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SIE 515 Brain-Computer Interfaces (BCI) and Sensory Substitution
Class 25
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Today’s Schedule BCI function BCI input devices
Neuroprostheses (retinal, cochlear, cortical implants) HCI challenges with BCI Output BCI devices Sensory substitution (various flavors) Ethics and BCI
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Overview What is BCI? Most HCI principles = indirect connection to the brain Direct BCI devices Replace sensory organ (implant) Monitor brain activity (EEG device)
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How Does BCI Work? Two categories based on information flow:
BCI input devices: Feed-forward processing of external signals BCI output devices: Measuring electrical activity from the brain Goal of BCI input Neuroprosthetics: Artificial device aims to restore function of damaged sense organ
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Figure of Retinal Implants
Goal = Transduction of stimulus energy into neural signal
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Figure of Cochlear Implant
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Cortical Implants
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HCI Considerations Problems with neuroprosthetics
What are two important HCI factors when designing BCI devices?
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BCI as Output Using electrical signals from the brain to control an interactive system Facilitates execution of movements without motor output Works by determining correspondence between electrical signals and motor response codes Role of population vectors and neural ensembles Two types of BCI output Implanted electrodes External device
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Monkey Figure
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External BCI Devices
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How Do External BCI Output Devices Work?
Works by measuring electrical activity of brain from outside the head Problems and challenges Requires brain wave entrainment p300 signal most important Future BCI devices could use blood oxygen changes (fMRI)
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Neural Motion Detection
Left panel: Voxels in both hemispheres did not reveal significant differences between rightward and leftward stimuli, both for moving and for static sounds. Right panel: The graph shows the classification accuracy for moving and for static sounds separately, the grey line indicates chance performance. In contrast to the conventional ROI analysis, the classifier was able to reliably differentiate between leftward and rightward moving stimuli.
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Sensory Substitution What is the goal of sensory substitution?
Difference between sensory substitution and neuroprosthetics Direct vs. indirect interface Intra-modal vs. inter-modal communication Assumptions underlying effective sensory substitution
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How Does Sensory Substitution Work?
Brain plasticity: Adapt to new stimuli/function Types of plasticity
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Visual Tactile Tongue Display
News in Science, Vol. 299, 14 March 2003
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Seeing With Sound Uses three translation dimensions
Horizontal position in image = Time Vertical position in image = Frequency Brightness of image = Loudness
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vOICe Demo
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vOICe Demo
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vOICe Demo
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vOICe Demo
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Vibro-audio Interface
Used Samsung tablet with 7-inch touchscreen Contact with onscreen visual elements synchronously triggered vibration and auditory cues Focal vibration to the finger allows for vibro-tactile perception of points, lines, and regions Vibro-Audio cues were optimized based on psychophysical studies (Raja, 2011)
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Ethical Considerations of BCI
Tapping our inner mental world Many mental states we would not want to be recorded or broadcasted Other potential issues: Animal research, mind control, electro-viruses…
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For Next Class Assignment 22: HCI Advancement Themes
Task 1: Write down two major themes that you think will be important to the advancement of HCI research and technology development moving forward. In doing so, think about how the changing trajectory of technology will impact future user demographics and interaction styles. Task 2: For each overarching theme, write about questions or thought experiments to discuss with the class about how future developments will change our current notions of human-computer interaction. What problems do you foresee with these developments and whether they are ultimately helpful or hindering. This will be the primary topic of the class, so everyone should read each other’s blog posts. Please post your response to the blog by 11:59PM on 4/27/16.
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