Spinal cord circuits for motor pattern selection in the turtle.

The turtle spinal cord contains neural circuitry capable of generating the motor patterns responsible for the flexion reflex and each of the three forms of the scratch reflex. This neural circuitry selects the appropriate motor pattern in response to a specific cutaneous stimulus. We understand some of the neuronal mechanisms responsible for motor pattern selection and generation; additional work is still required to understand other neuronal mechanisms functioning at the spinal cord level. These mechanisms, once understood at the spinal level, may be used to generate hypotheses concerning the roles of supraspinal structures in motor pattern selection and generation.