Three bars made of stainless steel are included in your order for motor function in mice and rats. Total length is 8 cm long with three bar diameters available: 2, 4 and 6 mm. Multiple colors available. Each bar is removable and replaceable to use for your individual test. Customized diameters are available, please inquire for more details.
Height: 50 cm default. For custom size please inquire for more details.
Price and Size
Mouse & Rat
- (3) Rod Diameter: 2, 4 and 6 mm
- (3) Rod length: 8 cm length
- (1) Rod holder: 50cm height
Animal performances in behavioral assays such as the Radial Arm Maze and the Morris Water Maze may be affected by motor impairments that may present themselves as cognitive impairments during the testing trials. Thus to ensure that results of behavioral assays requiring strength and motor coordination, it is vital to differentiate between the capable candidates. One such test used in assessing motor coordination is the Triple Horizontal Bars (THB).
The THB consists of two wooden columns with notches to hold the bars. At a time only one bar is used in testing. Different bars are of varying thicknesses are used to increase the difficulty of testing and to allow another layer of assessment accuracy.
Essentially the THB measures both motor coordination and muscle strength, unlike other static rod tests. Choosing an appropriate animal model is a crucial first step for any research or investigation. The motor capabilities of the animal can be affected with different pharmacological compounds or lesions and as a result of diseases.
Apparatus and Equipment
The apparatus consists of two acrylic/wooden columns that are notched and attached to an acrylic/ wooden base. Three brass bars (2, 4, 6 mm) are used for testing in different sessions. The thickness of the bars used can be varied to suit the needs of the investigation. The rods are positioned in the notches of the acrylic/wooden columns at the height of 49 cm above the platform surface.
Generally, the 2 mm bar is used for testing as most subjects attain maximum scores on this. Thus, bars with a larger diameter are used to improve the test results as subjects struggle to grip them.
The apparatus is thoroughly cleaned and sterilized before and after a session with different subjects. The rod is placed in the notch (49 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
The experiment is usually carried out first with the 2 mm diameter rod. Hold the subject by its tail and slide it gently about 20 cm on a platform in a backward stride to align it perpendicular to the bar. Rapidly raise it above the central point on the horizontal bar and allow it to grasp it with its forepaws only. Release the tail and immediately start the timer.
In case the subject fails to grasp the rod on the first attempt due to experimenter technique, repeat the placing procedure after a brief period. In case, the subject falls before the 5-second mark (with the right placement technique) repeat the trial for (up to three times) to achieve a greater than five-second score.
Repeat the trials with the other two thicker bars individually after allowing the subject to recover muscle strength.
The task is carried out for at least 30 seconds, during which the criterion point is: either the subject falls from the bar before reaching one of the acrylic/wooden column or the time until its forepaw touches the column.
The parameter used for measuring motor coordination in the THB is the time when the subject falls off the bar. The number of falls is recorded and usually scored as follows (for a 30-second trial):
- Falling between 1-5 sec = 1
- Falling between 6-10 sec = 2
- Falling between 11-20 sec = 3
- Falling between 21-30 sec = 4
- Falling after 30 sec = 5
- Placing one forepaw on a bar support without falling = 5
In case, the subject repeatedly fails to support itself for greater than 5 seconds; the score is marked as 1. The test is repeated with bars of varying thicknesses, and the final score is the cumulative total. Thus, if a subject scores 5 in the 2mm bar test but falls in 4 mm test after 13 seconds, then the score for that subject will be the summation of the trials’ scores, which is 8.
Strengths & Limitations
Unlike other static test apparatuses used for testing motor coordination, the THB is capable of measuring both motor coordination and strength. The apparatus can easily be utilized with rods of varying thickness to refine the test further and overcome the issues of the standard 2 mm thickness rod. The THB is a simple and straightforward task that is easy to use and setup and is not time intensive.
When using the standard 2 mm thickness rod, most subjects attain a high score due to the ease of grasping the narrow rod. This issue can be overcome by simply using rods of larger diameters. 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 Triple Horizontal Bar is a static apparatus.
● The THB measures both motor coordination and strength.
● Rods of varying diameter can be used to refine the test.
● Rods greater than 2 mm are challenging for the subjects.
● The time elapsed before the fall is recorded as the measure of motor performance.
● The subject is said to have completed the task successfully if it touches one of the two support columns with one of its forepaws.
● Poor performance on the THB can be seen in certain animal disease models, transgenic models, and subjects with certain lesions.
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Horiuchi M, Smith L, Maezawa I, Jin LW. CX3CR1 ablation ameliorates motor and respiratory dysfunctions and improves survival of a Rett syndrome mouse model. Brain Behav Immun. 2017 Feb;60:106-116. doi: 10.1016/j.bbi.2016.02.014. Epub 2016 Feb 13.