Electrical stimulator

For electrical current stimulation, we use a Digitimer Constant Current Stimulator, model DS7A. It can be used at 3T, 7T, as well as the mock scanner.

Most important specifications:

• MDD CE certified and FDA cleared medical device
• Pulse durations from 50µs to 2ms (DS7A) and 50µs to 200µs (DS7AH)
• 100mA (DS7A) constant current output from 400V
• Flexible TTL compatible trigger options or front panel push button
• Alternating Polarity control – a toggle switch allows the stimulator to operate in +ve, -ve or alternating polarities during stimulation

If you'd like to drive the stimulator with Matlab, make sure you initialise access to the driver with: config_io (http://apps.usd.edu/coglab/psyc770/IO64.html) Then assign the right address: address = hex2dec('AFE8'); %check address device manager, ports (COM &LP), LPT1 resources 1st entry iorange and flip the bits, for example like this:

       byte = 0; 
       outp(address,byte);
       byte = 255; 
       outp(address,byte);
       

An example script can be found here: