Dissociable Contributions of Anterior Cingulate Cortex and Basolateral Amygdala on a Rodent Cost/Benefit Decision-Making Task of Cognitive Effort

Abstract

Personal success often requires the choice to expend greater effort for larger rewards, and deficits in such effortful decision making accompany a number of illnesses including depression, schizophrenia, and attention-deficit/hyperactivity disorder. Animal models have implicated brain regions such as the basolateral amygdala (BLA) and anterior cingulate cortex (ACC) in physical effort-based choice, but disentangling the unique contributions of these two regions has proven difficult, and effort demands in industrialized society are predominantly cognitive in nature. Here we utilize the rodent cognitive effort task (rCET), a modification of the five-choice serial reactiontime task, wherein animals can choose to expend greater visuospatial attention to obtain larger sucrose rewards. Temporary inactivation (via baclofen-muscimol) of BLA and ACC showed dissociable effects: BLA inactivation caused hard-working rats to 'slack off' and 'slacker' rats to work harder, whereas ACC inactivation caused all animals to reduce willingness to expend mental effort. Furthermore, BLA inactivation increased the time needed to make choices, whereas ACC inactivation increased motor impulsivity. These data illuminate unique contributions of BLA and ACC to effort-based decision making, and imply overlapping yet distinct circuitry for cognitive vs physical effort. Our understanding of effortful decision making may therefore require expanding our models beyond purely physical costs.

Dopamine Antagonism Decreases Willingness to Expend Physical, But Not Cognitive, Effort: A Comparison of Two Rodent Cost/Benefit Decision-Making Tasks

“…However, rCET accuracy/performance for LR trials is significantly higher than for HR, suggesting that a 1.0-s stimulus is much easier to correctly identify than a brief 0.2-s stimulus. In addition, some experimental manipulations that affect physical effort decision-making paradigms also affect choice on the rCET, suggesting not only overlap in the neural loci involved but also some conceptual unity across the subtypes of effortbased choice (Hosking et al, 2014). Taken together, the rCET therefore appears to successfully model decision making with differing mental effort costs.…”

“…Baseline behavior for the rCET has been previously discussed at length (Cocker et al, 2012;Hosking et al, 2014), and as such will only be cursorily addressed here. As per previous cohorts, animals chose HR trials more than LR trials following saline injection (saline only-choice: F 1, 26 ¼ 13.461, p ¼ 0.001), and workers chose a significantly higher proportion of HR trials than slackers (group: F 1, 26 ¼ 40.814, po0.001).…”

“…Broadly, cognitive or mental effort costs are those that are nonphysical in nature, tax limited neurobiological resources, and are reflected in psychological constructs such as attention, response inhibition, and working memory; perhaps unsurprisingly, the underlying circuitry for cognitive versus physical effort appears in part distinct (Hosking et al, 2014;Schmidt et al, 2012). To account for the discrepancy in the literature, human studies have begun to incorporate physical costs in decision-making paradigms (Treadway et al, 2009) and have shown a similar involvement of dopamine in human decision making involving physical effort (Treadway et al, 2012;Wardle et al, 2011).…”

Δ9-Tetrahydrocannabinol decreases willingness to exert cognitive effort in male rats

“…Striking ly, the magnitude of this effect was correlated with CB 1 receptor density in the mPFC area encompassing prelimbic and anterior cingulate cortices (ACC) -areas previously implicated in task performance. 21,22 In contrast, CBD had no effect on performance, but partially attenuated THC's choice effects in slackers when coadministered at a ratio akin to that found in cannabinoid therapeutics. 3 Together, these data implicate the cannabinoid system in decision-making regarding the allocation of cognitive effort, but not necessarily in the performance of such cognitively demanding processes.…”

“…10 Inactivating the ACC decreased choice of HR trials on both the rCET used here, as well as a decision-making paradigm in which costs are physically rather than cognitively effortful. 22,32 Stimulation of this region in humans can also elicit feelings of endeavour and "gearing up" for an effortful challenge. 33 The ACC contains CB 1 receptors localized on glutamatergic terminals, which regulate excitatory input into this structure.…”