Objective measures of reward sensitivity and motivation in people with high vs low anhedonia

Background. Anhedonia, a diminished interest or pleasure in activities, is a core self-reported symptom of depression which is poorly understood and often resistant to conventional antidepressants. This symptom may occur due to dysfunction in one or more sub-components of reward processing: motivation, consummatory experience, and/or learning. However, the precise impairments remain elusive. Dissociating these components (ideally, using cross-species measures) and relating them to the subjective experience of anhedonia is critical as it may benefit fundamental biology research and novel drug development. Methods. Using a battery of behavioural tasks based on rodent assays, we examined reward motivation (Joystick-Operated Runway Task, JORT; and Effort-Expenditure for Rewards Task, EEfRT) and reward sensitivity (Sweet Taste Test) in a non-clinical population who scored high (N = 32) or low (N = 34) on an anhedonia questionnaire (Snaith-Hamilton Pleasure Scale). Results. Compared to the low anhedonia group, the high anhedonia group displayed marginal impairments in effort-based decision-making (EEfRT) and reduced reward sensitivity (Sweet Taste Test). However, we found no evidence of a difference between groups in physical effort exerted for reward (JORT). Interestingly, whilst the EEfRT and Sweet Taste Test correlated with anhedonia measures, they did not correlate with each other, lending support for the possibility of sub-groups within anhedonia. Conclusions. Our findings suggest that reward motivation and reward sensitivity are dissociable when tested in the same group of participants, and that anhedonia is a heterogenous symptom associated with impairments in reward sensitivity and effort-based decision-making.

The Aversion Function of the Limbic Dopaminergic Neurons and Their Roles in Functional Neurological Disorders

The Freudian theory of conversion suggested that the major symptoms of functional neurological disorders (FNDs) are due to internal conflicts at motivation, especially at the sex drive or libido. FND patients might behave properly at rewarding situations, but they do not know how to behave at aversive situations. Sex drive is the major source of dopamine (DA) release in the limbic area; however, the neural mechanism involved in FND is not clear. Dopaminergic (DAergic) neurons have been shown to play a key role in processing motivation-related information. Recently, DAergic neurons are found to be involved in reward-related prediction error, as well as the prediction of aversive information. Therefore, it is suggested that DA might change the rewarding reactions to aversive reactions at internal conflicts of FND. So DAergic neurons in the limbic areas might induce two major motivational functions: reward and aversion at internal conflicts. This article reviewed the recent advances on studies about DAergic neurons involved in aversive stimulus processing at internal conflicts and summarizes several neural pathways, including four limbic system brain regions, which are involved in the processing of aversion. Then the article discussed the vital function of these neural circuits in addictive behavior, depression treatment, and FNDs. In all, this review provided a prospect for future research on the aversion function of limbic system DA neurons and the therapy of FNDs.

Prospective mental imagery in depression: Impact on reward processing and reward-motivated behaviour

Background Mental imagery has long been part of cognitive behavioural therapies. More recently, a resurgence of interest has emerged for prospective mental imagery, i.e. future-directed imagery-based thought, and its relation to reward processing, motivation and behaviour in the context of depression. Method We conducted a selective review on the role of prospective mental imagery and its impact on reward processing and reward-motivated behaviour in depression. Results Based on the current literature, we propose a conceptual mechanistic model of prospective mental imagery. Prospective mental imagery of engaging in positive activities can increase reward anticipation and reward motivation, which can transfer to increased engagement in reward-motivated behaviour and more experiences of reward, thereby decreasing depressive symptoms. We suggest directions for future research using multimodal assessments to measure the impact of prospective mental imagery from its basic functioning in the lab to real-world and clinical implementation. Conclusion Prospective mental imagery has the potential to improve treatment for depression where the aim is to increase reward-motivated behaviours. Future research should investigate how exactly and for whom prospective mental imagery works.

Delayed-matching-to-position working memory in mice relies on NMDA-receptors in prefrontal pyramidal cells

A hypofunction of N-methyl-D-aspartate glutamate receptors (NMDARs) has been implicated in the pathogenesis of schizophrenia by clinical and rodent studies. However, to what extent NMDAR-hypofunction in distinct cell-types across the brain causes different symptoms of this disease is largely unknown. One pharmaco-resistant core symptom of schizophrenia is impaired working memory (WM). NMDARs have been suggested to mediate sustained firing in excitatory neurons of the prefrontal cortex (PFC) that might underlie WM storage. However, if NMDAR-hypofunction in prefrontal excitatory neurons may indeed entail WM impairments is unknown. We here investigated this question in mice, in which NMDARs were genetically-ablated in PFC excitatory cells. This cell type-selective NMDAR-hypofunction caused a specific deficit in a delayed-matching-to-position (DMTP) 5-choice-based operant WM task. In contrast, T-maze rewarded alternation and several psychological functions including attention, spatial short-term habituation, novelty-processing, motivation, sociability, impulsivity, and hedonic valuation remained unimpaired at the level of GluN1-hypofunction caused by our manipulation. Our data suggest that a hypofunction of NMDARs in prefrontal excitatory neurons may indeed cause WM impairments, but are possibly not accounting for most other deficits in schizophrenia.

Diurnal rhythms across the human dorsal and ventral striatum

The human striatum can be subdivided into the caudate, putamen, and nucleus accumbens (NAc). Each of these structures have some overlapping and some distinct functions related to motor control, cognitive processing, motivation, and reward. Previously, we used a “time-of-death” approach to identify diurnal rhythms in RNA transcripts in human cortical regions. Here, we identify molecular rhythms across the three striatal subregions collected from postmortem human brain tissue in subjects without psychiatric or neurological disorders. Core circadian clock genes are rhythmic across all three regions and show strong phase concordance across regions. However, the putamen contains a much larger number of significantly rhythmic transcripts than the other two regions. Moreover, there are many differences in pathways that are rhythmic across regions. Strikingly, the top rhythmic transcripts in NAc (but not the other regions) are predominantly small nucleolar RNAs and long noncoding RNAs, suggesting that a completely different mechanism might be used for the regulation of diurnal rhythms in translation and/or RNA processing in the NAc versus the other regions. Further, although the NAc and putamen are generally in phase with regard to timing of expression rhythms, the NAc and caudate, and caudate and putamen, have several clusters of discordant rhythmic transcripts, suggesting a temporal wave of specific cellular processes across the striatum. Taken together, these studies reveal distinct transcriptome rhythms across the human striatum and are an important step in helping to understand the normal function of diurnal rhythms in these regions and how disruption could lead to pathology.

Who Gets the Joke?

Using humor scholar Salvatore Attardo’s criteria for humor appreciation as a framework, this chapter describes the kinds of people who might be expected to have the greatest appreciation of humor. It explores joke difficulty, the level of threat a joke may activate in a listener, the available knowledge in the minds of the audience, and their processing motivation as factors that affect humor appreciation. The chapter links the traits of tolerance for ambiguity and need for cognition to humor appreciation, as both enhance an individual’s motivation and ability to process and appreciate a joke. It also includes a deep dive into the strange case of irony (with reference to All in the Family and The Colbert Report), which audiences can appreciate even when their interpretation is the opposite of the intended meaning of the joke’s producer.

Information Processing, Motivation, and Group Creativity

According to an information processing perspective, group creativity results from the combination of individual resources into a (creative) group product. This involves information processing at the individual as well as the group level (by means of communication). This chapter first discusses how individual-level information processing is affected by group interaction in terms of both cognitive interference and cognitive stimulation. It then discusses (1) the evidence linking group-level information processing (i.e., communication, information sharing, collaborative problem solving) to group creativity and (2) the factors that stimulate or reduce group-level information processing. It is argued that many research findings can be explained by assuming that group creativity involves motivated information processing of members.

Interlanguage: A Case Study of a Korean Learner of Bangla

This study has investigated the interlanguage features in spoken language of a Korean learner of Bangla. Data has been collected through interviews which were recorded and analyzed. The analysis of the respondents’ language has been made in terms of phonetic, morphological and syntactic aspects. The language deviations may be attributed to different factors such as L1 interference to some extent, and other aspects related to psychological processing, motivation and language use.

Nicotine addiction

Cigarette smoking presents with considerable health risks and induces high costs on healthcare resources. People continue to smoke cigarettes in the face of adversity because they contain nicotine, which is highly addictive. Nicotine is a stimulant that exerts its effects within the brain by acting at nicotinic acetylcholine receptors (nAChRs). nAChRs are located in areas of the brain involved in reward processing, motivation, and cognitive control, which results in disruptions to behaviour when nicotine addiction has developed. Disturbances to the brain and behaviour are particularly evident during early nicotine abstinence when people are in withdrawal. Importantly, treatments (e.g. varenicline, bupropion) that attenuate disturbances to reward and cognition in the brain during withdrawal in early nicotine abstinence are conferred with the efficacy to promote smoking cessation and protect against relapse.

Neurobiological processes in addiction

The brain is involved in controlling necessary motivational and cognitive processes optimized for survival. These processes can be disrupted by substances of addiction. The key neural substrates underlying these processes are made up of a network of four independent and overlapping brain circuits. These circuits govern reward processing, motivation and/or drive, learning and memory, and cognitive control. Anomalies within these circuits may also pre-date the addiction state, and facilitate the progress from experimentation to substance addiction. The subsequent excessive and chronic use of substances further exacerbates these abnormalities. Therefore, these brain circuits and key psychological processes related to their functioning must be understood if we are to develop and test new pharmacological and psychological treatment approaches in substance addiction.