Aims of the lab
We study vision in the primate brain. We focus on the cortex, specifically the area that allows object recognition: inferotemporal cortex or IT. IT contains neurons that give strong responses (a high number of action potentials) to images of particular object categories like faces, body parts or places. Many of these category-preferring neurons cluster into large groups called "domains." One of our goals is to define the function and development of IT neurons and these category-preferring domains. Because IT neurons exist in both humans and non-human primates, by studying macaque monkeys we can discover general principles of high-level vision that we share with other primates. One key question is whether these cortical domains are innate (i.e. largely encoded by a genetic program) or learned (i.e. largely created by common early experience).
How do we go about it?
We analyze IT neurons using functional imaging (fMRI), electrophysiology (single- and multi-electrode setups) and behavioral measures (looking behavior). To measure the relative contributions of genetic programs vs. intensive experience, we raise juvenile macaques under different conditions: for example, some are learn letters, numbers and other sets of human-made symbols in order to gain juice rewards; others are never shown certain visual categories, like faces, until they pass critical developmental windows. These early exposure manipulations dramatically change the response properties of IT neurons.
What insights have we gained?
We found that intensive early experience learning human symbols in young macaques can cause the development in monkeys of novel, entirely unnatural, domains, selectively responsive to human symbols. Conversely, monkeys raised without seeing faces do not develop face domains, which are present in normally raised humans and macaques. This double dissociation means that early experience is critical for the development of specialized domains. So if something as ubiquitous as face domains is not innate, what is the proto-organization that causes these domains to arise in stereotyped locations across monkeys and humans? We think it is maps: maps of the body, of the visual world, and of the auditory world, because we found that at birth, the cortex is already extensively covered by maps.