12:00-13:00, Dec 19, 2023 

E203,Biomedicine Hall, Tsinghua University

Disheng Tang(唐迪生)、Xinli Song(宋鑫莉)

Disheng Tang

Topic

Abstract

Stimulus type shapes the topology of cellular functional networks in mouse visual cortex

Information is processed by networks of neurons in the brain. On the timescale of sensory processing, those neuronal networks have relatively fixed anatomical connectivity, while functional connectivity, which defines the interactions between neurons, can vary depending on the ongoing activity of the neurons within the network. We thus hypothesized that different types of stimuli, which drive different neuronal activities in the network, could lead those networks to display stimulus-dependent functional connectivity patterns. To test this hypothesis, we analyzed electrophysiological data from the Allen Brain Observatory, which utilized Neuropixels probes to simultaneously record stimulus-evoked activity from hundreds of neurons across 6 different regions of mouse visual cortex. The recordings had single-cell resolution and high temporal fidelity, enabling us to determine fine-scale functional connectivity. Comparing the functional connectivity patterns observed when different stimuli were presented to the mice, we made several nontrivial observations. First, while the frequencies of different connectivity motifs (i.e., the patterns of connectivity between triplets of neurons) were preserved across stimuli, the identities of the neurons within those motifs changed. This means that functional connectivity dynamically changes along with the input stimulus, but does so in a way that preserves the motif frequencies. Secondly, we found that the degree to which functional modules are contained within a single brain region (as opposed to being distributed between regions) increases with increasing stimulus complexity. This suggests a mechanism for how the brain could dynamically alter its computations based on its inputs. Altogether, our work reveals unexpected stimulus-dependence to the way groups of neurons interact to process incoming sensory information.

Xinli Song

Topic

Abstract

Neural mechanism of estrous-driven sociosexual interests: sex-specific role of cortical-hypothalamic circuits

Estrous cycles, governed by the periodic release of ovarian hormones, influence female sexual receptivity across species. The estrous state of females is essential for sustaining reciprocal sociosexual interest between sexes and for facilitating the transition from sociosexual exploration to sexual behavior. The medial prefrontal cortex (mPFC) is identified as a critical region for representing conspecific sex, regulating sex disparities and modulating estrous-dependent sociosexual preference. However, the neural mechanism through which mPFC integrates social cues with internal estrous states to regulate sociosexual interests remains unknown. Using a combination of unbiased screens, we identified Cacna1h-expressing cortical neurons (mPFC^Cacna1h+) as the primary tracker of estrous status in the mPFC. Functionally, modulating the activity of mPFC^Cacna1h+ neurons or their projections in the anterior hypothalamic nucleus (AHN) resulted in estrous-dependent and sex-specific changes in sociosexual interests. The mPFC^Cacna1h+ neurons in estrous females exhibited enhanced activity in response to male social stimuli. Intriguingly, single-cell calcium imaging further revealed the mixed representation of conspecific sex information and the self-estrous status in the mPFC^Cacna1h+ neurons. Moreover, the periodic upregulation of Cacna1h, encoding T-type calcium channels, was instrumental in driving estrus-specific activity changes and mediating the sexually dimorphic function of mPFC^Cacna1h+ neurons. Overall, our findings unveil that estrus-sensitive neurons in the mPFC integrate social cues with intrinsic physiological states, flexibly orchestrating sociosexual interactions between sexes. This study highlights a crucial top-down modulation mechanism that is essential for the dynamic control of adaptive social behaviors.