Dr. Levitt studies the neural basis of visual perception, and the organization/development of mammalian cerebral cortex using electrophysiological and neuroanatomical techniques.
Senior Research Fellow, Institute of Ophthalmology, University College London, 1992-1998
Postdoctoral Fellow, University of Pittsburgh School of Medicine, 1990-1992
M.A. | Ph.D. in Experimental Psychology, Center for Neural Science, NYU, 1990
B.A. in Biophysics, University of Pennsylvania,1984
The Levitt laboratory aims to understand the physiological properties and anatomical connections of neurons in visual areas of mammalian cerebral cortex. The ultimate goal of this work is to understand visual perception in terms of its underlying neural substrates. We now know that there are a number of distinct areas of mammalian cerebral cortex with visual functions, yet we do not know why there are so many visual areas, or indeed how single neurons in any area come to have the functional properties that they do.
One line of work focuses on characterizing the organization and postnatal development of neuroanatomical circuits linking different areas of mammalian cerebral cortex. Parallel electrophysiological studies aim to characterize the responses of single neurons in visual cortex to visual stimuli. It is now clear that the responses of neurons are not so rigidly hardwired as previously thought. Rather, a single visual neuron's responses to a given stimulus vary dynamically according to the context in which that stimulus is viewed. Specifically, although responses can be evoked from a neuron only when stimuli fall within a restricted portion of the visual field, stimuli falling outside that region do not themselves evoke responses but at any moment can dramatically enhance or suppress a simultaneously evoked response. A major focus of our research is understanding this phenomenon and its development, crucial to our basic understanding of how the brain dynamically transforms sensory signals into neural responses.
A related focus of our work is characterizing the visual response properties of neurons in a number of different areas of cerebral cortex; understanding differences among areas will clarify the perceptual abilities mediated by those areas. To address these questions, we employ both electrophysiological recording as well as neuroanatomical techniques; these allow one to study not only the physiological properties of brain cells, but also the underlying structural basis for how such functional properties are constructed by the brain.
Levitt JB. 2009. "Receptive fields", In Encyclopedia of Perception (Goldstein EB ed., Sage Publications), Thousand Oaks, CA.
Shushruth S, Ichida JM, Levitt JB, and Angelucci A. 2009. Comparison of spatial summation properties of neurons in macaque V1 and V2. J Neurophysiology 102(4):2069-83.
Jeffery G, Levitt JB, Cooper H. 2008. Segregated hemispheric pathways through the optic chiasm distinguish primates from rodents. Neuroscience, 157: 637-643.
Xiao J, Levitt JB, Buffenstein R. 2006. The use of a novel and simple method of revealing neural fibers to show the regression of the lateral geniculate nucleus in the naked mole-rat (Heterocephalus glaber). Brain Res. 1077: 81-89.
Cantone G, Xiao J, Levitt JB. 2006. Retinotopic organization of ferret suprasylvian cortex. Vis. Neurosci. 23: 61-77.
Xiao J, Levitt JB, Buffenstein R. 2006. A stereotaxic atlas of the brain of the naked mole-rat (Heterocephalus glaber). Neuroscience, 141(3):1415-1435.
Cantone G, Xiao J, McFarlane N, & Levitt JB. 2005. Feedback connections to ferret striate cortex: direct evidence for visuotopic convergence of feedback inputs. J. Comp. Neurol. 487: 312-331.
Xiao J, Levitt JB. A new chamber method for mounting tissue sections. 2005. J. Neurosci. Meths. 144: 235-240
Levitt, J.B. and Lund, J.S. Levitt, J.B. and Lund, J.S. 2002. The spatial extent over which neurons in macaque striate cortex pool visual signals. Vis. Neurosci. 19: 439-452.
Levitt, J.B. and Lund, J.S. 2002. Intrinsic connections in mammalian cerebral cortex. In Cortical areas: unity and diversity (eds. A. Schuez and R. Miller). Taylor & Francis, London UK.
Angelucci, A., Levitt J.B., and Lund, J.S. 2002. Anatomical origins of the classical receptive field and modulatory surround field of single neurons in macaque visual cortical area V1. Prog Brain Res. 136: 373-388.
Angelucci, A., Levitt, J.B., Walton, E.J.S., Hupé, J.-M., Bullier, J. and Lund J.S. 2002. Circuits for local and global signal integration in visual cortex. J. Neurosci. 22: 8633-8646.
Kiper, D.C., Levitt, J.B., and Gegenfurtner, K.R. 1999. Chromatic signals in extrastriate areas V2 and V3. In: Color vision: from molecular genetics to perception (eds. K.R. Gegenfurtner and L.T. Sharpe). Cambridge University Press, New York NYLevitt, J.B. and Lund, J.S. 1997. Contrast dependence of contextual effects in primate visual cortex. Nature 387: 73-76.