Title: New perspectives on face patches through longitudinal single-unit recording and fMRI

Speaker: David A. Leopold, Ph. D.

Introduction to Dr. David A. Leopold:

David A. Leopold, Ph. D. is a Senior Investigator at National Institutes of Health, Section on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, NIMH and Director at Neurophysiology Imaging Facility, Core Facility for Imaging of Nonhuman Primates, NIMH, NINDS, NEI. He got his BSE in Biomedical Engineering at Duke University (USA) and PhD in Division of Neuroscience at Baylor College of Medicine (USA). The Leopold laboratory studies neural mechanisms of visual perception innonhuman primates. The laboratory combines electrophysiological, neuroimaging, and pharamacological approaches to interrogate cortical and thalamic visual circuits. Projects focus on three general themes: neural pathways that support the perceptual visibility of a stimulus, neural principles underlying of visuosocial perception in the ventral stream, and the basis of the brain’s spontaneous activity. 

Time: October 27 2015 (Tue) 13:00-15:00

Venue: Room 1113, Wangkezhen Building, Peking University

Host: Prof. Fang Fang

Abstract:

A prominent feature of the primate brain is the existence of several cortical areas in which neurons respond categorically to certain complex stimuli.  Most notably are the so-called "face patches", defined as regions in which fMRI signal is stronger to face images than to other types of visual object stimuli.  Recent advances in our laboratory have made it possible to record longitudinally from individual neurons across weeks and months, opening the door for new types of experiments to investigate the selectivity of face-selective neurons.  In my talk I will describe the results of several such experiments.  In one experiment, I will show that the visual selectivity of neurons in one face patch remain absolutely stable over a period up to a year, even during periods of intensive training on face identity. In another I will show that individual neurons in this area, which presented 10,000 stimuli in a conventional flashed manner over a period of 3 weeks, respond categorically for faces.  In another, I will show that the same population of "face cells", when evaluated during more naturalistic testing, respond deterministically, but in a manner that is uncorrelated between cells.  Finally, I will  illustrate two methods in which fMRI mapping  can be used to read out the local neural diversity from a single voxel and to create new types of neural categories based upon whole-brain network activation. 

Laboratory website:

http://lnpsych.nimh.nih.gov/leopold/