DYNAMICS OF SIGNALING PATHWAYS RELEVANT FOR SYNAPTIC PLASTICITY INDUCED DURING BEHAVIOURAL LEARNING

Behavioural learning relies on synaptic plasticity, yet the spatiotemporal dynamics of underlying signaling pathways remain poorly understood. My work focuses on characterizing these dynamics during behaviourally induced synaptic plasticity.
My study focuses on the mouse dorsale CA1 hippocampus, a structure well characterized for Hebbian plasticity, in which synaptic changes are induced through spatial learning. I implemented a two-phase spatial learning task: first, mice habituate to the environment and learn a reward’s location; then, the reward’s location is changed. This induces rapid behavioural adaptation, enabling the investigation of signaling dynamics at this moment when mice learn to locate the new reward’s position. Prior to real-time monitoring, I validated learning-induced changes in “slow”, tens-of-minute-scaled plasticity-related integrator signaling pathways using immunohistochemistry to assess ERK’s phosphorylation and RNAscope to detect immediate early genes transcription (Arc, c-Fos). Phosphorylated ERK levels were increased in a subpopulation of hippocampal neurons in mice learning a new reward location compared with control animals, confirming this pathway’s recruitment and pointing towards upstream signaling. I now investigate in vivo signaling dynamics in the dorsal CA1 hippocampus of behaving mice, using a home-made microscope ended with an optical fiber bundle, starting with calcium dynamics as measured with GCaMP8m. To monitor multiple pathways in the same cell, we are combining spectrally compatible biosensors to simultaneously image calcium (PinkyCaMP) and cAMP (GFlamp) or calcium and ERK activation (YEN) dynamics. Together, this approach aims to provide an integrated view of how intracellular signaling dynamics shape synaptic plasticity during learning.