spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online May 19, 2008
Journal of Experimental Biology 211, 1781-1791 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.013581
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Related articles in JEB
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Google Scholar
Right arrow Articles by Caspary, D. M.
Right arrow Articles by Hughes, L. F.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Caspary, D. M.
Right arrow Articles by Hughes, L. F.

Sensory encoding in hearing and balance

Inhibitory neurotransmission, plasticity and aging in the mammalian central auditory system

Donald M. Caspary1,*, Lynne Ling1, Jeremy G. Turner1,2 and Larry F. Hughes1

1 Southern Illinois University School of Medicine, Springfield, IL 62794, USA
2 Illinois College, Jacksonville, IL 62650, USA

* Author for correspondence (e-mail: dcaspary{at}siumed.edu)

Accepted 4 February 2008

Summary

Aging and acoustic trauma may result in partial peripheral deafferentation in the central auditory pathway of the mammalian brain. In accord with homeostatic plasticity, loss of sensory input results in a change in pre- and postsynaptic GABAergic and glycinergic inhibitory neurotransmission. As seen in development, age-related changes may be activity dependent. Age-related presynaptic changes in the cochlear nucleus include reduced glycine levels, while in the auditory midbrain and cortex, GABA synthesis and release are altered. Presumably, in response to age-related decreases in presynaptic release of inhibitory neurotransmitters, there are age-related postsynaptic subunit changes in the composition of the glycine (GlyR) and GABAA (GABAAR) receptors. Age-related changes in the subunit makeup of inhibitory pentameric receptor constructs result in altered pharmacological and physiological responses consistent with a net down-regulation of functional inhibition. Age-related functional changes associated with glycine neurotransmission in dorsal cochlear nucleus (DCN) include altered intensity and temporal coding by DCN projection neurons. Loss of synaptic inhibition in the superior olivary complex (SOC) and the inferior colliculus (IC) likely affect the ability of aged animals to localize sounds in their natural environment. Age-related postsynaptic GABAAR changes in IC and primary auditory cortex (A1) involve changes in the subunit makeup of GABAARs. In turn, these changes cause age-related changes in the pharmacology and response properties of neurons in IC and A1 circuits, which collectively may affect temporal processing and response reliability. Findings of age-related inhibitory changes within mammalian auditory circuits are similar to age and deafferentation plasticity changes observed in other sensory systems. Although few studies have examined sensory aging in the wild, these age-related changes would likely compromise an animal's ability to avoid predation or to be a successful predator in their natural environment.

Key words: aging, central auditory system, GABAA receptor, glycine receptor, inhibitory neurotransmission, plasticity


Related articles in JEB:

NEUROSENSORY ECOLOGY IN THE JEB
Kathryn Phillips
JEB 2008 211: i. [Full Text]  





© The Company of Biologists Ltd 2008