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Visually-induced auditory spatial adaptation in monkeys and humans

Visually-induced auditory spatial adaptation in monkeys and humans. Norbert Kopčo, I-Fan Lin, Barbara Shinn-Cunningham, Jennifer Groh Center for Cognitive Neuroscience, Duke University Hearing Research Center, Boston University Technical University, Košice, Slovakia. Way to go Red Sox!.

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Visually-induced auditory spatial adaptation in monkeys and humans

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  1. Visually-induced auditory spatial adaptation in monkeys and humans Norbert Kopčo, I-Fan Lin, Barbara Shinn-Cunningham, Jennifer Groh Center for Cognitive Neuroscience, Duke UniversityHearing Research Center, Boston UniversityTechnical University, Košice, Slovakia

  2. Way to go Red Sox! Way to go Red Sox! Introduction • Visual stimuli can affect the perception of sound location e.g. the Ventriloquism Effect • But does effect persist? SFN 07 San Diego

  3. Way to go Red Sox! Introduction • Visual stimuli can affect the perception of sound location e.g. the Ventriloquist Effect • But does effect persist? • - barn owls: prism adaptation (Knudsen et al.) • - monkeys: “ventriloquism aftereffect” (Woods and Recanzone, Curr. Biol. 2004) SFN 07 San Diego

  4. GOALS • Ventriloquism “aftereffect” in saccade task, in monkeys and humans? • - well-defined sensory-motor paradigm • - bridge to barn owl prism adaptation studies (on different time scale) • Reference frame of plasticity? • - Visual, auditory, or oculomotor reference frame? SFN 07 San Diego

  5. Methods • Basic idea: • 1. Pre-adaptation baseline: Measure auditory saccade accuracy • 2. Adaptation phase: Present combined visual-auditory stimuli, with visual location shifted • 3. Compare auditory saccade accuracy pre- and post-adaptation SFN 07 San Diego

  6. Methods • Initial experiment: Does it work? • Design: • Monkey • Pre-adaptation baseline – ~100 Auditory-only trials • Adaptation phase – • 80% V-A stimuli, visual stimulus shifted 6 deg. Left or Right • 20% Auditory-only • Compare Auditory-only trials from adaptation phase to pre- • adaptation phase Sounds: Loudspeakers Visual stimuli: LEDs SFN 07 San Diego

  7. RESULTS SFN 07 San Diego

  8. RESULTS SFN 07 San Diego

  9. RESULTS SFN 07 San Diego

  10. RESULTS SFN 07 San Diego

  11. Methods: reference frame ? Eye-centered? ? Oculomotor? Head (ear) -centered? SFN 07 San Diego

  12. Expected behavior • Magnitude (°) • Stimulus Location (°) Method • Induce shift: • - in only one region of space • - from a single fixation point • Test to see if shift generalizes • to the same sub-region in: • - head-centered space • - eye-centered space • Experiment divided into • 1-hour blocks: • (12 for humans, 16 monkeys) • Within a block, 3 types of • randomly interleaved trials: • - AV 50%, • - A-only, trained FP • - A-only, shifted FP • Audiovisual display SFN 07 San Diego

  13. Speakers • LEDs • FP • or Results: Humans • Audiovisual display • Trained FP A-only • responses: • - Shift induced in • trained sub-region • - Generalization to • untrained regions • (asymmetrical) • Magnitude of Induced Shift (°) • Shifted FP A-only • responses: • - Shift reduced in • center region • Head-centered • representation, • modulated by • eye position • Stimulus Location (°) • Expected Responses SFN 07 San Diego

  14. Speakers • LEDs • FP • or Results: Monkeys • Audiovisual display • Trained FP A-only • responses: • - Shift in trained sub- • region weaker • - Generalization to • untrained regions • stronger • (asymmetry oppo- • site to humans) • Magnitude of Induced Shift (°) • Shifted FP A-only • responses: • - Shift decreases on • the right • - Shift increases on • the left • Stimulus Location (°) • Expected Responses • Humans: Representation more mixed SFN 07 San Diego

  15. Summary • The main results are consistent across species: • Locally induced ventriloquist effect results in short-term adaptation, causing shifts in responses to A-only stimuli from trained sub-region. • The induced shift generalizes outside the trained sub-region, with gradually decreasing strength (However, the pattern of generalization differs across the species) • The pattern of induced shift changes as the eyes move. But, overall, it appears to be in a representation frame that is more head-centered than eye-centered. SFN 07 San Diego

  16. Discussion • Posterior • Parietal • Cortex • Neural adaptation could have been • induced at several stages along the • Pathway (IC, MGB, AC, PPX, MC, • SC). • In humans, multiple effects • observed at different temporal • scales  likely adaptation at • multiple stages • Future work • Extend Examine temporal and spatial factors influencing the eye-centered modulation. • Look at other trained sub-regions. • Cerebrum • Thalamus • Thalamus • Midbrain • Midbrain • Pons • Pons SFN 07 San Diego

  17. Summary and discussion • the main results are consistent across species:Locally induced ventriloquist effect results in short-term adaptation, causing shifts in responses to A-only stimuli from trained sub-region.The pattern of induced shift is modified as the eyes move. • Bad news – there is a lot of differences between species: • HumansMonkeysRepresentation head-centered, eye-modulated eye-centered • Generalizationto untrained sub-regions more on the side away from FP opposite • Difference betweenhyper- and hypometricshifts no yes • Representation whenshift induced on side (data not shown) head-centered, no eye modulation eye-centered SFN 07 San Diego

  18. Speakers • LEDs • FP Results: Humans • Audiovisual display • Human Behavior • Mean+SE • Magnitude of Induced Shift (°) • Expected Responses • Stimulus Location (°) SFN 07 San Diego

  19. Results: Humans • Audiovisual display • Expected Responses • Human Behavior • Data collapsed across • direction of induced • shift • Speakers • LEDs • FP • Trained FP A-only • responses: • - Shift induced in • trained sub-region • - Generalization to • untrained regions • (asymmetrical) • Stimulus Location (°) • Mean+SE • Shifted FP A-only • responses: • - Shift reduced in center • region • Head-centered repre- • sentation, modulated • by eye position SFN 07 San Diego

  20. Results: Humans vs. Monkeys • Human Behavior • Audiovisual display • Monkey Behavior • Monkey data • (only hypometric) • AV responses: • - as expected • 6 • Speakers • Mean+SE • Mean • LEDs • FP • Trained FP A-only • responses: • - Shift in trained sub- • region weaker • - Generalization to • untrained regions • stronger • (asymmetry opposite • to humans) • 6 • -24 0 24 • Mean+SE • Mean+individuals • -24 0 24 • Shifted FP A-only • responses: • - Shifted with eyes • Representation more • eye-centered • Mean+individuals • Mean+SE • -24 0 24 SFN 07 San Diego

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