Nathan Schoppa is an assistant professor in the Department of Physiology and Biophyics.
Our laboratory is interested in the fundamental mechanisms that neurons use to communicate with each other at synapses. We study cellular interactions at a number of different levels, including the properties of single synapses, how pairs of neurons interact with each other, as well as mechanisms of interactions within small groups of neurons. Towards this end, electrophysiological and optical methods are used in brain slices that allow us to record simultaneously from multiple neurons. Our goal ultimately is to combine experiments with computer-based modeling strategies to develop ideas about how neuronal computation occurs within an individual brain circuit.
Our present focus is on the olfactory bulb, which is the first brain structure involved in processing sensory information about odors. The bulb is ideally suited for studies of synaptic and circuit mechanisms because of its remarkably simple organization. The main excitatory neurons in the bulb, the mitral cells, are organized into discrete networks of ~25 cells, each of which is affiliated with single glomerular structures that line the outer surface of the bulb (see figure). Because each glomerulus receives afferent inputs from olfactory receptor neurons in the nose that express one type of odorant receptor (OR), each mitral cell network is functionally-defined to be OR-specific. Many on-going experiments in the lab attempt to determine exactly how different defined mitral cells interact with each other, leading to such important processes as synchrony and lateral inhibition. A major emphasis is on the role of GABAergic interneurons, granule cells and periglomerular cells, which make dendrodendritic connections onto mitral cells. Other studies, done at the level of single dendrodendritic synapses, examine mechanisms of dendritic neurotransmitter release. This research will form the basis for understanding how the olfactory system functions at a basic level, e.g., how we tell one odor from another, as well as how function might change after learning or during pathological conditions.
[The figure above illustrates a pair of mitral cells that were loaded with biocytin during whole-cell patch-clamp recordings. These two cells had adjacent cell bodies in the mitral cell layer but send primary dendrites to two well-separated glomerular structures (at arrows). Glomeruli are indicated by rings of propidium iodide-labeled periglomerular cells.]
* Schoppa, N. E. (2006) Synchronization of olfactory bulb mitral cells by precisely-timed inhibitory inputs. Neuron 49:271-283.
* Schoppa, N. E. (2005) Neurotransmitter mechanisms at dendrodendritic synapses in the olfactory bulb, Chapter in Dendritic Transmitter Release (M. Ludwig, ed., Kluwer Academic/Plenum Publisher).
* Schoppa, N. E. and Urban, N. N. (2003) Dendritic processing within olfactory bulb circuits. Trends in Neurosience 26, 501-506.
* Schoppa, N. E. and Westbrook, G. L. (2002) AMPA autoreceptors drive correlated spiking in olfactory bulb glomeruli. Nature Neurosci. 5, 1194-1202.
* Schoppa, N. E. and Westbrook, G. L. (2001) NMDA receptors turn to another channel for inhibition. Neuron 31, 877-879.
* Schoppa, N. E. and Westbrook, G. L. (2001) Glomerulus-specific synchronization of mitral cells in the olfactory bulb. Neuron 31, 639-651.
* Christie, J. M., Schoppa, N. E., and Westbrook, G. L. (2001) Tufted cell dendrodendritic inhibition in the olfactory bulb is dependent on NMDA receptor activity. J. Neurophysiol. 85, 169-173.
* Schoppa, N. E. and Westbrook, G. L. (1999) Regulation of synaptic timing in the olfactory bulb by an A-type potassium current. Nature Neurosci. 2, 1106-1113.
* Schoppa, N. E., Kinzie, J. M., Sahara, Y., Segerson, T. P., and Westbrook, G. L. (1998) Dendrodendritic inhibition in the olfactory bulb is driven by NMDA receptors. J. Neurosci. 18, 6790-6802.
* Schoppa, N. E. and Westbrook, G. L. (1997) Modulation of mEPSCs in olfactory bulb mitral cells by metabotropic glutamate receptors. J. Neurophysiol. 78, 1468-1475.
* Schoppa, N. E., McCormack, K., Tanouye, M. A., and Sigworth, F. J. (1992) The size of the gating charge in wild-type and mutant Shaker potassium channels. Science 255, 1712-1715.