Incentive-Elicited Brain Activation in Adolescents: Similarities and Differences from Young Adults

Abstract

Brain motivational circuitry in human adolescence is poorly characterized. One theory holds that risky behavior in adolescence results in part from a relatively overactive ventral striatal (VS) motivational circuit that readily energizes approach toward salient appetitive cues. However, other evidence fosters a theory that this circuit is developmentally underactive, in which adolescents approach more robust incentives (such as risk taking or drug experimentation) to recruit this circuitry. To help resolve this, we compared brain activation in 12 adolescents (12-17 years of age) and 12 young adults (22-28 years of age) while they anticipated the opportunity to respond to obtain monetary gains as well as to avoid monetary losses. In both age groups, anticipation of potential gain activated portions of the VS, right insula, dorsal thalamus, and dorsal midbrain, where the magnitude of VS activation was sensitive to gain amount. Notification of gain outcomes (in contrast with missed gains) activated the mesial frontal cortex (mFC). Across all subjects, signal increase in the right nucleus accumbens during anticipation of responding for large gains independently correlated with both age and self-rated excitement about the high gain cue. In direct comparison, adolescents evidenced less recruitment of the right VS and right-extended amygdala while anticipating responding for gains (in contrast with anticipation of nongains) compared with young adults. However, brain activation after gain outcomes did not appreciably differ between age groups. These results suggest that adolescents selectively show reduced recruitment of motivational but not consummatory components of reward-directed behavior.

The effect of graded monetary reward on cognitive event-related potentials and behavior in young healthy adults

“…Such guaranteed response-reward association may have elicited a distinct type of reward motivation different than motivation elicited by conditions in which the outcome is more uncertain. This distinction possibly exemplifies the differences between consummatory vs. anticipatory reward processing, respectively, which differ in their neural representations (Knutson, Fong, Adams, Varner, & Hommer, 2001;Bjork, et al, 2004). Because the monetary main effect was observed for the P3-W (which may be considered anticipatory) and it also approached significance for the P3-T (which may be considered consummatory), the exact motivational processes elicited by the current task remain to be delineated, possibly with a task that directly contrasts these different reward mechanisms.…”

Anticipation of monetary gain but not loss in healthy older adults

“…Event-related functional magnetic resonance imaging (fMRI) studies that have used this task in adolescents and younger adults have implicated striatal and insular activation in the anticipation of uncertain gains and losses 14,15 . Because healthy older adults report preserved (or even enhanced) positive affective experience relative to younger adults on a day-to-day basis 16 , we predicted that both subjective responses and neural activation in anticipation of rewards would be preserved in a healthy older sample.…”

Delay and reward choice in ADHD: An experimental test of the role of delay aversion.

“…2002) and the ability and/or willingness to tolerate delay to rewards grows exponentially (Bjork et al, 2004;Green et al, 1994Green et al, , 1996. This could mean that DAv becomes more difficult to index as individuals grow.…”