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Timing

Timing. Periodic Timing Cyclical behaviour controlled by 24 hour clock time or (circadian) Interval Timing Stopwatch timing. Periodic Timing. 4pm 8pm Midnight 4am 8am Mid-day. ACTIVITY. Light on. Light off. Controlled by daily time or by light off?.

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Timing

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  1. Timing • Periodic Timing • Cyclical behaviour controlled by 24 hour clock time or (circadian) • Interval Timing • Stopwatch timing

  2. Periodic Timing 4pm 8pm Midnight 4am 8am Mid-day ACTIVITY Light on Light off Controlled by daily time or by light off?

  3. Roberts (1965) • Activity cycle slightly less than 24 hours in constant dim light • Restoring visual cues produces a gradual shift back to correct time. • Entrainment: light acts as a zeitgeber (resets 24 hour clock)

  4. 19 hour 24 hour 29 hour Bolles & Stokes “Too Hot” “Just Right” “Too Cold”

  5. Bolles & Stokes (1965)

  6. Periodic Timing Paris 4am 8am Mid-day 4pm 8pm Midnight Light Dark Food New York 11pm 4am 8am Mid-day 4pm 8pm Light Dark Food

  7. Oscillators (Long Intervals)

  8. Example RRR RRG RGR RGG GRR GRG GGR GGG

  9. Interval Timing

  10. Peak Procedure

  11. Weber’s Law One vs. Two Seconds Absolute Difference = 1 Weber’s Ratio = 1/2 = 0.5 Prediction: Very Easy

  12. Weber’s Law Nineteen vs. Twenty Seconds Absolute Difference = 1 Weber’s Ratio = 1/20 = 0.05 Prediction: Very Hard

  13. Long or Short? 2 s Choose Lever 1 8 s Choose Lever 2 Absolute 2 s (2 + 8) / 2 = 5 5 s? 8 s Ratio 2 s 4 is twice 2 4 s? 8 is twice 4 8 s ((2)(8))1/2= 4

  14. Long CS Temporal Discrimination Short CS

  15. Absolute = (8+2) / 2= 5 Relative = ((8)(2))1/2 = 4 Bisection Testing

  16. Scalar Timing N x T N n=N x T n*=N x T x K b = about 2/3

  17. Scalar Timing • How do remember times scaleto real time? • Error is relative • error is a constant proportion of the timed interval • called scalar timing • So, if the memory of time is • just right, k = 1.0 • too early, k < 1.0 • too late, k > 1.0

  18. Dopamine • Clock Speed Theory • Agonists (speed clock, left-shifted, K < 1.0) • Antagonist (slowed clock, right shifted, K >1.0) • Threshold Theory • Agonists lower threshold (impulsivity) • Antagonist increase threshold (sluggish) • Striatum Theory • D1 affects general motivation (number of responses) • D2 affects response timing (time of peak)

  19. Some Data

  20. Parkinson's • Dopamine D1 depletion causes reduced motivation to respond (decrease in amount of responding) • Dopamine D2 depletion causes a leftward shift (late timing) • External stimulus might replace internal cues from the striatum

  21. Learning-to-Time (LET) P M T L C Behavior Sequence: Start P = Peck M = Move T = Turn L = Look C = Coo Stop

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