Semicircular canal geometry, afferent sensitivity, and animal behavior
Article first published online: 20 MAR 2006
Copyright © 2006 Wiley-Liss, Inc.
The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology
Special Issue: Structure and Function in the Auditory System: From Cochlea to Cortex
Volume 288A, Issue 4, pages 466–472, April 2006
How to Cite
Hullar, T. E. (2006), Semicircular canal geometry, afferent sensitivity, and animal behavior. Anat. Rec., 288A: 466–472. doi: 10.1002/ar.a.20304
- Issue published online: 23 MAR 2006
- Article first published online: 20 MAR 2006
- Manuscript Received: 29 DEC 2005
- Manuscript Accepted: 29 DEC 2005
- National Institute of Deafness and Other Communication Disorders. Grant Number: KO8 DC 006869
- McDonnell Center for Higher Brain Function
The geometry of the semicircular canals has been used in evolutionary studies to predict the behaviors of extinct animals. These predictions have relied on an assumption that the responses of the canals can be determined from their dimensions, and that an organism's behavior can be determined from these responses. However, the relationship between a canal's sensitivity and its size is not well known. An intraspecies comparison among canal responses in each of three species (cat, squirrel monkey, and pigeon) was undertaken to evaluate various models of canal function and determine how their dimensions may be related to afferent physiology. All models predicted the responses of the cat afferents, but the models performed less well for squirrel monkey and pigeon. Possible causes for this discrepancy include incorrectly assuming that afferent responses accurately represent canal function or errors in current biophysical models of the canals. These findings leave open the question as to how reliably canal anatomy can be used to estimate afferent responses and how closely afferent responses are related to behavior. Other labyrinthine features, such as orientation of the horizontal canal, which is reliably held near earth-horizontal across many species, may be better to use when extrapolating the posture and related behavior of extinct animals from labyrinthine morphology. Anat Rec Part A, 2006. © 2006 Wiley-Liss, Inc.