A new study published on September 10 in The Cerebellum provides initial experimental evidence that a single session of cerebellar High-Definition Transcranial Direct Current Stimulation (HD-tDCS) may help to maintain anticipatory and consummatory pleasure and enhance reward sensitivity in healthy individuals. 

The results highlight the multifaceted role of the cerebellum in reward processing and suggest its potential as a novel target for psychiatric intervention.

Reward processing is central to human motivation and emotion regulation, encompassing anticipation, consummatory pleasure, effort-based decision-making, sensitivity to rewards, and learning. Dysfunctions in these processes manifest as anhedonia and amotivation in disorders such as major depression and schizophrenia, and have also been associated with substance and eating disorders.

Although research has traditionally focused on the mesocorticolimbic reward circuit, converging evidence from human and animal studies indicates that the cerebellum also plays a critical role by modulating midbrain dopaminergic pathways. However, it remains unclear whether cerebellar neuromodulation could directly enhance reward functioning in humans.

To address this question, Dr. Raymond Chan and his colleagues from the Institute of Psychology of the Chinese Academy of Sciences conducted a pre-registered randomized, single-blind, pre–post controlled study with 63 healthy adults. Participants were randomly assigned to receive either active or sham HD-tDCS (1.7 mA, 20 minutes) targeting the right posterior cerebellum.

Reward processing was assessed before and after stimulation using three validated paradigms: the Monetary Incentive Delay (MID) task, the adaptive-coding version of the Effort-Expenditure for Rewards Task (EEfRT), and the Probabilistic Selection Task (PST). 

The results showed that the active stimulation group maintained their levels of anticipatory and consummatory pleasure in the MID task, whereas the sham group exhibited significant declines. Moreover, in the EEfRT, the active group displayed increased reward sensitivity from pre- to post-test, an effect absent in the sham group.

Overall, these findings suggest that cerebellar HD-tDCS may modulate reward processing in healthy individuals. Although preliminary, these findings open avenues for subsequent studies on its possible relevance to psychiatric disorders marked by altered motivation and pleasure.

This work was supported by the STI2030-Major Projects, the Scientific Foundation of the Institute of Psychology, and the Philip K. H. Wong Foundation.