Automated Ledged Balance Beam
Description by James E. Groer, Dragonfly R&D, Inc.

Ledged Balance Beam for Rats with Automated Foot Fault Counters

The need for such a device was pointed out to me by Dr. Frank Tortella and Dr. Anthony Williams from Walter Reed Army Instituteof Research in Forest Glenn, Maryland. The original designer of the Ledged Balance Beam, Dr. Timothy Schallert, University of Texas, has given me permission to offer this elegant automated model or his original idea, using his recommended dimensions.

The unit features Balance Beam designed for the adult rat, constructed of solid oak, and mounted on each end to a sturdy, wide based, adjustable height pole stand. The beam is divided into six (6) equal sections, three on the right, and three on the left. Each counter has a light narrow wooden rail sitting atop a switching array which allows only one count increment for each press and release (200 ms re-trigger specification between presses) of about 6 grams or more. The counts from each of the 6 sections are tallied and displayed on 6 individual count processors. Each processor has an individual reset button to return the count to zero. On the wide end of the beam (departure end) is a thin oak starting platform. On the narrow end of the beam (destination end) is a black Plexiglas TM enclosed "shelter" with a removable lid for easy removal of the animal. We can also optionally supply an appropriate noise generator for the departure end of the beam if you require. The unique design allows the beam to be assembled/disassembled easily by one person.

A totally computerized automated model via a data acquisition system connected to a PC, which replaces of the stand alone counters is also available (data acquisition system). The PC based system can record and store each of the six (6) switching events in real-time. Each switching array produces a DC square wave which is viewed graphically using commercially available software package for graphing DC voltage, which provides a very accurate graphic representation of the event time (i.e. how long the switch remains closed for each foot fault). A start and stop pulse (departure and destination) is generated automatically by a switching array mounted at the departure platform and another mounted at the entrance of the shelter/enclosure. The event begins when the rat leaves the platform, and ends when it enters the shelter/enclosure.

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