Opposing reward-epoch population coding in anterior insular cortex dissociates sign- and goal-tracking despite equivalent conditioned responding
- 1University of Maryland SOM, Baltimore
Abstract
When Pavlovian lever cues predict reward, rats diverge in how they express learned associations: sign-tracking (ST) rats approach and engage the cue with greater persistence, while goal-tracking (GT) rats approach the reward site and are more consistently outcome-sensitive. The anterior insular cortex (aIC) and its interactions with amygdala and striatal regions are differentially recruited across phenotypes, implicating aIC as a node where associative strategy diverges at the circuit level. To characterize this neural divergence independent of differences in conditioned responding, we recorded single-unit aIC activity in ST and GT rats performing an odor-guided sucrose discrimination task with equivalent approach behavior. At the population level, GT aIC was dominated by task-excited neurons that drove sucrose discrimination, while ST aIC carried a greater proportion of task-inhibited neurons whose suppression carried the dominant discrimination signal, a dissociation specific to the reward epoch. During cue sampling, the balance of excited and inhibited neurons did not differ between phenotypes, but temporal structure diverged: ST cue-excited neurons showed transient CS-onset responses without sustained discrimination, while GT cue-excited neurons maintained sustained CS+/CS- discrimination into the reward epoch. ST cue-period firing predicted post-cue approach latency, with stronger responses associated with slower goal approach, a relationship absent in GT. The majority of optogenetically identified aIC projection neurons targeting basolateral amygdala and nucleus accumbens were cue-inhibited. These findings reveal that individual differences in associative strategy are encoded in the organizational structure of aIC population activity, positioning aIC as a site where motivational strategy is translated into distinct outputs.
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BibTeX
@misc{keefer2026opposing,
title = {{Opposing reward-epoch population coding in anterior insular cortex dissociates sign- and goal-tracking despite equivalent conditioned responding}},
author = {S. E. Keefer and D. A. Martin and D. J. Calu},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.15.759424},
url = {https://www.biorxiv.org/content/10.64898/2026.10.15.759424v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Opposing reward-epoch population coding in anterior insular cortex dissociates sign- and goal-tracking despite equivalent conditioned responding
AU - S. E. Keefer
AU - D. A. Martin
AU - D. J. Calu
PY - 2026
DA - 2026/10/15
PB - bioRxiv
DO - 10.64898/2026.10.15.759424
UR - https://www.biorxiv.org/content/10.64898/2026.10.15.759424v1
AB - When Pavlovian lever cues predict reward, rats diverge in how they express learned associations: sign-tracking (ST) rats approach and engage the cue with greater persistence, while goal-tracking (GT) rats approach the reward site and are more consistently outcome-sensitive. The anterior insular cortex (aIC) and its interactions with amygdala and striatal regions are differentially recruited across phenotypes, implicating aIC as a node where associative strategy diverges at the circuit level. To characterize this neural divergence independent of differences in conditioned responding, we recorded single-unit aIC activity in ST and GT rats performing an odor-guided sucrose discrimination task with equivalent approach behavior. At the population level, GT aIC was dominated by task-excited neurons that drove sucrose discrimination, while ST aIC carried a greater proportion of task-inhibited neurons whose suppression carried the dominant discrimination signal, a dissociation specific to the reward epoch. During cue sampling, the balance of excited and inhibited neurons did not differ between phenotypes, but temporal structure diverged: ST cue-excited neurons showed transient CS-onset responses without sustained discrimination, while GT cue-excited neurons maintained sustained CS+/CS- discrimination into the reward epoch. ST cue-period firing predicted post-cue approach latency, with stronger responses associated with slower goal approach, a relationship absent in GT. The majority of optogenetically identified aIC projection neurons targeting basolateral amygdala and nucleus accumbens were cue-inhibited. These findings reveal that individual differences in associative strategy are encoded in the organizational structure of aIC population activity, positioning aIC as a site where motivational strategy is translated into distinct outputs.
ER -