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Neural Plasticity
Volume 2013, Article ID 565167, 6 pages
Research Article

Stimulation of Perforant Path Fibers Induces LTP Concurrently in Amygdala and Hippocampus in Awake Freely Behaving Rats

1Neuroscience Program, Trinity College, 300 Summit Street, Hartford, CT 06106, USA
2Department of Engineering, Trinity College, 300 Summit Street, Hartford, CT 06106, USA

Received 21 August 2012; Revised 21 December 2012; Accepted 22 December 2012

Academic Editor: Michael Stewart

Copyright © 2013 J. Harry Blaise and Rachel A. Hartman. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Long-term potentiation (LTP) which has long been considered a cellular model for learning and memory is defined as a lasting enhancement in synaptic transmission efficacy. This cellular mechanism has been demonstrated reliably in the hippocampus and the amygdala—two limbic structures implicated in learning and memory. Earlier studies reported on the ability of cortical stimulation of the entorhinal cortex to induce LTP simultaneously in the two sites. However, to retain a stable baseline of comparison with the majority of the LTP literature, it is important to investigate the ability of fiber stimulation such as perforant path activation to induce LTP concurrently in both structures. Therefore, in this paper we report on concurrent LTP in the basolateral amygdala (BLA) and the dentate gyrus (DG) subfield of the hippocampus induced by theta burst stimulation of perforant path fibers in freely behaving Sprague-Dawley rats. Our results indicate that while perforant path-evoked potentials in both sites exhibit similar triphasic waveforms, the latency and amplitude of BLA responses were significantly shorter and smaller than those of DG. In addition, we observed no significant differences in either the peak level or the duration of LTP between DG and BLA.