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Published April 1996 | public
Journal Article

Induction of a Calcium-dependent Long-term Enhancement of Excitability in the Rat Olfactory Bulb

Abstract

We have investigated whether a transient increase in extracellular calcium concentration is able to induce long-term modification of neuronal excitability in the olfactory bulb. High-calcium artificial cerebrospinal fluid containing picrotoxin (Ca-PTX solution) was applied locally near the mitral cell layer through a push-pull device for 10 min in anaesthetized rats. Changes in the neuronal excitability were monitored through electrically-evoked field potentials. Application of the Ca-PTX solution induced a rapid increase in the granule cell response amplitude, whereas mitral/tufted cells response amplitude increased more progressively and reached its maximum within a few hours. The increase in mitral/tufted cells response and granule cells response reached between 30 and 100% in experiments which lasted for 4–8 h. Pre-application of amino-phosphonovalerate (NMDA receptor blocker) potently reduced both short- and long-term enhancement produced by the Ca-PTX solution. Neither application of the high calcium solution alone nor the picrotoxin solution alone induced long-term changes. The results point out the possible importance of Ca^(2+) and NMDA receptors in persistent forms of olfactory bulb plasticity. Relevance of this phenomenon in normal olfactory bulb physiology remains to be examined.

Additional Information

© 1996 Oxford University Press. Received on March 30, 1995; accepted on January 5, 1996. The authors thank Pascal Chabaud and Philippe Litaudon for their help in the preparation of illustrations and an anonymous referee for his constructive suggestions.

Additional details

Created:
August 20, 2023
Modified:
October 24, 2023