Neural correlates of approach-avoidance conflict in the prelimbic prefrontal cortex

FERNANDEZ LEON, JOSE A.; ENGELKE, DOUGLAS; AQUINO MIRANDA, GUILLERMO; DO MONTE, FABRICIO

Puerto Rico

Simposio; 60th Annual Meeting of the American College of Neuropharmacology; 2020

Background: The ability to identify and discriminate cues associated with reward and aversive stimuli allows an organism to select the most appropriate behavioral response. Neurons in the prelimbic subregion of the prefrontal cortex (PL) respond to both reward- and threat-associated cues, but whether PL activity regulates the animals? decision to approach or avoid such cues remains unknown. Methods: Male Long-Evans rats with single-unit recording electrodes in PL were initially trained to press a bar for sucrose during the presentation of audiovisual cues. Next, rats were fear conditioned by pairing a neutral odor with electrical footshocks. During the test session, rats were placed in a rectangular arena (60cm x 26cm x 40cm) comprising two different zones: a hidden zone and an adjacent foraging zone where the bar, the food dish, and the odor port were located. Rats were exposed to three phases: only audiovisual cues (reward), only odor cues (fear), or both simultaneously (conflict). To search for food during the conflict phase, animals had to leave the hidden zone and confront the conditioned odor presented in the foraging zone. Results: During the reward phase, animals pressed the bar in ~95% of the cue presentations. During the fear phase, animals showed stronger defensive behaviors characterized by a reduction in time exploring the foraging zone and an increase in time spent in the hidden zone. Interestingly, two subpopulations of rats emerged during the conflict phase: rats that continued searching for food despite an increase in the latency to press the bar (pressers) vs. rats that remained in the hidden area and showed complete suppression of food-seeking responses (avoiders). PL recordings (n= 367 neurons, 32 rats) revealed that the magnitude of reward-cue responses observed during the conflict phase was similar to the reward phase for pressers, but was drastically reduced for avoiders (Z-score >2.58 for excitatory responses and