1. The Reward Factor in the Control of Action: A Neurophysiological Theory Johan Lauwereyns Victoria University of Wellington, New Zealand

2. How does the brain incorporate reward value in the control of action?

3. Studied in monkeys using saccadic eye movement tasks with asymmetrical reward schedule

4. Biased Saccade Task (BST)

10. Target position = unpredictable

11. Biased Saccade Task (BST) Reward association = known

12. Biased Saccade Task (BST)

15. No escape!

16. Biased Saccade Task (BST)

20. Saccade-related brain areas (macaque monkey) FEF: frontal eye field SEF: supplementary eye field LIP: area LIP of parietal cortex CD: caudate nucleus SNr: substantia nigra pars reticulata SC: superior colliculus Clbm: cerebellum SG: brainstem saccade generators

21. DA neuron responds to Reward & Reward Predictor

22. Signal Noise Neuronal activity Noise Signal +

23. Improved discrimination

24. Improved discrimination: Synergistic, multiplicative Sensory properties Non-linearly enhanced by reward Response = Input * Reward Gain Prefrontal cortex, parietal cortex Superior colliculus

25. General increase

26. General increase: Prospective, additive Bias in anticipatory activity Linearly enhances sensory activity Response = Input + Reward Bias Prefrontal cortex, basal ganglia Superior colliculus

27. Improved discrimination & General increase

28. Combination of both mechanisms Seen in all areas Loops between FC, BG and SC But most common in Superior Colliculus Response = (Input * Reward Gain) + Reward Bias On toward the oculomotor plant

29. Dopamine

30. Excitation

31. Dopamine Excitation Disinhibition

32. Synergistic, multiplicative Dopamine Excitation Disinhibition

33. Prospective, additive Synergistic, multiplicative Dopamine Excitation Disinhibition