Electrophysiological assessment of acupuncture's effect on single thalamic neurons in the cat: neural coding for pain at a thalamic level

A variety of thalamic nuclei were sampled with tungsten microelectrodes to record extracellularly the spontaneous activity of single neurons, unit responses to noxious and innocuous tactile stimulation, and effects of acupuncture stimulation on unit firing patterns elicited by discrete tactile stimuli. Approximately 41% of the spontaneously active thalamic units recorded were reactive to both noxious and innocuous tactile stimulation, and most of these responded with a burst of spikes, the number of action potentials and the duration of the burst being proportionally related to the stimulus intensity applied. Preliminary findings indicate that some thalamic units show an attenuated response to tactile stimulation during and following acupuncture stimulation.