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Published on: December 10, 2008
Range of motion (ROM) restriction influences quipazine-induced stepping behavior in postnatal day one and day ten
Misty M Strain1, Michele R Brumley1
1Department of Psychology, Idaho State University, 921 S 8th Ave, Stop 8112 Pocatello, ID 83209-8112, USA.
Insights
Neonatal rats adapt stepping with sensory feedback. Range of motion restriction impacts real-time coordination but not overall stepping amount in developing rat pups.
Area of Science:
- Neuroscience
- Developmental Biology
- Motor Control
Background:
- Neonatal rats exhibit adaptive stepping behaviors influenced by real-time sensory feedback.
- Understanding how motor development and sensory input interact is crucial for grasping locomotion control.
Purpose of the Study:
- To investigate the real-time and persistent effects of range of motion (ROM) restriction on stepping behavior in neonatal rats at postnatal day 1 (P1) and P10.
- To examine the influence of a serotonergic receptor agonist on stepping patterns during development.
Main Methods:
- Rat pups (P1 and P10) were tested for stepping behavior under conditions of baseline, ROM restriction, and post-restriction.
- Pups received either quipazine (a serotonergic agonist) or saline (vehicle control).
- A Plexiglas plate induced ROM restriction, limiting limb movement during stepping.
Main Results:
- Quipazine increased limb movement and alternated steps in both P1 and P10 pups; P10 pups showed more synchronized steps.
- ROM restriction suppressed forelimb movement and synchronized steps in real-time.
- No persistent effects of ROM restriction on stepping amount were observed, but intralimb coordination showed both real-time and persistent changes.
- Developmental differences in stepping time course were noted, with P10 pups exhibiting less overall stepping than P1 pups.
Conclusions:
- Sensory feedback significantly modulates locomotor activity during critical developmental periods of neural mechanism refinement.
- ROM restriction affects real-time intralimb coordination, highlighting the role of sensory input in motor pattern adaptation.
- Developmental stage influences stepping behavior and its response to sensory manipulation.
Abstract:
Previous research has shown that neonatal rats can adapt their stepping behavior in response to sensory feedback in real-time. The current study examined real-time and persistent effects of ROM (range of motion) restriction on stepping in P1 and P10 rats. On the day of testing, rat pups were suspended in a sling. After a 5-min baseline, they were treated with the serotonergic receptor agonist quipazine (3.0mg/kg) or saline (vehicle control). Half of the pups had a Plexiglas plate placed beneath them at 50% of limb length to induce a period of ROM restriction during stepping. The entire test session included a 5-min baseline, 15-min ROM restriction, and 15-min post-ROM restriction periods. Following treatment with quipazine, there was an increase in both fore- and hindlimb total movement and alternated steps in P1 and P10 pups. P10 pups also showed more synchronized steps than P1 pups. During the ROM restriction period, there was a suppression of forelimb movement and synchronized steps. We did not find evidence of persistent effects of ROM restriction on the amount of stepping. However, real-time and persistent changes in intralimb coordination occurred. Developmental differences also were seen in the time course of stepping between P1 and P10 pups, with P10 subjects showing show less stepping than younger pups. These results suggest that sensory feedback modulates locomotor activity during the period of development in which the neural mechanisms of locomotion are undergoing rapid development.
