Figure 3

Tuning curve types. Cluster analysis was applied to separate the single cells into distinct types of velocity tuning functions based on their individual tuning curves. The numbers (n) indicate how many cells belong to each cluster. (A – C) One symmetrical (A) and two asymmetrical tuning curve types (B &C) were discriminated when using absolute latencies as response parameter. (D &E) Two types were identified for the first ISI as response parameter. None of them showed velocity tuning, however, a subpopulation (E) showed directional tuning. (F – I) Four types of tuning curves were clustered for rate as response parameter. Two of them showed neither velocity nor direction tuning (F &G), but one (G) of these two had increased inter cell variability for upward movements. This was also the case for the two remaining, directional sensitive tuning curves (H &I) that mainly differed by their response rates. (K – N) Four tuning curve types resulted when using relative latencies as response parameter. One type (M) with increased relative latencies for upward movement, three types with increased latencies for downward movement (K, L, N). These differed mainly because of different durations of relative latencies. Data are mean ± s.d.