Stimulus Delivery and Response Systems

From MEG Core
Jump to navigation Jump to search

Visual Stimulus System

Visual Stimulus Delivery Software

1.. Stim Program – a DOS based software program which delivers visual stimuli.
2. 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.
3. Matlab - Tasks can be programed within the Matlab environment
4. Psychopy - A full function stimulus delivery program based on python.
5. E-prime - Commercially available stimulus delivery software with a graphical programming interface. Task programming requires purchase of a license and dongle.

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.
1. Features:
a. The image size is up to 40 degrees visual field for eye-screen distance of 37.2 to 52.5 cm.
b. 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.
c. Uses high brightness LEDs as a light source, giving a larger color gamut
d. The LEDs support high bit depth and high frequency full color stimulation.
e. Tachistoscopic stimulation capability.
2.Equipped with:
a. A complete digital I/O subsystem that synchronizes subject I/Os to video refresh with microsecond precision.
b. High-contrast white screen for precision color operation.
3. TO POWER ON - On the Propixx Projector, press the POWER BUTTON Power Button once. The power switch on the Controller Box should always be in the ON position.
Use this switch to turn the projector off and on!
Power Button picture.png
4. TO POWER OFF - press the POWER BUTTON 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.
Use this switch to turn the projector off and on!
Power Button picture.png
If you switch to the "OFF" position the projector will lose all programmed settings!
Power Switch picture.jpg

6. Positioning the Projector:
The position of the projector does not need to be changed. For further information or help see MEG Staff.

7. Lens Adjustments:
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.
a. Manual Adjustment
i. vTo Focus - Turn the knurled ring (the silver and black lens collar) at the outer end of the lens to adjust the focus until the image is sharp.
ii. To Zoom - Turn the smooth ring on the lens, closest to the case, to adjust the zoom so that the image fills the screen.

b. Program Adjustment:
All functions, like resolution, can be changed from the desktop of the stimulus computer. However, if changes are made, please change back to the default settings when done.

8. The Remote Controller:
a. The Remote control has a 40 degree reception angle. The Remote must be pointed at the projector's LED (which is located in the back left corner of the projector) within that 40 degree angle to be received.
b. Using The Remote To Power The Projector On - Press POWER ON on the Remote Control to switch the projector ON.
c. Using The Remote To Power The Projector Off - Press POWER OFF on the Remote Control to switch the projector to OFF / SLEEP mode.

9. Projector Status Indicators:
The Projector's LEDs supply info on the power status and the energy status of the projector.
Press the SILVER POWER Button and release, the projector will power ON.
The LED will be a solid BLUE light.
Press the POWER button for 3 secs,
the LEDs will be a solid RED.
Flashing RED LEDs indicates the projector is shuttered.

but still on!

If when done the light on the projector is a flashing BLUE Light, press the POWER OFF/ON BUTTON to power off!

11. Reversing The Projection Scheme For Supine Recording – To Be Determined
a. Press MENU.
b. Use OPTION2 menu
c. Select REAR projection- choose this option if pictures are projected from the rear of a reflective screen.
d. Select CEILING mount – choose this option if the projector is installed on the ceiling (or upside down).
12. Mirror Adjustments
a. Wall Mirror Adjustments for Seated Recording:
i. Project an image onto the mirror.
ii. Position the top mirror in front of the lens so that the image is reflected down to the bottom mirror.
iii. Adjust the bottom mirror so that the image is projected centered onto the screen.
13. Ceiling Mirror Adjustments for Supine Recording:
a. Place the ancillary wall mirror (smaller mirror) on the 2nd set of wall brackets.
b. Position the top mirror so that it projects onto the smaller mirror. Position the smaller mirror so that it projects onto the ceiling mirror.
c. Slide the ceiling mirror into position so that the image from the ceiling mirror is projected onto the screen.
14. Screen Adjustments
a. There are two screens
i. The original screen with the original color pallet and,
ii. A white screen for high-resolution color.
b. Position the screen so that the image is projected centered onto the screen. If possible, the screen should be perpendicular to the floor.
c. The screen distance can be increased or decreased by loosening the black knob located on the telescoping screen arm and adjusting the arm length.
d. 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.
e. Use the black knob located on the gantry mounting bar to raise and lower the screen.
If you use the high-resolution screen please put the original screen back in place when done.

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

Eye Tracking System

The SMI iView X Hi-Speed Drift-Free Eye Tracking System is an eye tracking system that uses infrared illumination and computer based image processing. Images of the eye are analysed in real-time by detecting the pupil, calculating the center, and eliminating artifacts. Once a calibration is performed, the pupil locations is translated into gaze data. User's manual:

1. The SMI iView Eye Tracking System consists of:
a. Dell Optiplex 7010 Computer iView X Workstation (located at the Stim Console on the floor). The workstation is the eye tracking computer system that runs the software and contains the hardware components that allow the system to capture eye movements. It controls all camera equipment and processes all eye and scene video signals from the experiment. Data and video files are collected there and additional data out is provided on the various IO interfaces of the workstation. The workstation is used to setup experiments, control the eye tracking camera system, and to trigger events, such as calibration, drift correction, start and stop recording.
b. iView X Eye Tracker Remote Camera System (located in the MSR)

2. Software Operation:
a. Turn on the power to the iView X Workstation (Dell Optiplex 7010 Computer).
b. Double click on the iView icon to start the program.
c. Go to Setup -> Hardware and make sure the Eye Tracking Devise is set to RED (Remote Eyetracking Device) 250 (USB).
d. Now click on the advanced button and set tracking mode to 250Hz in the RED properties.
e. Click on the Communications tab in the Setup -> Hardward window to set the Remote Interface 1 to Ethernet and check the option Accept Remote Commands.
f. Go to Setup -> Hardware -> Communications-> Configure and verify that the Interface and Port numbers are the same.
g. Go to Setup -> Tracking. Make sure that the Input Filter has Binocular Data checked and check the Output in Video Pixels for Pupil Diameter. *In Binocular mode the data is collected for both eyes.

3. Camera Setup / Calibration:
Calibration is one of the crucial steps in eye tracking. It normally consists in looking at several marks on a screen in order to collect enough data to modify the parameters of an adjustable model.
a. Go to Setup-Calibration. The following options are recommended:
i. Enable Accept Points Automatically.
ii. Enable Wait for Valid Data.
b. Start SMI Experiment Center or a stimulus program capable of running an automatic calibration.
c. In the stimulus program choose Calibration Background Color and Target Color so, that it is similar to the stimulus presentation (what you want to look at during recording).
d. Place your subject in a comfortable position in front of and centered to the screen and cameras.
e. If the eyes are tracked by the system, two white eye dots are visible in the RED Tracking Monitor screen.
f. If tracking is lost the white dots have disappeared from the RED Tracking Monitor.
g. Arrows indicate the optimum position for the test subject in front of the monitor:
i. If the test subject is too far away from the screen an up arrow ↑ indicates that the camera should be moved closer.
ii. If the test subject is too close to the screen a down arrow ↓ indicates that the camera should be moved further away.
iii. Other arrows direct the test subject to center his or her head in front of the monitor. The test subject is sitting correctly if all arrows have vanished. The correct distance should be between 60 and 80 cm.
h. Click in the Eye Control window to activate the eye tracker. The message in the System Log should read "Grab started". Then follow these steps:
i. Move the camera horizontally until the eyes are horizontally centered in the eye image control.
ii. Adjust the vertical position of the camera (camera tilt) until the eyes are vertically centered in the eye image control.
iii. Adjust the tilt of the mirror to remove possible reflections from the eye image, after which the vertical position/tilt of the camera probably needs to be readjusted.
iv. Adjust the focus until the corneal reflection is as small as possible. This assures optimal focus on the eyeball.
v. Ask the test subject to look at a center target of the stimulus display. Click on the Auto Adjust button to automatically adjust the image regarding pupil threshold and image balancing.
vi. The white cross-hair should be centered on the pupil and the black cross-hair on the corneal reflex (CR). If not, adjust them by moving the sliders.
vii. As the test subject to look at the four corners of the screen.
x. Setup is complete if both cross-hairs follow the pupil and cornea reflex during these eye movements.
i. If the image seems to be blurred, is too dark or too bright, click on the Image Adjust button to adjust brightness and contrast or you can also click on Auto Balance to let the eye tracker self-adjust its brightness and contrast.
j. The result of the measurement is an '.idf file' recorded and stored on the iView X computer. The resulting file can be laded into SMI BeGaze analysis software for visualization and further analysis.

Auditory Stimulus System

1. The Auditory Software includes:
a. SoundBlaster: The Sound Blaster software suite is a powerful audio platform equipped with cutting-edge audio technology. Provides premium audio quality, effects and features for ordinary PC systems equipped with only basic on board audio.
b. Presentation
Presentation is a stimulus delivery and experiment control program for neuroscience. It runs on any Windows PC, and delivers auditory, visual and multimodal stimuli with sub-millisecond temporal precision. Presentation is powerful enough to handle almost any behavioral, psychological or physiological experiment using fMRI, ERP, MEG, psychophysics, eye movements, single neuron recording, reaction time measures, other performance measures.
– Runs on Windows Vista/7/8/10
– Is built for precise stimulus delivery and accurate event logging
– Delivers 2D visual, 3D visual, and auditory stimuli separately or simultaneously
– Delivers compressed video with precise frame control
– Monitors responses on a variety of devices
– Interfaces with external hardware
– Is programmable
– Verifies time measurements for all events
– Is extensible
2. Auditory Stimulus Interface includes:
a. Stereo amplifier.
b. Binaural (stereo) auditory feed through a pair of low-distortion silicone tubes which have about a 10-11 msec delay and bandwidth of 5k Hertz.
c. Foam ear inserts (in various sizes) to fit in the subject’s ears.
d. Auditory tubing insert connecting nibs.
e. A sound level meter to calibrate sound delivered to the subject.
3.Inserting the Auditory Tubes (Earphones)
a. 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.
b. Attach the Foam Ear Tip Insert into the Auditory Tubing Inserts. A connector (nib) is required to attach the insert.
c. Slowly roll (rather than squeeze) the Foam Ear Tip into as small a diameter as possible.
d. Quickly insert the compressed plug well into the ear canal.
e. Hold in the ear with finger tip until expansion is complete.
f. Repeat process for the remaining ear.
g. The tubing may be taped on the subject’s cheek to assure that the insert does not become dislodged during testing.
h. From the Stimulus Computer desktop, at the operator's console, click on the auditory stimulus delivery software program, and adjust the sound intensity level (db).
Please Note: Insertion depth affects inter-aural 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.::::

Somatosensory / EMG Stimulus

1. The Grass S88 Nerve / Muscle Stimulator is a dual output general purpose stimulator intended for nerve and muscle stimulation procedures. There are two output channels which can be operated independently or synchronized to produce complex paradigms. The outputs are non-isolated constant voltage positive pulses. Features include computer compatibility and flexibility of synchronization circuits: the synchronous inputs and outputs are TTL, 5 volts, PC compatible. A rear DB25S connector permits external analog control of the timing circuits. The Stimulus Isolation Unit (SIU) allows for applications requiring isolation and/or constant current. Grass S88 Electrical Nerve/Muscle Stimulator - Stimulation is triggered via TTL outputs from the S88 to the MEG Omega 3500 electronics.
2. The Grass S88 Nerve / Muscle Stimulator features include:
a. Two output channels (S1 & S2) for separate nerve locations (with independent controls),
b. Quartz crystal controlled digital timing circuitry,
c. Variable pulse rates and durations,
d. Variable train rates and durations,
e. Variable delays, and
f. Variable stimulus voltage.
3. The S88 FUNCTION can be set to deliver:
a. Single – the RED SINGLE pushbutton is for manual operation (single independent pulses); also, delivers single repetitive stimulus.
b. Repeat – repetitive stimulus; continuous presentation of a selected stimulus pattern (recurring pulses).
c. Trains – trains per seconds (TPS) covers a range of 0.01 to 100 TPS; delivers a select number of pulses in defined intervals/delays.
d. Twin Pulses – pulse per seconds (PPS); delivers two pulses of identical voltage and duration; the time between the onset of the first and second twin pulse is determined by the DELAY Circuit; twin pulses can be obtained singly, repetitively on in trains of pulses (can be used to determine nerve and muscle refractory times.
e. Trains of Twin Pulses – delivers two pulses together in a series in defined intervals/delays from its single output.

One Channel Single Repetitive Nerve / Muscle Stimulation
*The Grass S88 has two stimulus channels: S1 Channel controls are silver; S2 Channel controls are black.

S88 Stimulator Settings - S1 Channel
Volt Variable Volt Multiplier 10 SIU
Rate (pulse/sec) Variable Rate Multiplier X1
Duration (ms) Variable Duration Multiplier X1
Delay (ms) *Optional Delay Multiplier *Optional
*Function Switch: Single
6. Grass Stimulator Controls:
All controls are equal to the setting on the dial multiplied by the setting indicated on the decade (multiplier) switch.
a. Rate – determines the rate at which pulses are delivered in pulses per second (1/100 sec to 100 PPS).
b. Delay – length of time before the pulse starts; pre-pulse interval (10usec to 10 sec).
c. Duration – pulse length; determines the length of time (T) in milliseconds that a pulse of a given frequency and voltage is delivered [1 msec to 10,000 msec (10 sec)].
d. Volt Control - Controls the intensity / strength of the pulse; range at the output is from 0.01 to 150 volts. Always begin with the VOLTS dial set to minimum (1) and increase until the desired stimulus intensity is achieved.
e. Voltage Decade (multiplier) Switch- multiplier switch; the output impedance is also determined from the Volts Decade Switch.
i. In the first four positions, the output impedance is 250 ohms and is constant at X.01, X.1, X1, and X10(SIU). At X10(25Ω) the output impedance is 25 ohms.
ii. For special applications requiring low impedance, high current output - set the multiplier to X10(25Ω). This position is provided for use with low impedance electrodes to obtain a relatively high current out. When using this mode, caution should be taken since very high stimulus currents can be delivered.
iii. When a Stimulus Isolation Unit (SIU) is connected in series with the output the X10(SIU) position is recommended for 15 to 150 volts out; *The SIU7 Isolation /Constant Current Unit should be operated at all times with the stimulator VOLTS multiplier set to the X10(SIU).
iv. X1 position is recommended for outputs of less than 15 volts.
f. Train Rate – in the S2 TRAIN position, trains of stimulus patterns are presented at the output of S2 at the rate set by this control.
g. Train Duration - in the S2 TRAIN position, trains of stimulus patterns are presented at the output of S2 at the duration set by this control.
h. Train Mode – To obtain trains, this switch must be in the SINGLE or REPEAT position.
5. Grass Stimulator Setup:
a. Turn on the Power for the Grass S88. The switch is located at the bottom right corner of the unit. The orange light should turn on.
b. The STIMULUS ON-OFF-ON LEVER SWITCH is located at the right-hand corner of each channel.
i. The upper ON position is for continuous voltage at the output; the lever switch will remain depressed (in the on position) when released; power will remain ON until the lever is switched to the up or off position.
ii. In the lower ON position the lever switch will remain ON only if it is depressed; it will return to the OFF position as soon as it is released.
c. Turn ON the S1 UNIT Press the ON Switch in the upward direction. The switch for the S1 (upper / silver) unit is located in the right upper corner flanked by the ON pilot lamp and the red Overload Lamp.
d. Set the S1 Volt Multiplier Switch to 10 SIU.
e. Set the S1 Volt Control Dial to 1 which is 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).
f. Select the S1 Duration Multiplier Switch scale. (It is recommended that the multiplier is set on the X1 scale).
g. Select the S1 Duration using the dial (pulse length in ms).
h. Determine the S1 Delay using the dial (ms) if any.
i. Set the S1 Rate Multiplier Switch to X1.
j. Select the S1 Rate (pulses per sec) using the dial. *Usually better to set at a slow pulse rate in order to find/locate the correct muscle/nerve then increase to the correct testing rate.
k. Set the S1 Function Switch to Single.
l. Attach the SIU (Stimulus Isolation Unit) -
mWhen the subject is seated outside of the MSR:
i. Plug the SIU into the S1 Stimulator OUT - ON THE FRONT OF THE GRASS S88 UNIT (unplug/unscrew the cable that is usually attached; re-attach original cable when done).
ii. Plug a Bar Electrode into the SIU. *Check to make sure that the Volt dial is set to zero then gradually increase.
n. When the subject is seated inside the MSR:
i. Open the Access / Penetration Panel Cabinet Door. Find the S1 Cable.
ii. Attach the SIU to the S1 Cable.
iii. Plug the Bar Electrode into the SIU. *Make sure that the Volt Dial is at zero and gradually increase.

The Stimulus Isolation Unit (SIU) / Constant Current Unit should be operated at all times with the stimulator VOLTS multiplier set to X10(SIU).
6.Grass SIU7 (Stimulus Isolation Unit 7) Setup::
a. Plug the Bar Electrode into the appropriate positive and negative jacks.
b. Set CURRENT RANGE to: 1-15MA
c. Set the POLARITY to: NORM.
7.Delivering the Stimulus:
a. Clean off the subjects skin using Nuprep. Brush off any residual grit.
b. Apply electrolyte to the electrodes ends of the Stimulus Bar Electrode.
c. Place the Stimulus Bar Electrode on the nerve or muscle to be stimulated. Gradually increase the voltage until you can see a twitch in the appropriate nerve or muscle. Decrease to motor threshold (subject can feel the pulse but there is no muscle twitch/movement), if desired. Tape into place.
d. Place a ground electrode / bar / pad on the subject distal to the stimulation site.
8.Grass Stimulator Specifications:
Train Rate (S1 and S2) 1/100 sec to 100 TPS (4 decades)
Train Duration 1msec to 10 secs (4 decades)
Rate (S1 and S2) 1/100 sec to 1000 PPS (5 decades)
Pulse Delay (S1 and S2) 10usec to 10 secs (6 decades)
Pulse Duration (S1 and S2) 10usec to 10 secs (6 decades)
Synchronous Outputs (TTL) S1, S2 S1 Delay, S2 Delay, Train
Rear Panel Outputs 1 or 10 msec and Train End
Synchronous Inputs (TTL) Train Duration, S1 Delay, S2 Delay,
Trigger Rising or Falling edge
Rear Connector (DB25S) All SYNC INPUTS and OUTPUTS;
Volts Out (S1 and S2) 10mV to 150V (4 decades)
Peak Output Current 150mA with 1000Ω on highest range
Output Impedance 250Ω nominal on all voltage ranges; 25Ω and 100kΩ on highest range
AC Power 115/230V, 50/60Hz, 125 watts peak, 20 watts standby
Maximum power output 22 watts
Current output 150 milliamperes
Output Impedance determined by the position of the VOLTS multiplier switch
Tolerance All parameters are accurate to +5%
8. Additional Notes
a. The output is a positive (with respect to chassis ground) non-isolated constant voltage square pulse.
b. The S88 cannot deliver a true symmetrical biphasic pulse which is equal in positive and negative amplitudes. However, if a Model Stimulus Isolation Unit (SIU)5 is used at either the S1 or S2 output, a biphasic waveform can be produced which, although not symmetrical, does have a negative and positive component which is equal in effective energy in terms of coulombs, if averaged over a sufficiently long period of time.
c. It is possible to obtain a true symmetrical biphasic pulse by mixing the output pulses from both S1 and S2 outputs through two Stimulus Isolation Units. Polarity can be changed only by connecting the S88 in series with an SIU and reversing polarity at the output of the SIU.
**Individual or ring electrode may be used as well. An electrolyte must be used with all electrodes.

Response Pads / Devices

We have are a range of fiber optic subject response devices designed specifically for use in the MEG environment including: handheld fiber optic response devices, response boxes, response pads, button boxes, and variable input devices like joysticks, trackballs, motion and force transducers.

•Lumitouch Response Pad
•Cedrus Lumina Response Pad
•FORP (Fibre Optic Response Pad)
•Optical Mouse
•Air Pressure Response Button
•Push Button Response Switch
•Optical Joystick (without a button)
•Motion Sensor
•Air Pressure Response Device
•Optical Microphone
•Two Button Split FORP
•One Button Split FORP
1. Lumitouch Response Pad
a. Lumitouch is a 5 key fiber optic response keypad. The system consists of 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.
b. There are five response buttons which are arranged in a row 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, and can be taped down, reducing subject arm motion.
2. Cedrus Lumina Response Pad
a. Lumina’s 5 key fiber optic response pad captures patients’ button presses and the triggers, time-stamps them with a millisecond accuracy, and converts them into simultaneous USB port and parallel outputs (time-stamped information is output only on the USB port). The response pads are built with 100% plastic and fiber optics.
3. Fiber Optic Response Pad (FORP)
a. The FORP is a fiber optic based response device which 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.
b. 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.
4. Optical Mouse
a. The optical mouse is a computer mouse which uses a light source, typically a light-emitting diode (LED), and a light detector, such as an array of photodiodes, to detect movement relative to a surface. It is an alternative to the mechanical mouse, which uses moving parts to sense motion.
5. Air Pressure Response Button
6. Push Button Response Switch
7. Optical Joystick (with & without a button)
a. The Optical Joystick is connected via cable through the guide panel to the stimulus computer. You may have to connect the cable labelled "Joystick" to the USB connector at the back of the stimulus computer. The Optical Joystick control box is located on the second shelf on the stand in front of the MSR labelled Optical Joystick Navigation Task Control Box.
b. Turn the power on for the Navigation Task Control Box.
c. Calibrate the joystick from the stimulus computer.
d. Open "Game Controller" software program.
e. Rotate the joystick in a circle 3 or 4 times.

8. Motion Sensor
9. Air Pressure Response Device
10. Optical Microphone
11. Two Button Split FORP
12. One Button Split FORP