Electrophysiological characterization of identified ventral tegmental area neurons in conscious rats

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NIDA	NEURO/BEHAV/SENSYS-21

Authors

• B Mileykovskiy
• L Kiyashchenko
• B Liu
• T Yamaguchi
• M Morales

Abstract

The presence of glutamate neurons in the ventral tegmental area (VTA), with discharge parameters similar to those of dopamine (DA) neurons, may be a source of misinterpretation of data obtained in electrophysiological experiments. We have recently developed a novel method that allows juxtacellular labeling of neurons after their recording in conscious rats (Mileykovskiy and Morales, 2011). We used this approach to analyze specific discharge characteristics of different types of neurons in the VTA. We found that both DA and non-DA/non-GABA neurons had similar broad triphasic spikes and showed slow irregular or bursting baseline activity. GABA neurons had significantly less average spike width than DA or non-DA/non-GABA neurons. Analysis of frequency histograms of spike negative deflections for all three types of recorded neurons showed that non-DA/non-GABA neurons might be distinguished from DA neurons but not from GABA neurons. However, because GABA neurons had higher baseline activity than DA and non-DA/non-GABA neurons, firing rate might serve as an additional criterion to distinguish these populations of neurons. Our results suggest that the duration of spike negative deflection taken together with spontaneous firing rate may serve as criteria for electrophysiological identification of VTA DA, GABA, and putative glutamate neurons recorded in behaving animals.

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