Inhibition of Neuronal Activity and Its Detection Using Electrophysiology in a Rat

Abstract

Source: Lai, J., et al. Simultaneous Electrophysiological Recording and Micro-injections of Inhibitory Agents in the Rodent Brain. J. Vis. Exp. (2015)

This video demonstrates a microinjection-based technique for simultaneous neuronal recording and inhibition in the rat superior colliculus. The procedure involves stereotaxic targeting, skull drilling, and the insertion of an injectrode, which delivers an inhibitory neurotransmitter while recording neuronal activity. Light stimulation evokes action potentials, while drug microinjection suppresses neuronal excitability. As neurotransmitter levels decline, neuronal activity returns to baseline, enabling the study of both inhibition and recovery.

Protocol

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.

1. Assembly of the Recording-injection Pipette

1. Pull an approximately 7 cm long glass capillary (1 mm outer diameter) using a pipette puller.
2. Break the tip of the capillary and check the aperture under a light microscope. Confirm that the inner diameter is between 30 µm to 40 µm.
3. Insert a 7 cm long silver wire into the glass capillary with approximately 1 cm protruding from the non-tapered end of the glass pipette.
4. Bend the excess filament orthogonally to the glass capillary.
....

Results

Figure 1: Schematic representation of the injectrode assembly. A micro syringe (A

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Injection pump (UltraMicroPump III)	WPI	#UMP3
Injection console (Micro4 Controller)	WPI	#SYS-MICRO4
Hamilton syringe	Hamliton	(80301) 701LT 10 µL SYR	Syringes between 5 and 10 μL used
Gel cyanoacrylate adhesive	Krazy Glue	KG86648R	The gel form is easier to apply on the shaft of the 30G hypodermic needle
Glass pipettes	WPI	#TW100F-4	Thin wall, 1mm OD, 0.75mm ID with filament pipettes used
720 Needle Pipette Puller	Kopf	720
Silver wire	A-M Systems, Inc.	782500	Bare 0.010”