Abstract Professor Banks studies the neural pathways of mice in response to audio stimuli and tests their cognition and perception. Since spatial arrangement affects the perception of sound, the location of where the sound is heard relative to where the sound is emitted is vital for research purposes. Monitoring the orientation of the head relative to the speaker box will allow the client to incorporate this data to eliminate variation within his results. The final design consists of a mouse headpiece with LED’s, a camera, and a camera stand to hold the camera. The camera records LED’s to track movement of mouse head.

Problem Statement GOAL: To develop a lightweight, non- obtrusive device to measure the position and orientation of a mouse head. GOAL: To develop a lightweight, non- obtrusive device to measure the position and orientation of a mouse head. MOTIVATION: The device would be used during an experiment to correlate the mouse head orientation to the neural response of a mouse to an auditory stimulus MOTIVATION: The device would be used during an experiment to correlate the mouse head orientation to the neural response of a mouse to an auditory stimulus

Research Our client studies effects of drugs on perception and cognition of auditory system in mice Our client studies effects of drugs on perception and cognition of auditory system in mice Brain waves of mice in response to sound stimuli are measured Position and orientation of head relative to speaker will affect brain activity (Poldrack et al., 2001)

Motivation Spatial orientation of mouse affects perception of sound (Winmaier et al., 2003) Spatial orientation of mouse affects perception of sound (Winmaier et al., 2003) Client needs to locate position and orientation of the mouse’s head with respect to the emitted sound Client needs to locate position and orientation of the mouse’s head with respect to the emitted sound Knowing the location of mouse’s head reduces the variables within client’s experiment Knowing the location of mouse’s head reduces the variables within client’s experiment

Design Specifications Weight of head piece < 1g Weight of head piece < 1g Detachable from mouse Detachable from mouse Collects data on position and angle of mouse head relative to sound Collects data on position and angle of mouse head relative to sound Does not interfere with or skew experimental data Does not interfere with or skew experimental data Minimal calibration before each use Minimal calibration before each use Does not pose a danger to the mice or researchers Does not pose a danger to the mice or researchers

Design Alternative - Magnetic Components Components Magnetic sensor grid underneath cage Magnetic sensor grid underneath cage 2 or 3 small magnets on head 2 or 3 small magnets on head Measure magnitude of voltage Measure magnitude of voltage Disadvantages Disadvantages Not sensitive enough to record signal from magnet on mouse Not sensitive enough to record signal from magnet on mouse Magnets may interfere with experimental data Magnets may interfere with experimental data Metallic objects would interfere with data collection Metallic objects would interfere with data collection

Design Alternative - Electric Components Components 3 conducting spheres with specific charges and positions above mouse head 3 conducting spheres with specific charges and positions above mouse head Measure electric potential Measure electric potential Ability to measure head orientation Ability to measure head orientation Disadvantages Disadvantages Interference Interference Need additional known variable Need additional known variable Complicated Complicated

Design Alternative - Optical Components Components Four LEDs Four LEDs Camera in fixed location Camera in fixed location Continuous tracking Continuous tracking Disadvantages Disadvantages Cannot measure orientation Cannot measure orientation LED can be obstructed LED can be obstructed

Final Design – Optical System System Components System Components Headpiece with LEDs Headpiece with LEDs Camera Camera Camera stand Camera stand Major Concerns Only one component of orientation tracked Weight of headpiece Size, frequency, and resolution of camera

System Diagram

Headpiece Needs to fit around attached amplifier Needs to fit around attached amplifier Shape Shape Trianglular vs diamond? Trianglular vs diamond? LED LED Infrared vs colored? Infrared vs colored?

Headpiece Diamond shape allows for four LEDs Diamond shape allows for four LEDs Redundancy if one LED is blocked by wire or cage Redundancy if one LED is blocked by wire or cage Infrared LEDs do not cause a neurological response in mice Infrared LEDs do not cause a neurological response in mice Less possibility of interference with experimental data Less possibility of interference with experimental data Weighs ~0.8g

Location of LEDs View from above

Circuitry Each LED receives 18mA Each LED receives 18mA Circuit contained in a switch box Circuit contained in a switch box Power light on box indicates if LEDs on Power light on box indicates if LEDs on Allows for replacement headpieces Allows for replacement headpieces

Camera Stand Camera Support Camera Support Two rings hold camera Two rings hold camera Camera Safety Camera Safety Strap Strap Foam Foam

Ethical Issues Headpiece weight minimized to reduce load on mouse Headpiece weight minimized to reduce load on mouse System does not cause additional discomfort to animal System does not cause additional discomfort to animal System does not pose any danger to mice or researchers System does not pose any danger to mice or researchers

Future Works Connect camera to computer Connect camera to computer Test system in an actual experiment Test system in an actual experiment Ideal software: Integrates the information from the speaker and the camera into spreadsheet form Ideal software: Integrates the information from the speaker and the camera into spreadsheet form Incorporate method to determine head orientation Incorporate method to determine head orientation

References Poldrack, Russell A. and Gabrieli, John D. E. Characterizing the neural mechanisms of skill learning and repetition priming. Brain. 124: Poldrack, Russell A. and Gabrieli, John D. E. Characterizing the neural mechanisms of skill learning and repetition priming. Brain. 124: Simon, D.A. “Intra-Operative Postion Sensing and Tracking Devices.” Accessed: September 20, URL: Simon, D.A. “Intra-Operative Postion Sensing and Tracking Devices.” Accessed: September 20, URL: Winmaier, Eric P., Raft, Hershel, Strang, Kevin T Human Physiology: The Mechanisms of Body Functions, 9th ed. McGraw-Hill, NY. Winmaier, Eric P., Raft, Hershel, Strang, Kevin T Human Physiology: The Mechanisms of Body Functions, 9th ed. McGraw-Hill, NY.