Relation between spontaneous motility and tuning of spinal reflexes

Relation between spontaneous motility and tuning of spinal reflexes - a developmental study in rats

Field: Motor systems and sensorimotor integration

Authors: Waldenstrom, Alexandra
Thelin, Jonas
Schouenborg, Jens

Address of presenting
author: Section for Neurophysiology, Dept of Physiological Sciences, Lund University, Sölvegatan 19, 223 62 Lund

E-mail: Alexandra.Waldenstrom@mphy.lu.se

Phone: 046-2224651

Fax: 046-2224546

Text of abstract: It is well known that early in the development of motor systems, vertebrate embryos show spontaneous movements. It has been suggested that these spontaneous activities play an important role in activity dependent tuning of neural circuits. One system that is functionally tuned during the first postnatal weeks is the nociceptive withdrawal reflexes (NWR). During this tuning process erroneous connections are eliminated/ depressed and adequate connections are strengthened. In the present study, we compared the development of spontaneous tail movements and tail NWR in postnatal rats (n=13).
Spontaneous movements and CO2-laser evoked NWR in awake intact rats were documented on video during the first 5 weeks.
The analysis of the tail withdrawal showed that the tuning of the different tail sections differed in time course. NWR elicited from the proximal tail were functionally adapted earlier than distal parts. During the first twelve days, about 70 % of the withdrawal movements elicited from the distal tail were directed towards the stimulus. Thereafter the number of erroneous movements was dramatically decreased. Already at P19 the rats performed as well as adults (5% errors).
The frequency of spontaneous tail movements peaked during the time interval P10 - P12, decayed dramatically during the following days, and had disappeared almost completely by P19.
The similarity in time courses may indicate that the spontaneous activity is related to the tuning of the withdrawal reflexes. We suggest that the sensory feedback following the spontaneous movements is used to calibrate the spinal motor circuitries.

Keywords: Plasticity, spontaneous motility, pain, spinal cord, adaptation

	Relation between spontaneous motility and tuning of spinal reflexes - a developmental study in rats
Field:	Motor systems and sensorimotor integration
Authors:	Waldenstrom, Alexandra Thelin, Jonas Schouenborg, Jens
Address of presenting author:	Section for Neurophysiology, Dept of Physiological Sciences, Lund University, Sölvegatan 19, 223 62 Lund
E-mail:	Alexandra.Waldenstrom@mphy.lu.se
Phone:	046-2224651
Fax:	046-2224546
Text of abstract:	It is well known that early in the development of motor systems, vertebrate embryos show spontaneous movements. It has been suggested that these spontaneous activities play an important role in activity dependent tuning of neural circuits. One system that is functionally tuned during the first postnatal weeks is the nociceptive withdrawal reflexes (NWR). During this tuning process erroneous connections are eliminated/ depressed and adequate connections are strengthened. In the present study, we compared the development of spontaneous tail movements and tail NWR in postnatal rats (n=13). Spontaneous movements and CO2-laser evoked NWR in awake intact rats were documented on video during the first 5 weeks. The analysis of the tail withdrawal showed that the tuning of the different tail sections differed in time course. NWR elicited from the proximal tail were functionally adapted earlier than distal parts. During the first twelve days, about 70 % of the withdrawal movements elicited from the distal tail were directed towards the stimulus. Thereafter the number of erroneous movements was dramatically decreased. Already at P19 the rats performed as well as adults (5% errors). The frequency of spontaneous tail movements peaked during the time interval P10 - P12, decayed dramatically during the following days, and had disappeared almost completely by P19. The similarity in time courses may indicate that the spontaneous activity is related to the tuning of the withdrawal reflexes. We suggest that the sensory feedback following the spontaneous movements is used to calibrate the spinal motor circuitries.

Keywords:	Plasticity, spontaneous motility, pain, spinal cord, adaptation

Index

Created 2000-03-15

Department of Physiological Sciences, Lund University

Web programming FormOnLine AB