Reversible Cooling-induced Deactivations to Study Cortical Contributions to Obstacle Memory in the Walking Cat

Summary

Complex locomotion in naturalistic environments requiring careful coordination of the limbs involves regions of the parietal cortex. The following protocol describes the use of reversible cooling-induced deactivation to demonstrate the role of parietal area 5 in memory-guided obstacle avoidance in the walking cat.

Abstract

On complex, naturalistic terrain, sensory information about an environmental obstacle can be used to rapidly adjust locomotor movements for avoidance. For example, in the cat, visual information about an impending obstacle can modulate stepping for avoidance. Locomotor adaptation can also occur independent of vision, as sudden tactile inputs to the leg by an expected obstacle can modify the stepping of all four legs for avoidance. Such complex locomotor coordination involves supraspinal structures, such as the parietal cortex. This protocol describes the use of reversible, cooling-induced cortical deactivation to assess parietal cortex contributions to memory-guided obstacle locomotion in the cat. Small cooling loops, known as cryoloops, are specially shaped to deactivate discrete regions of interest to assess their contributions to an overt behavior. Such methods have been used to elucidate the role of parietal area 5 in memory-guided obstacle avoidance in the cat.

Introduction

On naturalistic, uneven terrain, sensory information about an obstacle, which can be acquired via vision or touch, can rapidly modify locomotion for avoidance. This careful coordination of stepping movements involves multiple cortical regions^1,2. For example, areas of motor cortex^3,4 and parietal cortex^5,6,7 have been implicated during complex locomotor tasks such as obstacle avoidance. In quadrupedal animals, step modulations required for obstacle avoidance m....

Protocol

All procedures were conducted in compliance with the National Research Council's Guide for the Care and Use of Laboratory Animals (eighth edition; 2011) and the Canadian Council on Animal Care's Guide to the Care and Use of Experimental Animals (1993), and were approved by the University of Western Ontario Animal Use Subcommittee of the University Council on Animal Care.

The following procedure can be applied to experiments studying cortical contributions to locomotor control in the walking cat.

1. Apparatus

1. Construct the apparatus used to assess obstacle memory.
   NOTE: The apparatus con....

Results

This protocol has been successfully used to examine parietal cortex contributions to obstacle memory in the walking cat¹⁹. In this study, cryoloops were implanted bilaterally over parietal areas 5 and 7 in three adult (>6 months of age) female cats (Figure 5A). Animals were assessed in the tactile obstacle memory paradigm in the absence of cooling (warm, control condition), or when area 5 or 7 was bilaterally deactivated.

Discussion

The described paradigm employs cooling-induced deactivations of discrete cortical areas using the cryoloop in order to study memory-guided obstacle locomotion in the cat. The visual and tactile obstacle memory paradigms are fairly simple for animals to execute as they exploit naturalistic locomotor behaviors that occur with minimal effort when an animal is motivated to follow a moving food source. Thus, the majority of the training period is devoted to acclimating the animal the testing room and cooling equipment. Most a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Camera	IDS Imaging Development Systems GmbH	Model: UI-5240CP-C-HQ
Intake tubing	Restek	25306	Unflanged end is submerged in the methanol reservoir while the flanged end is connected to the pump
Pump	Fluid Metering, Inc.	Model: QG 150
Nalgene Dewar vacuum flask	Sigma-Aldrich	F9401
Teflon tubing	Ezkem	A051754
Microprobe thermometer	Physitemp	Model: BAT-12
Flanged tube end fittings	Valco Instruments Co. Inc.	CF-1BK	Assorted colours available for colour coding. Packages include the same number of washers as fittings
Washers	Valco Instruments Co. Inc.	CF-W1	Extra washers
Flanging kit	Pro Liquid GmbH	201553
Tubing connector	Restek	25323
Tubing cutter	Restek	25069
Male thermocouple connector	Omega	SMPW-T-M	Used to make cable connection to thermometer
Thermocouple wire	Omega	PP-T-24S	Used to make cable connection to thermometer
MATLAB	MathWorks	n/a