Kriss Franklin, Amanda Pollard and Justine Shaffer assisted in animal training and data collection. Sarah Freeman and Alisa Ivanova contributed to data analysis. This study is supported by WVU School of Medicine Start-Up, NIH/NIGMS U54GM104942, and NIH CoBRE P20GM109098.

The following training paradigm employs the analysis of phase adjustments of the average adult Sprague-Dawley rat. Please ensure that the protocol described herein is in accordance with your institutional animal care guidelines. All procedures in this study were performed in accordance with the Institutional Animal Care and Use Committee (IACUC) and Office for Laboratory Animal Welfare (OLAW) at West Virginia University School of Medicine and abides by the National Institutes of Health guidelines for the use of experimen...

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The authors have nothing to disclose.

The rationale for this study was to develop a behavioral task that quantitatively assesses the changes in precise control of asymmetric locomotor behaviors. The existence of the spinal CPG has been functionally demonstrated for some time20, but the anatomical and functional characteristics that describe its mechanism as well as its modulatory inputs from descending or sensory feedback pathways have not been characterized until the past decade6,21,22. The current consensus is that the intrinsic spina...

Post-stroke morbidity in the surviving population includes gross motor impairments that pose a challenge for quantitative evaluation in both humans post stroke and animal models of neurologic impairment1. In the clinical setting, these motor impairments are measured using subjective criteria which are more sensitive to severe rather than moderate impairment exhibited by the majority of patients. Similarly, such subjective assessments of post-injury motor behavior in animals are common, e.g., the Basso, Beattie, and Bresnahan (BBB) locomotor scale method2,3. While these subjective evaluation methods are helping translation between gait rehabilitation studies in quadruped animal models and humans, the details of motor deficits associated with activity of separate muscle groups are not assessed. Moreover, the assessment of motor cortical contribution to locomotion, as the putative culprit of motor deficit in cerebrovascular accident, can only be obtained indirectly even using the most novel automated quantitative methods4,5, as they rely on open-field or linear walking tasks. These tasks do not require cortical contribution and can be performed by the neural mechanisms of the spinal cord, i.e., the central pattern generator (CPG) network which is spared in most animal models of neural damage, e.g., spinalized animals6-8. Essential cortical contribution to these spinal mechanisms has been experimentally implicated in tasks that require anticipated postural adjustments9 and reaching10, as well as precise stepping10.
Moreover, most neurological damage is asymmetric; for example, stroke causes hemiparesis, i.e., weakness on one side of the body, which results in an asymmetric gait11-14. The asymmetry of hemiplegic gait is produced by asymmetric spatiotemporal muscle activation most significantly manifested in the shortening of the extensor-associated stance phase and the lengthening of the flexor-associated swing phase of the step cycle on the paretic side15,16. This trend has not yet been explored across a range of locomotor speeds in healthy or paretic animals. In the current study, we employed the analysis of phase duration characteristics17 that describes the relationship between the duration of swing or stance phases as a function of cycle duration in each step. The obtained linear regression model was then further described with an analysis of asymmetry across all limbs.
We report a novel low-cost method for assessing the activity of descending cortical inputs in the motor system of quadruped animals based on a precise stepping locomotor task. This task is designed to challenge the motor cortex by imposing demands on foot placement over a natural range of walking speeds. In addition, foot-placement requirements are manipulated to preferentially challenge the left or right side of the motor system. In a similar locomotor task, Metz &#38; Whishaw (2009) examined the rates of failure, the number of missed steps on irregular rung walkway, in rats. Our method is complimentary to this previous study, and it details the quality of phase control in &#34;successful&#34; steps18.

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asymmetric walkway: a novel behavioral assay for studying asymmetric locomotion

Behavioral assays are commonly used for the assessment of sensorimotor impairment in the central nervous system (CNS). The most sophisticated methods for quantifying locomotor deficits in rodents is to measure minute disturbances of unconstrained gait overground (e.g., manual BBB score or automated CatWalk). However, cortical inputs are not required for the generation of basic locomotion produced by the spinal central pattern generator (CPG). Thus, unconstrained walking tasks test locomotor deficits due to motor cortical impairment only indirectly. In this study, we propose a novel, precise foot-placement locomotor task that evaluates cortical inputs to the spinal CPG. An instrumented peg-way was used to impose symmetrical and asymmetrical locomotor tasks mimicking lateralized movement deficits. We demonstrate that shifts from equidistant inter-stride lengths of 20% produce changes in the forelimb stance phase characteristics during locomotion with preferred stride length. Furthermore, we propose that the asymmetric walkway allows for measurements of behavioral outcomes produced by cortical control signals. These measures are relevant for the assessment of impairment after cortical damage.

Figure 2 shows the analysis of asymmetry during the locomotor tasks for a single representative subject. The values were calculated for all conditions using Equation 1 and 2 from all subjects individually (Figure 2) and from composite data of 8 female Sprague-Dawley rats (250 - 400 g, Figure 3). Generally, the modulation of the forelimb stance phase was lesser for the side to which the locomotion condition was favored (short ISL), consist...

Watch this Scientific Journal Video about Asymmetric Walkway: A Novel Behavioral Assay for Studying Asymmetric Locomotion at JoVE.com

Asymmetric Walkway: A Novel Behavioral Assay for Studying Asymmetric Locomotion

Here, we present a protocol to quantify precise stepping in rodents. Cortical and the spinal central pattern generator signals are required for precise foot-placement during obstructed locomotion. We report here the novel constrained walking task that directly examines precise stepping behavior.

Behavioral assays are commonly used for the assessment of sensorimotor impairment in the central nervous system (CNS). The most sophisticated methods for ...

This video reports a novel low-cost method for assessing gait asymmetries in rats, using a precise locomotor limb-positioning task. The phase durations over a range of walking speeds of the quadrupedal gait are used to calculate an index to score the animals'abilities. Our rationale was to develop a behavioral task that quantitatively assesses the changes in precise control for symmetrical locomotor behaviors.This task offers an opportunity to discern the contributions of a descending pathway to the locomotor phase regulation. For example, simultaneous recordings or stimulation in the motor cortex would report as contribution to the modulation of muscle phases in this task. Build the apparatus as an open-topped plastic box with aluminum supports at each corner.Include a frame formed of grooved aluminium railing to provide flexible opportunities for peg placement. The placement of the pegs defines the imposed stride length on the animal. In each of the four corners, put a 20-centimeter square platform.The space between the platforms should accommodate the distance traversed by at least one full step cycle. To create a gait condition, attach aluminum pegs to the rails. These function as footholds for the rat's stride.The pegs should be pre-bent to two point five centimeters from the tip, and should be one centimeter in diameter. Secure the pegs with sliding brackets which can be adjusted with a screwdriver, and, thus, precisely position the footholds. After positioning the footholds, make sure the distances are correct, and that they are on the same horizontal level.Standardize the peg positions for three stepping tasks. First, make a symmetric motor task with 15-centimeter stride lengths by setting the left and right interstride lengths to seven point five centimeters. Second, create a symmetric condition with an interstride challenge by changing those lengths to six centimeters, and, thus, changing the stride to 12 centimeters.Thirdly, create an asymmetric task with a stride length of 15 centimeters. Adjust the position between the pegs to make the interstride length uneven by 20%The task has two configurations with either the left or right interstride being shorter. Thus, each walkway side can represent a separate gait condition.Now, to the side of the apparatus, position an HD camera that can record 60 frames per second. Adjust the field of view to cover about seven steps, and not include the steps closest to the platforms. First, prepare the training environment.Set the interstride lengths to just one centimeter, and place a reward on each platform. Now, let the rat freely explore the new environment for about five minutes. Next, guide the animal across the peg arrangement by presenting it with the reward.When the rat reaches a platform, in addition to the food reward, provide a verbal reward, and pet it on the back. Come right here, right here. You're so close.After five training runs, increase the space between the pegs by one or two centimeters for the next five runs. The goal is to gradually extend the peg distance until the symmetric 15-centimeter stride is accomplished. If the rat is having trouble learning the task, it will be evident from inconsistent stepping with frequent stops and crouching posture.Whenever an increased peg spacing induces anxiety or discomfort, just readjust the pegs to their previous positions and repeat that level of training. It is possible to train and then test the same rat in a single day if the rat is motivated. When the rat has learned the task, its walking will be consistent, without stops or missteps.Its head-bobbing will be minimal, its back will be arched, and its tail will be raised. Rapid stepping with little speed variability, however, is usually a sign that the rat is using a gallop rather than a walk. This behavior should be preventable by training the rat to move at lower speeds.From the camera's view, it is essential that each limb be visible at the onset and offset of the stance phase. When these criteria are all met, testing may commence. For the tests, use the four standardized peg configurations with a randomized session design, including breaks, to avoid adaptation to the task.Details are provided in the text protocol. Save the videos, and use video editing software to cull the walking bouts for analysis. The 60-frame per second rate is essential to the task scoring.For each walking bout, score the onset and offset of the kinematic phases. This can be done in a variety of software by frame-by-frame basis. In this case, custom software written in MATLAB is employed.Stance onset is scored when there is a loss of motion blur. Stance offset is scored when there is first evidence of motion blur. Once the swing phases are all counted, plot them as a function of the corresponding step cycle using a MATLAB script.Data was collected from eight subjects and analyzed as described. Seen here is the asymmetry analysis for one subject. The combined analysis of the eight subjects shows that, generally, the modulation of the forelimb stance phase was lessened for the side to which the locomotion condition was favored, and vice-versa.ANOVA with a conservative Bonferroni correction showed a significant difference between the two asymmetric conditions in the asymmetry indices, including the anterior horizontal symmetry index. The right vertical asymmetry showed a trend towards difference between the two conditions. Similarly, a significant difference was found in the diagonality index between two asymmetric conditions.No differences were found in this index between other tasks, based on ANOVA with a post hoc t test, and no alpha correction. Animal models of focal stroke and spinal cord amolesion cause movement deficits akin to those observed clinically, and lesioning of the cortical spinal track in this way impedes this precise stepping behavior. This may result in a delay in the onset of consecutive locomotor phases, which is consistent with an asymmetry in both the step-length ratio and the single limb support time observed in post-stroke patients.The animals which acquired the task are now prime for locomotor assessment in models of cortical injuries such as middle cerebral artery occlusion and traumatic brain injury.

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8.7K Görüntüleme.  West Virginia University School of Medicine. This video reports a novel low-cost method for assessing gait asymmetries in rats, using a precise locomotor limb-positioning task. The phase durations over a range of walking speeds of the quadrupedal gait are used to calculate an index to score the animals'abilities. Our rationale was to develop a behavioral task that quantitatively assesses the changes in precise control for symmetrical locomotor behaviors.This task offers an opportunity to discern the contributions of a descending ...