BENDING BUNDLES: In vivo, hair cells’ stereocilia move in a concerted manner against the tectorial membrane (1). In vitro, the tectorial membrane is removed to allow for stimulation by a probe (2 and 3). However, under low pressure conditions the stereocilia splay in response to the stimulation, and the full bundle is not activated (2). To mimic in vivo conditions, the pressure must be higher, which artificially inflates hair cells’ threshold for stimulus response in vitro (3).© LUCY READING-IKKANDA
The paper J.-H. Nam et al., “Underestimated sensitivity of mammalian cochlear hair cells due to splay between stereociliary columns,” Biophys J, 108:2633-47, 2015. A sound wave that hits your ear can only be perceived after it has been converted from mechanical to electrical energy through a process called mechanotransduction, which is carried out by hair cells within the cochlea, the snail shell–shape canal of the inner ear. To study hair cells, researchers typically excise a portion of the cochlea and use a tiny probe to stimulate bundles of stereocilia that protrude from the tops of the hair cells into the central duct of the cochlea. Stereocilia movement opens up potassium ion channels on the hair cell membrane, resulting in a change in membrane voltage, which ...
