Medial prefrontal-perirhinal cortical communication is necessary for flexible response selection

Abstract

The ability to use information from the physical world to update behavioral strategies is critical for survival across species. The prefrontal cortex (PFC) supports behavioral flexibility; however, exactly how this brain structure interacts with sensory association cortical areas to facilitate the adaptation of response selection remains unknown. Given the role of the perirhinal cortex (PER) in higher-order perception and associative memory, the current study evaluated whether PFC-PER circuits are critical for the ability to perform biconditional object discriminations when the rule for selecting the rewarded object shifted depending on the animal’s spatial location in a 2-arm maze. Following acquisition to criterion performance on an object-place paired association task, pharmacological blockade of communication between the PFC and PER significantly disrupted performance. Specifically, the PFC-PER disconnection caused rats to regress to a response bias of selecting an object on a particular side regardless of its identity. Importantly, the PFC-PER disconnection did not interfere with the capacity to perform object-only or location-only discriminations, which do not require the animal to update a response rule across trials. These findings are consistent with a critical role for PFC-PER circuits in rule shifting and the effective updating of a response rule across spatial locations.

Rodent age‐related impairments in discriminating perceptually similar objects parallel those observed in humans

“…In tasks that require choice between two potential outcomes presented simultaneously, rats tend to initially default to an egocentric response‐based strategy before learning to apply a more flexible task‐specific strategy (Hernandez et al, ; Lee & Solivan, ; Lee & Byeon, ; Jo & Lee, ). For example, both young and aged rats develop a strong bias toward selecting an object on a specific side of a choice platform (i.e., left vs. right) before learning to recognize and compare visual features and select a target object over a lure.…”

“…For example, both young and aged rats develop a strong bias toward selecting an object on a specific side of a choice platform (i.e., left vs. right) before learning to recognize and compare visual features and select a target object over a lure. Suppression of side bias as training progresses has been shown to correspond with an increase in correct responses guided by the task‐specific rule (Hernandez et al, ; Lee & Byeon, ). Based on the fact that both young and aged rats showed more checking behavior and better performance on Lure 1 trials, but less checking and poorer performance on Lure 2 and Lure 3 trials (Figures B and B), we asked whether rats showed evidence of suppressing a side bias when making correct responses across these trial types.…”

“…This analysis was motivated by observations that rats often default to simple, rule‐based response strategies on forced‐choice tasks, and must learn to suppress their initial strategy in order to apply a more complex task‐specific strategy. For example, in an object‐place paired‐associate (OPPA) task that requires learning object–reward associations contingent on spatial location within the test apparatus, rats initially adopt a side‐biased strategy to obtain the concealed food reward 50% of the time (Hernandez et al, ; Jo & Lee, ; Lee & Byeon, ; Lee & Solivan, ). We observed the same effect during initial object discrimination training in Experiment 1 (data not shown), and a side‐biased strategy remained evident on trials with greater target‐lure similarity during tests in Experiment 2.…”

Time-restricted feeding from adulthood to old age improves biconditional associative learning in geriatric rats regardless of macronutrient composition

“…Rats were trained on the biconditional association task (BAT) as previously published (8,10,12). Briefly, rats were first trained to alternate between left and right arms of a V-shaped maze (see Figure 1) with a macadamia nut reward at the end of each arm.…”

Sex Differences in Age-related Impairments Vary across Cognitive and Physical Assessments in Rats

“…While the objects remain the same throughout testing, the correct choice varies as a function of location within the maze. As this task requires the integration of object information with spatial location to flexibly update behavior, it depends on connectivity between the prefrontal cortex, perirhinal cortex and hippocampus [21][22][23]. Female rats have been documented as performing differently from males on other prefrontal cortical dependent behaviors, such as deliberative decision making in the face of risk of punishment [24].…”