Stimulus Delivery and Response Systems

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Stimulus / Response Equipment
                          *The stimulus should be set up prior to the subject’s arrival.

Visual Stimulus System
A. The Visual Stimulus Software includes:
Stim Program – a DOS based software program which delivers visual stimuli.
Presentation – a stimulus delivery and experimental control software system for neuroscience. Runs on Windows and uses standard PC hardware. Allows more precise timing for stimulus delivery and experimental control. Provides millisecond temporal precision and complete timing information for all stimulus and response events.
Features include:
- Images stored as bmp, jpg, or pcs (picture stimuli).
- Use any adapter display mode from 32 bit color to palletized display modes.
- Synchronizes stimulus appearance with monitor vertical scan (Picture Timing Control).
- Shows a new stimulus up to every vertical scan.
- AVI and MPEG video (video stimuli).
- Animations.
- Built-in programming language for custom control (PCL).
- Controls stimulus presentation in real-time.
- Adjusts stimuli based on responses or external inputs in real-time.
- Reports times for any event of interest (logfiles).
- Verifies all timing to detect operating system problems.

B. The Visual Interface includes the:
•DLP Visual Projector System which consists of:
-DLP Projector
-Remote Control
•Eye Tracker - which allows simultaneous visual stimulation and eye tracking for MEG applications consisting of:
-Eye Tracker

C. The Visual Projector System
The ProPixx DLP Back Projector system consists of a projector and a screen mounted to the gantry. Images are projected through a hole in the shielded room wall into a set of mirrors which projects the image onto the screen. The image size is up to 40 degrees visual field for eye-screen distance of 37.2 to 52.5 cm.
-a native resolution of 1920 x 1080 and can be driven with refresh rates up to 500Hz (RGB mode) or 1440 Hz (Greyscale mode) with deterministic timing.
-Uses high brightness LEDs as a light source, giving a larger color gamut
-The LEDs support high bit depth and high frequency full color stimulation.
-For stereo vision applications the high speed circular polarizer can project stereoscopic stimuli for passive polarizing glasses at up to 4000 Hz.
Equipped with:
-a stereo audio stimulator,
-a button box port for precise reaction-time measurement,
-triggers for electrophysiology and eye-tracking equipment, and
-a complete analog I/O subsystem that synchronizes subject I/Os to video refresh with microsecond precision.

Powering the Projector:
PROJECTOR STATUS - LEDs supply info on the: Power Status Energy Status
LEDS ON Blinking
BLUE LED Awake Mode LED Off mode
RED LED Sleep Mode Thermal Shutdown

AWAKE MODE: Press the POWER button and release, the projector will power ON.

The LED will be a solid BLUE light.

SLEEP MODE: Press the POWER button for 3 secs, the POWER indicator/LEDs will

be a solid RED and the projector will be in the sleep mode OR thermal shutdown.

THERMAL SHUTDOWN: Flashing RED LEDs indicates the lamp is shutting down.

When flashing stops, the projector is in the SLEEP Mode (OFF) as indicated by the solid RED LEDs.

1. TO POWER ON - On the projector, press the POWER button once.
2. TO POWER OFF - press the POWER Button and hold for 3 seconds. The projector will enter the thermal shutdown mode and after a short delay the power will turn off / enter the sleep mode.

*The Projector has a 30-40 ms delay before it displays an image.
**In order to preserve the bulb life, turn the projector "OFF" after each use.

Positioning the Projector:
The projector position may be adjusted manually by shifting slightly to the:
  • Left or Right and
  • Up or Down.

Lens Adjustments:
Manual Adjustment
1. Images may be focused by turning the silver and black lens collar located on the projector.
2. The projector lens should be centered in the middle of the screen and should be perpendicular to the mirror; otherwise the image will be distorted, making viewing difficult.

Program Adjustment
This function can be used to adjust the focus, zoom, and keystone settings. *Generally only manual adjustments are necessary.
1. Press LENS to select mode. Each time LENS is pressed, the screen changes.
2. Press ENTER to display test pattern.
3. Press the arrow buttons to make adjustments.
4. Press LENS until normal screen appears.
5. To reset the KEYSTONE setting, press UNDO.

Mirror Adjustments
Wall Mirror Adjustments:
1. Project an image onto the mirror.
2. Adjust the wall mirrors:
a. Position the top mirror in front of the lens so that the image is reflected down to the bottom mirror.
b. Adjust the bottom mirror so that the image is projected centered onto the screen.
Ceiling Mirror Adjustments ( for Supine Recording):
1. Place the ancillary wall mirror on the 2nd set of wall brackets.
2. Project an image onto the mirror.
3. Adjust the mirror back or forward so that the image is projected down onto the screen.

Screen Adjustments:
1. Position the screen so that it is in the center of the subject's visual field. Then center the image so that it is projected centered onto the screen. If possible the screen should be perpendicular to the floor.
2. The screen distance can be increased or decreased by loosening the black knob located on the telescoping screen arm and adjusting the arm length. *Note: that adjusting this distance will change the visual angle. Always change the screen back to its original position when done.
3. If necessary, the screen can also be removed and flipped so that it is closer to the subject. Loosen the knob located on the telescoping screen arm. Pull the arm out, flip the screen and re-insert. Position the screen and tighten the knob. *Note: adjusting the distance will change the visual angle. Always change the screen back to its original position when done.
4. Use the black knob located on the Gantry Mounting Bar to raise and lower the screen.

Black Screen Function:
This function can be used to superimpose a black screen over the projected image. The Remote Control or theTouch Pad located under the projector can be used to activate this function.
1. Blacking out the Projected Image WITH On-Screen Display:
a. Press BLACK SCREEN. The screen turns black and “BLACK SCREEN” is displayed on the screen.
b. To return to the original projected image, press BLACK SCREEN again.

           *For remote control operation, slide the MOUSE/ADJUSTMENT switch to the MOUSE position.

Optical Sensor System

The optical sensor is positioned in front of the projector (inside the projector tube). It measures the light output of the projector and is used to determine accurate timing of visual stimulus onset times.

The system includes:
•Optical Sensor
•DLP Projector
•Illumination Sensor Box
Operation / Setup:
1. Place the Power Switch for the Illumination Sensor Box (which is located on the stand outside of the MSR) in the ON position.
2. Adjust the Optical Sensor located in the projector tube. *Sensor may be taped to the lower mirror for better accuracy.
3. Check the rack to ensure that the optical sensor output is plugged in. It is typically on ADC 16.

Video Stimulus Presentation / Eye Tracking System

The Avotec Silent Vision Video Stimulus Presentation / Real Eye Tracking System allows simultaneous visual stimulation and eye tracking for MEG applications. The Avotec Binocular Fiber Optic Video Presentation System consists of an optic device for attachment to the MEG system gantry. The Real Eye Tracking System is an infrared eye position tracking system which takes a picture of the eyes.

It consists of four subsystems:

• Avotec Silent Vision - Video presentation system

• Eye Illumination Sensor – infrared eye illumination • Avotec Real Eye Tracker Interface – video based eye tracking system • Eye Tracking Computer Interface (currently not available)

1. Press the Power button for the Silent Vision which is located at the operator’s console.

2. Press the Power Switch for the Real Eye Tracker Interface located at the operator’s console.

3. Turn the Real Eye – Infrared Level Knob (IR) clockwise until (from high to low) approximately one-third of the LED indicator is lit.

4. The monitor of the Real Eye Tracker Interface should show an eye image.

5. If the eye image is rotated away from the horizontal, the image may be rotated using the Silent Vision Glasses Coupling Lens Assembly:

a. On the coupling lens assembly, slightly loosen the rotation lock screw by turning it counterclockwise. b. The rotation lock screw may then be pushed to the left or right until the eye image on the monitor is correctly oriented. c. Re-tighten the rotation lock screw.

Auditory Stimulus Uses SoundBlaster or Presentation Software.

The auditory stimulus interface includes: • Stereo amplifier. • Binaural (stereo) auditory feed through a pair of low-distortion silicone tubes which have about a 10-11 msec delay and a bandwidth of 5kHertz. • Foam ear inserts (in various sizes) to fit in the subject’s ears. • Auditory tubing inserts. • A sound level meter to calibrate sound delivered to the subject. Foam Ear Tip with with Auditory Tubing Insert & Low-Distortion Silicone Tube

1. Attach the short color coded Auditory Tubing Inserts onto the end of the Low Distortion Silicone Auditory Tubes which are hanging on each side of the Gantry mounting bar. Place Red on the right side and the Blue on the left.

2. Attach the Foam Ear Tip Insert into the Auditory Tubing Inserts. A connector (tube nibble) may be required to keep the insert from coming out.

3. Slowly roll (rather than squeeze) the Foam Ear Tip into as small a diameter as possible.

4. Quickly insert the compressed plug well into the ear canal.

5. Hold in the ear with finger tip until expansion is complete.

6. Repeat process for the remaining ear.

7. The tubing may be taped on the subject’s cheek to assure that

      the insert does not become dislodged during testing.

8. Click on the SoundBlaster or Presentation software from the desktop on the Stimulus Computer located at the operator’s console.

a. Adjust the sound intensity level (db). b. Click on Start.

Insertion depth affects interaural attenuation. Be sure to select the correct size Foam Ear Tip to obtain the best fit in the ear canal. Insert as far as possible into the ear canal.

Somatosensory / EMG Stimulus The Grass S88 Nerve / Muscle Stimulator features include:

• Two output channels for separate nerve locations (with independent control), • Quartz crystal controlled digital timing circuitry, • Variable pulse rates and durations, • Variable train rates and durations, • Variable delays, and • Variable stimulus voltage.

One Channel Single Repetitive Nerve / Muscle Stimulation

          The Grass S88 consists of two stimulus channels:  S1 unit controls are silver; S2 unit controls are black.

DIAL Setting MULTIPLIER SWITCH Setting Volt Control Variable Volt Multiplier 10 SIU

Rate Variable Rate Multiplier X1 Duration Variable Duration Multiplier X1 Delay (ms) *Optional Delay Multiplier *Optional Function Switch Single

1. Turn on the Power for the S88. The switch is located at the bottom right corner of the unit. The orange light should turn on.

2. Turn ON the S1 UNIT. The switch for the S1 (upper) unit is located in the right upper corner flanked by the ON pilot lamp and the red Overload Lamp. a. Press the ON Switch in the upward direction.

3. Set the S1 Volt Multiplier Switch to 10 SIU. a. Set the S1 Volt Control Dial to the lowest level. This will be equivalent to < 1 volt. (This is important because if the voltage is too high when the electrodes are plugged in, the subject might experience extreme discomfort).

4. Set the S1 Rate Multiplier Switch to X1. a. Select the S1 Rate (pulses per sec).

5. Select the S1 Duration Multiplier Switch scale. (It is recommended that the multiplier is set on the X1 scale). a. Select the S1 Duration (pulse length in ms).

6. Determine the S1 Delay Dial (ms) if any.

7. Set the S1 Function Switch to Single. Response Pads Lumitouch Response Pad Lumitouch is a 5 key fiber optic response keypad. The system consists of absolutely metal free keypads connected via fiber optic cable to an opto-electronic controller unit. The cabling is fabricated from 100% plastic materials and therefore does not cause electromagnetic interference.

There are five response buttons which are arranged so that all or a subset of fingers can be used in a natural order and comfortable positioning when responding to a visual and/or auditory stimuli. Designed for placing on the arm rest.

1. Instruct the subject in the use of the Lumitouch Response Pad.

FORP Response Pad The FORP (Fiber-Optic Response Pad) is a fiber optic based response device. The response pad is completely non-metallic and non-electronic. It is intended for use in MEG, MRI or other environments where metal or electronics could hinder data acquisition, degrade image quality, or pose safety risks.

There are 4 colored buttons which are arranged in a diamond pattern. It is designed to be held or cupped in the hand while using the thumb to respond to the appropriate color, position, number or pattern of the buttons.

1. Instruct the subject in the use of the FORP Response Pad.