CHROME · Cortical hierarchy of memories - deciphering the neuronal mechanisms of serial dependence in the human brain

“Perception is never purely in the present–it has to draw on experience of the past.” O. Sacks illustrates a grounding principle in cognitive neuroscience: Eyes are not vision. Instead, seeing is an inferential process, with the brain integrating incoming with past sensory information. This idea, that perception and memory are deeply intertwined, has shaped many theories of neural computation. Yet research on these building blocks of cognition has largely evolved in separate fields. In the long-term, I aim to overcome this conceptual divide and understand the mechanistic principles by which memory and perception shape each other. In this fellowship, I will lay the foundation for this research vision and acquire the skills necessary to lead a group on this innovative program. I will work with authorities in invasive electrophysiology (L. Melloni) and dynamical systems (V. Priesemann) to tackle a current frontier in the neurosciences and unravel the brain and circuit-level mechanisms of serial dependence. A perceptual memory integrating past with current percepts, serial dependence offers a unique window into the interplay of perception and memory: It comes in multiple flavors (attractive & repulsive effects) and occurs at multiple timescales. A simple, untested hypothesis may account for this diversity: I propose that there is a hierarchy of perceptual memories, with different integration times and tuning features, all acting jointly to shape perception. I will test this innovative framework with behavioral studies (to map the spatio-temporal tuning profile of serial dependence), computational modeling (to probe how intrinsic timescales of a hierarchically organized neural network affect serial dependence), and non-invasive and invasive electrophysiology (to identify the cortical & hippocampal brain mechanisms supporting serial dependence). If successful, this work will provide a unifying framework of how memory, in the form of serial dependence, alters perception.