Local injection of bicuculline into area 8 and area 6 of the rhesus monkey induces deficits in performance of a visual discrimination GO/NO-GO task.

While performing a symmetrically reinforced visual discrimination GO/NO-GO task, five monkeys were injected with a GABAA antagonist, bicuculline methiodide (BMI), into Brodmann's area 9, 8, 6, or 4. The task consisted of five periods: START, OFF, CUE, RESPONSE, and an inter-trial interval. The monkey was trained to make either the GO response (lever release) or the NO-GO response (continued pressing of the lever), depending on the color of the cue, during the RESPONSE period. Analysis was limited to 102 sites in which muscle convulsions of the forelimb and/or shoulder did not result from BMI injections. Errors in performance increased 10-60 min after injection into 10 of 33 sites in area 9, 9 of 25 sites in area 8, 20 of 34 sites in area 6, and 2 of 10 sites in area 4. The number of trials finished in a 120-min session decrease. Injections induced PRE-RESPONSE errors (release of the lever in either the OFF or CUE periods), GO RESPONSE errors (failure to release the lever when signaled), and NO-GO RESPONSE errors (release of the lever despite a signal not to release). The results suggest that both areas 8 and 6 are involved in correct performance of the GO/NO-GO task.