This article applies to:
E-Prime 3.0
Chronos
Detail
Experiment Author: Psychology Software Tools, Inc.
The Chronos Adapter for Magstim EGI EEG-TMS sample experiment illustrates how to use Task Events to send markers from the E-Prime experiment to the Magstim EGI EEG amplifier and the TMS device simultaneously.
Abstract
The sample experiment presents a Visual Oddball Task: each trial presents the letter "O" or "X" and the participant's task is to distinguish between these letters. 80% of the trials present the letter "O" and 20% of the trials present the letter "X". The experiment sends the marker value 1 when the letter "O" is shown and the value 128 when the letter "X" is shown to the EEG device. The experiment also sends a marker to the TMS device when the stimulus letter is displayed.
The Chronos Adapter for Magstim EGI EEG-TMS provides access to 8 digital outputs (from Chronos to the Magstim amplifier) via the DB25 connector. It also provides an additional digital output via the BNC1 connector to the TMS device. These outputs are shown below:
When Chronos sends a marker on its first digital output, the amplifier receives the value on DIN 1 (pin 1). When Chronos sends a marker on its eighth digital output, the amplifier receives it on Trigger In 9 (pin 9). The marker that is set on the ninth digital output goes to the TMS device. To determine which Magstim DIN on the amp receives the Chronos output, do the following:
- Represent the integer marker being sent as a binary number (see INFO: Choosing a marker value to send from E-Prime to an external device [42529] for more information on integer and binary numbers).
- Map the binary number to Chronos's digital outputs to determine which outputs are set high (set to 1).
- Examine which Magstim EGI EEG -TMS DIN and pin maps to the first eight Chronos digital outputs that are set high (the ninth Chronos digital output goes to the TMS device, so it does not impact the value sent to the amp).
For example, the sample sends the integer value 257 when the stimulus = the letter "O":
- Integer value 257 equals the binary number 0000 0001 0000 0001 (Least Significant Bit is right-most bit).
- 0000 0001 0000 0001 sets the first and ninth Chronos digital output high; all other digital outputs are low.
- As shown in the table above, the first Chronos Digital Output maps to DIN 1/pin 1.
The sample sends the integer value 384 when the stimulus = the letter "X":
- Integer value 384 equals the binary number 0000 0001 1000 0000.
- 0000 0001 1000 0000 sets the eighth and ninth Chronos digital output high; all other digital outputs are low.
- The eighth Chronos Digital Output maps to DIN 8/pin 9 ,
NOTE: Extract all the files in the attached .zip file to the same folder. The sample experiment displays images that must be located in the same folder as the experiment.
See Also:
E-Prime Extensions for Net Station - simplifies the experiment development, integration, and participant experience when integrating with Magstim EGI EEG systems
Chronos Custom Adapters for other Magstim amplifiers:
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