ACTIVITY MONITOR - Vanderbilt Kennedy Center

MED ASSOCIATES INC. ACTIVITY MONITOR
OFA system using the above mentioned thigmotaxis measure and by examining patterns
of exploration in a brightly lit arena with a dark area (See Dark Box Insert – Light/Dark
Conflict Test). In addition, other models with proven construct validity, such as the hole
board task and place preference, can also be performed with the MED Associates’
System. These add-on components make the MED Associates’ OFA system very versatile
and an excellent value for laboratories that are both space and cost conscience.
Two standard sized environments, the ENV-510, 10.75" X 10.75" X 8" H (27 X 27 X 20.3
cm) and the ENV-515, 17" X 17" X 12" H (43.2 X 43.2 X 30.5 cm) are suitable for mouse
and rat protocols, respectively. The system consists of a subject containment
environment (chamber), infrared (I/R) sources and sensors, a system power supply, an
environment data source controller, appropriate connecting cables, a PC/environment
interface card, and the data acquisition/analysis software. Subject location is tracked
using 16 evenly spaced I/R sources and sensors juxtaposed around the periphery of the
four sides of the chamber. This I/R beam array defines an X and Y coordinate "map" for
the system. The sensors detect the presence or absence of the I/R beam (i.e., the
subject) at these corresponding coordinates.
At user defined time intervals, the software has instructions to “poll” the environment for
the presence or absence of the I/R beam at each sensor. This is the scanning rate or
sampling rate of the system. If the I/R beam fails to reach the sensor, the system
registers this event as a broken beam and assumes the presence of the subject. Broken
beams at X 1,2,3,4 and Y 2,3,4,5 are averaged, with the resulting microprocessor derived
coordinate being X = 2.5 and Y = 3.5 or just 2.5, 3.5. The averaged beam breaks or
subject "centers" are the data that the software algorithms use to derive the behavioral
parameters such as distance traveled and time spent in a given zone. The software thus
has a resolution of 32 x 32.
By scanning or “polling” the environment many times a second, the OFA system can
effectively track the movement of a subject very precisely. The faster the scanning rate,
the greater the accuracy of the system for high speed behavioral measures such as
stereotypic behaviors, as well as for event-related, time-sorted data.
We offer variable scanning rates to accommodate personal preferences (
Table 3-1). Many researchers feel that there are few advantages to faster scanning rates
for long trial runs where the data of interest does not require the increased rates. After
all, faster scanning rates mean larger data files and longer post-hoc data analysis
processing times.
For such researchers, we have designed the software so that measurements may be
taken as small samples, repeated at preset intervals (
Table 3-1). This allows for focused data files and virtually eliminates the need to sort
through large quantities of data to extract the desired measures. Experience in this
matter will help to determine the test type, continuous or segmented, and the scanning
rate that is best for the application.
The addition of a photo beam array above a subject adds a second plane of detection to
the system. This is used to detect the presence or absence of a subject in this plane.
The "Z" coordinate is used to detect rearing or standing on the hind legs.
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