Forebrain electrophysiology related to pain has been studied in the Johns Hopkins Functional Neurosurgery Lab by thalamic single neuron or cortical local field potential (LFP) activity recorded directly from the brain at the time of awake surgeries or through implanted electrodes. The nature of human forebrain activity related to neural responses in the human thalamic principal sensory nucleus (Vc) to painful, nonpainful thermal and mechanical stimuli are characterized by low threshold calcium spike (LTS) bursts as well as single action potentials. Neurons responding to painful and cold stimuli are more likely to fire with

LTS bursts during the presentation of these stimuli.  Thalamic spike trains firing with LTS bursts are more likely than single spikes to activate cortex.Thalamic microstimulation with these burst patterns is more likely to produce the sensation of pain and temperature than other patterns, particularly in chronic pain patients. 

Thalamic activity will influence pain perception based upon connectivity with the cortical networks, which have been suggested by changes in hemodynamic activity in imaging studies.  The connections and connectional weights in these networks were demonstrated by studies of cortical LFPs, which have demonstrated that the pain related networks in the nociceptive pain networks are not fixed but change rapidly with changes in task and time relative to the stimulus.  Lesions and chronic pain cause substantial reorganization of these networks.  Finally, these results suggest specific therapies for acute and chronic pain based upon new targets for neuromodulation or for specific application of drugs that influence LTS burst firing. 

This work was supported by NIH-NINDS NS38493 and by the Hopkins Neurosurgery Pain Research Institute. 

图片为Dr. Frederick A. Lenz

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