Adolescent cognitive control and reward processing: Implications for risk taking and substance use

Adolescence is a unique, transitional period of human development. Once hallmark of this period is progressive improvements (relative to children) in cognitive control, core mental abilities enabling the ‘top-down’, endogenous control over behavior. However, as adolescents transition to more mature (adult) levels of functioning, limitations still exist in the ability to consistently and flexibly exert cognitive control across various contexts into the early twenties. Adolescence is also marked by peaks in sensation, novelty, and reward seeking behaviors thought to stem from normative increases in responsiveness in limbic and paralimbic brain structures, beginning around the onset of puberty. Asynchronous maturation in these systems during the adolescent period likely contributes to immature decision-making, strongly influenced by ‘bottom-up’ reward processes, and may help explain noted increases in risk taking behavior during adolescence. In this paper, structural and functional maturation in brain systems supporting reward and cognitive control processing are reviewed as a means to better understand risk taking. Particular emphasis is placed on adolescents' experimentation with drugs as a specific example of a risky behavior.     

Neural systems for behavioral activation and reward.

The circuitry mediating the integration of reward perception and adaptive behavioral responses has been further refined. Recent developments indicate that the nucleus accumbens has a primary role in motivational circuitry, whereas afferents to the nucleus accumbens, in part, subserve distinct functions. Dopaminergic afferents serve to signal changes in rewarding stimuli, whereas glutamatergic input from the amygdala serves to cue behavior to conditioned reward, and afferents from the prefrontal cortex integrate information from short-term memory into behavioral responses.     

Role of brain dopamine in food reward and reinforcement

The ability of food to establish and maintain response habits and conditioned preferences depends largely on the function of brain dopamine systems. While dopaminergic transmission in the nucleus accumbens appears sufficient for some forms of reward, the role of dopamine in food reward does not appear to be restricted to this region. Dopamine plays an important role in both the ability to energize feeding and to reinforce food-seeking behaviour; the role in energizing feeding is secondary to the prerequisite role in reinforcement. Dopaminergic activation is triggered by the auditory and visual as well as the tactile, olfactory, and gustatory stimuli of foods. While dopamine plays a central role in the feeding and food-seeking of normal animals, some food rewarded learning can be seen in genetically engineered dopamine-deficient mice.     

The effects of cognitive and behavioral control on coping with an aversive health examination.

The effects of cognitive and behavioral control on coping with an aversive health examination were tested in a 2 x 2 factorial design. Cognitive control was represented by sensory or health-education information; instruction or no instruction in abdominal relaxation constituted the levels of behavioral control. The study was conducted in the natural setting of a family-planning clinic with 24 young women who were undergoing a routine pelvic examination. Subjects who received sensory information prior to the examination showed less distress, as indicated by overt distress behaviors and pulse rates, than did subjects who received health-education information. Cognitive control did not show a significant effect on self-report of fear. No significant effects were demonstrated for the factor of behavioral control. The results suggested that cognitive control information, which emphasizes the sensory experiences typically accompanying an aversive event, limits reactivity to aversive stimuli. The reduction in reactivity is thought to result in an increased ability to cope with aversive events.     

A behavioral paradigm to study the persistence of reward memory extinction in Drosophila

<正>Drosophila has been proven to be a powerful animal model to study genetic mechanisms underlying different behaviors and diseases (Sokolowski,2001;Bier,2005).Extinction is a process that repeated presentation of a conditioned stimulus without reinforcement results in decreased conditioned responses (Bouton,2004) and receives increasing attention for treating its related diseases such as post-traumatic stress disorder (PTSD) and addiction     

Advice to young behavioral and cognitive scientists

Modeled on Medawar's Advice to a Young Scientist [Medawar, P.B., 1979. Advice to a Young Scientist. Basic Books, New York], this article provides advice to behavioral and cognitive scientists. An important guiding principle is that the study of comparative cognition and behavior are natural sciences tasked with explaining nature. The author advises young scientists to begin with a natural phenomenon and then bring it into the laboratory, rather than beginning in the laboratory and hoping for an application in nature. He suggests collaboration as a way to include research outside the scientist's normal competence. He then discusses several guides to good science. These guides include Tinbergen's [Tinbergen, N., 1963. On aims and methods of ethology. Zeitschrift für Tierpsychologie, 20, 410-433. This journal was renamed Ethology in 1986. Also reprinted in Anim. Biol. 55, 297-321, 2005] four "why" questions, Platt's [Platt, J.R., 1964. Strong inference. Science 146, 347-353, (http://weber.ucsd.edu/~jmoore/courses/Platt1964.pdf)] notion of strong inference using multiple alternative hypotheses, and the idea that positive controls help scientists to follow Popper's [Popper, K.R., 1959. The Logic of Scientific Discovery. Basic Books, New York, p. 41] advice about disproving hypotheses. The author also recommends Strunk and White's [Strunk, W., White, E.B., 1979. The Elements of Style, third ed. Macmillan, New York] rules for sound writing, and he provides his personal advice on how to use the anticipation of peer review to improve research and how to decode editors' and reviewers' comments about submitted articles.     

Experience-dependent adult cortical plasticity requires cognitive association between sensation and reward

We tested the involvement of cognition in adult experience-dependent neuroplasticity using primate cortical implants. In a prior study, learning an operant sensory discrimination increased cortical excitability and target selectivity. Here, the prior task was separated into three behavioral phases. First, naive animals were exposed to stimulus-reward pairings from the prior study. These yoked animals did not have to discriminate to be rewarded and did not learn the discrimination. The plasticity observed in the prior study did not occur. Second, the animals were classically conditioned to discriminate the same stimuli in a simplified format. Learning was accompanied by increased sensory response strength and an increased range of sensory inputs eliciting responses. The third study recreated the original operant discrimination, and selectivity for task targets increased. These studies demonstrate that cognitive association between sensory stimuli and reinforcers accompanies adult experience-dependent cortical plasticity and suggest that selectivity in representation and action are linked.     

Beautiful faces have variable reward value: fMRI and behavioral evidence.

The brain circuitry processing rewarding and aversive stimuli is hypothesized to be at the core of motivated behavior. In this study, discrete categories of beautiful faces are shown to have differing reward values and to differentially activate reward circuitry in human subjects. In particular, young heterosexual males rate pictures of beautiful males and females as attractive, but exert effort via a keypress procedure only to view pictures of attractive females. Functional magnetic resonance imaging at 3 T shows that passive viewing of beautiful female faces activates reward circuitry, in particular the nucleus accumbens. An extended set of subcortical and paralimbic reward regions also appear to follow aspects of the keypress rather than the rating procedures, suggesting that reward circuitry function does not include aesthetic assessment.     

The effectiveness of online cognitive behavioral treatment in routine clinical practice

Context

Randomized controlled trails have identified online cognitive behavioral therapy as an efficacious intervention in the management of common mental health disorders.

Objective

To assess the effectiveness of online CBT for different mental disorders in routine clinical practice.

Design

An uncontrolled before-after study, with measurements at baseline, posttest, 6-week follow-up, and 1-year follow-up.

Participants & Setting

1500 adult patients (female: 67%; mean age: 40 years) with a GP referral for psychotherapy were treated at a Dutch online mental health clinic for symptoms of depression (n = 413), panic disorder (n = 139), posttraumatic stress (n = 478), or burnout (n = 470).

Interventions

Manualized, web-based, therapist-assisted CBT, of which the efficacy was previously demonstrated in a series of controlled trials. Standardized duration of treatment varied from 5 weeks (online CBT for Posttraumatic stress) to 16 weeks (online CBT for Depression).

Main Outcome Measures

Validated self-report questionnaires of specific and general psychopathology, including the Beck Depression Inventory, the Impact of Event Scale, the Panic Disorder Severity Scale-Self Report, the Oldenburg Burnout Inventory, and the Depression Anxiety Stress Scales.

Results

Treatment adherence was 71% (n = 1071). Study attrition was 21% at posttest, 33% at 6-week FU and 65% at 1-year FU. Mixed-model repeated measures regression identified large short-term reductions in all measures of primary symptoms (d = 1.9±0.2 to d = 1.2±0.2; P<.001), which sustained up to one year after treatment. At posttest, rates of reliable improvement and recovery were 71% and 52% in the completer sample (full sample: 55%/40%). Patient satisfaction was high.

Conclusions

Results suggest that online therapist-assisted CBT may be as effective in routine practice as it is in clinical trials. Although pre-treatment withdrawal and long-term outcomes require further study, results warrant continued implementation of online CBT.     

多巴胺信号系统在衰老引起的行为和认知能力退化中的作用

衰老是生物体随时间推移各项生理功能逐渐发生改变的自然现象。动物的衰老伴随着行为和认知能力的降低,因此研究动物行为和认知功能退化的分子神经机制对于提高老年群体的生活质量具有重要意义。近年来,随着正电子发射断层扫描技术和功能性核磁共振脑成像技术在神经生物学上的广泛运用,越来越多证据表明多巴胺系统功能在衰老过程中显著降低,并且这是人类和动物行为和认知功能退化的重要原因。本文将概述自然衰老过程中多巴胺信号系统功能变化及机制和其在动物行为和认知退化中的作用等方面研究进展。     

The behavioral ecology of a cognitive constraint: limited attention

Limited attention may constrain animal behavior in situationsin which the rate of relevant information exceeds the thresholdprocessing capacity of the brain. In the present study, we examinewhy attention is limited by quantifying how attention affectsthe ubiquitous problem of balancing foraging and antipredatoractivity. We analyze how a given attentional capacity affectsfeeding requirements, the optimal attentional focus during predatorscanning, and the probability of detecting predators. Our modelindicates that because of the complex interplay between thecosts and benefits associated with a given attentional capacity,limited attention can be an optimal strategy, which allows effectiveand economical search for cryptic objects.     

Bright light exposure augments cognitive behavioral therapy for panic and posttraumatic stress disorders: a pilot randomized control trial

Sleep and Biological Rhythms - Bright light (BL) therapy is clinically utilized for treatment of sleep–wake disorders through the manipulation of circadian oscillation. It is also extended to...