Document Detail

Sensorimotor responsiveness and resolution in the giraffe.
MedLine Citation:
PMID:  23447665     Owner:  NLM     Status:  In-Data-Review    
The ability of an animal to detect and respond to changes in the environment is crucial to its survival. However, two elements of sensorimotor control - the time required to respond to a stimulus (responsiveness) and the precision of stimulus detection and response production (resolution) - are inherently limited by a competition for space in peripheral nerves and muscles. These limitations only become more acute as animal size increases. In this paper, we investigated whether the physiology of giraffes has found unique solutions for maintaining sensorimotor performance in order to compensate for their extreme size. To examine responsiveness, we quantified three major sources of delay: nerve conduction delay, muscle electromechanical delay and force generation delay. To examine resolution, we quantified the number and size distribution of nerve fibers in the sciatic nerve. Rather than possessing a particularly unique sensorimotor system, we found that our measurements in giraffes were broadly comparable to size-dependent trends seen across other terrestrial mammals. Consequently, both giraffes and other large animals must contend with greater sensorimotor delays and lower innervation density in comparison to smaller animals. Because of their unconventional leg length, giraffes may experience even longer delays compared with other animals of the same mass when sensing distal stimuli. While there are certainly advantages to being tall, there appear to be challenges as well - our results suggest that giraffes are less able to precisely and accurately sense and respond to stimuli using feedback alone, particularly when moving quickly.
Heather L More; Shawn M O'Connor; Emil Brøndum; Tobias Wang; Mads F Bertelsen; Carsten Grøndahl; Karin Kastberg; Arne Hørlyck; Jonas Funder; J Maxwell Donelan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  216     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-02-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1003-11     Citation Subset:  IM    
Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Canada.
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