Swimming movements elicited by electrical stimulation of the turtle spinal cord: The high spinal preparation

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Abstract

1. The movements of each limb of the turtle, Pseudemys scripta elegans, are out-of-phase with the movements of its ipsilateral neighboring limb during normal swimming. Protraction of one limb coincides with retraction of an adjacent limb. The period of the movement cycle in one limb is equal to that of its neighbor. This coordination pattern is termed 1::1 or absolute coordination. 2. Swimming movements of the limbs are not produced spontaneously in a turtle with an acute section of the spinal cord at the first cervical segment. This "high spinal" turtle can produce swimming movements in several limbs, however, in response to unpatterned, i.e. constant frequency, electrical stimulation applied to the dorsolateral funiculus (DLF) caudad to the spinal transection. On many occasions, it was possible to place a stimulating electrode in the DLF so that the swimming movements exhibited the normal pattern of absolute coordination (Figs. 2, 4, 5, 8). 3. On a few occasions, it was possible to place a stimulating electrode in the DLF so that the swimming movements elicited by electrical stimulation displayed an abnormal pattern of coordination. In these cases, protraction of the hindlimb coincided with every second occurrence of retraction of the forelimb. The period of the movement cycle of the hindlimb was twice as long as that of the ipsilateral forelimb. This coordination pattern is termed 2::1 coordination, and is an example of one type of relative coordination (Figs. 7, 11). 4. These results are consistent with the hypotheses (i) that each limb has its neural control center resident mainly in the spinal cord and (ii) that the neural elements necessary for interlimb coordination are not dependent upon supraspinal connections.

Original languageEnglish
Pages (from-to)203-210
Number of pages8
JournalJournal of Comparative Physiology □ A
Volume124
Issue number3
DOIs
StatePublished - Sep 1978

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