Cognitive Bias Under Adverse and Rewarding Conditions: A Systematic Review of Rodent Studies

Abstract

Background: Cognitive bias refers to emotional influences on cognition and provides a cognitive measure of negativity-or positivity-bias through assessment of the behavioral responses to ambiguous stimuli. Thus, under negative conditions an animal is more likely to judge ambiguous stimuli as negative, and under positive conditions as positive. The transfer of past experiences to novel but similar situations is highly adaptive, as it allows the animal to anticipate on the most likely outcome of the ambiguous cues. Methods: We conducted a systematic review to summarize the current state of evidence on cognitive bias in rodents under adverse and rewarding or supportive conditions. Results: In total 20 studies were identified, in which auditory, spatial, tactile, or visual tasks were used. Stressed rodents generally made fewer positive responses than their non-stressed conspecifics. Housing enrichment made rodents more positive in anticipation of ambiguous cues. Ethanol seeking rats generalized the ambiguous cues to sucrose and less to ethanol if sucrose was available. Amphetamine, fluoxetine, and ketamine shifted the bias toward positivity, while reboxetine elevated negative bias. Conclusion: The auditory tasks have been most extensively validated, followed by the tactile and spatial tasks, and finally the visual tasks. The tactile and spatial tasks use latency as readout, which is sensitive to confounding factors. It is yet uncertain whether spatial tasks measure cognitive bias. Across all tasks, with some exceptions, rodents exposed to stress show less positivity-bias when exposed to ambiguous cues, whereas rodents exposed to rewarding substances or treated with antidepressant drugs are biased toward reward. Considering the methodological heterogeneity and risk of bias, the present data should be interpreted with caution.

Knockout of the serotonin transporter in the rat mildly modulates decisional anhedonia

“…As discussed shortly in the introduction, decision-making under ambiguity was also conceptualized in the framework of cognitive/judgment bias, but with the focus on negative versus positive interpretations of ambiguous information (Roelofs et al 2016) . We previously summarized the cognitive bias studies in rodents, showing that there are two combinations of outcomes possible in "go/go" experiments: "reward/reward" and "reward/punishment" (Nguyen et al 2020) . In case of the "reward/reward" combination, for which no specific term was used under the framework of cognitive bias to distinguish it from the "reward/punishment" paradigm (Roelofs et al 2016) , the detection strength of negative bias is weakened.…”

“…However, most real-world decisions are based on ambiguous information (Huettel et al 2006;Lauriola and Levin 2001) . This type of decision-making is much related to emotion, not only in humans (Rustichini 2005) but also in animals (Nguyen et al 2020) . While positive or rewarding emotions may be experienced when the decision turns out to be a good one, untrustworthy ambiguous information triggers aversive emotions (FeldmanHall et al 2018) .…”

Serotonin transporter knockout in rats modulates category learning

“…Nine of them were homozygous 5-HTT KO rats, the others were wild-type (WT) siblings. The sample size based on previous experiments 11 (Guo et al 2020). The KO rats (Slc6a41Hubr) had been generated by targetselected ethylnitrosourea induced mutagenesis and outcrossed for at least 15 generations with commercial Wistar (albino) rats 22 .…”

“…Generalization is the process by which the brain processes information before taking actions. During this processing, the transfer of the stored information to novel situations/stimuli is required (Guo et al 2020). Typically, the novel stimuli are similar to the categorized stimuli to some extent, such as the frequency of sound, tactile feel of the material, or orientation of gratings 18 .…”

“…The two CSs can be distinguished at the perceptual dimension. When using a series of stimuli (Generalization stimuli, GS) that vary along with the defined stimulus dimension (the orientation of gratings), generalization performance can be tested in rodents (Guo et. al.…”