CNS*2026 Halifax

Introduction
Emotional contagion, the sharing of another individual’s emotional state, is a key component of social behavior and empathy. Neural population dynamics underlying internal affective states are increasingly studied using latent dynamical models that reveal structured activity patterns associated with behavioral states (Nair et al., 2022). In rodents, socially relevant experiences can also shape memory and internal state representations (Veyrac et al., 2015). Here, we investigate neural and behavioral dynamics in observer rats witnessing conspecifics receiving footshocks.


Methods
Adult observer rats were implanted with Neuropixels probes to record large-scale neuronal population activity while simultaneously measuring locomotor speed and pupil diameter. Animals observed a demonstrator receiving footshocks in an adjacent compartment. Spike trains were converted to firing rates and analyzed using a recurrent Switching Linear Dynamical System (rSLDS), a state-space model that captures both discrete neural states and continuous latent dynamics underlying population activity.


Results
Shock observation produced significant increases in pupil dilation and reductions in locomotor speed, with MANOVA revealing significant inter-rat and inter-shock variability. The rSLDS identified discrete neural states that shifted around shock events and captured coordinated dynamics across neural and behavioral signals. Importantly, a distinct neural latent state emerged following shock observation and persisted longer than the behavioral responses, indicating sustained internal processing beyond immediate physiological changes.


Discussion
Our findings demonstrate that latent dynamical modeling reveals structured neural state transitions associated with socially transmitted distress. While neural and behavioral responses showed synchronized shifts around shock events, neural population activity displayed a prolonged state not fully explained by pupil dilation or immobility. These results support the presence of emotional contagion, suggesting that observer animals maintain a sustained neural representation of another individual’s distress.


References
Nair, A. et al. (2022).An approximate line attractor in the hypothalamus encodes an aggressive state. Cell, 185(25), 4841–4859.https://doi.org/10.1016/j.cell.2022.11.027
Veyrac, A., Allerborn, M., Gros, A., Michon, F., Raguet, L., Kenney, J., Godinot, F., Thevenet, M., García, S., Messaoudi, B., Laroche, S., & Ravel, N. (2015). Memory of occasional events in rats: Individual episodic memory profiles, flexibility, and neural substrate. Journal of Neuroscience, 35(20), 7575–7586. https://doi.org/10.1523/JNEUROSCI.3941-14.2015


Acknowledgement
This work is supported by Dutch Brain Interface Initiative (DBI2), project number 024.005.022 of the research programmed Gravitation, which is financed by the Dutch Ministry of Education, Culture, and Science (OCW) via the Dutch Research Council (NWO)