[A simply designed apparatus and its use for measuring vertical and horizontal motor activities in methamphetamine-treated mice].

A simple apparatus using the infrared ray, which can divide spontaneous motor activity (SMA) of mice into two behavioral components, a vertical movement (VM) and a horizontal movement (HM) was designed. VM and HM were evaluated by counting the number of times that infrared rays were blocked by the mouse in the activity cage [300(H) X 260(D) X 130(W) mm] with 9 infrared photo-couplers for measuring VM and one infrared photo-coupler for measuring HM. When methamphetamine (MAM) was subcutaneously administered to mice pretreated with saline (0.1 ml/10 g, sc) for 3 days, VM and HM were as follows: 1) At 0.1 mg/kg of MAM, the same level of activity was observed as with saline. 2) At 1.0 mg/kg of MAM, increased activity was noted. 3) At 10 mg/kg of MAM, a marked increase was noted, showing more enhancement of HM than VM, which had developed into a stereotyped behavior. In summary, this new apparatus was found capable of dividing the SMA of mice into the two behavioral patterns of VM and HM, and providing their measurements.