Coherent motion of stereocilia assures the concerted gating of hair-cell transduction channels.
The hair cell's mechanoreceptive organelle, the hair bundle, is highly sensitive because its transduction channels open over a very narrow range of displacements. The synchronous gating of transduction channels also underlies the active hair-bundle motility that amplifies and tunes responsiveness. The extent to which the gating of independent transduction channels is coordinated depends on how tightly individual stereocilia are constrained to move as a unit. Using dual-beam interferometry in the bullfrog's sacculus, we found that thermal movements of stereocilia located as far apart as a hair bundle's opposite edges showed high coherence and negligible phase lag. Because the mechanical degrees of freedom of stereocilia are strongly constrained, a force applied anywhere in the hair bundle deflects the structure as a unit. This feature assures the concerted gating of transduction channels that maximizes the sensitivity of mechanoelectrical transduction and enhances the hair bundle's capacity to amplify its inputs.
Kozlov
Andrei S
AS
Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
Risler
Thomas
T
Hudspeth
A J
AJ
D000818:Animals; D006198:Hair Cells, Auditory / Q000502:physiology* / Q000648:ultrastructure*; D066298:In Vitro Techniques; D007368:Interferometry / Q000379:methods; D015640:Ion Channel Gating / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*; D008027:Light; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008959:Models, Neurological; D009038:Motion; D010812:Physical Stimulation / Q000379:methods; D011892:Rana catesbeiana; D012444:Saccule and Utricle / Q000166:cytology
D007473:Ion Channels