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Title:Dynamic Modulation of an Immediate -Early Gene in the Songbird Forebrain
Author(s):Kruse, Amy Ann
Doctoral Committee Chair(s):Clayton, David F.
Department / Program:Neuroscience
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Neuroscience
Abstract:In the nervous system, immediate-early gene (IEG) induction is observed following exposure to salient events. Although the function of IEGs is not fully understood, one prominent model suggests that they are needed to consolidate memories of the inducing event---a "feed-back" model. However, a new "feed-forward" model suggests that IEG induction may serve to facilitate consolidation of experiences that come after the inducing event. These competing theories, and other related questions, were tested using the zebra finch (Taeniopygia guttata). In this model system, thirty minutes of novel song playback induces the IEG zenk in regions of the auditory forebrain (caudomedial neostriatum (NCM) and caudomedial hyperstriatum ventrale (CMHV)). Three hours of playback leads to the stimulus-specific habituation of this gene response. Here I show that a brief stimulus (1.5 minutes of song) was sufficient to induce zenk mRNA and protein, but still could not habituate the zenk response, arguing against the "feed-back" model. Additional testing revealed that this brief stimulus could fully and selectively habituate the zenk response if it was presented one hour after the gene had been induced by another song, thus supporting the new, "feed-forward" model of IEG function. This ability to facilitate memory formation of later, distinct events raised questions about what other kinds of factors could modulate zenk expression in NCM/CMHV. To answer this I first tested whether or not familiar songs could induce zenk when presented in a novel context. Changing the speaker or reducing the volume of song playback both caused induction, as did presentation of a novel light stimulus that was synchronized to each song presentation. Next, I explored the influence of the listener's social identity by examining zenk expression in the female NCM/CMHV. When compared to data collected from male zebra finches, this new data revealed an enhanced basal expression in females (but no difference in induced levels). These results are reminiscent of the elevated basal levels seen in juveniles of both sexes. Collectively the data presented in this thesis suggest the hypothesis that zenk expression levels in NCM/CMHV reflect the animal's attention to the auditory scene.
Issue Date:2001
Description:176 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.
Other Identifier(s):(MiAaPQ)AAI3017132
Date Available in IDEALS:2015-09-25
Date Deposited:2001

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