The postnatal development of spinal sensory processing

Abstract

The mechanisms by which infants and children process pain should be viewed within the context of a developing sensory nervous system. The study of the neurophysiological properties and connectivity of sensory neurons in the developing spinal cord dorsal horn of the intact postnatal rat has shed light on the way in which the newborn central nervous system analyzes cutaneous innocuous and noxious stimuli. The receptive field properties and evoked activity of newborn dorsal horn cells to single repetitive and persistent innocuous and noxious inputs are developmentally regulated and reflect the maturation of excitatory transmission within the spinal cord. These changes will have an important influence on pain processing in the postnatal period.

Figure 1

Peripheral receptive fields: change with age and after inflammation. Representations of the peripheral receptive fields. Those in black represent cells receiving afferents from inflamed skin, whilst those in grey are the control. The mean receptive field size ±SEM (as a percentage of the total plantar foot area) is 50 ± 5.6% at P3, 36 ± 2.9% at P6, 20 ± 1.97% at P10, and 15 ± 1.62% at P21. For those with inflamed feet, the receptive field sizes are 47 ± 6.4% at P10 and 52 ± 12.2% at P21.