title: A stretch reflex in extraocular muscles of species purportedly lacking muscle spindles.
abstract: It is generally assumed that proprioceptive feedback plays a crucial role in limb posture and movement. However, the role of afferent signals from extraocular muscles (EOM) in the control of eye movement has been a matter of continuous debate. These muscles have atypical sensory receptors in several species and it has been proposed that they are not supported by stretch reflexes. We recorded electromyographic activity of EOM during passive rotations of the eye in sedated rats and squirrel monkeys and observed typical stretch reflexes in these muscles. Results suggest that there is a similarity in the reflexive control of limb and eye movement, despite substantial differences in their biomechanics and sensory receptors. Like in some limb skeletal muscles, the stretch reflex in EOM in the investigated species might be mediated by other length-sensitive receptors, rather than muscle spindles.
authors.affiliation: Department of Neurology, University of Rochester Medical Center, 601 Elmwood Ave, Box 673, Rochester, NY 14642, USA. Numa_Dancause@urmc.rochester.edu
authors.forename: Numa
authors.initials: N
authors.lastname: Dancause
authors.forename: Michael D
authors.initials: MD
authors.lastname: Taylor
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Plautz
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Radel
authors.forename: Thomas
authors.initials: T
authors.lastname: Whittaker
authors.forename: Randolph J
authors.initials: RJ
authors.lastname: Nudo
authors.forename: Anatol G
authors.initials: AG
authors.lastname: Feldman
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D005133:Eye Movements / Q000502:physiology*; D008297:Male; D009470:Muscle Spindles / Q000502:physiology*; D009801:Oculomotor Muscles / Q000294:innervation / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012026:Reflex, Stretch / Q000502:physiology*; D012453:Saimiri