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Jeremy G. Turner

Bio: Jeremy G. Turner is an academic researcher from Illinois College. The author has contributed to research in topics: Tinnitus & Auditory cortex. The author has an hindex of 27, co-authored 39 publications receiving 3131 citations. Previous affiliations of Jeremy G. Turner include Northern Illinois University & Southern Illinois University Carbondale.

Papers
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Journal ArticleDOI
TL;DR: Findings of age-related inhibitory changes within mammalian auditory circuits are similar to age and deafferentation plasticity changes observed in other sensory systems.
Abstract: 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 GABA A (GABA A R) 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 GABA A R changes in IC and primary auditory cortex (A1) involve changes in the subunit makeup of GABA A Rs. 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 animal9s ability to avoid predation or to be a successful predator in their natural environment.

415 citations

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TL;DR: It is suggested that gap detection reflex procedures might be effective for rapid tinnitus screening in rats when the gap was embedded in a background similar to their tinnitis.
Abstract: The study describes a novel method for tinnitus screening in rats by use of gap detection reflex procedures. The authors hypothesized that if a background acoustic signal was qualitatively similar to the rat's tinnitus, poorer detection of a silent gap in the background would be expected. Rats with prior evidence of tinnitus at 10 kHz (n = 14) exhibited significantly worse gap detection than controls (n = 13) when the gap was embedded in a background similar to their tinnitus. No differences between tinnitus and control rats were found with 16 kHz or broadband noise backgrounds, which helped to rule out explanations related to hearing loss or general performance deficits. The results suggest that gap detection reflex procedures might be effective for rapid tinnitus screening in rats.

343 citations

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TL;DR: Preliminary physiology data suggest that salicylate induced tinnitus is associated with sound evoked hyperactivity in auditory cortex and spontaneous hypoactivity.

230 citations

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TL;DR: It was concluded that cochlear trauma in general, rather than its specific features, leads to multiple changes in central activity that underpin tinnitus, particularly affected was a subpopulation ensemble of IC neurons with the described unique triad of features.
Abstract: A longstanding hypothesis is that tinnitus, the perception of sound without an external acoustic source, is triggered by a distinctive pattern of cochlear hair cell (HC) damage and that this subsequently leads to altered neural activity in the central auditory pathway. This hypothesis was tested by assessing behavioral evidence of tinnitus and spontaneous neural activity in the inferior colliculus (IC) after unilateral cochlear trauma. Chinchillas were assigned to four cochlear treatment groups. Each treatment produced a distinctive pattern of HC damage, as follows: acoustic exposure (AEx): sparse low-frequency inner hair cell (IHC) and outer hair cell (OHC) loss; round window cisplatin (CisEx): pronounced OHC loss mixed with some IHC loss; round window carboplatin (CarbEx): pronounced IHC loss without OHC loss; control: no loss. Compared with controls, all experimental groups displayed significant and similar psychophysical evidence of tinnitus with features resembling a 1-kHz tone. Contralateral IC spontaneous activity was elevated in the AEx and CisEx groups, which showed increased spiking and increased cross-fiber synchrony. A multidimensional analysis identified a subpopulation of neurons more prevalent in animals with tinnitus. These units were characterized by high bursting, low ISI variance, and within-burst peak spiking of approximately 1,000/sec. It was concluded that cochlear trauma in general, rather than its specific features, leads to multiple changes in central activity that underpin tinnitus. Particularly affected was a subpopulation ensemble of IC neurons with the described unique triad of features.

221 citations

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TL;DR: These findings indicate that auditory circuits in mice with behavioral evidence of tinnitus respond to stimuli in a more robust and spatially distributed manner because of a decrease in GABAergic inhibition.
Abstract: Tinnitus has been associated with increased spontaneous and evoked activity, increased neural synchrony, and reorganization of tonotopic maps of auditory nuclei. However, the neurotransmitter systems mediating these changes are poorly understood. Here, we developed an in vitro assay that allows us to evaluate the roles of excitation and inhibition in determining the neural correlates of tinnitus. To measure the magnitude and spatial spread of evoked circuit activity, we used flavoprotein autofluorescence (FA) imaging, a metabolic indicator of neuronal activity. We measured FA responses after electrical stimulation of glutamatergic axons in slices containing the dorsal cochlear nucleus, an auditory brainstem nucleus hypothesized to be crucial in the triggering and modulation of tinnitus. FA imaging in dorsal cochlear nucleus brain slices from mice with behavioral evidence of tinnitus (tinnitus mice) revealed enhanced evoked FA response at the site of stimulation and enhanced spatial propagation of FA response to surrounding sites. Blockers of GABAergic inhibition enhanced FA response to a greater extent in control mice than in tinnitus mice. Blockers of excitation decreased FA response to a similar extent in tinnitus and control mice. These findings indicate that auditory circuits in mice with behavioral evidence of tinnitus respond to stimuli in a more robust and spatially distributed manner because of a decrease in GABAergic inhibition.

208 citations


Cited by
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Journal ArticleDOI
TL;DR: Data will be reviewed using the acoustic startle reflex in rats and humans based on attempts to operationally define fear vs anxiety, finding that symptoms of clinical anxiety are better detected in sustained rather than phasic fear paradigms.

1,249 citations

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TL;DR: The results of this work suggest that patterns of transcription regulation represent the molecular signatures of long-term synaptic changes and memory formation.
Abstract: Transcription is a molecular requisite for long-term synaptic plasticity and long-term memory formation. Thus, in the last several years, one main interest of molecular neuroscience has been the identification of families of transcription factors that are involved in both of these processes. Transcription is a highly regulated process that involves the combined interaction and function of chromatin and many other proteins, some of which are essential for the basal process of transcription, while others control the selective activation or repression of specific genes. These regulated interactions ultimately allow a sophisticated response to multiple environmental conditions, as well as control of spatial and temporal differences in gene expression. Evidence based on correlative changes in expression, genetic mutations, and targeted molecular inhibition of gene expression have shed light on the function of transcription in both synaptic plasticity and memory formation. This review provides a brief overview ...

902 citations

Journal ArticleDOI
TL;DR: This review will discuss recent literature on Nox protein tissue distribution, subcellular localization, activation, and the resulting signal transduction mechanisms.

757 citations

Journal ArticleDOI
24 Jun 2010-Neuron
TL;DR: A testable model for tinnitus is proposed that is grounded in recent findings from human imaging and focuses on brain areas in cortex, thalamus, and ventral striatum and aims to enable the development of effective treatment.

607 citations

Journal ArticleDOI
12 Nov 2009-Neuron
TL;DR: The similarity of sparseness patterns for both neural events and distinct spread of activity may reflect similarity of local processing and differences in the flow of information through cortical circuits, respectively.

580 citations