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. 2016 Oct 19;3(4):27.
doi: 10.3390/bioengineering3040027.

A Simple Picaxe Microcontroller Pulse Source for Juxtacellular Neuronal Labelling

Anthony J M Verberne  1
Affiliations

A Simple Picaxe Microcontroller Pulse Source for Juxtacellular Neuronal Labelling

Anthony J M Verberne. Bioengineering (Basel). .

Abstract

Juxtacellular neuronal labelling is a method which allows neurophysiologists to fill physiologically-identified neurons with small positively-charged marker molecules. Labelled neurons are identified by histochemical processing of brain sections along with immunohistochemical identification of neuropeptides, neurotransmitters, neurotransmitter transporters or biosynthetic enzymes. A microcontroller-based pulser circuit and associated BASIC software script is described for incorporation into the design of a commercially-available intracellular electrometer for use in juxtacellular neuronal labelling. Printed circuit board construction has been used for reliability and reproducibility. The current design obviates the need for a separate digital pulse source and simplifies the juxtacellular neuronal labelling procedure.

Keywords: Picaxe; juxtacellular; microcontroller; neuron; neurophysiology.

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Conflict of interest statement

The author has no financial conflict of interest to disclose.

Figures

Figure 1
Figure 1
Schematic of the Picaxe microcontroller pulse generator. Main components include IC1 (Picaxe 14M2 microcontroller) and IC2 (CD4066 quad bilateral switch). SW2A and SW2B (function selector switch) determine the pulser output. The 50 K trim potentiometers are used to calibrate the output voltage.
Figure 2
Figure 2
WPI electrometer panel modifications. (A), The front panel power switch has been removed and fixed to the back panel of the instrument. In its place is an aluminium panel (a1) onto which is fixed the 10-turn (10k) potentiometer (a2) and 6-position function switch (SW2A,B; a3). The power switch (SW1; a4) and the LED monitor (a5) are mounted to the right of the panel. (B), Side-on view of the 10-turn potentiometer (b1) and the function switch (b3). (C), Pulser printed circuit board (PCB) (c1) mounted inside the WPI Intra 767 case between power supply section at left (c2; not shown) and main circuit board (c3). Note that this is a working prototype but is not the final PCB design available in the Supplementary files. (D), Rear panel showing new location of main power switch (d1) and trigger output connector (d2). LED = Light Emitting Diode.
Figure 3
Figure 3
Voltage divider circuit operation. The outputs of the CD4066 chip are fed to a voltage divider consisting of a 240 K fixed resistor, a 50 K 25-turn trim potentiometer and a fixed 1 K resistor. A total resistance of 250 K will result in a current of I = 5/250,000 = 20 µA flowing through the voltage divider. This will result in a fixed potential of Vd = 20 × 1000 = 20 mV. The WPI Intra 767 will produce current pulses of 1 nA for a 20 mV input.
See this image and copyright information in PMC

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