-chain omega-3 fatty acids (eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)) was related to variation in impulse control and PFC activity during performance of an inhibitory task in adolescents (n= 87; 51.7% female, mean age 13.3+1.1 years) enrolled in a longitudinal neuroimaging study. Intake of DHA+EPA was assessed using a food frequency questionnaire and adjusted for total energy intake. Inhibitory control was assessed using caregiver rating scale (BRIEF Inhibit subscale) and task performance (false alarm rate) on a Go/No-Go task performed during functional MRI. Reported intake of long-chain omega-3 was positively associated with caregiver ratings of adolescent ability to control impulses (p=0.017) and there was a trend for an association between intake and task-based impulse control (p=0.072). Furthermore, a regression of BOLD response within PFC during successful impulse control (Correct No-Go versus Incorrect NoGo) with energy-adjusted DHA+EPA intake revealed that adolescents reporting lower intakes display greater activation in the dorsal anterior cingulate, potentially suggestive of a possible lag in cortical development. The present results suggest that dietary omega-3 fatty acids are related to development of both impulse control and function of the dorsal anterior cingulate gyrus in normative adolescent development. Insufficiency of dietary omega-3 fatty acids during this developmental period may be a factor which hinders development of behavioral control.

neuroscience↗