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Developmental learning in a pain-related system: Evidence for a cross-modality mechanism

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Author

Summary, in English

The nociceptive spinal reflex system performs highly precise sensorimotor transformations that require functionally specified synaptic strengths. The specification is gradually attained during early development and appears to be learning dependent. Here we determine the time course of this specification for heat-nociceptive tail withdrawal reflexes and analyze which types of primary afferents are important for the learning by applying various forms of noninvasive sensory deprivations. The percentage of erroneous heat-nociceptive tail withdrawal reflexes (i.e., movements directed toward the stimulation) decreased gradually from 64.1 +/- 2.5% ( mean +/- SEM) to <10% during postnatal days 10-21. This improvement was completely blocked by anesthetizing the tail during the adaptation period, confirming that an experience-dependent mechanism is involved in the specification of synaptic strengths. However, the results show that the adaptation occurs to a significant extent despite local analgesia and protection of the tail from noxious input, provided that tactile sensitivity is preserved. Therefore, it appears that a nociceptive input is not necessary for the adaptation, and that input from tactile receptors can be used to guide the nociceptive synaptic organization during development. Sensory deprivation in the adult rat failed to affect the heat-nociceptive withdrawal reflex system, indicating that the adaptation has a "critical period" during early development. These findings provide a key to the puzzle of how pain-related systems can be functionally adapted through experience despite the rare occurrence of noxious input during early life.

Publishing year

2003

Language

English

Pages

7719-7725

Publication/Series

Journal of Neuroscience

Volume

23

Issue

20

Document type

Journal article

Publisher

Society for Neuroscience

Topic

  • Neurosciences

Keywords

  • cord
  • spinal
  • activity-dependent learning and memory
  • pain
  • somatosensory
  • development
  • sensorimotor transformation

Status

Published

Research group

  • Neurophysiology
  • Radiology Diagnostics, Malmö

ISBN/ISSN/Other

  • ISSN: 1529-2401