The Effects of Mechanical and Thermal Stimuli on Local Field Potentials and Single Unit Activity in Parkinson's Disease Patients.
BACKGROUND
Chronic pain is a major, debilitating symptom of Parkinson's disease (PD). Although, deep brain stimulation (DBS) has been shown to improve pain outcomes, the mechanisms underlying this phenomenon are unclear. Microelectrode recording allows us to measure both local field potentials (LFPs) and single neuronal unit activity (SUA).


OBJECTIVE
In this study, we examined how single unit and LFP oscillatory activity in the basal ganglia are impacted by mechanical and thermal sensory stimuli and explored their role in pain modulation.


METHODS
We assessed changes in LFPs and SUAs in the subthalamic nucleus (STN), globus pallidus interna (Gpi), and globus pallidus externa (Gpe) following exposure with mechanical or thermal stimuli. Sensory thresholds were determined pre-operatively using quantitative sensory testing. Based on these data, patients were exposed to innocuous and noxious mechanical, pressure, and thermal stimuli at individualized thresholds.


RESULTS
In the STN, LFP alpha oscillatory activity and SUA increased in response to innocuous mechanical stimuli; SUA further increased in response to noxious mechanical, noxious pressure, and noxious thermal stimuli (p < 0.05). In the Gpe, LFP low betaactivity and SUA increased with noxious thermal stimuli; SUA also increased in response to innocuous thermal stimuli (p < 0.05). In the Gpi, innocuous thermal stimuli increased LFP gammaactivity; noxious pressure stimuli decreased low betaactivity; SUA increased in response to noxious thermal stimuli (p < 0.05).


CONCLUSIONS
Our study is the first to demonstrate that mechanical and thermal stimuli alter basal ganglia LFPs and SUAs in PD. While STN SUA increases nearly uniformly to all sensory stimuli, SUA in the pallidal nuclei respond solely to thermal stimuli. Similarly, thermal stimuli yield increases in pallidal LFP activity, but not STN activity. We speculate that DBS may provide analgesia through suppression of stimuli-specific changes in basal ganglia activity, supporting a role for these nuclei in sensory and pain processing circuits.
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Abigail
A
Belasen
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Youngwon
Y
Youn
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.|Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA.
Lucy
L
Gee
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Julia
J
Prusik
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Brant
B
Lai
Department of Neurology, Albany Medical Center, Albany, NY, USA.
Adolfo
A
Ramirez-Zamora
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Khizer
K
Rizvi
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA.
Philip
P
Yeung
Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA.
Damian S
DS
Shin
Department of Neurology, Albany Medical Center, Albany, NY, USA.
Charles
C
Argoff
Department of Neurosurgery, Albany Medical Center, Albany, NY, USA. jpilitsis@yahoo.com.|Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA. jpilitsis@yahoo.com.
Julie G
JG
Pilitsis
D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D001479:Basal Ganglia / Q000166:cytology*; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D005917:Globus Pallidus / Q000502:physiology; D006801:Humans; D008297:Male; D008839:Microelectrodes; D008875:Middle Aged; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D010300:Parkinson Disease / Q000628:therapy; D010812:Physical Stimulation / Q000009:adverse effects; D020531:Subthalamic Nucleus / Q000502:physiology; D013696:Temperature
Chronic pain; deep brain stimulation; local field potential; mechanical threshold; microelectrode recording; pressure pain threshold; quantitative sensory testing; single unit activity; thermal threshold