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Really, how much time does it take to detect and odor? PowerPoint Presentation
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Really, how much time does it take to detect and odor? - PowerPoint PPT Presentation

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Really, how much time does it take to detect and odor?
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  1. Really, how much time does it take to detect and odor?

  2. So on the one hand, if we parse time by significant operational milestones, the delay from onset responses in the OB (as measured optically) and behavioral responses can be as little as ~100 ms.

  3. Question: what if the animal is challenged by increasing task demands?

  4. The vapor-phase liquid dilution olfactometer and training/testing cage Time measures: “Sample time” is defined by the amount of time the snout was in the olfactometer (based on breaking, unbreaking a light beam sensor). “Response time” defined as the time between exiting the olfactometer and touching the water licker. • Operant Training • Animals rewarded for • Licking the feeder (water) • Nose pokes into the olfactometer port • Keeping the snout in the port until the odor is presented. (160 trial process) • Training then continued until mouse could reliably poke nose wait for odor then respond with a lick.

  5. Mean sample time on S+ trials, increased from 347 ms in the first 100-trial to 392 ms in the last (A): longer sample time = better performance. A subsequent drop in concentration dropped accuracy for 1-2 blocks and insignificantly increased sample time to 415 ms (B) 50% increase in flow did not affect sample time but 50% decrease in flow did. (C vs. D) but recovers when flow is restored (E). Differential reinforcement of S+ and S- odors did not yield differential response times (F). Size of reward from 3ul to 15ul had no effect (G)

  6. Over training (extended number of conditioning trials) does not sample time in detection tasks but does in discrimination tasks (for the S+)

  7. Increasing task difficulty lowers performance and increases sample time However, again as sampling time increased accuracy improved (B,D,F&G2 to differing degrees). B. Switch from water S- to odor S- D. decrease in concentration of the S- from 0.5% to 0.375% F. Change S+ from 0.5% to 0.0005% G1. 99:1 blend S+ G2. 80:20 Blend of S+

  8. Close up of G2 (for chance-level responding mice) reveals that even though they failed to discriminate to criterion S+ and S- response times diverged normally