Type

Journal Article

Authors

Robert Hester
Hugh Patrick Garavan
Liam Nestor

Subjects

Pharmacology

Topics
humans adult magnetic resonance imaging time use cannabis female limbic system substance withdrawal syndrome psychology putamen blood male image processing computer assisted young adult physiology adverse effects pharmacology cues motivation neostriatum reward oxygen drug users marijuana abuse brain dopamine

Increased ventral striatal BOLD activity during non-drug reward anticipation in cannabis users (2009)

Abstract Despite an increased understanding of the pharmacology and long-term cognitive effects of cannabis in humans, there has been no research to date examining its chronic effects upon reward processing in the brain. Motivational theories regarding long-term drug use posit contrasting predictions with respect to how drug users are likely to process non-drug incentives. The reward deficiency syndrome (RDS) of addiction posits that there are deficits in dopamine (DA) motivational circuitry for non-drug rewards, such that only drugs of abuse are capable of normalizing DA in the ventral striatum (VS). Alternatively, the opponent process theory (OPT) holds that in individuals prone to drug use, there exists some form of mesolimbic hyperactivity, in which there is a bias towards reward-centred behaviour concomitant with impulsivity. The current study examined BOLD responses during reward and loss anticipation and their outcome deliveries in 14 chronic cannabis users and 14 drug-naive controls during a monetary incentive delay (MID) task. Despite no significant behavioural differences between the two groups, cannabis users had significantly more right VS BOLD activity during reward anticipation. Correlation analyses demonstrated that this right VS BOLD response was significantly correlated with life-time use and reported life-time cannabis joints consumed. No correlations between cannabis abstinence and BOLD responses were observed. We also observed a number of group differences following outcome deliveries, most notably hypoactivity in the left insula cortex in response to loss and loss avoidance outcome notifications in the cannabis group. These results may suggest hypersensitivity during instrumental response anticipation for non-drug rewards and a hyposensitivity to loss outcomes in chronic cannabis users; the implications of which are discussed with respect to the potentially sensitizing effects of cannabis for other rewards.
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Full list of authors on original publication

Robert Hester, Hugh Patrick Garavan, Liam Nestor

Experts in our system

1
Robert Hester
Trinity College Dublin
Total Publications: 14
 
2
Hugh Garavan
Trinity College Dublin
Total Publications: 160
 
3
Liam Nestor
Trinity College Dublin
Total Publications: 7