RESEARCH INTEREST

Optical measurements of electrical activity; excitation-secretion coupling; simple nervous systems in vitro; enteric nervous system.


RESEARCH TECHNIQUES

Multiple-site optical recording of membrane potential (absorption and fluorescence) and calcium transients with milli-second time resolution; intrinsic optical signals; primary cultures of identified invertebrate neurons; optical recording of electrical activity in mammalian networks, with single cell resolution.


RESEARCH SUMMARY

I am interested in the application of optical techniques to a variety of physiological problems. These include excitation-secretion coupling, and studies of functional connectivity in small neuronal ensembles. Most of my recent work has employed a system for Multiple Site Optical Recording of Transmembrane Voltage (MSORTV), which, in conjunction with voltage-sensitive dyes, permits one to monitor electrical events in cells or parts of cells not easily accessible with conventional electrophysiological techniques. For example, we have been able to measure the electrical activity (using dyes) and the resultant secretory events (using light scattering) at the nerve terminals of the vertebrate neurohypophysis. We have also used optical techniques to study patterns of electrical activity in simple nervous systems, including small ensembles of identified neurons in tissue culture, and rings of submucosal ganglia of the guinea-pig small intestine.

KEY WORDS:   Voltage-sensitive dyes; light scattering; excitation-secretion coupling; enteric nervous system; submucous plexus.


KEY REFERENCES

Kim, G.H., P. Kosterin, A.L. Obaid, and B.M. Salzberg. A mechanical spike accompanies the action potential in mammalian nerve terminals Biophysical Journal. 92:3122-3129, 2007. Online PDF File    Related Online PDF File

Kosterin, P., Kim, G.H., Muschol, M., Obaid, A.L., Salzberg, B.M. Changes in FAD and NADH fluorescence in neurosecretory terminals are triggered by calcium entry and by ADP production. J Membr Biol. 208(2):113-124, 2005.

Obaid, A.L., Nelson, M.E., Lindstrom, J., and Salzberg, B.M.,Optical studies of nicotinic acetylcholine receptor subtypes in the guinea-pig enteric nervous sytem, J Experi Biol 208:2981-3001, 2005.

Salzberg, B.M., Kosterin, P.V., Muschol, M., Obaid, A.L., Rumyantsev, S.L., Bilenko, Yu., and Shur, M.S. An ultra-stable non-coherent light source for optical measurements in neuroscience and cell physiology, J. Neuroscience Methods 141 (1):165-169 2005.

Obaid, A.L., L.M. Loew, J.P. Wuskell, and B.M. Salzberg. Novel naphthylstyryl-pyridinium potentiometric dyes offer advantages for neural netowrk analysis. J. Neuroscience Methods 134:179-190, 2004. Online PDF File

Obaid, A.L., T. Koyano, J. Lindstrom, T. Sakai, and B.M. Salzberg. Spatio-temporal patterns of activity in an intact mammalian network with single cell resolution: Optical studies of nicotinic activity in an enteric plexus. J. Neurosci . 19: 3073-3093, 1999.

Obaid, A.L., and B.M. Salzberg. Micromolar 4-aminopyridine enhances invasion of a neurosecretory terminal arborization: Optical recording of action potential propagation using an ultrafast photodiode-MOSFET camera and a photodiode array. J. Gen. Physiol . 107: 353-368, 1996.