Fig. 6.

(A) Two monkeys performing a visual discrimination test using in-cage touchscreen. They choose between two symbols representing different amounts of juice. Symbol size was reduced from 4.5 cm to 2 mm over time to test acuity. (Left) Monkey 5 choosing a 4.5 cm “U” (worth 15 drops) over “3” (3 drops); his mouth is on the juice tube. (Middle) Monkey 5 choosing a 2 mm “W” (12 drops) over “7” (7 drops). (Right) Monkey 6 choosing a 4 mm “A” (24 drops) over “K” (18 drops). The juice tube was 25 cm from the screen, so the 4.5 cm symbols subtended about 10° of visual angle, and 2 mm symbols subtended 0.5° visual angle. These video images were made 2 months after the last of five BBB disruptions in monkey 5 and 48 h after the last of five BBB disruptions in monkey 6. (B) Daily performance of monkeys 5–7 before and after each of five sessions of BBB disruption to bilateral LGN and foveal visual cortex (arrowheads). The different symbol sizes are represented as indicated in the left graph. For monkey 5 the symbol size was gradually decreased between treatments, and for monkey 6 the second smallest symbol size was used throughout the treatment series. No decline in function or acuity was observed for any animal. Contrast-enhanced T1-weighted MRI showing bilateral volumetric BBB disruption in the gray matter components of the primary visual cortex over five successive sessions are shown for in monkey 6–7 (scale bars: 1 cm). In addition, volumes centered in the LGN were sonicated.