Properties of an adult spinal sensorimotor circuit shaped through early postnatal experience.

Research output: Contribution to journalArticle

Abstract

During development, information about the three-dimensional shape and mechanical properties of the body is laid down in the synaptic connectivity of sensorimotor systems through adaptive mechanisms. This functional adaptation occurs through alteration of connection properties. Here, we characterize the differences between strong and weak connections in the nociceptive withdrawal reflex in adult decerebrate spinal rats, representing the preserved end product of the developmental adaptation process. Stronger excitatory reflex connections from the skin onto a muscle had relatively higher gain in their input-output relations, shorter onset latencies ( up to similar to 150 ms) and lower trial-to-trial variability in relation to response amplitude (SD similar to mean(1/2)) than weaker pathways. Although inhibitory and excitatory nociceptive receptive fields of a muscle overlap to some degree, the results indicate that the inhibitory input is not a major determinant of the gain distribution within the excitatory receptive field and vice versa. The N-methyl-D-aspartate ( NMDA) receptor antagonist, D-2-amino-5-phosphonovalerate (0.1 - 1 mug), applied topically on the spinal cord reduced the gain, whereas the response amplitude was mainly reduced by an absolute number by the alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor antagonist, 6-nitro-7-sulfamoylbenzo(f) quinoxaline-2,3- dione ( 1 - 10 mug). The results indicate that NMDA receptors have a critical role in gain regulation in the nociceptive withdrawal reflex system. It is suggested that after normal postnatal experience-dependent adaptation, the number of connections from a given skin site onto the reflex encoding interneurons is a major determinant of the difference in gain.

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Subject classification (UKÄ) – MANDATORY

  • Neurosciences
Original languageEnglish
Pages (from-to)280-288
JournalJournal of Neurophysiology
Volume92
Issue number1
Publication statusPublished - 2004
Publication categoryResearch
Peer-reviewedYes

Related research output

Marcus Granmo, 2008, Unit for Neurophysiology, Neuronano Research Center, Dept. of Experimental Medical Science. 74 p.

Research output: ThesisDoctoral Thesis (compilation)

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