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Seeing motion : From neural circuits to perceptual decisions

Seeing motion : From neural circuits to perceptual decisions. From D. Hubel, 1995. From D. Hubel, 1995. From D. Hubel, 1995. From D. Hubel, 1995. From D. Hubel, 1995. From D. Hubel, 1995. Where do we go from here???. Sensory representation of motion. ??.

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Seeing motion : From neural circuits to perceptual decisions

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  1. Seeing motion : From neural circuits to perceptual decisions

  2. From D. Hubel, 1995

  3. From D. Hubel, 1995

  4. From D. Hubel, 1995

  5. From D. Hubel, 1995

  6. From D. Hubel, 1995

  7. From D. Hubel, 1995

  8. Where do we go from here???

  9. Sensory representation of motion ?? Abstract decision representation?? ?? Pre-oculomotor circuitry Oculomotor circuitry

  10. An Eye Movement Matching Task

  11. An Eye Movement Matching Task

  12. An Eye Movement Matching Task

  13. An Eye Movement Matching Task

  14. An Eye Movement Matching Task

  15. An Eye Movement Matching Task

  16. An Eye Movement Matching Task 30 sec 10 sec independent, Poisson processes (constant rate) 30 sec 10 sec

  17. An Eye Movement Matching Task 30 sec 10 sec independent, Poisson processes (constant rate) 30 sec 10 sec 25% 75% Matching: response ratio = reward ratio

  18. An Eye Movement Matching Task 30 sec 10 sec independent, Poisson processes (constant rate) 30 sec 10 sec 25% 75% Matching: response ratio = reward ratio frequent unsignaled changes in reward ratio

  19. 6:1 1:6 1:1 3:1 1:3 1:1

  20. Crosscorrelograms Correlation Coefficient Lead (responses)

  21. “Experienced value” (EV) = (weighting function) X (reward history)

  22. Area LIP in the Macaque Brain LIP http://www.loni.ucla.edu/data/monkey

  23. Firing rate is related to experienced value (n=21) Targ on Sac 0.8 0.6 Response (peak normalized) 0.4 0.2 0 0 200 400 600 -600 -400 -200 0 Time (msec)

  24. Conclusions - Experienced Value (EV) 1. Under our conditions, EV is computed within a relatively short time window, extending no more than 5-10 trials into the past. 2. EV is represented in LIP, and the effects are often as large as those of the eye movement itself. EV is NOT computed in LIP.

  25. General Conclusions 1. We have established a causal relationship between the sensory representation of motion direction in the cortex and perceptual judgments of motion. 2. Candidate neural correlates of the decision process exist in at least three pre-oculomotor areas of the frontal lobe, parietal lobe and the upper midbrain. Causality is not yet established between these neural circuits and behavioral decisions. (We’re working on it!) 3. At least one of these brain structures (area LIP) represents additional decision variables such as the previously experienced value of alternative actions.

  26. Indeed there are now no logical (and I believe no Insurmountable technical) barriers to the direct study of the entire chain of neural events that lead from the initial central representation of sensory stimuli, through the many sequential and parallel transformations of those neural images, to the detection and discrimination processes themselves, and to the formation of general commands for behavioral responses and detailed instructions for their motor execution. V . B . Mountcastle, Handbook of Physiology, 1985

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