Early Visual Cortex Supports One-Shot Episodic Memory via Spatially Tuned Reactivation.

Episodic memory retrieval is thought to rely on the reactivation of prior perceptual representations in sensory cortex, a phenomenon known as cortical reinstatement. Support for this idea in early sensory areas comes from studies involving repeated exposure and explicit recall instructions. In everyday life, however, people often remember details from single events without repeated practice or instruction. We used fMRI to test whether memory responses emerge in early visual cortex after a single encoding event. Twenty adults viewed objects presented once in one of four parafoveal locations, then later completed recognition (old/new) and location recall tasks in which objects were shown foveally. We observed low amplitude responses in V1 to V3 during both memory tasks. These responses were tuned to the encoded parafoveal location, even though the recognition task did not ask the participant to remember the encoded location. These responses were more robust and precise for successfully remembered items, linking neural tuning in early visual cortex to one-shot memory performance. Our findings demonstrate that early visual cortex supports the defining property of episodic memory, the ability to retrieve sensory details from a single event.