Practice changes the hippocampal-neocortical communication - 陈霓虹实验室

Visual learning involves not only adjustments in local functionality but also dynamic reshaping of connectivity among cortical areas in the brain network. Reshaping of connectivity is needed to provide task-relevant context, as mediated by the hippocampus, and to provide reinforcement signals, as mediated by the anterior cingulate cortex (ACC). Here we demonstrated a practice effect in hippocampus and ACC, which happened at the very initial stage of learning. Subjects were asked to detect a pause in the flickering of the visual stimuli in the right visual field. Whole-brain BOLD signals were measured with fMRI on two different days. Using the region activated by the visual stimuli in V1 as the seed, we calculated its functional connectivity with hippocampus and ACC, with the task-related activity regressed out. The connectivities among V1, hippocampus and ACC showed distinct changes across runs during the first day. While the connectivity between V1 and hippocampus decreased, the connectivity between V1 and ACC increased. The connectivity between hippocampus and ACC also increased. These effects were only observed on the first day. No change in the connectivity among these areas was observed on the second day. Connectivities between V1 and extrastriate visual areas V2-V4 remained constant throughout the experiment. The dynamic disengagement of hippocampus and engagement of ACC to V1 reflect the evolving needs of contextual information and task monitoring. It is also consistent with the view that hippocampus supports rapid learning and gradual transfer of learning to the neocortex (Kumaran et al., 2016).