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Category :
Languages : en
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Text (Electronic thesis) in PDF format.

Author: Lisa Tanner
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Category : Auditory pathways
Languages : en
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ABSTRACT: The prepulse inhibition (PPI) of mice exposed to the AAE was compared to that of non-exposed mice to observe short-term and long-term effects. Results showed that the prepulse inhibition of the AAE exposed mice did not differ significantly from that of the non-exposed mice. However, it is possible that the measurement used, PPI, may not have been appropriate or that the AAE may not have been an appropriate simulation of the NICU environment.

Author:
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Category :
Languages : en
Pages : 43

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The acoustic startle reflex (ASR) is an automated motor response to an unexpected and intense auditory stimulus (Ouagazzal, Reiss, & Romand, 2006). When an audible 'prepulse' stimulus is presented before the intense, startle-evoking stimulus (SES); the startle reflex response is reduced and this is known as prepulse inhibition (PPI). The degree of ASR inhibition serves as a measure of the behavioral salience of the prepulse (Carlson & Willott, 1996). This study aimed to obtain a psychometric function from the amount of PPI of the ASR that resulted from varying intensity levels of a prepulse stimulus (PPS). Twelve mice were used for this study and each was tested twice. Six of the mice were of the C57BL/6J background (a common strain often used as a control) and six were wild-type offspring of mice that had a mutation of the ephrin (EphA4) gene (labeled as EphA4+/+wt and were expected to be normal aside from possible early rearing effects from their mutant parents. An accelerometer measured amount of movement associated with the SES with and without the PPS. The PPS randomly varied between 13 different intensities in the range of 25 dB SPL to 75 dB SPL. In addition, there were two control trials of the SES with a PPS of 0 dB SPL and one random trial with no sound at all. Therefore, there were a total of 16 trials which were presented randomly in each of 11 blocks. For each test session, the PPS randomly varied by frequency filter; high-pass (HP) or band-pass (BP). The SES was presented at an intensity of 120 dB SPL for a duration of 15 ms and medium inter-stimulus interval (ISI) of 50 ms was used for all trials. A psychometric function was successfully obtained. There was no significant difference between the twostrains of mice (p=0.15) so data between the groups was pooled. A significant effect (p=0.04) of frequency filter was seen as more PPI was obtained with the HP vs. BP filter. The obtained threshold ranged from 19 dB SPL to 45.8 dB SPL depending on how threshold was defined.

Author: Jeremy D. Bailoo
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ISBN:
Category : Developmental psychobiology
Languages : en
Pages : 104

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"Pre-pulse inhibition (PPI) is a tool that may be used to identify how early life stress can result in a deficient adult nervous system (as represented by a deficit in sensorimotor gating). Since both animals and humans demonstrate a PPI, animal research on PPI can be used to model the relation of the early social environment to later susceptibility to maladaptive adult behavioral phenotypes. The current study examined the effect on adult PPI of early life stress in C57BL/6 offspring reared under four social conditions: Animal-Facility Reared (Control), Early Handling (EH, daily 15 min separation), Maternal Separation (MS, daily 4 hr. separation from dam) and Maternal Peer Separation (MPS, daily 4 hr. separation from dam and of littermates); and two post weaning housing conditions: Socially Housed (SH, 2-3 individuals/cage) and Social Isolation (IH, 1 individual/cage). Four different PPI types; 0, 76, 80, or 84 dB; each 20ms duration, and a startle stimulus of 120 dB, 40ms duration, were presented and the percentage reduction of the startle response that occurred with a prepulse in comparison to the startle response that occurred without a prepulse (i.e., 0 dB prepulse) was calculated. The results indicated that EH subjects displayed lower levels of PPI and ASR than AFR, MS & MPS offspring. The post weaning manipulation did not affect display of PPI or the ASR. Consistent with the human and animal literature, male mice displayed a greater ASR and PPI of the ASR than females."--Abstract from author supplied metadata.

Author: Jane Elizabeth Sutherland
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ISBN:
Category :
Languages : en
Pages : 416

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Category :
Languages : en
Pages : 16

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The purpose of my Honors Research Project was to assist Dr. Megan Klingenberg in completing part of the research in her final dissertation project. Dr. Klingenberg’s project was based off of a study done by Allen and Ison in 2010. This study tested the auditory spatial acuity of mice using pre-pulse inhibition of the startle reflex as the response for detecting the sound stimulus. The goal of Dr. Klingenberg’s AuD project was “to explore the methodological, functional, and genetic influences on sound localization using pre-pulse inhibition of the acoustic startle response in mice”. Dr. Klingenberg’s project was broken into three sections: the effect of the test chamber on acoustic startle responses, the effect that the EphA4 mutation would have on the mouse’s ability to localize sound, and the ability to use the acoustic startle response (ASR) to study efferent processing. My role in the research was to work on the first goal of the project in finding a chamber that would accurately reproduce Allen and Ison’s findings. In this reflection, I will describe the basic terms used in the experiment, the importance and benefits of working with mice in a research setting, the general procedure of the experiment, the results from the various chambers, and a brief description of my experience in the lab.

Author:
Publisher:
ISBN:
Category : Audiology
Languages : en
Pages : 34

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The acoustic startle response (ASR) is a reliable reflexive behavioral response in mammals elicited by an unexpected intense acoustic startle eliciting stimulus (SES). It is mediated by a sub-cortical pathway that includes the inferior colliculus (IC). The ASR amplitude can be measured with an accelerometer beneath the subject attached to the cage, and can be decreased in amplitude by presenting a less intense, non-startling stimulus 20-300 ms before the SES. This reflexive decrement in ASR is called pre pulse inhibition (PPI) and indicates that the relatively soft pre pulse was heard. Murine species have been used to study this response for psychoacoustical estimates of hearing thresholds and to understand the effects of genetic mutations on the ASR, PPI and the afferent auditory neural pathway. The Eph/ephrin signaling pathway is known to be important in directing developing auditory afferents, including connections to various subdivisions of the IC. In this experiment, we measured the effect of Eph/ephrin mutations on PPI in mice with a control strain (C57BL/6J), a strain with compromised EphA4 signaling (EphA4lacZ), and a knockout ephrin-B3 strain (ephrin-B3null). The control strain and EphA4lacZ strain showed robust PPI (up to 75% decrement in ASR) to an offset of a 70dB SPLrms background noise at 50ms before the SES. Ephrin-B3 knockout mice were only marginally significant in PPI (

Author:
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Category :
Languages : en
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Sound localization is an important aspect of normal hearing. The Eph/ephin family of signaling proteins, studied here, is known to guide the formation of central auditory connections in early development, particularly topographic inputs from the lateral superior olive (LSO) to the inferior colliculus (IC). Processing in the LSO and its influences on the IC are known to be heavily involved in sound localization tasks. One way to study sound localization in mice is through pre-pulse inhibition (PPI). PPI is the phenomenon by which a weak prestimulus inhibits the response to a subsequent startle stimulus. In studying sound localization, the prestimulus here is a soft, ongoing sound that switches between two speakers 180 degrees apart. If the mouse hears a change in location, the acoustic startle response will decrease. Here we report three important considerations with this PPI speaker swap procedure. First, we show that the cage in which the mouse is tested is critically important. Depending on the testing chamber, we observed 17%, 33% and 100% of responsiveness noted in previously published studies. Second, homozygous but not heterozygous EphA4 mutations appear to affect sound localization. Finally, there appears to be subtle differences in startle responses for different mouse strains, with altered responses in both heterozygous and homozygous EphA4 mutants as compared with C57BL/6J controls. The connection between genetic effects on both afferent and efferent responsiveness may provide an experimental link between audiology and speech pathology, and thereby may serve as an animal model of altered central pattern generators.

Author: Jennifer R. O'Steen
Publisher:
ISBN:
Category : Auditory pathways
Languages : en
Pages :

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ABSTRACT: In addition to genetic influences, peripheral hearing loss and central auditory processing factors must be taken into consideration.

Author: Michael Douglas Gedestad
Publisher:
ISBN: 9781267758897
Category :
Languages : en
Pages :

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Dietary copper deficiency is known to have severe effects on the central nervous system of developing mammals, and the deleterious effects of this insult are particularly striking when the deficiency occurs prenatally. Numerous studies have targeted copper's role in central nervous system development with respect to both dietary copper deficiency and copper deficiency induced by genetic diseases. In this study we tested whether perinatal copper deficiency in mice results in sensorineural hearing loss. Data from our study will add to a rapidly growing body of literature highlighting the crucial role of copper during prenatal and early postnatal development. Dietary copper deficiency (Cu Def) was induced in pregnant C57Bl6 mouse dams beginning at gestational day (GD) 18. Pups born to Cu Def dams displayed characteristic biochemical signs of hepatic and plasma copper deficiency at postnatal day (PND) 30, at which point they underwent prepulse inhibition (PPI) to acoustic startle testing and auditory brainstem response (ABR) testing. A 30-day copper repletion was then conducted on Cu Def pups to observe the effects that repletion had by PND 60. Results showed no significant differences in ABR thresholds between diet groups at either time point. Cu Def offspring tended to show lower response to the acoustic prepulse stimulus trials at PND 30 compared to Cu adequate (Cu Ad) offspring, however the results were marginally insignificant. When previously Cu deficient offspring were repleted with Cu for 1 month, acoustic startle response was similar between the Cu Ad and copper repleted mice at PND 60. This study addresses the importance of the timing of copper deficiency on prenatal development, and sets the stage for future research to investigate how dietary deficiencies affect the auditory and cognitive processing pathways.