Having an optimal ability to experience pleasurable events and rewarding activities is important for our everyday life functioning. This kind of ability, however, has been shown to be reduced or impaired in people with mental disorders such as schizophrenia and major depressive disorder, a clinical condition we refer to be anhedonia and amotivation. Recent findings suggest that such impairment may be due to the alternation of value representation in these people. 

In a recent study published in Schizophrenia Bulletin, Dr. Raymond Chan’s team from the Institute of Psychology, the Chinese Academy of Sciences and his collaborators have shown that, despite people with high levels of social anhedonia exhibited intact range adaptation compared to people with low levels of social anhedonia, their range adaptive coding was positively associated with diminished willingness to expend effort for a suboptimal option. 

Range adaptation is the ability for people to represent a perceived stimulus value, in form of either sensory or social perception, based on its relative position in the range of pre-experienced values. An optimal range adaptation depends on the balance between neurochemical substances known as glutamate (Glu) and gamma-aminobutyric acid (GABA), termed as the excitation-inhibition balance (EIB). However, the underling neural mechanism between EIB, social anhedonia and social functioning remains largely unclear. 

On the other hand, advanced theoretical framework also suggests people with subclinical features of anhedonia/amotivation such as people with high levels of social anhedonia may exhibit a similar but a less severe form of range adaption and social functioning impairments. 

In order to further investigate the underlying relationship between range adaptation, social anhedonia and social functioning, Dr. Raymond Chan and his collaborators conducted two separate studies to examine the resting-state neural correlates of range adaptation and its associations with social anhedonia and social functioning. 

In the first study, they recruited 60 college students to undertake the resting-state magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI) brain scans. All participants were also requested to complete a behavioural effort-based decision-making paradigm and a set of self-reported measures after the brain scans. EIB was calculated as the ratio of Glx to GABA+. 

Their findings showed that range adaptation correlated with EIB and ventral prefrontal cortex (vPFC) functional connectivity. Such vPFC functional connectivity was also correlated with social functioning positively. More importantly, range adaptation was determined by the EIB through mediation and ventral-medial PFC functional connectivity. 

In the second study, they followed the same procedure to recruit two independent samples comprising 52 (main sample) and 80 (replication sample) participants to repeat the first study. However, this time they further classified the participants into 26 high levels and 26 low levels of social anhedonia (main sample), and 40 high levels and 40 low levels of social anhedonia (replication sample). 

Their findings showed that both high and low levels of social anhedonia participants exhibited comparable EIB. These two groups also did not differ in range adaptation related vPFC resting-state connectivity. However, both EIB and vPFC connectivity were negatively correlated with social anhedonia and social functioning only in participants with high levels of social anhedonia. More importantly, such findings were further verified in the replication sample. 

Taken together, these findings suggest that EIB and vPFC functional connectivity is potential neural correlate for range adaptation and may index a potential underlying mechanism of anhedonia and amotivation in schizophrenia spectrum disorders. Dr. Chan’s team is now undertaking studies to adopt a multimodal design to specifically investigate the underlying neural mechanism of range adaptive valuation in schizophrenia spectrum disorders and other mental disorders sharing similar clinical manifestations. They hope such multi-modal range adaptation can advance our knowledge of anhedonia and amotivation and help formulate appropriate neuromodualtion intervention for these clinical and subclinical groups. 

This study was supported by grants from the Scientific Foundation of Institute of Psychology, Chinese Academy of Sciences and the Philip K. H. Wong Foundation.

This study was published online on March 4, in Schizophrenia Bulletin 

- Wang, L. L., Li, G. Y., Yan, C., Wang, Y., Gao, Y., Wang, Y., Lui, S. S. Y., Li, J. Q., Chan R. C. K.* (2025). The relationship between range adaptation, social anhedonia and social functioning: A combined magnetic resonance spectroscopy and resting-state fMRI study. Schizophrenia Bulletin 51, S2, S160-S172

Related publication 

- Wang, J., Huang, J., Yang, X. H., Lui, S. S. Y., Eric, E. F. C., Chan, R. C. K.* (2015).Anhedonia in schizophrenia: deficits in both motivation and hedonic capacity. Schizophrenia Research, 168: 465-474. 

- Wang, L. L., Lam, C. Y. T., Huang, J., Cheung, E. F. C., Lui, S. S. Y., Chan, R. C. K.* (2021). Range-adaptive value representation in different stages of schizophrenia: A proof of concept study. Schizophrenia Bulletin, 47(6), 1524–1533