The responses of VIP neurons are sufficiently sensitive to 1 support heading judgments

35 The ventral intraparietal area (VIP) of the macaque monkey is thought to be 36 involved in judging heading direction based on optic flow. We recorded neuronal 37 discharges in VIP while monkeys were performing a two-alternative, forced-choice 38 heading discrimination task to relate quantitatively the activity of VIP neurons to 39 monkeys’ perceptual choices. Most VIP neurons were responsive to simulated 40 heading stimuli and were tuned such that their responses changed across a range 41 of forward trajectories. Using ROC analysis, we found that most VIP neurons were 42 less sensitive to small heading changes than was the monkey, although a minority 43 of neurons were equally sensitive. Pursuit eye movements modestly yet 44 significantly increased both neuronal and behavioral thresholds by approximately 45 the same amount. Our results support the view that VIP activity is involved in 46 self-motion judgments. 47 48 49