Foot stimulation module
The Foot Stimulation module enables several tests that rely on electrical shocking of the test subject:
1. Drink test: This option enables measurement of free- and conflict drinking. It relies upon a circuit that detects drinking and gives parameters of lick counts, drinking bout (each drinking event length) and mean lick count per bout as a function of time (the user defines the size of the time block). The animal is placed in the test chamber and the drinking behavior is evaluated by measuring the start and end of the drinking and the time in free drinking distribution during any given time up to days are recorded[YP1]. For conflict drinking, the user can pre-set the number of lick counts so that when licks reach that specific number, the animal will receive a shock via the water bottle sprout. The conflict between the desire for drinking and fear of the shock serves as a model of fear and anxiety.
2. Foot drop test: In this option, the mouse feels its paws on the metal mesh while moving along. Its foot can drop (faults) through the mesh hole (1.2 x 1.2 cm), and touching the tray and detected by a current monitor circuit. The metal mesh pad is placed 1 cm above a metal tray that is placed under the mesh pad, which is connected to the SmartCage for monitoring. The number of foot drops increases when sensorimotor coordination is impaired, providing a metric of impairment.
3. Step-through passive avoidance task: This option tests for memory of the shock experienced inside while the mouse or rat steps through the open door of the dark box. The test relies upon a metal grid pad placed above a metal tray and connected to the SmartCage for monitoring. The dark box is placed above the metal grid at one side. The latency entering the dark box is an indicator of retention of learned fear.
4. Tone and contextual conditioning fear test: Footshock can be paired with a sound tone. In this way, “learned fear” can be induced in the subject, in which an auditory cue (a tone) induces immobilization by conditioning with an electric shock to the foot. This makes it possible to conduct contextual fear association learning and memory tests between the tone and the shock. This test should be conducted ideally in a sound-attenuated cabinet.