The responses of neurones of the superficial dorsal horn to ionophoretically applied glutamate ion

Abstract

Extracellular spikes were recorded from neurones in the marginal zone and substantia gelatinosa of the cat lumbar spinal cord using low-noise carbon fibre microelectrodes. Ionophoretic ejection of glutamate ion was used to distinguish soma/dendrite from axon spikes. The receptive fields of the units and their response to percutaneous electrical stimulation was investigated. The majority of units had low-threshold receptive fields on the hair and skin of the toes and foot. The receptive fields indicated a convergence of different modality afferents onto single cells. Ionophoretic glutamate acted synergistically with the action of the natural transmitter from the low-threshold afferents onto the substantia gelatinosa cells.