Input–Output Functions of Vestibular Afferent Responses to Air-Conducted Clicks in Rats
| Autor: | Jerome Allison, Adel Maklad, Steve Highstein, Wu Zhou, Xuehui Tang, Wei Wei, Hong Zhu, Richard D. Rabbitt, William Mustain |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Action Potentials Otolithic membrane Audiology Extraocular muscles Rats Sprague-Dawley Otolithic Membrane medicine otorhinolaryngologic diseases Reaction Time Animals Neurons Afferent Otolith Vestibular system Semicircular canal business.industry Anatomy Sensory Systems Semicircular Canals Rats medicine.anatomical_structure Sound Otorhinolaryngology Acoustic Stimulation Vestibule Models Animal Brainstem Saccule sense organs Vestibule Labyrinth business Research Article |
| Popis: | Sound-evoked vestibular myogenic potentials recorded from the sternocleidomastoid muscles (the cervical vestibular-evoked myogenic potential or cVEMP) and the extraocular muscles (the ocular VEMP or oVEMP) have proven useful in clinical assessment of vestibular function. VEMPs are commonly interpreted as a test of saccular function, based on neurophysiological evidence showing activation of saccular afferents by intense acoustic click stimuli. However, recent neurophysiological studies suggest that the clicks used in clinical VEMP tests activate vestibular end organs other than the saccule. To provide the neural basis for interpreting clinical VEMP testing results, the present study examined the extent to which air-conducted clicks differentially activate the various vestibular end organs at several intensities and durations in Sprague–Dawley rats. Single unit recordings were made from 562 vestibular afferents that innervated the otoliths [inferior branch otolith (IO) and superior branch otolith (SO)], the anterior canal (AC), the horizontal canal (HC), and the posterior canal (PC). Clicks higher than 60 dB SL (re-auditory brainstem response threshold) activated both semicircular canal and otolith organ afferents. Clicks at or below 60 dB SL, however, activated only otolith organ afferents. Longer duration clicks evoked larger responses in AC, HC, and SO afferents, but not in IO afferents. Intra-axonal recording and labeling confirmed that sound sensitive vestibular afferents innervated the horizontal and anterior canal cristae as well as the saccular and utricular maculae. Interestingly, all sound sensitive afferents are calyx-bearing fibers. These results demonstrate stimulus-dependent acoustic activation of both semicircular canals and otolith organs, and suggest that sound activation of vestibular end organs other than the saccule should not be ruled out when designing and interpreting clinical VEMP tests. |
| Databáze: | OpenAIRE |
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