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Investigator

David A. Leopold, Ph.D.


Building 49 Room B2J-45, MSC-4400

Bethesda MD 20892-4400
Office: (301) 594-0582

Fax: (301) 480-1644
leopoldd@mail.nih.gov

Dr. Leopold earned his B.S. in biomedical engineering from Duke University in 1991 and his Ph.D. from Baylor College of Medicine in 1997, where he studied neurophysiological mechanisms of multistable perception. During postdoctoral training with Nikos Logothetis at the Max Planck Institute for Biological Cybernitics in Tübingen, he worked on topics related to visual perception, face recognition and fMRI. Dr. Leopold came to the NIH in 2004 to establish the Unit on Cognitive Neurophysiology and Imaging and to head the Neurophysiology Imaging Facility Core. His laboratory combines electrophysiology, neuropharmacology, and functional imaging techniques to explore large scale mechanisms of brain function that underlie our visual perception.



Throughout his career, Dr. Leopold has been interested in the large-scale organization of brain activity that underlies aspects of visual perception. His early work on the neurophysiological mechanisms of bistable perception used visual illusions to establish that neurons in certain areas of the cerebral cortex vigorously respond to a perceptual state, rather than to a physical stimulus. These studies highlighted mechanisms underlying the inherently interpretive nature of vision: even sensory areas such as the visual cortex are "intelligent" in that they embellish the physical information with assumptions and prior knowledge, and this is reflected in neural firing. An example of this is the reconstruction of the third dimension, where the brain creates the percept of a 3-D scene despite the fact that the retina is only two-dimensional. Recently, the Leopold lab has addressed the nature of visibility itself, asking how does activity in the brain elevate a stimulus or scene to reach conscious perception? At first, this question seems strange, since one might think a stimulus striking the retina should always be visible. However, under some conditions such as during an optical illusion, or following the inactivation of a specific neural circuit, a stimulus that is normally salient can become perceptually invisible. In a series of experiments, Dr. Leopold's group has studied the role of the visual cortex and thalamus in the establishment and maintenance of stimulus visibility. This central research theme of the laboratory is ongoing.

In parallel, Dr. Leopold's laboratory also studies neural responses related to the visual perception of social stimuli. Social perception, such as reading a facial expression or observing an exchange between two individuals requires a multiple levels of visual interpretation. It frequently also hinges on deciphering stimuli that are inherently dynamic. We are therefore measuring behavioral and brain responses to a variety of expressive photos and natural videos in an effort to probe the neural mechanisms by which the social meaning is extracted. This project requires considerable methodological development, as it strays from conventional neurophysiological and functional imaging experimental designs. In one developmental direction, the laboratory is exploring how a neuron’s specialized responses to social stimuli come about in the first place, and how they change over time. To longitudinally measure neural plasticity associated with learning, we have developed special microelectrodes for monitoring individual cells over days and weeks. This method for the first time allows us to track changes in the stimulus-selectivity of visual neurons in the brain during periods of focused visual learning of new faces and other stimuli.

In its study of visual perception, the Leopold laboratory uses a host of cutting-edge technical methods, including the functional magnetic resonance imaging (fMRI) capabilities of the imaging core facility that Dr. Leopold directs . Projects in the lab typically combine behavioral, neurophysiological and fMRI measurements in the same subjects. In some projects, these methods are further complemented by local pharmacological manipulation of particular circuits. In others, they are guided by information gleaned from diffusion-weighted MR imaging. The convergence of multiple methods allow one to tap into aspects of the functional circuitry to study questions related to vision that were previously out of reach. Gaining insights into the neural basis of our percepts is critical for understanding certain pathologies of the cognition, as are commonly found in neuropsychiatric disorders. In addition, such experiments provide a unique window on the fascinating and eternal problem of how the brain gives rise to the mind.

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  • 1) Liu C, Ye FQ, Yen CC, Newman JD, Glen D, Leopold DA, Silva AC (2018)
  • A digital 3D atlas of the marmoset brain based on multi-modal MRI
  • Neuroimage, 169, 106-116
  • 2) Papoti D, Yen CC, Hung CC, Ciuchta J, Leopold DA, Silva AC (2017)
  • Design and implementation of embedded 8-channel receive-only arrays for whole-brain MRI and fMRI of conscious awake marmosets
  • Magn Reson Med, 78, 387-398
  • 3) Toarmino CR, Yen CCC, Papoti D, Bock NA, Leopold DA, Miller CT, Silva AC (2017)
  • Functional magnetic resonance imaging of auditory cortical fields in awake marmosets
  • Neuroimage, 162, 86-92
  • 4) Turchi J, Chang C, Ye FQ, Russ BE, Yu DK, Cortes CR, Monosov IE, Duyn J, and Leopold DA (2018)
  • The basal forebrain regulates resting state fMRI fluctuations
  • Neuron, 97(4), 940-952
  • 5) Park SH, Russ BE, McMahon DBT, Koyano K, Berman RA and Leopold DA (2017)
  • Functional subpopulations of neurons in a macaque face patch revealed by single-unit fMRI mapping during natural vision
  • Neuron, 95(4), 971-981
  • 6) Leopold DA, Mitchell JF, and Freiwald WA (2017)
  • Evolved mechanisms of high-level visual perception in primates. Evolution of Nervous Systems
  • 2nd Edition, Ed. Jon Kaas, 3(12):203-235
  • 7) Miller CT, Freiwald WA, Leopold DA, Mitchell JF, Silva AC, Wang X (2016)
  • Marmosets: A Neuroscientific Model of Human Social Behavior
  • Neuron, 90, 219-233
  • 8) Hung CC, Yen CC, Ciuchta J, Paparoti D, Leopold DA and Silva AC (2015)
  • Functional mapping of face-selective regions in the extrastriate visual cortex of the marmoset
  • J Neurosci , 35(3), 1160-72
  • 9) McMahon DBT, Russ BE, Elnaiem HD, Kurnikova AI and Leopold DA (2015)
  • Single unit activity during natural vision: diversity, consistency and spatial sensitivity among AF face patch neurons
  • J Neurosci , 14, 5537-48
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