PulsePal Testing of Sensitivity to Pulsing Light Changing Frequencies

cbaker

Hi there.

I am trying to figure out how to adjust my PulsePal code in order to deliver four pulse trains of the same length but of different frequencies, each at different time points. Is this possible to do on one channel to dynamically update the code such that the frequency of the pulse train delivered is contingent upon the time point? I read in the Sanders (2014) publication that "Since the same microcontroller controls pulse timing and USB communication, Pulse Pal cannot be updated while a pulse train is being delivered." But the article goes on to describe that "updates can be achieved rapidly between experimental trials." Is it possible to achieve this with tic and toc in MATLAB during the same run? For instance, would the below code work for what I am proposing? What modifications should I make? Or is this not logistically feasible with one channel?

%%
PulsePal
%%
load ParameterMatrix_Example; % Loads the default parameter matrix

ProgramPulsePal(ParameterMatrix); % Sends the default parameter matrix to Pulse Pal

% Start time tracking
startTime = tic;  % Start timer to track elapsed time

Voltages    = [5 5 5 5 5 1];
% Target times in seconds (15 min, 25 min, etc.)
PulseTimes = [15, 25, 35, 45, 59]*60; 

while true
    elapsedTime = toc(startTime);  % Check elapsed time in seconds

    % Train 1: 0.5 Hz at 15 minutes for 90 seconds
    if elapsedTime >= 0
        ProgramPulsePalParam(1, 'Phase1Voltage', 5);
        ProgramPulsePalParam(1, 'Phase1Duration', 0.1);     % On duration: 0.1 ms
        ProgramPulsePalParam(1, 'InterPulseInterval', 1.9); % Off duration: 1.9 ms (0.5 Hz)
        ProgramPulsePalParam(1, 'BurstDuration', 90);       % Burst duration: 90 seconds
        ConfirmBit = TriggerPulsePal(1);


    % Train 2: 1 Hz at 25 minutes for 90 seconds
    elseif elapsedTime >= 20
        ProgramPulsePalParam(1, 'Phase1Voltage', 5);
        ProgramPulsePalParam(1, 'Phase1Duration', 0.1);     % On duration: 0.1 ms
        ProgramPulsePalParam(1, 'InterPulseInterval', 0.9); % Off duration: 0.9 ms (1 Hz)
        ProgramPulsePalParam(1, 'BurstDuration', 90);
        ConfirmBit = TriggerPulsePal(1);
        %% send custom train 1 to channel 1
        ProgramPulsePalParam(1, 'CustomTrainID', 1); 
        ProgramPulsePalParam(1, 15, 1);

    % Train 3: 2 Hz at 35 minutes for 90 seconds
    elseif elapsedTime >= 30
        ProgramPulsePalParam(1, 'Phase1Voltage', 5);
        ProgramPulsePalParam(1, 'Phase1Duration', 0.25);    % On duration: 0.25 ms
        ProgramPulsePalParam(1, 'InterPulseInterval', 0.25);% Off duration: 0.25 ms (2 Hz)
        ProgramPulsePalParam(1, 'BurstDuration', 90);
        ConfirmBit = TriggerPulsePal(1);
        %% send custom train 1 to channel 1
        ProgramPulsePalParam(1, 'CustomTrainID', 1); 
        ProgramPulsePalParam(1, 15, 1);

    % Train 4: 3 Hz at 45 minutes for 90 seconds
    elseif elapsedTime >= 40
        ProgramPulsePalParam(1, 'Phase1Voltage', 5);
        ProgramPulsePalParam(1, 'Phase1Duration', 0.15);    % On duration: 0.15 ms
        ProgramPulsePalParam(1, 'InterPulseInterval', 0.15);% Off duration: 0.15 ms (3 Hz)
        ProgramPulsePalParam(1, 'BurstDuration', 90);
        ConfirmBit = TriggerPulsePal(1);
         %% send custom train 1 to channel 1
        ProgramPulsePalParam(1, 'CustomTrainID', 1); 
        ProgramPulsePalParam(1, 15, 1);
    end

%%
TriggerPulsePal(1)
%%
% AbortPulsePal
% %%

Josh

Hello cbaker,

I'm not sure I understand the full picture.
CustomTrainID is set to 1, but a custom train isn't loaded with SendCustomPulseTrain().

If you use MATLAB's clock to time the calls to TriggerPulsePal(), even if your custom train is the same length as the interval between calls, you'll have some clock drift between Pulse Pal's clock and the PC clock so it isn't guaranteed that the pulse train will play exactly up to the next call to ProgramPulsePalParam().

You shouldn't use ProgramPulsePalParam while a pulse train is being delivered, as it could interfere with stimulus timing.

I hope this helps,
Josh

cbaker

Hi Josh,

Thanks for your reply. I will try to elaborate on my proposed experimental design so that maybe we can find a better solution together.

Essentially, I want to conduct a neurometric analysis where I test the response to different frequencies of flashing light. In one hour, I would like to have four pulse trains, each spaced roughly 10 minutes apart. Each pulse train should be a different frequency. I understand that I shouldn't use ProgramPulsePalParam while a pulse train is actively being delivered, but is it possible to make it so that the pulse pal parameters of one channel change between stimulation deliveries, such that the pulse trains ten minutes apart are of different frequencies? I was thinking I could do this with tic and toc perhaps so that after a pulse train is delivered the parameters will be updated so that the next pulse train is of a different frequency? Does this make sense? I am okay with some clock drift if there is a way to track when the stimulus was actually delivered by Pulse Pal. There would be 10 minutes between the pulse trains so there is a lot of time to be able to update the frequency, which is the aspect of the experiment that is most important.

Josh

Hello cbaker,

Your design makes sense. You can trigger each pulse train, time its duration plus a conservative buffer to be sure the stimulus is no longer playing, then use ProgramPulsePalParam to update the frequency.

If you're using the PC for timing, I'd consider using WaitSecs (part of PsychToolbox) for better precision than tic/toc.

-Josh