Tracking Light-Induced Synaptic Engrams in in-vitro Neuronal Networks

The concept that activity-dependent synaptic plasticity is at the core of learning and memory is a cornerstone of neuroscience. This intricate process entails synapses' capacity to adjust their strength in reaction to neural circuit activation, facilitating the nervous system's adaptation to environmental stimuli and information storage. Despite its acknowledged significance, there remains a wealth of knowledge to be uncovered regarding the precise mechanisms through which synaptic plasticity influences learning processes, particularly concerning the specific cellular and connectivity alterations within memory circuits, often referred to as engrams. Advancing our understanding of synaptic strength and plasticity in living organisms, especially within natural behavioral contexts, faces significant challenges due to limitations in available measurement and control tools. To address this gap, we have developed a strategy enabling precise manipulation and observation of synaptic dynamics for generating engram circuits in vitro. Our approach integrates various experimental techniques, including electrophysiology, imaging, optogenetics, and molecular manipulations, each has strengths and limitations in probing synaptic function within engrams. By outlining these strategies, we pave the way for future research to unravel the complex interplay between synaptic plasticity and engram circuits.