Responses Of Peripheral Vestibular Neurons To Angular And Linear Accelerations In The Squirrel Monkey

Abstract

Peripheral neurons innervating semicircular canals can respond to constant linear accelerations. Evidence is presented that, in our preparation, the response is artifactual and arises from thermal gradients introduced by the surgical exposure. Otolith neurons do not respond to even intense angular accelerations. Canal plugging abolishes the response of the corresponding afferents to angular acceleration, without obviously affecting resting activity. The procedure does not prevent the canals from responding to linear accelerations. The latter response, unlike that seen in intact canals, is not due to thermal gradients and may be related to the mechanisms underlying the persistent component of barbecue nystagmus. Acta OtolaryngolSOActa Otolaryngol Downloaded from informahealthcare.com by Nyu Medical Center on 05/25/15For personal use only. Acta Otolaryngol80Acta Otolaryngol Downloaded from informahealthcare.com by Nyu Medical Center on 05/25/15For personal use only. Acta OtolaryngolSOActa Otolaryngol Downloaded from informahealthcare.com by Nyu Medical Center on 05/25/15For personal use only.

The coding of head orientations in neurons of bilateral vestibular nuclei of cats after unilateral labyrinthectomy: response to off-vertical axis rotation

“…Presumably the utricle on the left side was effectively activated based on the directional sensitivity of its afferents (Fernandez and Goldberg 1976a;Tomko et al 1981). In the 14 HL cats in which the left middle ear (i.e., on the labyrinth-intact side) was surgically exposed to enable implantation of the stimulating electrodes, it should be cautioned that the thermal gradient created across the open ear may to some extent affect the tilt sensitivity of the canal afferents (Goldberg and Fernandez 1975). Nevertheless, it is pertinent to note that the response patterns observed in these cats were not different from those obtained in HL cats in which the left ear was not exposed.…”

Efferent-Mediated Fluctuations in Vestibular Nerve Discharge: A Novel, Positive-Feedback Mechanism of Efferent Control

“…Once an afferent was isolated, a series of manual rotations and tilts were used to determine which organ it innervated (Goldberg and Fernández 1975). As recordings were confined to the superior vestibular nerve, no posterior canal (PC) afferents were encountered.…”

Resting Discharge Patterns of Macular Primary Afferents in Otoconia-Deficient Mice

“…The discharge patterns of macular afferents in the absence of head motion (i.e., resting discharge) have been characterized in detail in mammals (Baird and Lewis 1986;Baird and Schuff 1994;Dickman et al 1991;Fernandez et al 1972Fernandez et al , 1990Fernandez and Goldberg 1976a;Goldberg et al 1990b, a;Goldberg and Fernandez 1975;Loe et al 1973;Tomko et al 1981) and to some extent in birds (Anastasio et al 1985;Jones and Jones 2000;Manley et al 1991;Si et al 1997). However, similar studies have not been completed in the absence of gravity loading of macular systems.…”

“…Evidence supporting this consensus hypothesis includes the observation that spontaneous discharge of neurons is reduced or eliminated by destroying hair cells (Kiang et al 1976;Li and Correia 1998;Muller et al 1997;Salvi et al 1994Salvi et al , 1998 or by otherwise isolating neurons from hair cells in mature (Santos-Sacchi 1993) and neonatal animals (Risner and Holt 2006). Furthermore, uncoupling ambient stimuli fails to block spontaneous activity in some hair cell systems (e.g., plugging canals: Fernandez 1975 andFlock 1967; removing the cupula: Harris and Milne 1965), thus demonstrating an independence from external stimulation.…”