HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 95/6/3645    most recent 00040.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Colom, L. V. Articles by Garrido-Sanabria, E. R. Search for Related Content PubMed PubMed Citation Articles by Colom, L. V. Articles by Garrido-Sanabria, E. R.

Septo-Hippocampal Networks in Chronically Epileptic Rats: Potential Antiepileptic Effects of Theta Rhythm Generation

Department of Biological Sciences and Center for Biomedical Studies, The University of Texas at Brownsville/Texas Southmost College, Brownsville, Texas

Submitted 12 January 2006; accepted in final form 7 March 2006

A series of experiments was carried out testing the hypothesis that the septal region decreases the hippocampal susceptibility to hyperexcitability states through theta rhythm generation. Medial septal neurons were simultaneously recorded with hippocampal field potentials to investigate the septo-hippocampal function in the pilocarpine model of chronic epilepsy. The theta rhythm from chronically epileptic rats had lower amplitude (20% less) and higher frequency than controls (from 3.38 to 4.25 Hz), suggesting that both generator and pacemaker structures are affected during the epileptic process. At the cellular level, the group of rhythmically bursting firing medial septal neurons, in the epileptic animals, significantly and chronically increased their firing rates in relation to controls (from 13.86 to 29.14 spikes/s). Peristimulus histograms performed around hippocampal sharp waves showed that all high-frequency firing neurons, including rhythmically bursting neurons and most slow firing neurons, decreased firing rates immediately after hippocampal epileptic discharges. Thus inhibitory hippocampo-septal influences prevail during hippocampal epileptic discharges. The occurrence of epileptic discharges was reduced 86–97% of the number observed during spontaneous theta and theta induced by sensory (tail pinch) or chemical stimulation (carbachol), suggesting that the presence of the theta state regardless of how it was produced was responsible for the reduction in epileptic discharge frequency. The understanding of the theta rhythm "anti-epileptic" effect at the cellular and molecular levels may result in novel therapeutic approaches dedicated to protect the brain against abnormal excitability states.

This article has been cited by other articles:

				D. J. Englot, A. M. Mishra, P. K. Mansuripur, P. Herman, F. Hyder, and H. Blumenfeld Remote Effects of Focal Hippocampal Seizures on the Rat Neocortex J. Neurosci., September 3, 2008; 28(36): 9066 - 9081. [Abstract] [Full Text] [PDF]