1. Temporal dynamics of a neural solution to the aperture problem in visual area MT of macaque brain  Pack & Born Nature (2001) Harvard Medical School

2. Q: Who solves the aperture problem? OR… What is the function of MT?

3. Alternatives: MT solves aperture problem MT does not solve aperture problem

4. L:  V1 creates aperture problem because it has a small RF (is looking for edge) and MT solves because it’s neurons/RF are bigger  MT response should be tuned for actual direction of motion and not for orientation of the contour (not in actual direction of the motion)

5. Methods:  Train macaques to fixate on small red square for liquid reward  Using microelectrodes record monkey’s tuning curve in MT once fixated  Field of moving bars (8 directions, 3 relative orientations) as stimulus presented 10 times  Spikes recorded from 60-80 ms after onset of stimulus motion and recorded during the last 1,500 ms

6. Results:  In the beginning, is MT fooled and tuned like V1  Response then converges regardless of orientation

7. Interpretation:  MT solves the aperture problem

8. Problems:  Assumes that early MT responses reflects output from V1  What if there is no problem in V1? Need to measure time course in V1 V1 should never converge