Figure 2.

CNQX injections into the flocculus had a powerful effect on VOR cancellation but did not consistently affect the VOR in darkness. Top traces, Before the injection, eye velocity was opposite to head velocity during the VOR at 0.2 Hz but remained near zero during VOR cancellation. After CNQX was injected into the left flocculus, the VOR was not cancelled for leftward rotation. After bilateral CNQX injections, the VOR was not cancelled for either direction. A, When CNQX was injected unilaterally, cancellation, which was normalized to a 100% initial value for each cat, decreased immediately to 50% for ipsilateral rotation. There was no significant effect during contralateral rotation (n = 9; pooled data from cats K, H, and N). B, When unilateral injections were made, there was no effect on the VOR at 0.2 Hz 3 min after the injection (n = 9). An asymmetry appeared over time, with a higher gain for ipsilateral half-cycles. C, At 2 Hz, VOR gain increased slightly for contralateral rotation at 3 min after the injection (n = 5; pooled data from cats K and N). At later times, gain was increased for both directions. Neither effect was statistically significant. In this and all figures, VOR gain was normalized to an initial value of 1.0 for each cat because of individual differences in the baseline gains (see Materials and Methods for details).