Spatial encoding properties of subnucleus reticularis dorsalis neurons in the rat medulla

The effect of spatial summation, produced by noxious thermal stimuli, was i nvestigated on medullary Subnucleus Reticularis Dorsalis (SRD) neurons of a naesthetized rats. Neurons with 'whole body' receptive fields were excited by a random sequence of thermal stimuli involving four different surface ar eas of a hindpaw (1.9, 4.8, 7.5 and 18 cm(2)). The responses of SRD neurons progressively decrease when the area of noxious stimulation exceeded 4.8 c m(2). The shape of the stimulus-response curve closely match the shape of d orsal horn convergent neurons, previously recorded under similar experiment al conditions. These results suggest that, with respect to spatial encoding properties, SRD neurons are driven by the same supraspinally-mediated inhi bitory mechanisms as dorsal horn convergent neurons. (C) 2000 Elsevier Scie nce B.V. All rights reserved.