1. La percezione del movimento

2. La selettività neurale per il movimento

3. Il detettore (parziale) di Reichardt Preferita Nulla

4. Il detettore (completo) di Reichardt Movie

6. L ’ illusione dell ’ insegna dei barbieri

8. demo

15. V1 MT

16. Waterfall illusion (Addams, 1834)

17. Positional motion aftereffect (PMAE) Snowden (1998) Curr. Biol. Nishida & Johnson (1999) Nature

18. Movimento complesso: flusso ottica

19. Lettura Morrone, M.C., Burr, D.C., and Vaina, L. (1995). Two stages of visual processing for radial and circular motion. Nature 376, 507-509. Morrone, M.C., Tosetti, M., Montanaro, D., Burr, D.C., Fiorentini, A., and Cioni, G. (2000). A cortical area that responds specifically to optic flow, revealed by function Magnetic Resonance Imaging. Nature Neuroscience 3, 1322-1328.

20. Neural response in MSTd Duffy & Wurtz, 1991

22. Psychophysical evidence for detection of optic flow in humans?

23. Spatial summation

24. Signal-to-noise Predictions S α N sectors σ 2 α N sectors σ α √N sectors S/σ α √N sectors

25. Spatial summation in noise

26. Signal-to-noise Predictions S α N sectors σ 2 = k (constant) S α N sectors

27. Spatial summation of contrast

28. Two-stage motion analysis Σ Local motion detectors Contrast thresholded Complex motion integrator

29. Spatial summation of contrast in noise

31. Temporal summation of contrast sensitivity

32. Motion coherence sensitivity 10 secs noise signal

33. Summation constants

34. Segmentation has different temporal integration. Even a weak signal embedded in noise can be seen given a long enough view

35. Summation with large fields

36. Summation with large fields in noise

37. Spatial summation for flow is extensive

38. Spatial summation of contrast sensitivity of sinusoids Anderson and Burr, 1987

39. Interim Conclusions There exists psychophysical evidence for detectors tuned to complex optical flow. Evidence suggest that the detectors are “second-stage” after contrast thresholding. Temporal summation is extensive: ~ 3 sec. Spatial summation is extensive, ~ 70°.

40. A neural centre for optic flow?

42. FLOW (30 s) NOISE (30 s) 2 s Inverting Direction Rotation Radial Translation

43. MT Time (s) Response Inverting Rotation / Inverting Noise Continuous Rotation / Noise Gradually Changing Flow / Noise MC b a c d e f

45. Translation Flow SB

46. Experiment in dos Biological motion http://www.biomotionlab.ca/Demos/BMLwalker.html

47. Adult plasticity: paraplegia affects perception of “biological motion” The mirror system? (Giacomo Rizzolatti)

48. Sensitivity impaired for biological motion but not contrast sensitivity for orientation Controls Patients Arrighi et al., Current Biol. (2011)

49. Paraplegic sensitivity worse for visual motion, especially biological motion Arrighi et al., Current Biol. (2011)

50. The results point to shared neural circuits for production and perception of movement – the mirror system?

51. CONCLUSIONS  Paraplegic adults have reduced sensitivity to biological motion: shared neural mechanisms for perception and production of motion

52. L’illusione di Ouchi