Behavioral assessment

A modified Brinkman board test was employed to assess quantitatively the extent of motor recovery (i.e., manual dexterity) from SCI, as described elsewhere [17]. Briefly, the Brinkman board (100 mm x 200 mm) was placed on a monkey chair. A total of 50 slots (15 mm long x 8 mm wide x 6 mm deep each), consisting of 25 vertical and 25 horizontal slots, were randomly located on the board. Each slot was filled with a fruit-flavored pellet (5 mm in diameter, 94 mg; BioServe, NJ, USA). The monkeys were trained to take out as many pellets as possible within 30 sec (one session) and forced to perform consecutive five sessions a day. The behavioral assessment based on the modified Brinkman board test was done twice a week (three to four days apart). When the monkey took out a pellet from a vertical or horizontal slot to convey it to the mouth successfully, each performance was defined as a vertical- or horizontal-slot task, respectively. Such motor performance was evaluated as the number of pellets collected per session (through both the vertical and the horizontal slots, the vertical slots only, or the horizontal slots only).