NACS Seminar: Dr. David Leopold

What’s in a Face Patch? The good, the bad, and the ugly

Our laboratory has been investigating the electrophysiological activity of neural populations within fMRI-identified face patches in the monkey. The use of longitudinal microwire recordings permitted us to track the response profiles of single neurons over extended periods of time. As a consequence, we have been able to characterize the responses of individual cells to a wide range of visual stimuli and paradigms in multiple temporal cortex face patches. In my talk, I will focus on one finding that is shared among three spatially disparate face patches (AF, AM, ML), namely that the average face plays a central role in the basic tuning of neurons. I will demonstrate the temporal dynamics of this phenomenon over time scales ranging from milliseconds to months, speculate on a potential circuit mechanism, show its resistance to plasticity in the adult, and discuss its bearing on norm-based theories of human face recognition. Next, I will then show that the same neural populations, when faced with a different visual paradigm appear to undertake a very different type of feature analysis. I will make the case that theories of visual processing based on a narrow range of stimuli or testing paradigms are apt to be inherently fragile and contextual. Finally, I will briefly describe a method using fMRI in combination with single unit recording, which allows for a characterization of visually driven cell activity in a way that need not make reference to stimulus features.

Dr. David Leopold is the senior investigator at the National Institute of Mental Health, NIH.

The event is free and open to the public.