The thalamic reticular nucleus orchestrates social memory

Social memory has been developed in humans and other animals to recognize familiar conspecifics and is essential for their survival and reproduction. Here, we demonstrated that parvalbumin-positive neurons in the sensory thalamic reticular nucleus (sTRN^Pvalb) are necessary and sufficient for mice to memorize conspecifics. sTRN^Pvalb neurons receiving glutamatergic projections from the posterior parietal cortex (PPC) transmit individual information by inhibiting the parafascicular thalamic nucleus (PF). Mice in which the PPC^CaMKII→sTRN^Pvalb→PF circuit was inhibited exhibited a disrupted ability to discriminate familiar conspecifics from novel ones. More strikingly, a subset of sTRN^Pvalb neurons with high electrophysiological excitability and complex dendritic arborizations is involved in the above corticothalamic pathway and stores social memory. Single-cell RNA sequencing revealed the biochemical basis of these subset cells as a robust activation of protein synthesis. These findings elucidate that sTRN^Pvalb neurons modulate social memory by coordinating a hitherto unknown corticothalamic circuit and inhibitory memory engram.