An imaging study associated greater delay discounting with activation during choices involving delayed rewards. The finding does not mean that an amygdala signal directly reveals how much a person likes an option or proves that delayed rewards were experienced as aversive.
Hoffman and colleagues compared 19 recently abstinent methamphetamine-dependent adults with 17 controls using functional MRI during a delay-discounting task. Participants considered smaller immediate and larger delayed monetary alternatives.
The design examined both decision difficulty and the selection of immediate or delayed outcomes. These contrasts address the processing involved in a particular choice, rather than measuring a universal trait with a single brain-region value.
Controls showed greater activation in several regions, including areas involved in cognitive control. Discounting magnitude was associated with activity in regions including the amygdala, dorsolateral prefrontal cortex and posterior parietal cortex.
The authors proposed that delayed choices might have greater negative salience for people who heavily discount them. That is a possible account of the association, not a directly measured subjective aversion. The task did not isolate every component of evaluating, comparing and selecting an option.
Brain activation can accompany conflict, attention, arousal or the effort needed to choose against a preference. It cannot be interpreted simply as liking or disliking without supporting behavioral evidence. The small, abstinent sample also cannot establish acute methamphetamine effects or exclude pre-existing differences.
This primary human study contributes a hypothesis about decision processing. It does not validate mind-reading from fMRI, establish causation or measure methamphetamine in a specimen. Applying its findings to an individual’s judgment or impairment requires evidence beyond a group-level monetary-choice association.
See different components of inhibitory control during abstinence.
Cortical activation during delay discounting in abstinent methamphetamine dependent individuals. doi:10.1007/s00213-008-1261-1.