IDENTIFICATION AND ANALYSIS OF SINGLE UNIT ACTIVITY IN CENTRAL NERVOUS SYSTEM 



275 



to 

 Ampliher 



Fig.l 9 



FIG. I7..-1. A double-barrelled microelectrode and its immediate connections. Typical values are 

 given of the several electrical characteristics which are significant in the use of the electrode. B. 

 Enlarged view showing approximate equivalent circuit with motoneuron ignoring reactance. 

 [From Coombs el al. (14).] 



FIG. 18. Diagram of arrangement for recording the response of a motoneuron to rectangular current 

 pulse delivered through an intracellular electrode. MN, motoneuron; Rp, microelectrode resistance; 

 R/, resistance of spinal cord and bath; b, unit dry cell; r, 50012 (6 and r compensate for membrane 

 and electrode potentials); R2, 2 kO; r', 2000; R,, 98.3 Mil; R/, 0.92 MU. Rectangular pulses applied 

 between E and D. Spike potentials recorded from A and C. Current through electrode was moni- 

 tored by recording potential across R,'. [From Araki & Otani (8).] 



FIG. ig. Two arrangements used for stimulating and recording through a single micropipette 

 electrode. R, : i kit; R2: 10 kQ; Rj: 44MS2. Electrode resistance R,. usually between 10 and 100 Mil. 

 The resistor of the calibrator (Cal) and the variable resistor of the compensator (Comp), lOoO each. 

 The fi.xed resistor of the compensator 300S2 and the battery supplies 1.5 v. Stimulating and cali- 

 brating pulses are applied through radio-frequency stimulus isolation units. The indiflTerent electrode, 

 I.E., is a silver -silverchloride wire and is usually placed in the cat's mouth. Sw is a switch used for 

 d.c. compensation and for measurement of Re. In A stimulating current is measured by the voltage 

 drop across R2, which is equal to the drop across R3 when the bridge is balanced. B shows an alterna- 

 tive method for measuring current. R. and R3 are same as in A. R, has a value of 5 Ml2, and two 

 preamplifiers of balanced gain are used for differential recording of the voltage drop across Rj. 

 CRO is a double-beam oscilloscope indicating electrode current and voltage. [From Frank & Fuortes 

 (27).] 



