The 1-hr Locomotor Activity and Exploration test assesses general activity, exploratory behavior and anxiety-like behavior in rodents. It also serves as a control test in order to identify any differences in general activity (hypoactivity, hyperactivity) that may interfere with interpretation of later cognitive, social or emotionality tests that require motoric response. Animals are evaluated over a 1-hr period in a 47.6 x 25.4 x 20.6 cm enclosure using beambreaks for tracking horizontal and vertical movement. Kinder Scientific Motor Monitor software collects variables such as ambulation (horizontal movement), rearing, location and entries into the center and perimeter zones. The center zone measures 33 x 11 cm and the perimeter zone comprises a 5.5 cm border along the walls of the apparatus.
The Accelerating Rotarod Test is used to assess motor learning, motor coordination and balance. The animal is required to keep their balance and navigate the accelerating rotating rod. Performance is quantified as latency to fall from the rod. Shorter latencies as compared to controls may indicate motor coordination and/or balance impairment. Lack of improvement in latency times across days as compared to controls may indicate motor learning impairment.
Our standard protocol tests animals at 4-40 rotations per minute (rpm) acceleration for 300s max for three trials/day for two consecutive days, then at 8-80 rpm acceleration for 300s max for three trials/day for two consecutive days. The rotarod is programmable and can accommodate other schedules and accelerations, up to a max speed of 80rpm. Available for mice and juvenile rats only.
The Acoustic Startle/Prepulse Inhibition (PPI) task measures sensorimotor gating, or the plastic-adaptive operations in the brain for preventing overstimulation and helping the brain focus on a specific stimulus among other distractors. The startle motor response is a reflexive survival mechanism of alarm that alerts and prepares an organism against a potential threat. It involves a rapid and sequential activation of involuntary muscles across species with 6-10ms of the startle stimuli. Our test uses acoustic stimuli to produce a startle response which is measured by a force plate. The startle response can be modulated by emotional state or drugs such as sedatives and can be potentiated by fear. Increased startle response as compared to controls can indicate an anxiety phenotype.
The startle response can also be inhibited by an immediate prepulse. The prepulse is a low dB tone that immediately precedes the startle stimulus (100ms between prepulse and startle). The reduction in startle reaction following the prepulse as compared to the startle reaction without a prepulse is called prepulse inhibition (PPI). PPI is notably impaired in humans and models of schizophrenia and dysregulated in other disorders such as dementia, Tourette’s syndrome and autism. This task is conducted in one day and is available for mice or rats. This task can be confounded by weight or activity levels, therefore appropriate statistical designs will be considered in these situations.
The Balance Beam task is primarily used to evaluate sensorimotor functions of rodents. The test consists of an acrylic beam (either 6mm, 12mm, 24mm, or 48mm in width) that has a dark “goal” box at one end of the beam The beam is 125cm long and elevated 54cm above the ground with a net suspended under the beam to catch animals that fall. Varying the widths of beams, elevation, and inclination allows control of the difficulty of the task.
Data collected includes the time to fall (up to 60 seconds), walk score (did the animal move?), and whether the animal reached the goal box.
The Balance Beam task is more suitable for active strains of rodents. However, less active subjects can be trained on the beam using a positive stimulus before the actual experiment.
This task uses CatWalk XT (Noldus), a gait analysis system that evaluates spontaneous, voluntary gait via footprint. The CatWalk apparatus consists of an elevated walkway of adjustable width, lit from below to illuminate footprints in bright green light allowing for detection by gait analysis software. Animals are first acclimated to the walkway, then on the following day three (or more) sessions of walking/running across the Catwalk are acquired. Acceptable parameters are defined prior to data collection (speed variability, duration, etc.)
The following information can be analyzed from the data acquired from the Catwalk: traditional gait measures (stride, swing, and stand variables as well as base of stance), intrinsic speed variability, applied force during gait, and a variety of spatiotemporal, postural and inter-step variability gait measures. The CatWalk may be preferred over the DigiGait for models of spontaneous gait measures, differential force during gait, and to detect gait differences induced by physical abnormalities that an animal cannot overcome with motivation to move, such as pain and anxiety.
We highly recommend that animals with toe IDS not be used in this task, as such alterations affect distribution of weight across the surface area of the feet. An alternative form of ID such as eartags or earpunches should be used. Available for mice and rats.
The DigiGait is a high-throughput computerized system of gait analysis. It consists of a motorized treadmill with a transparent belt above a high-speed camera, which captures video of the animal’s ventral plane. The software extracts the animal’s “digital paw prints” to produce a variety of spatiotemporal, postural and inter-step variability gait measures. Unlike free-moving gait assays, the forced movement of the treadmill running allows gait parameters to be compared at a consistent speed across animals.
The belt speed can be adjusted as appropriate for juvenile or adult animals or motor impaired animals, and can also be used with mice as young as P17 (FVB) or P21 (C57) and rats. The DigiGait may be preferred over the CatWalk when direct comparisons of gait without varied velocity, the greatest influencer of gait, are possible.
Animals with toe IDs cannot be used in this task as it alters the distribution of weight across the surface area of the feet. An alternative form of ID such as eartags or earpunches must be used.
The grip strength test assesses the maximum force that can be exerted by the forepaws of a mouse. “Forelimb grip strength [is] evaluated in the mice through the use of a grip strength meter” (Wozniak et al. 2007)*. The test serves to detect any differences in the motor function of mice via the forepaws, as well as determine a baseline to check for differences in strength after treatment or physical decline. Developed in the 1970s, the grip strength test has been a hallmark of rodent behavioral testing. The test is completed over 4 days with 2 days of habituation, followed by two days of testing. The grip strength apparatus from Ugo Basile produces a continuous read-out of force units, allowing the experimenter to determine the maximum grip strength of the mouse as the mouse is gently pulled and ultimately releases the force bar.
*Wozniak, D.F., Xiao, M., Xu, L., Yamada, K. A., & Ornitz. D. M. (2007). Impaired spatial learning and defective theta burst induced LTP in mice lacking fibroblast growth factor 14. Neurobiology of Disease, Volume 26 (1), 14-26. ISSN 0969-9961. https://doi.org/10.1016/j.nbd.2006.11.014.
The Rotarod test is used to assess motor coordination and balance. The animal is required to keep their balance and navigate a rotating rod. Performance is quantified as latency to fall from the rod. Shorter latencies as compared to controls may indicate motor coordination and/or balance impairment. The standard protocol is designed to minimize effects of motor learning on performance. The standard test is conducted at three time points with three days between each time point. Each time point comprises one stationary trial, two continuous speed trials and two accelerating trials. Available for mice and rats.
A battery of tests collectively assessing balance, strength, coordination and motoric initiation. Tasks include walk initiation (motoric initiation), balancing on a ledge and platform (balance ability) or balance beam (rats only), climbing a pole (fine motor coordination), and climbing on 60° and 90° angled screens and an inverted screen (coordination and strength). Testing is completed across two consecutive days. Different sizes of ledges and platforms are available for mice and rats, including obese animals.
The von Frey tactile sensitivity task measures tactile sensitivity via reflexive response to a punctate stimulus. Hyperalgesia, increased sensitivity to pain, and mechanical allodynia, a phenomenon where generally innocuous touch is experienced as painful, can be identified with this task. The von Frey filaments are applied to the plantar surface of the animal’s hind paw and withdrawal response is recorded. A serial response method is used to assess response at gradually increasing force application. Alternatively, an up-down method can be used to determine threshold force required to induce reflexive withdrawal. A mechanical sensitivity response curve is also produced in this task which is used to determine the development of hyperalgesia or mechanical allodynia. Available for mice.
The Virtual Optomotor System (VOS) assesses the optomotor reflex in rodents and measures visual acuity and contrast sensitivity in each eye. The optomotor reflex (OMR) is elicited through a subcortical pathway and is considered unconscious sight. It is a stereotyped head movement in response to movement in the surrounding environment and is highly conserved among vertebrates. During assessment, subjects are placed on a platform and surrounded by computer screens to create a virtual drum. This virtual drum shows a vertical sinusoidal grating, a pattern of light and dark strips, that is “spun” to rotate clockwise or counterclockwise. If the OMR is elicited, the head movement of the animal will drift in the direction of rotation. OMR is scored by a trained scorer blinded to the true direction of rotation. Subjects are tested on sessions of varying rotation direction, grating widths and grating contrasts to find threshold limits for visual acuity and contrast sensitivity. Available for mice and rats.