title: Factors Influencing Short-term Synaptic Plasticity in the Avian Cochlear Nucleus Magnocellularis.
abstract: Defined as reduced neural responses during high rates of activity, synaptic depression is a form of short-term plasticity important for the temporal filtering of sound. In the avian cochlear nucleus magnocellularis (NM), an auditory brainstem structure, mechanisms regulating short-term synaptic depression include pre-, post-, and extrasynaptic factors. Using varied paired-pulse stimulus intervals, we found that the time course of synaptic depression lasts up to four seconds at late-developing NM synapses. Synaptic depression was largely reliant on exogenous Ca(2+)-dependent probability of presynaptic neurotransmitter release, and to a lesser extent, on the desensitization of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptor (AMPA-R). Interestingly, although extrasynaptic glutamate clearance did not play a significant role in regulating synaptic depression, blocking glutamate clearance at early-developing synapses altered synaptic dynamics, changing responses from depression to facilitation. These results suggest a developmental shift in the relative reliance on pre-, post-, and extrasynaptic factors in regulating short-term synaptic plasticity in NM.
authors.affiliation: Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University, Evanston, IL, USA. ; Department of Neurobiology and Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA.
authors.forename: Jason Tait
authors.initials: JT
authors.lastname: Sanchez
authors.affiliation: Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University, Evanston, IL, USA.
authors.forename: Karla
authors.initials: K
authors.lastname: Quinones
authors.affiliation: Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL, USA.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Otto-Meyer
keywords: AMPA receptors; desensitization; development; glutamate transporters; nucleus magnocellularis; short-term synaptic depression