ARU Research Facilities
-- Intravenous Self-Administration Lab

The intravenous self-administration facility (IVSA) consisted of 10 experimental stations with 10 others under construction. This was one of the more advanced experimental techniques in which some graduate and a few undergraduate students were trained. For information about this experimental method, click here.
Large door for the experimenters, small door for the rats? Well, not really. Each behavioral testing room had individual automatic light controls and chart recorders monitoring the temperature and humidity 24 hours per day. The equipment 'closet' is located next to each entry door.

Individual operant chambers were housed in sound-attenuating enclosures. Rows of test chambers were arranged along two walls to maximize space utilization in this small lab.
Like in the other behavioral testing facilities, the operant and sound-attenuating chambers were custom fabricated to meet specific requirements not available with commercially produced equipment. This made construction of these laboratories particularly time-consuming but was necessary to avoid experimental artifacts often present in published reports using this technique.
Computers controlled the operant contingencies and the drug-infusion parameters. Traditional paper chart recordings were also made in 'real-time' for several test chambers. The pattern of intravenous self-administration is important for interpreting the data. And although it can be recreated from the computer data file that precisely recorded the time of each injection, visual observation during data collection can be invaluable for detecting problems and particularly interesting effects.
The intravenous catheters for each rat were flushed with a heparinized saline solution before and after testing. This tested catheter patency and helped to maintain free-flowing catheters for months of testing. (Thank you, Dr. Pudiak, for the demonstration. I know you're camera shy, but it's the only photograph I have of this procedure -- so you're drafted.)
Each rat had a small stainless steel tube permanently mounted on its head that permitted connection of its intravenous catheter to the infusion line with a minimum of restrain. Contrary to popular belief, the rats 'enjoy' participating in these experiments and willingly remain immobile while they are being connected to the infusion line for testing. 
Operant chambers contained two levers and two cue lights for programming various experimental contingencies. Drug infusions were delivered by computer activation of a stepping motor on a syringe pump (shown here disconnected for sterilization of the infusion line). Computer programs were written for conducting studies using simple reinforcement schedules and for complex progressive-ratio testing.

Click here for a brief video (1.36 MB MPEG) of a rat pressing for cocaine injections on an intermittent reinforcement schedule. 
The above photographs show the typical behavioral sequel during intravenous drug self-administration.

Top left: rat approaches lever.
Top middle: rat depresses lever.
Top right: intravenous infusion begins and lasts for 28 seconds.
Bottom left: intravenous infusion continues as the rat begins to become more aroused.
Bottom middle: the rat 'sits back' and enjoys the intensely rewarding effects of the cocaine injection; in this case he engages in stereotypic sniffing and gnawing on the chamber floor. Other times rats show increased locomotor activity with bouts of stereotypic sniffing (Click here for a brief video clip showing this behavior from self-administered cocaine.).


Copyright 2001-2003 Michael A. Bozarth
Revised 05 March 2003 15:03 EST
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