1. Multi-Channel Gustometer
Kevin A. Johnson
Advisor: Dr. David H. Zald
Neuroimaging Engineer: Patrick Henry

2. Multi-Channel Gustometer
General Design Objective
Device to present an array of taste stimuli.
Delivery of stimuli must be in a controlled manner.
Intended for functional neuroimaging (fMRI) studies on human participants.
Adaptable to a variety of experiment protocols.

3. Gustometer Background
Multi-channel gustometers have been used for psychophysical studies on monkeys.
(Reilly et al. 1994)  Computer Automated
Current gustometers for neuroimaging provide only a few (generally 1 or 2) taste stimuli. (Zald et al & 2002)
 NOVELTY: Multi-channel gustometer for functional neuroimaging.

4. fMRI Background Strong magnet field environment (3T).
 Safety and interference considerations.
Time course of neural-physiological response to be measured is quite rapid.
 Requires precise control of stimuli delivery and response measurement.
Imaging technique is very sensitive to physical movement of participant.
 Need passive reception of stimuli.

5. Specification Demands
1. fMRI Friendly
No ferrous materials within 10 ft. of participant (preferably farther than 10ft).
Minimal electronics close to subject.
Note: In past experiments, this demand has been achieved by delivering fluid stimulus through extended tubing.

6. Specification Demands (cont.)
Ability to deliver up to 10 different fluids.
Ability to deliver from 0.5 – 5 ml discrete boluses of liquid.
(Accuracy:  15%)
Safety: consider amount intake.

7. Specification Demands (cont.)
Ability to switch in a relatively constant flow (no more than 250 ms pause) from one stimulus to another.
Note: It is fine if there is a time lag (< 1 s) between a stimulus pulse (stimulus switch) and the time it reaches the participant, as long as the timing is consistent ( 250 ms).

8. Specification Demands (cont.)
A fixed flow rate of 0.5 ml/s is acceptable.
Ability to deliver up to 50 cc in a session for each stimulus, with one stimulus (for saline) able to deliver more (up to 200 cc).
Ability to exchange stimulus containers quickly (exchange all 10 in less than 5 minutes).

9. Specification Wishes
Expandable to deliver more than 10 different fluids.
Ability to vary flow rate (as low as .25 ml/s or as high as 1 ml/s).
Easily to sanitize (contamination resistant).

10. Specification Wishes (cont.)
Easily portable.
Protective covering.
User-friendly.
Quick development time of device.
8. Reasonable cost.

11. Innovative Approaches?
Electrical Simulation of Taste?
 Perceptual Problems
Single pump with stimuli prearranged in single tube?
 Contamination Problems
Solid taste stimuli?
 Numerous Problems
Pneumatic-Controlled Pumps Closer
 More components, re-setup time
 Use concept, possible alternative

13. Probable Merging Unit Configuration

14. Delay = (Distance)/(Speed)
Stimulus Delay
Delay = (Distance)/(Speed)
Max Delay: 1 second
Max Pump Speed: cm/mn (?)
 Max Tubing Distance

15. Current Status Verified pump/syringe specifications.
Verified pump control via computer.
Need to finalize merging design and order tubing components.
 Spoke concept.