Excitatory Connections Between CA1 Pyramidal Cells Revealed by Spike Triggered Averaging in Slices of Rat Hippocampus are Partially NMDA Receptor Mediated.

Thomson, A.M. and Radpour, S. (1991) Excitatory Connections Between CA1 Pyramidal Cells Revealed by Spike Triggered Averaging in Slices of Rat Hippocampus are Partially NMDA Receptor Mediated. European Journal of Neuroscience, 3 (6). pp. 587-601. 10.1111/j.1460-9568.1991.tb00845.x.

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DOI: 10.1111/j.1460-9568.1991.tb00845.x

Abstract

Spike triggered averaging was used to record local circuit connections between pairs of CA1 pyramidal neurons in isolated slices of rat hippocampus. Of 795 pairs of neurons tested, six were connected. These epsps were only partially blocked by 2-amino-5-phosphonovalerate (AP-5), which decreased the amplitude and half width of the epsp, but did not affect the early rising phase. In contrast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocked all phases of the epsp and combinations of AP-5 and CNQX blocked the epsp almost entirely. These results indicate that these epsps were mediated by both N-methyl-d-aspartate (NMDA) and non-NMDA excitatory amino acid receptors. Moreover, they exhibited a voltage relation typical of neuronal responses to NMDA, increasing in amplitude and duration as the postsynaptic cell was depolarized. These epsps were brief (10 - 90% rise time < 5 ms, width at half amplitude < 20 ms), indicating a proximal location. Increasing presynaptic firing rate (1 - 4 spikes/s) reduced average epsp amplitude by almost 50%. When epsps were evoked by pairs of spikes (interval 3 - 25 ms), a large response to the first spike precluded a large response to the second. No evidence for selective enhancement of the NMDA receptor component by paired spike activation was found. It is concluded that a significant NMDA receptor mediated input to CA1 is provided by local circuit CA1 - CA1 connections and that these synapses can be demonstrated under control conditions.

Item Type:Article
Uncontrolled Keywords:LTP (long-term potentiation);excitatory amino acids;epsp (excitatory postsynaptic potential);ipsp (inhibitory postsynaptic potential)
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:2662
Journal or Publication Title:European Journal of Neuroscience
Deposited By:Library Staff
Deposited On:13 Jan 2012 16:26
Last Modified:13 Jan 2012 16:27

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