Cerebellin-2 neurons in the parafascicular thalamic nucleus regulate self-grooming behavior

Self-grooming represents a stereotyped repetitive behavior which is commonly observed in various neuropsychiatric disorders. Deep brain stimulation (DBS) targeting the centromedian / parafascicular complex (CM/PF) has been shown to alleviate obsessive-compulsive disorder/behavior (OCD/OCB) symptoms in human. However, little is known about the neural circuits of the PF that are involved in the regulation of self-grooming behavior in rodents. Here, we report that cerebellin-2 positive ( Cbln2 ⁺ ) neurons in PF bidirectionally encode self-grooming. Chemogenetic activation of Cbln2 ⁺ PF neurons significantly reduces both physiological and pathological self-grooming, and chemogenetic inhibition of Cbln2 ⁺ PF neurons increases physiological self-grooming. Moreover, activating synaptic excitatory inputs to Cbln2 ⁺ PF neurons inhibits self-grooming, while synaptic inhibitory inputs enhance it. Cbln2 ⁺ PF neurons independently transmit neural signals to the dorsal and ventral striatum. Activation of PF-dorsal striatum and PF-ventral striatum pathways both inhibit self-grooming behavior. Most excitingly, we alleviate excessive grooming in OCD mice by the activation of PF neurons using non-invasive ultrasound stimulation. Together, these data reveal that Cbln2 ⁺ PF neurons are integral components of a brain network involved in self-grooming behavior and highly promising targets in the non-invasive therapy of OCD.