Fig. 1: Experimental protocol.
From: Causal contribution of optic flow signal in Macaque extrastriate visual cortex for roll perception
a Schematic plot of the 3D spiral space (left), roll plane (middle) and translation plane (right). Complex optic flow pattern used in tuning measurement and discrimination task were selected from the two perpendicular planes based on deviation in rotation component (\({\theta }_{R}\)) and translation component (\({\theta }_{T}\)) from straight forward (\({\theta }_{R}=0^\circ,{\theta }_{T}=0^\circ\)). b Events flow in the main 4-AFC discrimination tasks. Each trial was initiated with a center fixation point and four choice targets appeared symmetrically around the fixation point (top, down, left, and right). c Each 4-AFC task can be divided into roll direction discrimination task (CCW vs. CW), translation direction discrimination task (rightward vs. leftward), and flow-pattern discrimination task (roll vs. translation). d Fine (left) and coarse (right) version of the tasks. In the fine version, motion stimulus was expanding forward (\({\theta }_{R}=0^\circ,\,{\theta }_{T}=0^\circ\)) with a small CCW (\({-}{{\theta }}_{R}\)) or CW (+\({{\theta }}_{R}\)), or a small rightward (\({-}{{\theta }}_{T}\)) or leftward (\(+{{\theta }}_{T}\)) motion component. In the coarse task, only pure roll (\({{\theta }}_{R}=\pm 90^\circ\)) or laminar motion (\({{\theta }}_{T}=\pm 90^\circ\)) was presented, and the visual coherence was varied across trials.
