Microelectrodes for studying neurobiology

Abstract

Microelectrodes have emerged as an important tool used by scientists to study biological changes in the brain and in single cells. This review briefly summarizes the ways in which microelectrodes as chemical sensors have furthered the field of neurobiology by reporting on changes that occur on the subsecond time scale. Microelectrodes have been used in a variety of fields including their use by electrophysiologists to characterize neuronal action potentials and develop neural prosthetics. Here we restrict our review to microelectrodes that have been used as chemical sensors. They have played a major role in many important neurobiological findings.

Figure 1

a) Behavioral discrimination (mean (SEM) of approach probability) between conditioned stimuli based on predictive value. Rats approached the predictive CS+ significantly more than the nonpredictive CS- in sessions 6–12. After ten conditioning sessions, animals underwent surgery for implantation of the voltammetric recording apparatus (indicated by break in graph). (b) Representative changes in dopamine signaling during individual CS+ (top) and CS- (bottom) trials. (c) Three-dimensional representation of mean electrochemical data collected during reward-predictive CS+ trials. CS+ presentations evoked an immediate rise in signal that returned to baseline levels in seconds. (d) Mean (SEM) increase in [DA] evoked by CS+ onset was significantly greater than baseline [DA] at 0.3–1.4 s after CS+ onset. No increase in signal was observed relative to reward delivery. (e) Three-dimensional representation of mean electrochemical data collected during CS- trials. CS- presentations evoked relatively smaller increases in signal. (f) Mean (SEM) [DA] also changed after CS- onset. Reprinted with permission from (28)

Figure 2

NO mediates the NMDA-induced vasodilations. (a) Left axis, The mean vascular dilation induced by NMDA (n = 7; black) is abolished by TTX (1 μM; n = 7; red) or L-NAME (1 mM; n = 4; blue). Right axis, NO flux (green trace) elicited by NMDA (n = 5). The SEM envelopes the mean traces. (b) Infrared images of an intraparenchymal cerebellar blood vessel preconstricted with U46619 (75 nM) that reversibly dilated to NMDA (100 μM) application. Scale bar, 10 μm. The asterisk indicates a region of high vascular reactivity. (c) Spatiotemporal response of the blood vessel shown in (b). Note the spatially restricted constriction (from blue to yellow) under U46619 (75 nM) application (red box) that reversed to a dilation (from yellow to green) after NMDA application (black box). Right, Infrared image of the blood vessel before U46619 application with the locations of measurements indicated by black lines. Reprinted with permission from (35).