Filtering Properties of Hair Cellsa

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Abstract
Three questions were asked about filtering properties of hair cells. First, it was asked if hair cells in different receptors showed different filtering properties to match the receptor response to the particular characteristics of the stimulus? It seems that the answer is yes, since for example, the resonant frequencies of pigeon semicircular hair cells at membrane potentials around the RMP are in a range (12-280 Hz) that could match angular head frequencies. Since critical frequency tuning of one frequency probably is not necessary for the semicircular canals it is quite reasonable that the largest quality factor (Qe) of resonance in pigeon semicircular canal hair cells for membrane potentials around the RMP is 4 times lower than the largest Qe in bullfrog saccular hair cells and 10 times lower than Qe in the turtle basilar papilla. Second, it was asked if hair cells of the same morphological type but in different regions of the neuroepithelium have different filtering properties. It seems that this question needs more careful study since most available data on hair cells that show different filtering properties depending on their location in the neuroepithelium show subtle morphological differences and therefore the hair cells could be classified as different types. Finally, it was asked if different hair cell types (based on morphology and innervation) have different filtering properties. The currents in pigeon and guinea pig type I and type II semicircular canal hair cells, guinea pig inner and outer cochlear hair cells, goldfish short and tall saccule hair cells and chick short and tall cochlea hair cells suggest that the answer to this question is yes. The challenge is to continue to precisely specify the filtering properties of different types of hair cells in different places on the neuroepithelium of different receptors.