Strong interactions between learned helplessness and risky decision-making in a rat gambling model

Abstract

Risky decision-making is characteristic of depression and of addictive disorders, including pathological gambling. However it is not clear whether a propensity to risky choices predisposes to depressive symptoms or whether the converse is the case. Here we tested the hypothesis that rats showing risky decision-making in a rat gambling task (rGT) would be more prone to depressive-like behaviour in the learned helplessness (LH) model. Results showed that baseline rGT choice behaviour did not predict escape deficits in the LH protocol. In contrast, exposure to the LH protocol resulted in a significant increase in risky rGT choices on retest. Unexpectedly, control rats subjected only to escapable stress in the LH protocol showed a subsequent decrease in riskier rGT choices. Further analyses indicated that the LH protocol affected primarily rats with high baseline levels of risky choices and that among these it had opposite effects in rats exposed to LH-inducing stress compared to rats exposed only to the escape trials. Together these findings suggest that while baseline risky decision making may not predict LH behaviour it interacts strongly with LH conditions in modulating subsequent decision-making behaviour. The suggested possibility that stress controllability may be a key factor should be further investigated.

Exposure to Unsolvable Anagrams Impairs Performance on the Iowa Gambling Task

“…A similar result has been reported for rats in a rat gambling task who were exposed to inescapable footshocks (Nobrega et al, 2016). The exact result pattern of the current study indicates that the individuals exposed to unsolvable anagrams reach a positive IGT netscore during trials 61–80, while control participants already reached a positive netscore during trials 21–40.…”

“…The results of the current study indicate that the exposure to an unsolvable anagram task led to a decrease in decision-making performance in the IGT, which is initially an ambiguous decision-making task. A similar result has been reported for rats in a rat gambling task who were exposed to inescapable footshocks (Nobrega et al, 2016 ). The exact result pattern of the current study indicates that the individuals exposed to unsolvable anagrams reach a positive IGT netscore during trials 61–80, while control participants already reached a positive netscore during trials 21–40.…”

“…However, recent studies indicate that stress induction with social evaluative stressors affects performance on the IGT (Preston et al, 2007 ; van den Bos et al, 2009 ; Wemm and Wulfert, 2017 ). In addition, a recent animal study reported effects of inescapable footshocks on a rat gambling task (Nobrega et al, 2016 ). Rats that were exposed to inescapable footshocks showed an increase in disadvantageous choices relative to control rats.…”

Redefining the Endophenotype Concept to Accommodate Transdiagnostic Vulnerabilities and Etiological Complexity

“…Returning to the example of midbrain DA function, a now sizable body of literature indicates that low tonic striatal DA activity and blunted striatal DA reactivity during reward anticipation imbue an anhedonic, irritable mood state that characterizes ADHD, other externalizing disorders, unipolar depression, and intentional self-injury [ 11 ]. Moreover, comorbidity rates between ADHD and unipolar depression are high [ 38 ], the disorders share molecular genetic liability [ 38 , 39 ], and both are characterized by present bias in decision-making (preference for immediate overdelayed rewards) [ 40 ]. Although the heritability of anhedonia has not been evaluated in large twin studies, irritability is moderately heritable [ 41 ].…”

Enhanced Risky Choice in Male Rats Elicited by the Acute Pharmacological Stressor Yohimbine Involves Prefrontal Dopamine D1 Receptor Activation

“…Acute stress can markedly alter decision-making under risk and uncertainty ( Starcke and Brand, 2016 ). For instance, under acute stress, rats made more risky choices in a rodent Iowa gambling task ( Nobrega et al, 2016 ). However, the effects of acute stressors on risky choice are complex and influenced by several variables, such as stressor identity (e.g., restraint, predator exposure in rodents), task structure (e.g., risk/uncertainty profile, working memory load), or sex (see Braun and Hauber, 2013 ; Bryce et al, 2020 ).…”