Talk:Hearing - Neural Pathway
|About Discussion Pages|
Cite this page: Hill, M.A. (2019, July 24) Embryology Hearing - Neural Pathway. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Hearing_-_Neural_Pathway
Effects of transient auditory deprivation during critical periods on the development of auditory temporal processing
Int J Pediatr Otorhinolaryngol. 2018 Jan;104:66-71. doi: 10.1016/j.ijporl.2017.10.045. Epub 2017 Nov 7.
Kim BJ1, Kim J2, Park IY3, Jung JY4, Suh MW5, Oh SH6.
OBJECTIVES: The central auditory pathway matures through sensory experiences and it is known that sensory experiences during periods called critical periods exert an important influence on brain development. The present study aimed to investigate whether temporary auditory deprivation during critical periods (CPs) could have a detrimental effect on the development of auditory temporal processing. MATERIALS AND METHODS: Twelve neonatal rats were randomly assigned to control and study groups; Study group experienced temporary (18-20 days) auditory deprivation during CPs (Early deprivation study group). Outcome measures included changes in auditory brainstem response (ABR), gap prepulse inhibition of the acoustic startle reflex (GPIAS), and gap detection threshold (GDT). To further delineate the specific role of CPs in the outcome measures above, the same paradigm was applied in adult rats (Late deprivation group) and the findings were compared with those of the neonatal rats. RESULTS: Soon after the restoration of hearing, early deprivation study animals showed a significantly lower GPIAS at intermediate gap durations and a larger GDT than early deprivation controls, but these differences became insignificant after subsequent auditory inputs. Additionally, the ABR results showed significantly delayed latencies of waves IV, V, and interpeak latencies of wave I-III and wave I-V in study group. Late deprivation group didn't exhibit any deterioration in temporal processing following sensory deprivation. CONCLUSION: Taken together, the present results suggest that transient auditory deprivation during CPs might cause reversible disruptions in the development of temporal processing. Copyright © 2017 Elsevier B.V. All rights reserved. KEYWORDS: Critical period; Gap detection; Otitis media; Startle reflex; Temporal processing; Transient auditory deprivation
PMID: 29287884 DOI: 10.1016/j.ijporl.2017.10.045
The precise temporal pattern of prehearing spontaneous activity is necessary for tonotopic map refinement
Neuron. 2014 May 21;82(4):822-35. doi: 10.1016/j.neuron.2014.04.001.
Clause A1, Kim G2, Sonntag M3, Weisz CJ4, Vetter DE5, Rűbsamen R3, Kandler K6.
Patterned spontaneous activity is a hallmark of developing sensory systems. In the auditory system, rhythmic bursts of spontaneous activity are generated in cochlear hair cells and propagated along central auditory pathways. The role of these activity patterns in the development of central auditory circuits has remained speculative. Here we demonstrate that blocking efferent cholinergic neurotransmission to developing hair cells in mice that lack the α9 subunit of nicotinic acetylcholine receptors (α9 KO mice) altered the temporal fine structure of spontaneous activity without changing activity levels. KO mice showed a severe impairment in the functional and structural sharpening of an inhibitory tonotopic map, as evidenced by deficits in synaptic strengthening and silencing of connections and an absence in axonal pruning. These results provide evidence that the precise temporal pattern of spontaneous activity before hearing onset is crucial for the establishment of precise tonotopy, the major organizing principle of central auditory pathways. Copyright © 2014 Elsevier Inc. All rights reserved.
Formation and maturation of the calyx of Held
Hear Res. 2011 Jun;276(1-2):70-8. doi: 10.1016/j.heares.2010.11.004. Epub 2010 Nov 18.
Nakamura PA1, Cramer KS.
Sound localization requires precise and specialized neural circuitry. A prominent and well-studied specialization is found in the mammalian auditory brainstem. Globular bushy cells of the ventral cochlear nucleus (VCN) project contralaterally to neurons of the medial nucleus of the trapezoid body (MNTB), where their large axons terminate on cell bodies of MNTB principal neurons, forming the calyces of Held. The VCN-MNTB pathway is necessary for the accurate computation of interaural intensity and time differences; MNTB neurons provide inhibitory input to the lateral superior olive, which compares levels of excitation from the ipsilateral ear to levels of tonotopically matched inhibition from the contralateral ear, and to the medial superior olive, where precise inhibition from MNTB neurons tunes the delays of binaural excitation. Here we review the morphological and physiological aspects of the development of the VCN-MNTB pathway and its calyceal termination, along with potential mechanisms that give rise to its precision. During embryonic development, VCN axons grow towards the midline, cross the midline into the region of the presumptive MNTB and then form collateral branches that will terminate in calyces of Held. In rodents, immature calyces of Held appear in MNTB during the first few days of postnatal life. These calyces mature morphologically and physiologically over the next three postnatal weeks, enabling fast, high fidelity transmission in the VCN-MNTB pathway. Copyright © 2010 Elsevier B.V. All rights reserved.
Tonotopic reorganization of developing auditory brainstem circuits
Nat Neurosci. 2009 Jun;12(6):711-7. doi: 10.1038/nn.2332. Epub 2009 May 10.
Kandler K1, Clause A, Noh J.
A fundamental organizing principle of auditory brain circuits is tonotopy, the orderly representation of the sound frequency to which neurons are most sensitive. Tonotopy arises from the coding of frequency along the cochlea and the topographic organization of auditory pathways. The mechanisms that underlie the establishment of tonotopy are poorly understood. In auditory brainstem pathways, topographic precision is present at very early stages in development, which may suggest that synaptic reorganization contributes little to the construction of precise tonotopic maps. Accumulating evidence from several brainstem nuclei, however, is now changing this view by demonstrating that developing auditory brainstem circuits undergo a marked degree of refinement on both a subcellular and circuit level. PMID 19471270