PhD Scientific Days 2021

NE_I_L: Neurosciences I. Lectures

A New Brain Mechanism Promoting Physical Contact in Social Behaviour

Text of the abstract

We previously identified the posterior intralaminar thalamic nucleus (PIL) as a relay station of socially relevant sensory information innervating and activating oxytocin-secreting neurons upon social encounter. Here, we addressed to characterize the exact role of the PIL in the regulation of the social behavior, especially its neurons projecting to the preoptic area of the hypothalamus.
Projections from the PIL were analyzed using anterograde tract-tracing. We determined the effect of chemogenetic stimulation of PIL neurons on social interactions between familiar adult female rats using the DREADD technique. The brain activation patterns were determined following direct social interaction, and also with the exclusion of physical interaction using the c-Fos technique. The selective chemogenetic stimulation of the preoptic area-projecting PIL neurons was performed using double viral injections and also by using intracerebral cannula for CNO administration directly into the preoptic area.
PIL projects to several socially implicated brain regions, such as the the medial amygdala, the medial preoptic area, the paraventricular and dorsomedial hypothalamic nuclei and the infralimbic cortex. Chemogenetic stimulation of the PIL resulted in the activation of previously anatomically identified target areas and also increased the duration of direct interactions during social behavior. Direct contact during social interaction caused the largest increase in the activity in the medial preoptic area. Specific chemogenetic stimulation of the PIL-preoptic pathway led to elevated direct social contact.
The results suggest that posterior thalamic PIL neurons convey socially relevant information to a variety of different forebrain centers, among which the preoptic area is involved in the processing of physical contact. Thus, we identified an important novel component of the social brain network, which may increase the motivation for positive direct interactions.
Support: New National Excellence Program of the Ministry of Human Capacities, Cooperative Doctoral Programme, Excellence Program of the Semmelweis University, EFOP-3.6.3-VEKOP-16-2017-00009, NKFIH-4300-1/2017-NKP_17 and OTKA K116538.

University and Doctoral School

Semmelweis University, János Szentágothai Doctoral School of Neurosciences