Faculty Bibliography

The delay aversion hypothesis argues that the tendency for impulsive choice (preference for smaller sooner over larger later rewards) is motivated by the escape of negative affective states associated with delay. This model predicts that individuals with ADHD find the imposition of delay before an outcome or event especially aversive and its escape reinforcing. Consistent with this, fMRI studies show that ADHD is associated with amygdala hyper-sensitivity to cues of delay. However, evidence that delay escape is reinforcing is lacking. Here we extend fMRI research by using electrophysiological methods to study the reinforcing properties of delay-escape in ADHD. Thirty controls and 25 adolescents with ADHD aged 10-15 years performed the Escape Delay Incentive (EDI) task- in which pre-target cues indicated three conditions: i) CERTAIN DELAY: delay would follow a response irrespective of response speed ii) CONDITIONAL DELAY: delay would only follow if the response was too slow and iii) NO DELAY: delay would follow the response whatever the speed. We focused on the Contingent Negative Variation (CNV), a cue-evoked marker of motivated response preparation, across two time windows (CNV1 and CNV2). We took measures of parent, teacher and self-rated ADHD symptoms, task performance (RT) and self-rated delay aversion. We isolated CNV components and compared these between ADHD and controls. Adolescents with ADHD displayed a larger CNV2 to the CONDITIONAL DELAY than the CERTAIN DELAY cues compared to controls. However, this effect was not mirrored at the performance level and was unrelated to self-reported delay aversion. Our study provides the first ERP evidence that delay escape differentially reinforcers neural activation of attention preparation in ADHD cases. Future studies should examine the impact of varying cognitive load on task EDI performance.

Early life maltreatment by the caregiver constitutes a major risk factor for the development of later-life psychopathologies, including fear-related pathologies. Here, we used an animal model of early life maltreatment induced by the Scarcity-Adversity Model of low bedding (LB) where the mother is given insufficient bedding for nest building while rat pups were postnatal days (PN) 8-12. To assess effects of maltreatment on the expression of threat-elicited defensive behaviors, animals underwent odor-shock threat conditioning at three developmental stages: late infancy (PN18), adolescence (PN45) or adulthood (>PN75) and tested the next day with odor only presentations (cue test). Results showed that in typically developing rats, the response to threat increases with maturation, although experience with maltreatment in early infancy produced enhanced responding to threat in infancy and adulthood, but a decrease in maltreated adolescents. To better understand the unique features of this decreased threat responding in adolescence, c-Fos expression was assessed within the amygdala and ventromedial prefrontal cortex (vmPFC) associated with the cued expression of threat learning. Fos counts across amygdala subregions were lower in LB rats compared to controls, while enhanced c-Fos expression was observed in the vmPFC prelimbic cortex (PL). Correlational analysis between freezing behavior and Fos revealed freezing levels were correlated with CeA in controls, although more global correlations were detected in LB-reared rats, including the BA, LA, and CeA. Functional connectivity analysis between brain regions showed that LB reared rats exhibited more diffuse interconnectivity across amygdala subnuclei, compared the more heterogeneous patterns observed in controls. In addition, functional connectivity between the IL and LA switched from positive to negative in abused adolescents. Overall, these results suggest that in adolescence, the unique developmental decrease in fear expression following trauma is associated with distinct changes in regional function and long-range connectivity, reminiscent of pathological brain function. These results suggest that early life maltreatment from the caregiver perturbs the developmental trajectory of threat-elicited behavior. Indeed, it is possible that this form of trauma, where the infant's safety signal or "safe haven" (the caregiver) is actually the source of the threat, produces distinct outcomes across development.

Objective: To explore the applicability of an ambulatory inertial sensor (G-walk) to characterize gait function during the Timed Up and Go (TUG) Test under three different conditions.
Background(s): In Parkinson's disease (PD), the current lack of both reliable and feasible biomarkers of gait function and mobility limits the objective characterization of motor ability, clinical progression, and responsiveness to treatments. Current assessments of motor function rely on a clinicians' subjective judgement and/or the patient's self-reported questionnaires, which are not sensitive in capturing subtle changes over time and restrict comparability across raters. Ambulatory inertial sensors allow for non-invasive, wireless transmission of accurate quantitative data and therefore, may represent a useful tool in ambulatory settings. Design/Methods: Nineteen (19) PD patients (H&Y <4) and 10 agematched controls (CTRL) were consecutively enrolled to undergo inertial TUG (iTUG) testing under three experimental conditions: normal walking (iTUGnorm), dual task walking (iTUGcog), and at maximum speed (iTUGfast). The time needed to complete each test was sub-divided into six distinct phases quantified by the sensor: sitto- stand (1), forward gait (2), mid-turn (3), return gait (4), end-turn (5) and stand-to-sit (6). Other assessments included UDPRS Part III, MoCA, depression, fatigue, Benton and Rey-Osterrieth visual tests.
Result(s): A total of nineteen PD patients and ten CTRLs completed all assessments. PD patients were divided into mild (H&Y=2, n=12) and moderate (H&Y=3, n=7) disease severity. One-way-ANOVA and correlation analysis were performed. Different patterns of kinematic performance were observed (figure 1.A and 1.B). In PD, iTUG correlations were found with cognitive function, visual performance and motor severity, while in CTRLs there was only a correlation with motor performance only. iTUGfast performance seemed more sensitive experimental condition when PD was stratify by severity (figure 1.B).
Conclusion(s): iTUG assessed by an ambulatory inertial sensor is a quick, sensitive and feasible tool for objective measurements of functional mobility in PD. Utilizing validate tests for mobility and gait under different stress conditions can provide distinct information of gait function and mobility. Future longitudinal studies are warranted to better characterize the sensitivity to disease progression and the potential for monitoring and optimizing therapeutic interventions in this patient population. (Figure Presented)

BACKGROUND:Substance use and unprotected sex are prevalent among adolescents. The link between substance use and unprotected sex is well-established. Research has also highlighted how adolescents' attitudes and risk perceptions regarding unprotected sex, including concerns about pregnancy ("Getting pregnant would force me to grow up too fast"), are associated with unprotected sex and unplanned pregnancy. However, less research has examined the potential relationship between pregnancy concerns and substance use among adolescents. OBJECTIVES/OBJECTIVE:The study prospectively examined (1) differences in pregnancy concerns across patterns of substance use and (2) whether pregnancy concerns mediate the relationship between substance use and later unprotected sex among a sample of middle and high school students. METHOD/METHODS:98 adolescents [M(SD) age = 14.28(1.68), 59.4% female, 59.4% black/African American] completed self-report measures of marijuana and alcohol use, pregnancy concerns, and unprotected sex across three time points over 6 months (T1-T3). RESULTS:Substance users (alcohol/marijuana) reported fewer pregnancy concerns compared to non-substance users (t = 2.99, p = .04). Pregnancy concerns at T2 mediated the relationship between T1 lifetime substance use and later unprotected sex (T3) (indirect effect: b = 0.10, CI[.01-.41]; direct effect: b = 0.15, p = .32), controlling for gender, age, and race. More frequent substance use (T1) was related to fewer pregnancy concerns at T2 (b = -0.10, p = .04); fewer pregnancy concerns were related to increased likelihood of later unprotected sex (b = -1.02, p = .02). CONCLUSIONS:Findings offer new insight into associations between substance use and unprotected sex and suggest that substance use and sexual health interventions should target pregnancy concerns.

Unwanted sexual incidents on university campuses pose significant public health and safety risks for students. This study explored survivors' perspectives on secondary prevention of campus sexual assault and effective strategies for intervention programs for unwanted sexual incidents in university settings. Twenty-seven student survivors of unwanted sexual experiences participated in semi-structured in-depth interviews. Data were analyzed using thematic analysis and a constructionist perspective. The findings were contextualized using the ecological model. Barriers to reporting included concerns about one's story not being believed, personal minimization of the incident, belief that no action will be taken after reporting, confidentiality concerns, and other perceived costs of reporting. Survivors provided valuable insight on potentially effective prevention and intervention strategies to address the problem of unwanted sexual incidents on university campuses. These findings may be useful for prevention and intervention policies and programs in university settings and for providers who assist survivors of unwanted sexual experiences.

This study examined the effect of an interference task on the consolidation of duration in long-term memory. In a temporal generalization task, the participants performed a learning phase with a reference duration that either was, or was not, followed 30 min later by a 15-min interference task. They were then given a memory test, 24 h later. Using different participant groups, several reference durations were examined, from several hundred milliseconds (600 ms) to several seconds (2.5, 4, and 8 s). The results showed that the scalar timing property (i.e., precision proportional to judged duration) was preserved despite the interference task given during the memory consolidation process. However, the interference task increased the variability of time judgment and tended to produce a lengthening effect in all reference duration conditions. The modeling of individual data with parameters derived from scalar expectancy theory suggests that disrupting the memory consolidation of learned reference durations introduces noise in their representation in memory, with time being specifically distorted toward a lengthened duration.