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This study presents a model for the step cycle patterns used during both hopping and swimming by the leopard frog, Rana pipiens. The two behaviors are essentially similar in movement pattern and in the ways they are modified from quadrupedal gaits. In hopping, there is marked hind limb extension throughout stance. The swing begins with a suspension(More)
This paper reports the development of a large-scale model of some spinal reflex circuitry, useful for studying the dynamic interactions among neuronal populations during simple behaviors. The included populations and properties of the neurons and terminals were derived from the literature, mainly on cat spinal cord. The model was conceived as a symmetrical(More)
Electromyography (EMG) was used to examine muscle activity of the major hip, knee, and ankle extensors during both hopping and swimming in leopard frogs. Chronic EMG electrodes were implanted for periods of 7-10 days. This permitted us to record EMG activities during both hopping and swimming from the same electrode, allowing a direct comparison of the(More)
The activation pattern of many hindlimb flexor and extensor motoneurons (MNs) in walking can be described as simple: a single burst of spikes in the appropriate phase of walking. However, in muscles which cross more than one joint (here called bifunctional muscles), the activation pattern is complex, consisting of activity during both the flexion and(More)
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