A Novel Method for Assessing Proximal and Distal Forelimb Function in the Rat: the Irvine, Beatties and Bresnahan (IBB) Forelimb Scale

This video demonstrates the Irvine Bates and Bresnahan fall limb scale or IBB, which can detect recovery of proximal and distal fall function. Rats are first adapted to the testing environment and observed following unilateral C six SCI. The animals are then recorded while eating two differently shaped cereals of a consistent size.

The videos are used to assess features of fallen use such as joint position, object support, digit movement and grasping technique, and the presence of different behavioral features is recorded onto the IBB score sheet. The IBB shows a consistent pattern of recovery that is sensitive to injury severity. Furthermore, the IBB scale can be used to assess recovery following other types of injury that impact normal fallen function.

Although there are several behavioral assays that are sensitive to different aspects of four limb recovery and experimental models of cervical spinal cord injury. Few techniques provide detailed information on the recovery of fine motor control and digit movement. This method may help answer key questions about recovery from spinal cord injury, like the role of particular axonal tracts in the return of proximal and distal foe limb function.

For example, the rubrospinal tract or the corticospinal tract. The implications of this technique extend towards therapy of humans. The majority of human spinal cord injuries occur at the cervical level.

Additionally, a key priority for patients with cervical spinal cord injury is restoration of hand and arm function. Thus, outcome measures that assess both proximal and distal fore limb functions are needed. Though this method can provide insight into fore limb recovery following spinal cord injury, it can also be applied to other types of injury that impact normal fore limb functions such as stroke or peripheral neuropathies.

Individuals new to this method may have difficulty because of the number of behavioral features they're asked to assess while the rat is eating. We first had the idea for this method when we were watching the rats eat during their recovery following spinal cord injury. This method builds on prior work by other investigators including Ian Wisha and his collaborators.

Visual demonstration of this method is critical as the behavioral features of for limb movement occur very quickly and thus, video examples of the behaviors that are scored or needed to train observers in the technique. Animals should be exposed to the smell and taste of the cereal as soon as they arrive at the animal facility so they can become accustomed to eating this food. The animals should also be adapted to the testing environment.

A perspex or plexiglass cylinder place a few pieces of cereal in the cylinder on the floor before placing the rat inside it. Excessive grooming, urinating, defecating, and jumping are all indicators that the animal is stressed and more time is required for acclimation. Once the animal is well adapted to the testing environment, the next step involves video recording of the animals eating the cereal during filming.

It is best to hold the camcorder as the animal will likely shift positions during eating. Film the animal eating one entire spherical and one donut shaped cereal piece as the required movements vary between shapes and the best assessment involves observing both sequences. Collect the data for each shaped piece separately on a score sheet, and then combine the scores to create an overall score for that rat on that day post-injury.

Now let's see some tips for assessing the videos. Assessment of the animal's falling function should commence as soon as the animal starts to eat the cereal and stop as soon as the cereal piece eaten. Assessments should only be made with spherical and donut shaped cereals that are of a consistent size and shape prior to the initiation of eating.

Animals should not be scored when eating pieces of cereal that are broken Prior to testing for assessment, it is strongly advised that the speed of the videos be slowed down to at least half the original speed as even when injured rats can eat quickly and the incidence of key behaviors may be missed. This can be achieved in programs such as QuickTime and Windows media player while observing the animal. Use the IBB score sheet to note the presence of the following behavioral features, which we will now outline.

The rat is assessed for the predominant elbow position, which is the most common position assumed by the elbow during the eating phase occurring more than 50%of the time extended where the elbow is held straight with an angle of more than 160 degrees partially flexed where the elbow is flexed with an angle of less than 160 degrees, but more than 90 degrees fully flexed where the elbow is flexed with an angle of less than 90 degrees. The rat is assessed for proximal fall movements, which are movements made by the shoulder and or elbow of the impaired fall limb. The movements may or may not result in contact of the fall limb with the serial none where there are no shoulder and or elbow movements of the impaired fall limb slight where there are movements through less than a third, the range of the shoulder and or elbow joint twitches and shrugs fall into this category extensive where movements are more than half the range of the shoulder and or elbow joint.

In early recovery, these movements can be numerous and erratic. The rat is assessed for its ability to use the non volla surface of the impaired for limb to stabilize the cereal piece. In doing so, the rat is maintaining it in a position to aid eating.

Areas of the for limb that may act as supports are the forearm above the wrist, the wrist or the back of digits, none, where there is no non VLA support by the for during the eating phase. Some where non-A support of the object does occur during the eating phase, but not always and almost always where non VOA support of the object occurs nearly always or always during the eating phase. 95 to 100%of the time the rat is assessed for the predominant fopo position, which is the position assumed by the digits more than 50%of the time during eating clubbed, fixed and flexed where the digits are flexed and held in a fist with joint angles of about 90 degrees.

Extended non adaptable where the digits are extended with an angle of greater than or equal to 160 degrees and do not conform to the shape of the held object partially flexed adaptable, where the digits are partially flexed and conform to the shape of the object. The rat is assessed for contact vola support, which is its ability to use the vola surface of the impaired fopo to stabilize the serial piece and in doing so, maintaining it in a position to aid eating none where there is no support with the vola surface of the for PO during eating or less than 5%of the time. Some where support of the object with a vola surface of the for pour does occur during eating, but not always or less than 95%of the time, and almost always the support of the object with the vola surface of the fopo occurs nearly always or always during eating, or 95 to 100%of the time.

The rat is assessed for the presence of wrist movements of the impaired for pore during eating. Once vola support has been established, movements of the risks that occur in the absence of contact between the impaired for PO and the serial are not scored. These scored movements can occur in any direction.

For example, a dorsal to ventral direction or medial to lateral direction, possible scores include yes or no. A minimum of one wrist movement is required for the rat to be counted as yes for this behavior. The rat is assessed for movements made by the impaired forelimb that are synchronized with successful manipulatory movements of the unimpaired forelimb and that contribute to the proper manipulation of the serial.

None where there are no serial adjustments made by the impaired fall limb exaggerated where there are movements by the shoulder and or elbow and or wrist of the impaired for limb that produce a complete loss of contact between the fopo and the serial. These incidences are brief and typically occur just prior to successful manipulatory movements of the serial with the vol surface of the impaired fopo subtle, where there are movements by the shoulder and or elbow and or wrist of the impaired fall limb that occur without a loss of contact between the fopo and the cereal during eating, the rat is assessed for the presence of movements made by the individual digits during eating. These movements can be either non-contact or contact manipulatory for non-contact movement.

Movements of the digits occur but do not result in contact with the serial for contact manipulatory movements. Movements of the digits occur that do result in vola contact of the digit with the object, and in doing so, contribute to manipulation of the serial possible scores include simply yes or no. The rat is assessed for the most common grasping technique used during the eating phase, which occurs more than 50%of the time.

Several grasping methods exist, but the most common are the piner, the hook, and the whole grasp. The grasping techniques used by the rat are stereotypical depending on the size and shape of the serial piece. Possible scores include abnormal where there is consistent use of an alternative method of grasping to the method used prior to injury to support and control the cereal piece during the eating phase, sometimes normal, where there is inconsistent use of the grasping method used prior to injury to support and control the cereal piece during the eating phase and almost always normal.

Where there is consistent use of the grasping method used prior to injury to support and control the serial piece during the eating phase. Once mastered filming can be done in five to 10 minutes, assessment and scoring will require a bit more time due to the need for reducing the speed of the video and to occasionally reexamine ambiguous behaviors. While attempting this procedure, it's important to remember to film the rat eating a complete piece of cereal and to film closeup and in focus to enable the rat to be judged accurately Following this procedure, histological analysis of the lesion site can be performed in order to answer additional questions like which axons or which neuronal cell populations are important for the return of key features of the movements after its development.

This technique will help researchers in the field of spinal cord injury to explore proximal and distal fore limb recovery and rodents and relate it to recovery in primates and people. After watching this video, you should have a good understanding of how to train the animals to eat in the testing environment while they're being filmed to identify the different behavioral features and note them down using the IBB score sheet and then to be able to assign a score.