Description

The asymmetric walkway is an intricate apparatus used for measurement of behavioral outcomes in walking asymmetries, especially in spinal pathologies. The MazeEngineers Asymmetric walkway allows for both mice and rats to step from one platform to another. 4 platforms, 88 pegs, and the base in which the pegs can be attached are included in your order.

Customizations including colored platforms, obstructions and novel sizing can be created with your order. Please inquire with our form.

 

Price & Dimensions

Mouse

$ 1890

  • Overall Length: 120cm
  • Overall Width: 120cm
  • Height: 70cm
  • Side platforms (4): 20cm x 20cm.
  • Individual Pegs(88): 20 cm x 1 cm x 0.5 cm, Bend length: 2.5cm.

Rat

$ 1990

  • Overall Length: 200cm
  • Overall Width: 200cm
  • Height: 115cm
  • Side platforms (4): 33cm x 33cm
  • Individual Pegs(88): 33 cm x 1.67 cm x 0.83 cm, Bend length: 4.2cm.

Documentation

Introduction

Asymmetric walkway protocol is a novel task that is used to evaluate walking asymmetries in rodents using a precise foot placement locomotor test. (Tuntevski, K., Ellison, R., Yakovenko, S, 2016)

The locomotor behavior is a tightly integrated network of intrinsic spinal, sensory feedback, and descending commands. This task assesses the cortical inputs to the spinal CPG (central pattern generator) and it also allows the measurement of behavioral outcomes produced by the descending cortical inputs in the motor system.

The main goal of this task is to assess the contributions of motor cortex, spinal and descending pathways in regulating the asymmetric walking behavior. (Martin JH et.al. 1998)

The asymmetric tasks rely profoundly on the motor system when compared with the symmetric tasks. Asymmetric walkway protocol exploits this characteristic, and investigate asymmetric walking behavior in relevance to the symmetric walking behavior acting as control.

As the motor cortex is directly involved in asymmetric walking behavior, the analysis of phase modulation with respect to asymmetric challenges can provide concrete evidence regarding the changes in voluntary control. Continuous stimulations of the motor cortex would report as contribution to the modulation of kinematic phases in this task.

A pegged pathway is employed to impose symmetrical and asymmetrical locomotor tasks simulating lateralized movement deficits.

The peg way is manipulated to challenge the left and right side of the motor cortex by imposing demands on foot placement. The peg placement on each side is manipulated to produce four stepping challenge conditions. Two challenges are symmetric while the other two are asymmetric.

Symmetric challenges

The symmetric locomotor task is produced by dividing the stride lengths (length between two successive pegs on the same side) into two equidistant lengths.

The first symmetric condition (SL15) is executed by changing the right inter-stride length (rISL) and left inter-stride length (lISL) to 7.5 cm each.

The second symmetric condition (SL12) is executed by changing the right inter-stride length and left inter-stride length to 6 cm each.

Asymmetric challenges

For the asymmetric challenge of the motor system, the right inter-stride length and the left inter-stride length is kept unequal.

The rISL and lISL are fluctuated by 20% to impose short inter-stride lengths either on the right or on the left side.

L9R6 (right favored) condition is manifested by lISL of 9 cm and the rISL of 6 cm whereas L6R9 (left favored) condition is manifested by lISL of 6 cm and the rISL of 9 cm.

In general, the modulation of forelimb stance phase was lessened for the side to which the locomotion condition was favored, whereas the stance phase was elongated on the preferred side as the speed of locomotion decreased

The asymmetric walkway paradigm is developed by Kiril Tuntevski et.al in 2016. They analyzed the duration and attributes of kinematic phases. (Halbertsma, J. M, 1983)

They also analyzed the correlation between stance and swing phase durations with respect to the cycle duration in each step.

Kiril Tuntevski et.al. model is complimentary to horizontal rung ladder task proposed by Met and Whishaw. (Metz, G. & Whishaw, I. Q, 2009)

However, this novel model specifies the quality of phase control in successful steps.

Apparatus and Equipment

The apparatus consists of an open arena created with 4 aluminum supports. The overall dimensions are are 120 cm x 120 cm.

Each corner is provided with a platform approx. 20 cm x 20 cm separating the four manipulated conditions for walking.

An alternate peg way (both for left and right foot placement) runs along the perimeter of the box.

The pegs are made up of aluminum bars approx. 20 cm x 1 cm x 0.5 cm in dimension. The bars are bent at the tip approx. 2.5 cm for secure foot placement of rodents.

The grooved aluminum bars are secured using sliding inside brackets to change the positioning of the pegs. The position is adjusted with the aid of a screwdriver.

The movement of the rodents is recorded with the help of a video tracker such as Noldus Ethovision XT pointing perpendicularly to the field of movement and covering seven steps. The first and last step near the platforms is neglected.

Training Protocol

The purpose of the asymmetric walking task is to evaluate walking behaviors in rodents in a control vs. disease model/intervention group, by assessing their walking behavior in manipulated stepping conditions.

Pre-training

The subjects are habituated with the apparatus by placing and rewarding them on the platform for at least 5 minutes. Initially, set the inter-stride length at 1 cm and guide the subject to the opposite platform by offering food reward.

After the initial session, perform another 5-minute session by spacing the pegs an extra 1-2 cm apart.

If the subject is making slow progress, train the animal on shorter stride length (SL12) before advancing to longer stride length (SL15).

If the subject is uneasy with the new spacing, readjust the pegs to the previous setting and repeat the training session.

The subjects are trained until the stride length for the four conditions is achieved.

Evaluation of stepping challenge conditions

The subjects are tested for S12, S15, L6R9, and L9R6 tasks randomly. In order to avoid adaptation within a task, the conditions are not tested successively.

Evaluation of stance onset and offset

The stance onsets and offsets of kinematic phases are recorded with the video tracker.

Stance onset is indicated by the loss of motion blur, when the subject places the limb securely on a peg, whereas stance offset is indicated by the first evidence of motion blur when the subject lifts its limb from a peg.

The time between two successive onsets is recorded as the swing phase.

The walking should be consistent and should not involve any stops or missteps. Furthermore, the subject’s back should be arched and tail raised while the head-bobbing should be minimal.

Inconsistent behaviors with respect to over ground quadrupedal walking such as double swing phase (both forelimbs/hindlimbs off the ground simultaneously) are neglected.

Modifications

The apparatus can be modified easily as it is provided with sliding inside brackets. The conditions can be manipulated to suit one’s experimental needs.

Sample Data

The sample data is represented by plotting the duration of each phase as a function of the corresponding step cycle duration. The relationship is visualized by a linear regression model.

Strengths & Limitations

Strengths

Asymmetric walkway protocol is a cost effective technique to evaluate asymmetries in rodents.

This model effectively scrutinizes the flexor associated swing phase and extension associated stance phase (antagonistic phases) that drive the spinal CPG with different speed demands, presumably regulated by higher levels of motor control hierarchy. (Yakovenko, S, 2011)

Therefore, this model is significant for assessing moderate motor impairment in rodents.

Limitation

One of the prominent drawbacks of this method is its applicability. This task is not applicable for the analysis of severely affected animals.

Summary and Key Points

  • Asymmetric walkway protocol is a novel task that is used to evaluate walking asymmetries in rodents using a precise foot placement locomotor test.
  • The apparatus consists of plastic box braced with an alternate peg way to study the walking behavior of the rodents.
  • The animals are tested on four manipulated conditions namely S12, S15, L9R6, and L6R9 tasks.
  • The apparatus is highly adaptable and can be modified effortlessly.

References

Tuntevski, K., Ellison, R., Yakovenko, S. Asymmetric Walkway: A Novel Behavioral Assay for Studying Asymmetric LocomotionJ. Vis. Exp. (107), e52921, doi: 10.3791/52921 (2016)

Halbertsma, J. M. The stride cycle of the cat: the modelling of locomotion by computerized analysis of automatic recordings. Acta physiologica Scandinavica. 521, 1-75 (1983).

Metz, G. & Whishaw, I. Q. The ladder rung walking task: a scoring system and its practical application. Journal of Visualized Experiments: JoVE. (28), 4-7 (2009).

Yakovenko, S. Chapter 10 – A hierarchical perspective on rhythm generation for locomotor control. Progress in Brain Research. 188, Elsevier BV. (2011).

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