eLife digest | Temporal structure in associative retrieval
Seeing an object triggers a complex and carefully orchestrated dance of brain activity. The spatial pattern of the brain activity encoding the object can change multiple times even within the first second of seeing the object. These rapid changes appear to be a core feature of how the brain understands and processes objects.
Yet little is known about how these patterns unfold through time when we remember an object. Remembering, or retrieving information about objects, is how we use our knowledge of the world to make good decisions. It is not clear whether, during remembering, there are rapid changes in the patterns similar to those that happen when directly seeing an object. Mapping brain activity during remembering could help us understand how stored information can guide decisions.
Using recently developed methods in brain imaging and statistics, Kurth-Nelson et al. found that two distinct patterns of brain activity appeared when viewing particular objects. One occurred around 200 milliseconds after viewing an object, and the other appeared a bit later, by about 400 milliseconds. Later, when remembering the object, these patterns reappeared in the brain, but at different points in time. Furthermore, these two patterns had distinct roles in learning associated with the objects to guide later decisions.
This work shows that rapid changes in the pattern of neuronal activity are central to how stored information is retrieved and used to make decisions.