Automated, Quantitative Cognitive/Behavioral Screening of Mice: For Genetics, Pharmacology, Animal Cognition and Undergraduate Instruction

Summary

Fully automated system for measuring physiologically meaningful properties of the mechanisms mediating spatial localization, temporal localization, duration, rate and probability estimation, risk assessment, impulsivity, and the accuracy and precision of memory, in order to assess the effects of genetic and pharmacological manipulations on foundational mechanisms of cognition in mice.

Abstract

We describe a high-throughput, high-volume, fully automated, live-in 24/7 behavioral testing system for assessing the effects of genetic and pharmacological manipulations on basic mechanisms of cognition and learning in mice. A standard polypropylene mouse housing tub is connected through an acrylic tube to a standard commercial mouse test box. The test box has 3 hoppers, 2 of which are connected to pellet feeders. All are internally illuminable with an LED and monitored for head entries by infrared (IR) beams. Mice live in the environment, which eliminates handling during screening. They obtain their food during two or more daily feeding periods by performing in operant (instrumental) and Pavlovian (classical) protocols, for which we have written protocol-control software and quasi-real-time data analysis and graphing software. The data analysis and graphing routines are written in a MATLAB-based language created to simplify greatly the analysis of large time-stamped behavioral and physiological event records and to preserve a full data trail from raw data through all intermediate analyses to the published graphs and statistics within a single data structure. The data-analysis code harvests the data several times a day and subjects it to statistical and graphical analyses, which are automatically stored in the "cloud" and on in-lab computers. Thus, the progress of individual mice is visualized and quantified daily. The data-analysis code talks to the protocol-control code, permitting the automated advance from protocol to protocol of individual subjects. The behavioral protocols implemented are matching, autoshaping, timed hopper-switching, risk assessment in timed hopper-switching, impulsivity measurement, and the circadian anticipation of food availability. Open-source protocol-control and data-analysis code makes the addition of new protocols simple. Eight test environments fit in a 48 in x 24 in x 78 in cabinet; two such cabinets (16 environments) may be controlled by one computer.

Introduction

To bring the powerful techniques of genetics, molecular genetics, molecular biology, and neuropharmacology to bear on elucidating the cellular and molecular mechanisms that mediate basic mechanisms of cognition, we need high-volume, high-through-put psychophysical screening methods that quantify physiologically meaningful properties of cognitive mechanisms. A psychophysically measurable, physiological meaningful quantitative property of a mechanism is a property that can be measured by behavioral means and also by electrophysiological or biochemical means. Examples are the absorption spectrum of rhodopsin, the free-running period of the circadian clock, and the refrac....

Protocol

The three fully automated protocols in the TSsystem (matching, appetitive instrumental and classical conditioning) and the switch protocol have been approved by the Animal Care and Facilities Committee at Rutgers New Brunswick.

1. Setting Up the Physical System

1. Set up the test environments in the cabinets (see Figure 1).
2. Install the experiment-control software provided with the test environments on the protocol-control computers.
   Note: Do not use these computers for any other purpose!

2. Setting Up the Software System

1. Set up the LAN....

Results

The system can and should be used to run protocols tailored to the aims of the individual investigator or classroom teacher. However, we have developed a suite of 3 protocols that should prove useful in large-scale screening of genetically manipulated mice and large-scale pharmacological testing: the matching protocol, the 2-hopper autoshaping protocol, and the switch protocol. The matching protocol measures the mouse's capacity to estimate incomes (food pellets per unit time) at two different locations, to remember whic.......

Discussion

Our method yields a wide range of physiological meaningful, quantitative results on the functioning of several different mechanisms of cognition, learning and memory, for many mice at once, in a minimum amount of time, with a minimum of human labor, and with no handling of the experimental subjects during days, weeks, or months of testing. These attributes suit it for genetic and pharmacological screening programs. It uses minimally modified off-the-shelf hardware (test boxes and nest tubs). It produces more data from mo.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
SmartCtrl Connection Panel	Med Associates	SG-716B (115)	control panel for inputs/outputs
SmartCtrl Interface Module	Med Associates	DIG-716B (114)	smart card for each chamber
Universal Cable	Med Associates	SG-210CB (115)	cable from smart card to control panel
Tabletop Interface Cabinet	Med Associates	SG-6080C (109)	cabinet to hold smart cards
Rack Mount Power Supply	Med Associates	SG-500 (112)	28 volt power
Wide Mouse Test Chamber	Med Associates	ENV-307W (31)	test chamber
Filler Panel Package	Med Associates	ENV-307W-FP (32)	various-size panels for test chamber
Wide Mouse Modular Grid Floor	Med Associates	ENV-307W-GF (31)	test chamber floor grid
Head Entry Detector	Med Associates	ENV-303HDW (62)	head entry/pellet entry into hopper
Pellet Dispenser	Med Associates	ENV-203-20 (73)	feeder
Pellet Receptacle	Med Associates	ENV-303W (61)	hopper
Pellet Receptacle Light	Med Associates	ENV-303RL (62)	hopper light
House Light	Med Associates	ENV-315W (43)	house light
IR Controller	Med Associates	ENV-253B (77)	entry detector for tube between nest and test
Fan	Med Associates	ENV-025F28 (42)	exhaust fan for each chamber
Polypropylene Nest Tub			nest box
Acrylic Connection Tube			connection between nest and test areas
Steel Cabinet			cabinet to hold test chambers (78"H, 48"W, 24"D)
Windows computer			running MedPC experiment-control software
Server			running Matlab, linked to exper-control computer by LAN
Software
MedPC software	Med Associates		proprietary process-control programming language
Matlab w Statistics Toolbox	Matlab		proprietary data analysis and graphing programing system
TSsystem		in Supplementary Material w updates from senior author	Open-source Matlab Toolbox
Note: This is the euipment needed for one cabinet, containing 8 test environments. Hardware must be replicated for each such cabinet. However one computer can control 2 cabinets (16 test environments)