The light-dark paradigm is a widely used quick and easy test on unconditioned anxiety (trait anxiety) in rodents that does not require prior training. It is based on a conflict between the innate aversion to a brightly lit area and the spontaneous exploratory drive in response to a novel environment. If given a choice between a brightly lit and a dark compartment, rodents spontaneously prefer the dark. Anxiolytic compounds increase the time spent in the bright compartment – anxiogenic compounds work the opposite way.
Special dark inserts made from infrared permeable acrylic material can be placed into the ActiMot2 Open Field to quickly convert the Open Field into a Light-Dark test arena. Inserts are available in 50% or 33% size – the smaller insert increases the aversiveness of the bright area. The dark insert has a central opening in species-specific size – a manually operated door is available as an option.
The movement of the animal between compartments is monitored with the high-resolution ActiMot2 light-beam frame. The ActiMot2 software package offers a large variety of dedicated results parameters calculated from these movement data. In addition to the standard parameters latency to enter the dark or bright compartment (depending on the start position) as well as the total time of stay and entries in both compartments many more behavioral measures are provided as compared to other systems that rely on simple transfer detection only. Output rearing as a measure of exploration (up to 2 rearing levels are possible), calculate activity periods, use custom zones to further divide the area into regions of interest, display a pattern of movement – the advanced analysis features allow a comprehensive analysis of the anxiety state of the animal.
The Light-Dark paradigm is also available in the TSE VideoMot2 system and the TSE Multi Conditioning system.
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