Stimulation in the Rat Anterior Insula and Anterior Cingulate During an Effortful Weightlifting Task

Abstract

When performing tasks, animals must continually assess how much effort is being expended, and gage this against ever-changing physiological states. As effort costs mount, persisting in the task may be unwise. The anterior cingulate cortex (ACC) and the anterior insular cortex are implicated in this process of cost-benefit decision-making, yet their precise contributions toward driving effortful persistence are not well understood. Here we investigated whether electrical stimulation of the ACC or insular cortex would alter effortful persistence in a novel weightlifting task (WLT). In the WLT an animal is challenged to pull a rope 30 cm to trigger food reward dispensing. To make the action increasingly effortful, 45 g of weight is progressively added to the rope after every 10 successful pulls. The animal can quit the task at any point – with the rope weight at the time of quitting taken as the “break weight.” Ten male Sprague-Dawley rats were implanted with stimulating electrodes in either the ACC [cingulate cortex area 1 (Cg1) in rodent] or anterior insula and then assessed in the WLT during stimulation. Low-frequency (10 Hz), high-frequency (130 Hz), and sham stimulations were performed. We predicted that low-frequency stimulation (LFS) of Cg1 in particular would increase persistence in the WLT. Contrary to our predictions, LFS of Cg1 resulted in shorter session duration, lower break weights, and fewer attempts on the break weight. High-frequency stimulation of Cg1 led to an increase in time spent off-task. LFS of the anterior insula was associated with a marginal increase in attempts on the break weight. Taken together our data suggest that stimulation of the rodent Cg1 during an effortful task alters certain aspects of effortful behavior, while insula stimulation has little effect.

Dorsomedial prefrontal neural ensembles reflect changes in task utility that culminate in task quitting

“…However, lesions to the Cg1 of rats has consistently resulted in avoidance of high-effort options (climbable-barriers, highratio lever presses) when relatively lower effort options are available (45)(46)(47)(48). We have shown previously that electrical stimulation to Cg1 biases rats to quit earlier in our WLT (49).These results seem to be at odds with one another: lesioning Cg1 results in rats shifting their choice preference towards lower effort options, but does not affect high effort performance on progressive ratio tasks. Wang et al (50) provided some clarity on this discrepancy by showing that inactivation of rat Cg1 impairs performance in a novel "do more get more" task, suggesting that Cg1 is critical for self-paced effort expenditure.…”

An orbitofrontal cortex–anterior insular cortex circuit gates compulsive cocaine use

“…Furthermore, to test the specificity of OFC-aIC circuit in compulsive cocaine use, we evaluated whether a gain function of another aIC-related circuit could induce compulsive cocaine use. A previous study found that aIC also received input projections from cingulate cortex area 1 (Cg1) ( 17 , 23 ) (fig. S5), which showed a similar expression of c-Fos between sensitive and resistant rats (Fig.…”

“…For chemogenetic regulation of OFC-aIC circuit, AAV 2/1 -hSyn-Cre was bilaterally infused into OFC followed by bilateral infusion of AAV-EF1α-DIO-hM4D(Gi)-mCherry-WPRE-PA, AAV-EF1α-DIO-hM3D(Gq)-mCherry-WPRE-PA, or AAV-EF1α-DIO-mCherry-WPRE-PA in aIC before catheter implantation. For chemogenetic regulation of Cg1-aIC circuit ( 23 ), AAV 2/1 -hSyn-Cre was bilaterally infused in the Cg1 (AP, +3.7; ML, ±0.4; DV, −1.0 mm) followed by bilateral injection of AAV-EF1α-DIO-hM3D(Gq)-mCherry-WPRE-PA or AAV-EF1α-DIO-mCherry-WPRE-PA in aIC before catheter implantation. Moreover, we validated the accuracy of the OFC-aIC and Cg1-aIC labeling (fig.…”