Coordination between presynaptic and postsynaptic properties measured at single terminals in hippocampal cultures

I examined the spatial scale at which pre-synaptic activity interacts with synaptic strength and developmental events in the post-synaptic cell. I performed this work in primary hippocampal cultures of postnatal Sprague-Dawley rats after 8-10 days in vitro. I measured electrophysiologically the functional addition of GluR2 and NR2A subunits to AMPA and NMDA receptors, respectively, as well as the absolute strength of AMPA- and NMDA-mediated currents. I examined both spontaneous quantal events and local responses using glutamate iontophoresis at putative single-synaptic sites. I monitored pre-synaptic strength via vesicle staining with FM dyes. I found an inverse correlation between pre-synaptic and post-synaptic strength at individual synapses: Intensity of presynaptic FM-staining was inversely correlated with AMPA current magnitude measured by local iontophoretic stimulation. I also found a negative correlation at individual puncta between FM-staining intensity and decay time of iontophoretically-evoked NMDA decay current. Presumably, this correlation reflects a higher proportion of NR2A subunits at presynaptically more active synapses. I propose that homeostatic feedback mechanisms may operate at a subecellular level to maintain excitatory synaptic input at a single synapse or within a dendritic branch. In order to stimulate individual synaptic sites, I used a novel iontophoresis system, presented here. The system incorporates a 0.1 [mu]m electrode tip for local stimulation, combined with fast capacitance compensation to achieve high-speed application from a high-resistance tip.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Murnick, Jonathan G. (Jonathan George), 1972-

Advisor dc:contributor.advisor

• Guosong Liu.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/87455

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/87455