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Prism Adaptation

Prism Adaptation. Prism Adaptation. Example. Prism Adaptation. Place yoked prism (base left or right) OU Subject makes motor responses Measure how quickly adaptation occurs Take prism off to measure after-effect. Prism Adaptation.

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Prism Adaptation

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  1. Prism Adaptation

  2. Prism Adaptation • Example

  3. Prism Adaptation • Place yoked prism (base left or right) OU • Subject makes motor responses • Measure how quickly adaptation occurs • Take prism off to measure after-effect

  4. Prism Adaptation • The adaptation phase is where the motor system adapts to a new visuospatial coordinates created by the yoked prisms. • The aftereffect is a method to measure the amount of adaptation that has taken place once the prisms have been removed.

  5. Prism adaptation • Parietal cortex • Cerebellum • Motor cortex

  6. Prism Adaptation • Held Experiment (1965) • Plasticity of the visual system • Depends on interaction between the motor and visual systems

  7. Ruiz & Diaz (1999) • Subjects throw ball at a target 2 meters away • Baseline, adapt to prism, after-effect • Investigated adaptation by number of throws and amount of prism

  8. Prism Adaptation • 10, 20 and 30 prism diopters of prism power • Varied number of throws 3, 6, 9, 13, 25

  9. Prism Adaptation • Conclusions • Larger prism power leads to greater displacement on first throw and increases the number of throws needed to adapt • Aftereffect depends on the number of visual motor interactions (throws) not on wearing time. • Aftereffect does not have the same magnitude as the adaptation

  10. Prism Adaptation in Neglect Patients • Can we use prism adaptation to aid patients with left side neglect? • http://www.youtube.com/watch?v=B-89qYu9Ov8&feature=related

  11. Prism Adaptation in Neglect Patients • Frassinetti et al 2002 Brain • 13 right brain injury patients • Half the patients where in a control group • Wore base left prism that shifted the field 10 degrees (34 cm viewing distance)

  12. Prism Adaptation in Neglect Patients • Pointed to objects in a box-similar to Held paradigm • 2 sessions a day for 2 weeks • The after effect lasts much longer in these patients (6 to 12 hours)

  13. Frassinett et al Study • Conclusions • Treatment resulted in long term effects • Treatment transferred to a wide variety of skills • Do not need awareness of the condition for improvements to occur. Bottom up task

  14. Why? • Neurological correlates of prism adapation • Cerebellum • Posterior parietal cortex • Motor cortex

  15. Possible Theories • Effect balance between right and left parietal areas • In neglect patient may force them to attend to right hemisphere information

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