Prefrontal neurons encode context-based response execution and inhibition in reward seeking and extinction

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Cognitive Neuroscience

Background:

• The medial prefrontal cortex (mPFC) in rodents, specifically the prelimbic (PL) and infralimbic (IL) subregions, is traditionally viewed with distinct roles: PL for action execution (
• go
• ) and IL for behavioral inhibition (
• stop
• ). This dichotomy is well-established for fear behaviors but less clear for reward-directed actions. Limited single-neuron recordings exist for PL/IL activity during reward-related tasks.

Purpose of the Study:

• To investigate the functional roles of PL and IL neuronal activity during reward-seeking and extinction behaviors.
• To determine if PL and IL neurons exhibit a strict "go" vs. "stop" topographical organization.
• To identify single-neuron correlates of behavior initiation and suppression in the context of reward contingencies.

Main Methods:

• Neuronal activity was recorded in the PL and IL regions of the medial prefrontal cortex (mPFC) in rodents.
• The study involved phases of discriminative stimulus-driven sucrose seeking followed by multiple days of extinction.
• Neuronal activity was analyzed in relation to specific behaviors: lever pressing (initiation) and withholding (suppression).

Main Results:

• Contrary to the "go"/"stop" hypothesis, cue-evoked activity was observed in both PL and IL during both reward seeking and extinction phases.
• Neurons in both PL and IL encoded contextually appropriate behavioral initiation during reward seeking.
• Neurons in both PL and IL also encoded contextually appropriate behavioral withholding during extinction, demonstrating context-dependent signaling.

Conclusions:

• The PL and IL subregions of the mPFC signal contextual information to regulate behavior, rather than strictly mediating "go" or "stop" responses.
• Behavioral regulation relies on context-dependent signaling within both PL and IL, optimizing action based on reward contingencies.
• This contextual signaling is crucial for maximizing utility by directing effort when rewarded and conserving energy when not.