1 meter length metal bars 4 mm in diameter are fixed 30 mm (on their centers) apart by wooden supporting columns at their ends. Both Acrylic and wooden models available. The bars are 60 cm above the floor.
A small modification allows for the total length between the end supports to be adjustable, as the end supports can be moved inwards. Please inquire for more details.
Price and Size
Mouse & Rat
- (2) Bar Length: 1m
- (2) Bar width: 4mm
- Height: 60cm
Motor abilities of the subject can significantly affect the outcome of behavioral tasks. Most behavioral tasks require a good level of motor coordination and activity. Motor coordination is not just a critical requirement for behavioral assays but can also be used to assess the effects of pharmacological compounds and in the characterization of motor phenotypes in transgenic and knock-out animals.
The Parallel Bars task is used in measuring and determining motor capabilities. The apparatus uses two parallel rods suspended using wooden columns on either end of the rods. The distance between the two columns or the space between the two parallel rods can be altered to create different levels of difficulty.
The task measures the motor coordination capabilities of the subject which can be affected by pharmacological alterations, lesions, or diseases. To ensure the accuracy of behavioral tests, subjecting the animals to motor coordination assessment, such as the Parallel Bars, can be of great value.
Apparatus and Equipment
The apparatus consists of two wooden support columns on a heavy wooden based platform, which raises the bars to the height of 60 cm above the floor. The bars itself are made of steel and are 1 m in length and have a diameter of 4 mm. The bars are placed parallel to each other with a gap of 30 mm between them.
The apparatus is thoroughly cleaned and sterilized before and after a session with different subjects. The rods are placed on the support columns (60 cm above the platform surface), and a soft cushion is placed on the platform to avoid injury to the subject in case it falls.
The task does not require any pre-training and testing can be performed immediately once the apparatus is set-up. The subjects are brought into the room 5 to 20 minutes before testing to habituate and are allowed resting periods between each trial to allow muscle strength recovery.
To assist with the manual scoring, video and tracking software such as the Noldus Ethovision XT can also be used.
Evaluation of motor coordination
Bring the subject into the testing room and allow it to acclimate if required. Place the subject in the center of the two bars with both the front paws on one bar and both the hind paws on the other. Immediately begin the timer.
Two measures are recorded during the task: Orientation time and Transit time. Orientation is dependant on the subject staying upright. Allocate a maximum score of 120 sec (arbitrarily set test time) in case the subject turns upside down and clings to the rod. Further, allocate maximum score for transit time too, since a subject that transits upright is more coordinated than that clings the rod upside down.
Stop testing if the subject falls off after more than 5 seconds on the rods. In case, the subject falls within the initial 5 seconds of the testing session, replace it once again on the rods and allow a maximum of three trials, of which select the best results.
Once the subject completes the task or falls off the rods, remove it and place it in its home cage and allow it to recover before testing it again.
Two measures are recorded for the Parallel Bars task:
- Orientation time: The time taken to orientate 90° to the start position.
- Transit time: The time taken to reach one of the end supports.
A successful transit is recorded when the subject travels the rods in an upright position as it indicates good motor coordination.
Scoring is done based on the test time that is set. For example, if the test time is set to 120 seconds then falling or upside down orientation and transit time is allocated the maximum score of 120 seconds. The orientation time is allocated as the time taken by the subject to orient itself 90° to the start position and transit time as the time taken to reach one of the end supports.
The number of times that the subject places its two hind paws on one rod, drops a hind paw below the rod, or falls or swings under the rods is also recorded. The Parallel Bars task is sensitive to hind paws, and scoring can also be done based on the number of errors made per meter in 1 minute time. For example below is a sample scoring for a Parallel Bars task based on error scoring (Ding et al., 2002),
|1||Less than 1 error made within 1 min per meter length|
|2||Equal or more than one error made within 1 min per meter length|
|3||More than two error made within 1 min per meter length|
|4||More than 3.5 error made within 1 min per meter length|
|5||More than six errors or cannot traverse|
The data can also be visualized as graphs to compare results between different strains of rodents or disease/intervention groups.
Strengths & Limitations
Unlike the RotaRod, the Parallel Bars do not have a rotating element to it, thus making it a simple and straightforward task that is easy to use and setup. The task serves as a simple measure of motor coordination and is hind paw sensitive (Ding et al., 2002). Unlike other bar tests, the Parallel Bars use two rods placed parallel, as the name suggests. The distance between the two rods can be altered to create different levels of difficulty. Additionally, the two wooden columns can be moved on the based platform to create different lengths of traversable paths.
When positioning the subject, the experimenter may not correctly position the subject on the bar leading to the subject failing to grasp the bar and falling. Further, some subjects may fail to grip the bar assuming they are still supported.
Summary and Key Points
- The Parallel Bars is a static apparatus, unlike the RotaRod.
- The Parallel Bars measure motor coordination.
- The task is hind paw sensitive.
- Two rods are placed parallel to each other with a distance of 30 mm between them.
- If the subject orients upside-down on the rod then it is allocated the maximum score for both orientation time and transit time.
- A subject that traverses the rod in an upright position has better motor coordination than the subject that orients upside-down on the rod.
- The subject is said to have completed the task successfully when it reaches one of the end support columns.
- Poor performance on the Parallel Bars can be seen in certain animal disease models, transgenic models, and subjects with certain lesions.
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