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Neural Plasticity
Volume 2012, Article ID 931780, 7 pages
http://dx.doi.org/10.1155/2012/931780
Research Article

The Gain Modulation by N-methyl-D-aspartate in the Projection Neurons of Robust Nucleus of the Arcopallium in Adult Zebra Finches

1Key Laboratory of Ecology and Environmental Science in Higher Education of Guangdong Province, School of Life Sciences, South China Normal University, Guangzhou 510631, China
2School of Education, Shaoguan University, Shaoguan 512000, China

Received 19 December 2011; Revised 6 March 2012; Accepted 6 March 2012

Academic Editor: Małgorzata Kossut

Copyright © 2012 Su-Qun Liao et al. 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.

Abstract

The song of zebra finch is stable in life after it was learned successfully. Vocal plasticity is thought to be a motor exploration that can support continuous learning and optimization of performance. The activity of RA, an important pre-motor nucleus in songbird’s brain, influences the song directly. This variability in adult birdsong is associated with the activity of NMDA receptors in LMAN-RA synapses, but the detailed mechanism is unclear. The control of gain refers to modulation of a neuron's responsiveness to input and is critically important for normal sensory, cognitive, and motor functions. Here, we observed the change of gain in RA projection neurons after exogenous NMDA was applied to activate NMDA receptors using the whole-cell current clamp recording. We found that NMDA substantially increased the slope (gain) of the firing rate-current relationship in RA projection neurons. The AMPA receptor-dependent excitability played a crucial role in the modulation of gain by NMDA. These results suggested that NMDA receptors may regulate the dynamics of RA projection neurons by input-output gain.