Organization of Spinal Locomotor Networks and their Afferent Control in the Neonatal Rat
In this short review we discuss recent findings on the details of the transmitter-induced hindlimb motor pattern, the afferent control of the centrally generated rhythm and the localization of putative rhythm generating spinal neurones in neonatal rats aged 0–4 days. With regard to the motor output, it is concluded that multiple transmitters (like 5-HT and dopamine) control different aspects of both the rhythm and pattern in the neonatal rat. Like in adult animals the centrally generated rhythm can be perturbed by peripheral muscle afferents in an organized fashion, although the resetting from low threshold extensor muscle afferents in the neonatal rat (P0–P3) is to a new flexor phase and not to a new extensor phase as in the adult cat. We suggest, however, that these findings can provide a tool for identification of spinal neurones engaged in rhythm generation. Moreover, based on the use of sulforhodamine 101, a newly identified activity marker, we suggest that cells located in lamina VII and around the central canal are engaged in generating locomotor behaviour in the neonatal rat.
KeywordsLocomotor Activity Biceps Femoris Central Pattern Generator Locomotor Rhythm Spinal Locomotor
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