In Situ Voltammetry with Microelectrodes Reliably Distinguishes Temporal Lobe Gray from White Matter.
Abstract number :
3.196
Submission category :
Year :
2001
Submission ID :
605
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
P.A. Broderick, Ph.D., Physiology, Pharmacology and Neurology, CUNY and NYU Medical School, New York, NY; S.V. Pacia, M.D., Comprehensive Epilepsy Center, NYU Medical School, New York, NY; W.K. Doyle, M.D., Neurosurgery, NYU Medical School, New York, NY;
RATIONALE: We analyzed voltammetric signals from microelectrodes in resected temporal lobes to determine whether gray and white matter structures could be reliably distinguished.
METHODS: We used microvoltammetry with Broderick Probe[reg] stearic acid microelectrodes to detect norepinephrine (NE), dopamine (DA), ascorbic acid (AA), and serotonin (5-HT) in resected temporal lobes of 14 patients with temporal lobe epilepsy. Neurotransmitters were detected in separate signals within the same recording within seconds in 3 gray matter (temporal neocortex, hippocampal pyramidal and dentate gyrus granular layer) and 3 white matter structures (temporal stem, subiculum, and alveus), by experimentally derived oxidative potentials, determined in vitro in Ringers Lactate or PO4 Buffer. Ag/AgCl reference and stainless steel auxiliary microelectrodes were placed in each specimen 4-6 mm from indicator microelectrodes (patented) (manufactured on site). Methods are published (Broderick, Neurosci. Lett. 95, 1988; Br. Res. 495, 1989; Broderick et al. Br. Res. 878, 2000; Pacia et al. Br. Res. 899, 2001). We analyzed all signals for the presence of diffusion peaks in early oxidative species (indicating white matter).
RESULTS: Of 35 temporal lobe gray matter structures sampled only 1 (3%) revealed signals consistent with white matter, while 26 out of 32 (81%) white matter structures were correctly identified as white matter. Additionally, white matter tended to have substantially lower concentrations of catecholamines and 5-HT as well as lower ratios of catecholamines to 5-HT.
CONCLUSIONS: In situ microvoltammetry with microelectrodes reliably distinguishes temporal lobe gray from white matter. These results have important implications for in vivo neurochemical analysis of human epilepsy. Moreover, these findings should enable more precise intraoperative neuroanatomic localization.
Support: Parents Against Childhood Epilepsy (PACE)