The role of the posterior intralaminar thalamic nucleus on contact
sequence in mouse social interaction
Abstract
Efficient social interaction is essential for an adaptive life and
consists of sequential processes of multisensory events with social
counterparts. Social touch/contact is a unique component that promotes a
sequence of social behaviors initiated by detection and approach to
assess a social stimulus and subsequent maintenance of touch/contacts to
form prosocial relationships. We hypothesized that the thalamic sensory
relay circuit from the posterior intralaminar nucleus of the thalamus
(pIL) to the paraventricular nucleus of the hypothalamus (PVN) and the
medial amygdala (MeA) plays a key role in the social contact-mediated
sequence of events. We found that neurons in the pIL along with the PVN
and MeA, were activated by social encounters, and that pIL activity was
more abundant in a direct physical encounter, whereas MeA activity was
dominant in an indirect via grid encounter. Chemogenetic inhibition of
pIL neurons selectively decreased the investigatory approach and
sniffing of a same-sex, but not an opposite-sex, stimulus mouse in an
indirect encounter situation and decreased the facial/snout contact
ratio in a direct encounter setting. Furthermore, chemogenetic pIL
inhibition had no impact on anxiety-like behaviors or body coordinative
motor behaviors, but it impaired whisker-related and plantar touch
tactile sense. We propose that the pIL circuit can relay social tactile
sensations and mediate the sequence of non-sexual prosocial interactions
using an investigatory approach through tactile contact.