Single-trial visual familiarity memory acquisition

We’ve all experienced a sense of familiarity—that vague sense that we’ve met someone, been in a room, or seen a movie before—even if we can’t quite remember the specifics. Recent experimental work has shown that we can pick out familiar images out of tens of thousands, even after only seeing the image one time, and for just a few seconds. This remarkable ability to remember whether we have previously encountered specific people, objects or scenes is called “visual familiarity memory.” Impairments in visual familiarity memory, including those that accompany disorders such as dementia, lead to devastating inabilities to recognize one’s own family or home.  Unfortunately, we currently have only a rudimentary understanding of the processing in the brain responsible for this type of memory. One reason for this is that previous studies were only able to look at one or just a few neurons at a time, and then averaged their activity in response to repeated presentations of a stimulus like a visual scene. However, for visual familiarity memory, which by definition can be formed with just a single exposure, averaging across repeated trials is not the best way to study it. New developments in measuring the activity of neurons allow us, for the first time, to observe many neurons at once as these memories are formed and retrieved. We will examine multiple brain areas, such as the inferotemporal cortex, which is know to be involved in objet recognition, as well as the brain region that provides its input, the visual area V4, which processes more basic visual features. By studying the interactions between these two brain regions, we will determine exactly how familiarity is established. By elucidating these mechanisms, we can better understand some of the fundamental properties of our remarkable memories, and use these insights to unravel how memories break down in disease.