Auditory Responses of Single Cells in the Inner Ear of the Alligator Lizard

• Published in: The Journal of the Acoustical Society of America Vol. 54; no. 1_Supplement; p. 274
• Main Authors: Weiss, T. F., Mulroy, M. J., Altmann, D. W.
• Format: Journal Article
• Language: English
• Published: 01-07-1973
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.1977979

Micropipets were used to record electric responses to sound in the basilar papilla of the inner ear of the alligator lizard. This organ is considered to be equivalent to the mammalian organ of Corti. Intracellular responses were less than 3 mV peak-to-peak. Responses to acoustic clicks and tone bursts were asymmetrical: the positive (depolarizing) portion was generally larger than the negative (hyperpolarizing) portion. Responses to 50-msec tone bursts showed an “ac” response superimposed on a positive “de” shift. Two types of intracellular responses to acoustic clicks were identified: Type A has dominant large oscillations that interleave in time for condensation and rarefaction clicks; Type B has a dominant component that occurs almost simultaneously with the initial, negative (N1) component of the compound action potential of the auditory nerve. We tentatively conclude that Type-A responses occur in hair cells and Type B in supporting cells. Certain features of the response to clicks appear to correlate with the morphological direction of polarization of hair cells in the papilla. Fourier transforms of the intracellular responses to acoustic clicks exhibit frequency selectivity (tuning). We used the method of intracellular dye marking to infer the cellular recording site. [Supported by NIH grants and the Joint Services Electronics Program.]