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Noga Vardi, Ph.D.

Research Professor, 
Department of Neuroscience 
122 Anatomy/Chemistry Building/6058  (215) 898-4520 FAX: (215) 898-6228
email:   noga@retina.anatomy.upenn.edu
More information on Noga's research: http://retina.anatomy.upenn.edu/~noga/noga.html

Click here for selected publications since Dr. Vardi's arrival at Penn

RESEARCH INTERESTS

Retinal processing with focus on chemical architecture and principles of signal processing.

RESEARCH TECHNIQUES

RESEARCH SUMMARY

General Description: the retina can serve as an excellent model system for signal processing because the input (visual image) is well defined, the output (i.e. ganglion cell responses) has been thoroughly studied, and circuits of parallel pathways from photoreceptor to ganglion cells were described. Consequently, in retina one can address questions at all levels and integrate molecular and biochemical information with high percepts of vision. To reliably transfer the signal from photoreceptor to ganglion cells through these pathways under a large range of luminances the retina employs gain control and noise removal mechanisms. Gain is adjusted by GABAergic and glycinergic feedback circuits in the outer and inner plexiform layers. These circuits tune photoreceptor, bipolar and ganglion cells' responses by averaging and feeding back ambient light information. Noise in retina is reduced by convergence, thresholding mechanisms, feedback circuits, and gap junction modulation. Our goal is to investigate exactly how these mechanisms operate. We therefore study the anatomical and chemical details of the circuit design. Currently we are focusing on the second messenger cascade in ON bipolar cells. The ON bipolar cells express the metabotropic glutamate receptor mGluR6. We have recently found that mGluR6 activates the G-protein G o , and this eventually closes a nonspecific cation channel. Much effort is now devoted to identify the bipolar transduction channel. Tangent to this, we have recently discovered that mGluR6 is present in epithelial cells. This was surprising because mGluR6 was thought to be retina-specific. Using calcium and chloride imaging, we are now trying to investigate the broad function of mGluR6.

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