Schizophrenia (SZ) is a complex neuropsychiatric disorder that affects how a person thinks, feels, and behaves. Recent studies in rodents have been focused on social cognition impairments related to SZ to explain its poor social functioning. We have previously reported that restricted ablation of NMDAR in cortical GABAergic interneurons during early postnatal development results in SZ-like phenotypes in adulthood (KO). The medial prefrontal cortex (mPFC) controls many high cognitive functions reported impaired in SZ including aspects of social interactions. To date, little is known about how mPFC ensembles encode social information and how this representation might be altered in SZ. Here, we use an in-vivo electrophysiological approach to record putative pyramidal mPFC neurons activity in KO and control mice (Ctrl) while they perform a discrimination task on an enriched linear track with a novel social stimulus (adult male) and an inanimate object. In Ctrl, we identified units capable of encoding different aspects of the task, including neurons that discriminate social stimuli from the object and vice versa. The proportion of this type of units increased throughout the task in Ctrl. Conversely, KO displayed a higher proportion of non-coding units, suggesting an impaired representation of social stimuli at the population level. These results place an insight on how the mPFC neurons encode social information through a complex representation and how this may be disrupted in SZ.