Fig. 2. Spatial arrangements of room cues and target areas for the RT task (A) and those of target circles on the LCD monitor for the RT and VT tasks (B). A, The monkey sat in a chair in a cab and could see various landmarks in the experimental room, such as a stereomicroscope, a refrigerator, a table, a rack, and some experimental devices, which were available to identify its position in the experimental field. In the RT tasks, the monkey moved the cab to one of four reward areas in the four corners of the experimental field (TA1–TA4) by manipulating the joystick. Area in the thick-lined box, 2.5 × 2.5 m experimental field; area in the dotted-lined box, range of movement of a center of the cab where the monkey sat in a chair.Refrig, Refrigerator; Stereotaxic, stereotaxic apparatus; Oscillo, oscilloscope;Expri, experimenter; D.W., microcomputer for Datawave; Amp, main amplifier; Contr, task controller; PC-98, microcomputer for monitoring movements of the cab and joystick. B, A window frame indicated by a thick-lined box, which was proportional to the experimental field at the ratio of 1:12.61, appeared on the LCD monitor with a warning tone. In the VT tasks, the monkey moved a pointer on the LCD monitor to one of four reward areas in the four corners of the LCD monitor (TC1–TC4) by manipulating the joystick. In the RT tasks, one of the four target circles, each of which corresponded to each of the target areas in the experimental field, was presented on the LCD monitor to specify the destination. Area in the dotted-lined box, Range of movement of the pointer on the LCD monitor.