BASi
Bioanalytical System Inc.
BASi is a drug development firm providing contract research services and unique products for the pharmaceutical, biotechnology and medical device industries.
Force Plate Actimeter
What is a Force Plate Actimeter?
The term “actometer” has been used to describe devices that record and are used to objectively score the movements of mammals (primarily rats and mice). Most of the devices that are commercially available use phototonic methods of detection, where the interruption of a light beam is detected, or a video camera continuously records movement. Computer programs acquire the raw data and subsequently provide a means of analyzing it. Although these actometers are widely used, they fail to detect smaller and more subtle movements and sterotypies. For example, an overhead video is unable to detect and quantitate tremor. If the video camera is located adjacent to the subject, the subject must remain oriented in a direction that would ensure recording of tremor when it occurred. Quantitation would still remain difficult. A subject traveling through a box of intersecting light beams will have larger displacements (e.g. 2 to 3 cm) recorded, while smaller movements (< 2 cm) will usually be missed, unless the animal coincidentally remains stationary in front of a beam. Examples of such smaller movements would include stereotypies, the highly repetitive, rhythmic behaviors seen in rodents such as nose-poking, head bobbing, excessive grooming, sniffing, all of which occur without locomotion.
The term “force plate actimeter” has been coined to describe this new device, which records and scores movement and activity, but at a much finer scale than has been previously possible. This “activity-meter” detects and scores stereotypies, tremor, and may be used to detect startle, or interpret more complex movements such as ataxia. It simultaneously records larger movements such as locomotion (with mm scale resolution) and fine movements (with frequency resolution up to 25 Hz).
What species are most suitable for this device?
The first release of the FPA has been designed to accommodate both rats (15 to 500 g) and mice (15 g). Other species, including hamsters, young guinea pigs, flightless birds (e.g. chicks) may be accommodated if they are within the weight range of 15g to 500 g. If you need to work with larger or smaller animals, we’d like to hear from you. The current weight range was selected according to needs of the majority of users likely to require this technology, but we are interested in learning about other applications as well.
What is the significance of tremor?
- Tremor is the involuntary, spasmodic movement of a body part, or parts
- Resting tremor - when tremor occurs in resting positions
- Postural tremor - when tremor results from attempts to maintain postures
- Essential tremor
- Tremor with basal ganglia disease
- Cerebellar postural tremor
- Post-traumatic tremor
- Alcoholic tremor
- Kinetic tremor - also called action tremor, results when making a motion
- Hysterical tremor - also called psychogenic tremor; reduced when subject is distracted
- Drug-induced tremor
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Tremor - Harmaline/Propranolol |
Tremor - Sprague-Dawley rat dosed with 16 mg/kg harmaline.
What is the duration of a force-plate actimeter experiment?
The time that an animal resides in the FPA is relatively short, typically lasting for less than 1 hour. The force plate actimeter is not a traditional cage, and does not include food, water, or bedding materials that would be required for longer term housing and the comfort of the study subject. Modifications to the inner cage may be made by the user, including the addition of food and/or water dispensers. However, devices which drop water or drop food onto the force plate will contribute signals that are recorded by the device, and may therefore confound data. Evaluation of drugs with a long half-life (t ½) can be done by dosing the animals well in advance of their installation into the FPA, or limiting use of the device to a period approximating the maximal concentration of the drug in plasma (Cmax).
What environment and other devices are needed to operate for this instrument?
The FPA is a laboratory instrument. It was designed for use in procedure rooms, laboratories or vivaria. Surface cleaning of the outer enclosure is intended, in compliance with USDA and NIH guidances. The following requirements should be noted by those considering the use of an FPA in their laboratory:
- Requires a stable (24" x 24 ") surface to support the instrument such as a benchtop or table capable of supporting 150lb (68 kg).
- Requires a personal computer (Win XP, 1GHz processor, 250MB RAM, 40GB hard drive) for data acquisition and analysis (not included with purchase).
- Requires one electrical outlet 90-264 VAC, 47-63 Hz universal input, 50 VA maximum.
- Due to the typically short duration of studies conducted on this device, an uninterruptible power supply (UPS) is not required, but is always recommended for both the FPA and the associated computer to avoid the heartbreak of lost data during local power interruptions.
- Should not be located adjacent to other devices capable of creating vibrations which would interfere or confound data acquisition (e.g. centrifuges, reciprocal shakers, vortex mixers, vacuum pumps, ultrasonic dismembrators, etc.)
- Temperature range: 60 to 160°F (15 to 72°C)
- Humidity range: up to 80% RH
- The force plate and inner cage are both washable (by hand, not by machine). The outer enclosure should be wiped down with a disinfectant – it should never be immersed in wash water due to the electrical hazard.
What is included with the purchase of an FPA?
- Outer enclosure – a sound-proofed box with a hinged access door, viewing port, ventilation fan, overhead lamp, and manifold for the wires and cord connections to devices outside the enclosure.
- Force plate transducer assembly – ballast base with 4 transducers mounted
- One force plate. This is easily removed and washed between uses to eliminate odor-stressors left from the previous subject. A spare force plate is a recommended accessory for quick changeovers from one subject to the next: use one while washing the other one.
- Cage assembly – this component restricts the animals movement to the space defined by the cage. It is not in direct contact with the force plate, but is instead suspended above the floor so that there is no contribution of weight or force by this cage. A standard open enclosure is provided with the FPA. This enclosure may be modified by the user, to introduce mazes, circles, suspended parallel wire flooring, or other modifications according to the needs of the study.
- Calibration weights – a set of weights designed specially for the FPA and used during initial setup and periodic recalibrations of the device
- Data Acquisition Interface. This small device is used to transfer data to the computer where the FPA software resides, It resides on top of the outer enclosure, or when multiple FPAs are stacked together, the DA interfaces can likewise be stacked next to the computer(s).