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Cognitive Control Signals for Neural Prosthetics

Cognitive Control Signals for Neural Prosthetics . Sam Musallam The Andersen Lab sam@vis.caltech.edu. What is a cognitive signal? . Signals that lie along the sensory to motor pathway but away from sensory and away from motor Not visual Not motor Encode higher order variables Intention

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Cognitive Control Signals for Neural Prosthetics

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  1. Cognitive Control Signals for Neural Prosthetics Sam Musallam The Andersen Lab sam@vis.caltech.edu

  2. What is a cognitive signal? • Signals that lie along the sensory to motor pathway but away from sensory and away from motor • Not visual • Not motor • Encode higher order variables • Intention • Motivation • Value of a reward

  3. Cognitive-based rather thanmotor-based • May require fewer cells, less invasive • Cognitive variables-expected value • Hierarchical control using smart machines PMC

  4. Arrays are Implanted in the Medial Intraparietal Sulcus and Dorsal Premotor Cortex A5

  5. Electrodes C Arrays are Implanted in Medial Intraparietal Sulcus

  6. We are currently implanting 160 electrodes in PRR and in DPMC • - 32 electrode arrays • - Made from platinum and iridium • - 80 microns at the shaft • 2-3 micron tip

  7. Decoding Goals E Reach Trials Brain control trials

  8. Database Built on Memory Period Activity Monkeys are in the dark and are not allowed to move their: • Hands • Eyes This memory period activity is cognitive

  9. 75% chance chance Example of feedback performance:6 Parietal neurons Fixation maintained throughout trial. Decoding 900 ms of memory period

  10. More neurons also improve the decode(dPMC) 8 targets decoded with 16 neurons

  11. At 100 ms, predictions are still significantly above chance (25%)

  12. 2 types of databases used • Adaptive • Database updated after every successful feedback trial • Frozen • Database ‘frozen’ after the end of the reach trials

  13. Frozen or adaptive database? Doesn’t seem to matter

  14. Type of reward changes the tuning of neurons in PRR Black=orange juice Red = water

  15. Tuning is also enhanced for increased probability and magnitude of reward

  16. Our decoding ability improves with preferred reward condition Decode on 5 single units

  17. Overall decode improvement

  18. Decoding the value of reward

  19. Decoding Direction and Reward from a monkey with no single units Without the reward schedule barely above chance. Reward schedule improves decode

  20. Advantages of a Cognitive Prosthetics • Cognitive signals will allow us to directly determine the mood of patients • This can be done without requiring patients to indicate this preference using overt behavior. • Optimize control of prosthetic devices • counter neuronal sample biases.(surgical placement of electrodes, etc.) • allow multiple tool use.(update or variable functionality of prosthesis)

  21. Conclusion • Cognitive neural activity not directly related to visual input or motor output can be used for as prosthetic control signals. • Cognitive signals can also give us information about the patient’s preference or mood.

  22. Kelsie Pejsa Lea Martel Viktor Shcherbatyuk Tessa Yao Richard Andersen Brian Corneil Bradley Greger Hans Scherberger Grant Mulliken Rajan Bhattacharyya Igor Fineman Bijan Pesaran Daniella Meeker Acknowledgment

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