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Faces are our primary source for recognizing people and reading their emotional and mental states. Freiwald is interested in how the brain’s visual system extracts social meaning from a face and then drives other brain circuits to generate emotional reactions, activate memories, direct attention, and drive social actions.

From patterns of light received by the eyes, the brain constructs our perception of a three-dimensional world, inhabited by objects with shape, color, and motion. To understand the mechanisms that make this happen, Freiwald studies attention and a particular category of objects, faces, using functional imaging of the entire brain and electrophysiological recordings from single cells. Because a dedicated circuit exists for processing them, faces offer a unique opportunity to study object recognition. Likewise, as potent stimuli for attention, emotion, memories, and thoughts, faces provide a powerful means to study social cognition.

Using functional magnetic resonance imaging (fMRI), Freiwald has discovered specialized neural machinery for face processing. By combining fMRI with electrophysiological techniques, he and his colleagues showed that this machinery is composed of a fixed number of face-selective regions, each dedicated to a different dimension of facial information. Yet all except one of these regions are interconnected to form a face-processing network. Because this system is specialized to process only one class of complex forms, and because its computational components are spatially segregated, it offers a unique opportunity to dissect the neural mechanisms and computational principles of object recognition.

Freiwald’s lab aims to understand the inner workings of this system, from the level of individual cells to the interactions of brain areas, to answer questions such as: How does face selectivity emerge in a single cell? How is information transformed from one face area to another? What is the contribution of each face area to different abilities, such as the recognition of a friend or a smile, and how do the face areas interact?

The lab uses the face-processing network to uncover fundamental principles of brain organization: Why is visual information processing organized in hierarchies? How do populations of neurons extract and integrate information? And how does activity propagate through the cortex? Furthermore, by studying how the face-processing system is functionally embedded in the brain, the Freiwald lab is exploring its links to social behavior: How does a smile elicit an emotional response and cause someone to smile back? How does a face activate old memories? Understanding the circuits of the social brain that implement these complex functions may aid in understanding disturbances of social behavior in disease, such as autism.

The Freiwald lab is also interested in how the brain exerts attentional control, how attention interacts dynamically with the environment, and how attention and object representations interact. Vision is an active process, aided by attention, and it selects what is relevant and dismisses what is not. Freiwald uses fMRI to determine the entire network of brain areas involved in attention, its connections, and functional properties. The group has also identified a new cortical area for attention control. Faces, due to their high social importance, give rise to specific attentional deployments, and the lab aims to utilize this link to better elucidate general attention mechanisms.