Prelimbic cortical excitatory overdrive and inhibitory underdrive accompany environmental suppression of food seeking

Abstract

Cues associated with food, such as fast-food advertising, can provoke food cravings and may lead to unhealthy overeating. Environmental enrichment (EE) that enhances cognitive and physical stimulation can reduce cue-evoked sucrose seeking in mice and recruitment of sucrose cue-reactive neurons or ‘neuronal ensembles’ in the prelimbic cortex (PL), which regulates appetitive behaviors. Hence, EE provides us with a behavioral model and neuronal targets to identify ‘anti-craving’ relevant mechanisms. Here, we investigated in the PL how EE modulated neuronal excitability and activity patterns in cue-reactive neuronal populations. Chemogenetic inhibition of cue-reactive neurons in PL blocked cue-evoked sucrose seeking, thereby confirming the function of these neurons in sucrose cue memory. EE boosted the baseline excitability of ‘originally’, or before EE exposure, cue-reactive, excitatory pyramidal cells in PL. Furthermore, their sucrose cue-specificity was lost – resulting in their persistent activation and non-cue selective activation or ‘excitatory overdrive’. Furthermore, EE reduced recruitment of cue-reactive, inhibitory interneurons reflecting ‘inhibitory underdrive’. Taken together, impaired neuronal food cue processing due to simultaneous prefrontal cortical excitatory ‘overdrive’ and inhibitory ‘underdrive’ likely underlies EE’s anti-craving action, thereby serving as potential neurophysiological targets to develop novel medications that help control food cravings. (Figure presented.)