gamma oscillations in the somatosensory thalamus of a patient with phantom limb pain: case report

Do gamma oscillations in the primary somatosensory cortex reflect pain perception?

Gross, J., Schnitzler, A., Timmermann, L. & Ploner, M. Gamma oscillations in human primary somatosensory cortex reflect pain perception. PLoS Biol. 5, e133 (2007). 10. Hauck, M., Lorenz, J. & Engel, A. K. Attention to painful stimulation enhances gamma-band activity and synchronization in human sensorimotor cortex. J.

Which gamma-band oscillations are associated with pain?

In some studies in humans, the strongest increase in pain-associated gamma-band oscillations has been reported in the high gamma domain (i.e., 70–80 Hz) 9, 28.

What is somatosensory pain memory?

Katz and Melzack (1990) found that 42% of their sample reported a 'somatosensory pain memory' which resembled the quality and location of a painful, or non-painful pre-amputation sensation. For many amputees, pain memories are vivid experiences which incorporate both emotional and sensory aspects of the pre-amputation pain (Katz 1992).

Does pre-amputation pain influence phantom limb pain?

Pain experienced in a limb prior to amputation may influence the course of phantom limb pain many months later. Katz and Melzack (1990) found that 42% of their sample reported a 'somatosensory pain memory' which resembled the quality and location of a painful, or non-painful pre-amputation sensation.

ABBREVIATIONS

AC = anterior commissure; DBS = deep brain stimulation; ET = essential tremor; LFP = local field potential; PC = posterior commissure; PSD = power spectrum density; Vc = ventral caudal somatosensory nucleus of the thalamus; Vim = ventral intermediate nucleus of the cerebellar thalamus; Vop = ventral oral posterior nucleus of the thalamus.

Case Report

Recordings were collected from 1 patient with phantom limb pain (a 42-year-old man), 4 patients with neuropathic pain, and 5 patients with essential tremor (ET) during microelectrode-guided mapping of the thalamus for DBS surgery.

Discussion

In this paper, we describe widespread spontaneous gamma activity in the Vc of a patient with a phantom limb.

Acknowledgments

Research support was provided to Dr. Hutchison from the Canadian Institutes of Health Research MOP grant no. 98006.

Disclosures

Diellor Basha, Dr. Hutchison, and Dr. Lozano report receiving grants, and/or travel funds, and/or lecture honoraria from Medtronic. Dr. Lozano reports being a consultant for Medtronic, St. Jude, and Boston Scientific.

Author Contributions

Conception and design: Basha. Acquisition of data: Hutchison, Kalia, Hodaie, Lozano. Analysis and interpretation of data: Hutchison, Basha, Dostrovsky. Drafting the article: Basha. Critically revising the article: Hutchison, Basha, Dostrovsky, Lozano. Reviewed submitted version of manuscript: Hutchison, Dostrovsky, Kalia, Hodaie, Lozano.

Supplemental Information

Portions of this work were presented in poster form as proceedings at Neuroscience 2013, the annual meeting of the Society for Neuroscience, in San Diego, California, November 9–12, 2013.

Where do gamma oscillations occur?

Gamma oscillations can occur within the cerebral cortex during many cognitive processes such as attention, learning, diverse types of memory etc. 4, thereby raising the question whether they are causally linked to pain perception or only unspecifically so, for example, via the modulation of attention 6.

Which somatosensory cortex correlates with subjective pain perception?

In humans, gamma-band oscillations in the primary somatosensory cortex (S1) correlate with subjective pain perception. However, functional contributions to pain and the nature of underlying circuits are unclear.

Which neuron is involved in descending modulation of pain?

Notably, gamma activity in the S1 led to a marked increase in the activity of neurons in the midbrain nuclei located in the rostroventral medulla (RVM) that are prominently involved in descending modulation of pain.