Each myelinated type I afferent synapses with one inner hair cell (IHC) and each IHC is contacted by 10–30 unbranched type I afferent dendrites ( Liberman, 1982). The two types of SGNs differ not only in proportion but also in innervation pattern as illustrated in Figure 1 H, I. Type I afferents constitute 90–95% of all SGNs, with type II afferents making up the remaining 5% ( Perkins and Morest, 1975 Berglund and Ryugo, 1987). The spiral ganglion neurons (SGNs) of the cochlea are divided into type I afferents that sensitively encode sound intensity, timing, and frequency, and type II afferents that respond only to loud, broadband sound ( Robertson, 1984 Brown, 1994 Robertson et al., 1999 Flores et al., 2015 Weisz et al., 2021). Overall, calcium imaging can report type II afferent responses to damage even in mature and noise-exposed animals and reveals previously unknown tissue hyperactivity subsequent to acoustic trauma. In addition, days after acoustic trauma, acute photoablation triggered a novel response pattern in type II afferents and surrounding epithelial cells, delayed bursts of activity occurring minutes after the initial response subsided. Mature type II afferents responded to acute photoablation damage less often but at greater length compared with prehearing neurons. Two known marker genes ( Th, Drd2) and one new marker gene ( Tac1), expressed in type II afferents and some other cochlear cell types, drove GCaMP6f expression to reveal calcium transients in response to focal damage in the organ of Corti in all turns of the cochlea. To explore this hypothesis further, calcium imaging was used to determine the impact of acoustic trauma on the activity of type II cochlear afferents of young adult mice of both sexes. Altogether, these lines of evidence suggest that type II afferents sense loud, potentially damaging levels of sound. Limited recordings of type II afferents from cochlear apex of prehearing rats reveal they are activated by widespread outer hair cell stimulation, ATP, and by the rupture of nearby outer hair cells. While type I afferents convey information about the frequency, intensity, and timing of sounds, the role of type II afferents remains unresolved. 1864, Kentucky.Auditory stimuli travel from the cochlea to the brainstem through type I and type II cochlear afferents. 1843, Kentucky.Ĭhildren of DELILAH BOYD and MORGAN JARRELL are: vii. More About MORGAN JARRELL and DELILAH BOYD:Ĭhildren of DELILAH BOYD and NATHANIEL WOODS are:ģ9. Marriage: August 31, 1836, Franklin County, Virginia More About NATHANIEL WOODS and DELILAH BOYD: He was born 1826, and died in Floyd County, Ky. She married (2) MORGAN JARRELL 1851 in Floyd County, Kentucky. He was born 1812 in Virginia, and died 1848 in Floyd County, Ky. She married (1) NATHANIEL "NATHAN" WOODS Augin Franklin County, Virginia, son of HENRY WOODS and FRANCIS UNKNOWN. DELILAH "LILA"4 BOYD (WILLIAM "BILLY"3, JAMES2, WILLIAM1) was born 1826 in Patrick County, Virginia, and died Aft. Nathaniel Woods died circa 1848 at Floyd County, Kentucky.Ĭhildren of Nathaniel Woods and Delilah Boydġ6. Nathaniel Woods married Delilah Boyd, daughter of William Boyd and Nancy Read, on 31 August 1836 at Franklin County, Virginia. He was the son of Henry Woods and Frances ?. Nathaniel Woods was born in 1819 at Patrick County, Virginia. Nathaniel Woods died circa 1848 at Floyd County, Kentucky. He was the son of Henry Woods and Frances ? Nathaniel Woods married Delilah Boyd, daughter of William Boyd and Nancy Read, on 31 August 1836 at Franklin County, Virginia.
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