An important aspect of our decision-making process is the influence of our surroundings on the choices we make. However, the capacity to encode predictive information from the environment to guide future actions remains unclear, and its neural mechanisms have only recently become the focus of systematic research. Recent evidence from our laboratory reveals a novel form of cellular memory formed through predictive learning, involving the accumulation of δ opioid receptors (DOPR) on the surface of cholinergic interneurons located in the nucleus accumbens shell. This DOPR-based memory is demonstrated to be critical in modifying brain circuitry, enabling predictive learning to exert its influence on decision-making, even much later in time. By combining sophisticated behavioural protocols with state-of-the-art neuroscience techniques, including optogenetics, electrophysiology, and fibre photometry, I aim to enhance our understanding of the neural mechanisms underpinning the formation of this intriguing memory system.