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315 464-5531

Daniel Tso, PhD

4111 Institute For Human Performance (IHP)
505 Irving Avenue
Syracuse, NY 13210
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Associate Professor of Neurosurgery
Associate Professor of Neuroscience and Physiology
Associate Professor of Ophthalmology and Visual Sciences




Biomedical Sciences Program
Neuroscience Program


Neuronal mechanisms of visual perception, studied through physiological, anatomical and functional imaging techniques. Adult cortical plasticity.


American Association for the Advancement of Science (AAAS)


Postdoctoral Fellow: Rockefeller University
PhD: Harvard Medical School, 1987


Cortical Machinery for Visual Perception

The long-term goal of our work is to arrive at a deeper understanding of the neural mechanisms underlying visual perception. Although we have chosen to focus on the processing in the visual system, the mechanisms of neuronal organization, interaction and connectivity that we are studying hold broad implications for our understanding of brain in both normal and diseased states. One important theme concerns the classes of neuronal interactions between different cortical areas, the study of which should lead to an understanding of why and how the brain is divided up into so many areas, many of which seem to have functions that to some degree overlap with those of other areas. We are studying how the various visual areas interact, what kinds of information are passed between these areas, why multiple cortical areas instead of one are necessary, and how in general do multiple cortical areas cooperate with each other. A second theme in our research addresses the types of functional organization in the neocortex, just how segregated each functional domain is, what the different patterns of organization are, and how functional domains interact within a given cortical region. These studies have important implications for our understanding of how the cortex represents multiple processing dimensions in the same cortical area.

Our studies using anatomical, physiological and functional imaging techniques, have revealed separate pathways for distinct aspects of visual processing. Optical imaging results show a patchwork of cortical modules or cortical maps dedicated to visual features, such as form, color and depth. Multi-electrode single-cell electrophysiology has shown both the properties of individual neurons, and how ensembles of neurons cooperate to ultimately yield visual perception, object recognition and visually-guided behavior.

Our research should not only lead to a better understanding of the nature of brain function and architecture, but will provide insights into disease states that involve neuronal connectivity, such as Alzheimer's and epilepsy, as well as central visual disorders.

Noninvasive retinal imaging

We have adapted the technique of intrinsic signal optical imaging of neural activity to the noninvasive functional imaging of retina, and demonstrated the feasibility and potential of this new method for the functional assessment of the retina. Like its counterpart for studies of neocortex, this retinal functional imaging technique measures functionally correlated intrinsic optical signals in the retina such as total hemoglobin concentration and deoxy/oxy-hemoglobin exchange. Via a modified fundus camera, this technique enables us to visualize the patterns of activity in the intact retina while presenting visual stimuli. The most anticipated applications of this technology are those in ophthalmology, in the study, diagnosis and treatment of retinal diseases, as well as in basic research of retinal function.

Selected References

-Ts'o, DY, Frostig RD, Lieke, EE, Grinvald, A.  Functional organization of primate visual cortex revealed by high resolution optical imaging of intrinsic signals.  Science (1990) 240:417-420.
-Roe, AW and Ts'o, DY.  Visual topography in primate V2: multiple representation across functional stripes. J. Neurosci. (1995) 15:3689-3715.
-Ghose, GM, and Ts'o, DY. Form processing modules in primate area V4. J. Neurophys. (1997) 77:2191-2196.
-Abramoff, M, Kwon, Y, Tso, DY, Soliz, P, Zimmerman, B. Pokorny, J, Kardon, R. (2006) Visual Stimulus-Induced Changes in Human Near-Infrared Fundus Reflectance. IOVS 2006 47: 715-721.
-Yang, JN, Szeverenyi, NM, Tso, DY. Neural Resources Associated with Perceptual Judgement across Sensory Modalities. Cerebral Cortex, (2008) 18: 38-45.
-Lu HD, Chen G, Ts'o DY, Roe AW. A rapid topographic mapping and eye alignment method using optical imaging in Macaque visual cortex (2009) Neuroimage 44(3):636-46.
-Tso D, Zarella M, Burkitt G. (2009) Whither the Hypercolumn? J. Physiol. 587:2791-2805.
-Schallek, JB, Li, H, Kardon, R, Kwon, Y, Abramoff, Soliz, P, Tso, DY. Stimulus-Evoked Intrinsic Optical Signals in the Retina: Spatial and Temporal Characteristics. (2009) Invest. Ophthal. Vis. Sci. 50:4865-4872.
-Schallek, JB, Kardon, R, Kwon, Y, Abramoff, Soliz, P, Tso, DY. Stimulus-Evoked Intrinsic Optical Signals in the Retina: Pharmacological Dissection Reveals Outer Retinal Origins (2009) Invest. Ophthal. Vis. Sci. 50:4873-4880.
-Tso, DY, Schallek, JB, Kwon, Y, Kardon, R, Abramoff, Soliz, P. (2009) Non-Invasive Functional Imaging of the Retina Reveals Outer Retinal and Hemodynamic Intrinsic Optical Signal Origins, Jap. J. Ophthal. 53: 334-344.
-Schallek, JB, Tso, DY. Blood contrast agents enhance intrinsic signals in the retina: Evidence for an underlying blood volume component. Invest. Ophthal. Vis. Sci. 52: 1325-1335 (2011).
-Schallek. JB, McLellan, G, Viswanathan, S and Ts'o, DY.  Retinal Intrinsic Optical Signals in a Cat Model of Primary Congenital Glaucoma, Invest. Ophthal. Vis. Sci. 53: 1971-81 (2012).


-Tso, DY and Roe, AW. Functional compartments in visual cortex: segregation and interaction. The Cognitive Neurosciences, Gazzaniga, MS (ed), MIT Press (1994), Cambridge, pp. 325-337.
-Tso, DY and Roe, AW. The functional architecture of area V2 in the macaque monkey: Physiology, topography and connectivity. Cerebral Cortex, Kass, J. and Rockland, K. (eds), Plenum Press (1998).


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