Abstract
Attention does not only modulate what we see, but also what we remember about an experience. Despite this connection in behavior, little is known about how attention influences the formation of memories in the brain. Using high-resolution fMRI, we investigated the hypothesis that attentional states are represented in the hippocampus — a brain region necessary for long-term memory — and that the quality of these representations during encoding influences whether the attended information is later remembered. The study consisted of three phases. In Phase 1, observers performed an attention task in which, on every trial, they were presented with an image consisting of a room with a painting and then searched through a stream of four other images. The search target was specified by a cue at the beginning of the trial: either a painting from the same artist (art state) or a room with the same layout (room state). We then used all trials of each attentional state to identify an average pattern of activity within each hippocampal subfield that corresponded to the representation of that state. Phase 2 used an incidental encoding design: observers performed a 1-back task with trial-unique images (rooms with art), attending to the art in one block and the room layouts in the other. Memory for the attended feature of each image (art or room) was tested in Phase 3. We predicted that when observers correctly remembered a feature (e.g., spatial layout), it was because their hippocampus was more strongly in an attentional state that prioritized that feature (e.g., room state) during encoding. This was measured by correlating trial-by-trial activity patterns from Phase 2 with the state representations from Phase 1. Our predictions were confirmed in the CA2/3 subfield of the hippocampus. Together, these results offer a mechanistic window into how attention enhances memory.
Meeting abstract presented at VSS 2015