Investigating the Impact of Cognitive Load and Motivation on Response Control in Relation to Delay Discounting in Children with ADHD

Enhancement of visual dominance effects at the response level in children with attention-deficit/hyperactivity disorder

Previous studies have widely demonstrated that individuals with attention-deficit/hyperactivity disorder (ADHD) exhibit deficits in conflict control tasks. However, there is limited evidence regarding the performance of children with ADHD in cross-modal conflict processing tasks. The current study aimed to investigate whether children with ADHD have poor conflict control, which has an impact on sensory dominance effects at different levels of information processing under the influence of visual similarity. A total of 82 children aged 7 to 14 years, including 41 children with ADHD and 41 age- and sex-matched typically developing (TD) children, were recruited. We used the 2:1 mapping paradigm to separate levels of conflict, and the congruency of the audiovisual stimuli was divided into three conditions. In C trials, the target stimulus and the distractor stimulus were identical, and the bimodal stimuli corresponded to the same response keys. In PRIC trials, the distractor stimulus differed from the target stimulus and did not correspond to any response keys. In RIC trials, the distractor stimulus differed from the target stimulus, and the bimodal stimuli corresponded to different response keys. Therefore, we explicitly differentiated cross-modal conflict into a preresponse level (PRIC > C), corresponding to the encoding process, and a response level (RIC > PRIC), corresponding to the response selection process. Our results suggested that auditory distractors caused more interference during visual processing than visual distractors caused during auditory processing (i.e., typical auditory dominance) at the preresponse level regardless of group. However, visual dominance effects were observed in the ADHD group, whereas no visual dominance effects were observed in the TD group at the response level. A possible explanation is that the increased interference effects due to visual similarity and children with ADHD made it more difficult to control conflict when simultaneously confronted with incongruent visual and auditory inputs. The current study highlights how children with ADHD process cross-modal conflicts at multiple levels of information processing, thereby shedding light on the mechanisms underlying ADHD.

Reward-related episodic future thinking and delayed gratification in children

Cuing adults to imagine their personal futures enhances prudent choice in delay discounting tasks. However, it has not been established that such cueing also reduces discounting in children. We assessed the effect of episodic future thinking (EFT) on delay of gratification in children using EFT cues specifically related to the rewards on offer. One hundred and thirty-nine 8-12-year-olds were assigned to one of three conditions: (i) EFT (imagine spending money in the future), (ii) Imagine Place (imagine being in a certain place), or (iii) No Cue. They were cued on each trial of two tasks: a delay discounting task with hypothetical monetary rewards and a real delay choice task involving choices between real rewards over real delays (coins that could be swapped for treats). In the delay discounting task, the Imagine Place group showed significantly higher discounting than the other two groups. In the real delay choice task, the Imagine Place group made significantly fewer delayed choices than the EFT group. However, the EFT group did not differ from the No Cue group in either task. The lack of a difference between the EFT and No Cue conditions supports previous findings suggesting children struggle to benefit from EFT cues. Poorer performance of the Imagine Place group suggests that cued imagination is cognitively taxing for children, using up cognitive resources required to delay gratification.

Beyond Massive Univariate Tests: Covariance Regression Reveals Complex Patterns of Functional Connectivity Related to Attention-Deficit/Hyperactivity Disorder, Age, Sex, and Response Control

Background

Studies of brain functional connectivity (FC) typically involve massive univariate tests, performing statistical analysis on each individual connection. In this study, we apply a novel whole-matrix regression approach referred to as covariate assisted principal regression to identify resting-state FC brain networks associated with attention-deficit/hyperactivity disorder (ADHD) and response control.

Methods

Participants included 8- to 12-year-old children with ADHD (n = 115; 29 girls) and typically developing control children (n = 102; 35 girls) who completed a resting-state functional magnetic resonance imaging scan and a Go/NoGo task. We modeled three sets of covariates to identify resting-state networks associated with an ADHD diagnosis, sex, and response inhibition (commission errors) and variability (ex-Gaussian parameter tau).

Results

The first network includes FC between striatal-cognitive control (CC) network subregions and thalamic-default mode network (DMN) subregions and is positively related to age. The second consists of FC between CC-visual-somatomotor regions and between CC-DMN subregions and is positively associated with response variability in boys with ADHD. The third consists of FC within the DMN and between DMN-CC-visual regions and differs between boys with and without ADHD. The fourth consists of FC between visual-somatomotor regions and between visual-DMN regions and differs between girls and boys with ADHD and is associated with response inhibition and variability in boys with ADHD. Unique networks were also identified in each of the three models, suggesting some specificity to the covariates of interest.

Conclusions

These findings demonstrate the utility of our novel covariance regression approach to studying functional brain networks relevant for development, behavior, and psychopathology.

Purkinje cells translate subjective salience into readiness to act and choice performance

The brain selectively allocates attention from a continuous stream of sensory input. This process is typically attributed to computations in distinct regions of the forebrain and midbrain. Here, we explore whether cerebellar Purkinje cells encode information about the selection of sensory inputs and could thereby contribute to non-motor forms of learning. We show that complex spikes of individual Purkinje cells change the sensory modality they encode to reflect changes in the perceived salience of sensory input. Comparisons with mouse models deficient in cerebellar plasticity suggest that changes in complex spike activity instruct potentiation of Purkinje cells simple spike firing, which is required for efficient learning. Our findings suggest that during learning, climbing fibers do not directly guide motor output, but rather contribute to a general readiness to act via changes in simple spike activity, thereby bridging the sequence from non-motor to motor functions.

Delay aversion in school-aged children with attention-deficit hyperactivity disorder

This study considered whether children with attention-deficit hyperactivity disorder displayed a stronger preference for smaller, more immediate rewards over larger, but delayed rewards (delay aversion) when compared to typically developing controls and, furthermore, whether age and gender influenced their preference in any way. Children, between 6 and 15 years of age, living in Limpopo province of South Africa, participated in the study. Two hundred sixteen children in total (108 with attention-deficit hyperactivity disorder and 108 matched controls without attention-deficit hyperactivity disorder symptoms) were assessed, on a task of delay aversion. The Two Choice Impulsivity Paradigm, which assesses immediate and delayed responses, was administered to both the attention-deficit hyperactivity disorder and control groups. The performance of both groups was compared on the Two Choice Impulsivity Paradigm, and the scores were analysed as a function of gender and age. The attention-deficit hyperactivity disorder group chose significantly more immediate, smaller responses than the neurotypical control group, which preferred significantly more delayed but larger responses. Gender and age did not affect the response choices for both immediate and delayed measurements. Children with attention-deficit hyperactivity disorder show a greater need for more immediate gratification, even if the reward is smaller, than the neurotypical control group who could delay gratification to receive a larger reward. Gender and age did not influence their preferences.

Temporal Reward Discounting in Children with Attention Deficit/Hyperactivity Disorder (ADHD), and Children with Autism Spectrum Disorder (ASD): A Systematic Review

Children with ADHD and ASD may present differences in the affective-motivational processes. We systematically review the literature regarding temporal discounting in children up to 12 years with ADHD and ASD. Six articles were included, five studies with ADHD children (n = 231), one with ASD children (n = 21), all including typically developing children as controls (n = 210). Five studies (four with ADHD and one with ASD) found greater temporal reward discounting for clinical groups. Occurrence of ADHD appears to rush even more the decision-making process at this stage of development, but there is still a lack in the literature, especially evaluating individuals with ASD.

Association of Affected Neurocircuitry With Deficit of Response Inhibition and Delayed Gratification in Attention Deficit Hyperactivity Disorder: A Narrative Review

The neural networks that constitute corticostriatothalamocortical circuits between prefrontal cortex and subcortical structure provide a heuristic framework for bridging gaps between neurocircuitry and executive dysfunction in attention deficit hyperactivity disorder (ADHD). “Cool” and “Hot” executive functional theory and the models of dual pathway are supposed to be applied within the neuropsychology of ADHD. The theoretical model elaborated response inhibition and delayed gratification in ADHD. We aimed to review and summarize the literature about the circuits on ADHD and ADHD-related comorbidities, as well as the effects of neurocircuitry on the executive dysfunction in ADHD.

Decline of prefrontal cortical-mediated executive functions but attenuated delay discounting in aged Fischer 344 × brown Norway hybrid rats

Despite the fact that prefrontal cortex (PFC) function declines with age, aged individuals generally show an enhanced ability to delay gratification, as evident by less discounting of delayed rewards in intertemporal choice tasks. The present study was designed to evaluate relationships between 2 aspects of PFC-dependent cognition (working memory and cognitive flexibility) and intertemporal choice in young (6 months) and aged (24 months) Fischer 344 × brown Norway F1 hybrid rats. Rats were also evaluated for motivation to earn rewards using a progressive ratio task. As previously reported, aged rats showed attenuated discounting of delayed rewards, impaired working memory, and impaired cognitive flexibility compared with young. Among aged rats, greater choice of delayed reward was associated with preserved working memory, impaired cognitive flexibility, and less motivation to work for food. These relationships suggest that age-related changes in PFC and incentive motivation contribute to variance in intertemporal choice within the aged population. Cognitive impairments mediated by PFC are unlikely, however, to fully account for the enhanced ability to delay gratification that accompanies aging.