Altered hedonic capacity may be the result of neurophysiological dysfunction and is considered to be vulnerability marker that precedes the onset of neuropsychiatric disorders. Recent studies have shown that this kind of altered hedonic capacity, usually in form of a reduced capacity known as anhedonia, is also observed in non-clinical sample as a behavioral manifestation of an enduring trait. However, previous studies on anhedonia in both clinical and non-clinical samples have been primarily focused on monetary rewards rather than affective and social rewards. It is still unclear whether the underlying neural mechanisms of the monetary-based and affect-based anhedonia may have distinct neural mechanisms.
Previous work done by Dr. CHAN Raymond and his team from the Institute of Psychology have shown that individuals with social anhedonia exhibited a domain-specific deficit towards social affective information but not towards monetary-based rewards. These findings suggested that incentive type could confound the findings on the dissociation of anticipatory and consummatory hedonic capacities.
Based on these preliminary findings, Dr. CHAN and his team have conducted a study to examine the neural mechanisms of monetary-based and affective-based hedonic capacity in individuals with social anhedonia. In so doing, they administered the Affective Incentive Delay (AID) and the Monetary Incentive Delay (MID) imaging tasks to 28 adolescent participants. A cue signaling the type of forthcoming feedback (reward or punishment) was displayed to the participants, followed by a target-hit task with corresponding reward or punishment. Their findings showed that the striatal and limbic regions were activated during the anticipatory phase of MID, while there was no brain activation during the anticipatory phase of AID. In the consummatory phase, the MID task activated the medial frontal cortex, while the AID task activated the frontal and dorsal limbic regions. In a subsequent subtype analysis, they found that individuals with social anhedonia exhibited significant hypoactivation than those without social anhedoniaat the left pulvinar, the left claustrum and the left insula to positive cuesin the anticipatory phase of the AID task.
The present study represents an important extension of the extant literature on anticipation and consummation of affective and monetary incentive rewards. This is also the first study that examines functional brain responses to affective and monetary incentives in individuals with and without anhedonia. These findings demonstrate that the AID and the MID tasks have unique activation patterns. More importantly, the AID task may be more sensitive in detecting anhedonia in individuals with trait anhedonia.
This study was supported by a grant from the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences, the National Science Fund China, and the Beijing Training Project for Leading Talents in S&T.
The paper is now available online from Neuropsychology.
