neurobio 918 ch 11 of Bear's book: the auditory and vestibular systems part 3 (frequency cochlea p
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describe the vestibular nucleus
Primary vestibular axons from cranial nerve VIII make direct connections to the vestibular nucleus on the same side of the brain stem, as well as to the cerebellum. The vestibular nuclei also receive inputs from other parts of the brain, including the cerebellum, and the visual and somatic sensory systems, thereby combining incoming vestibular info. with data about the motor system and other sensory modalities
why does the VOR work even when you are in the dark or when your eyes are closed?
because the VOR is a reflex triggered by the vestibular input rather than visual input.
describe the vestibulo-ocular reflex
the VOR keeps your eyes pointed in a particular direction despite the movement of your body in various directions. each eye can be moved by a set of six extraocular muscles. Because the VOR works by sensing roations of the head, it immediately commands a compensatory movement of the eyes in the opposite direction. The movement helps keep your line of sight tightly fixed on a visual target.
the effectiveness of the VOR depends on complicated connections from the ______ ____, to the _____ ______, to the ___ _____ ______ that excite the extraocular muscles
the efectiveness of the VOR depends on complicated connections from the semicircular canals to the vestibular nucleus, to the cranial nerve nuclei that excite the extraocular muscles.
Why would the transduction process in hair cells fail if the stereocilia as well as the hair cell bodies were surrounded by perilymph?
Endolymph, which is similar to intracellular fluid, surrounds stereocilia and hair cell bodies. It has a high K+ concentration and a low Na+ concentration. The high K+ concentration is responsible for a K+ equilibrium potential of 0 mV. As a result, when K+ channels open, hair cells depolarize, moving toward the equilibrium potential of K+, which is 0 mV. In contrast, neurons, which have a K+ equilibrium potential of –80 mV, hyperpolarize when K+ channels open. Perilymph has an ionic concentration similar to CSF, which is low K+ and high Na+. If perilymph surrounds the stereocilia and hair cell bodies, hair cells will not depolarize when K+ channels open.
what is the acoustic radiation?
axons that interconnect the MGN to the auditory cortex
how does the attenuation reflex help to understand speech in a noisy environment?
the reflex suppresses low-frequency sounds, which allows us to understand speech better in a noisy environment