How to perform a for loop and if statements with series of conditions?

Please could you check this code to see if it represents what I am trying to achieve? I feel like I've done everything right, but I'm not getting the result that I need.

Normally gex(t+1) = gex(t) * exp (-0.02)

But anytime I reach t = a number in t_US, gex(t) = gex(t) + 1.2

Anytime, I reach t = a number in t_CS, gex(t) = gex(t) + gCS, where gCS is a value that changes based on these conditions:

• Everytime V(t) > -54, gCS increases by gCS = gCS + (y) . For this function, the max value of gCS must be 1.2
• Everytime t is a number in t_CS, gCS decreases by gCS = gCS + (x). For this function, the min value of gCS must be 0

The initial gex is 0, and the initial gCS is 0.

timeframe = 0: 0.1 : 1000;
t_US = 101: 100 : 601;
t_CS = 90: 100: 190;
V = zeros (1, length(timeframe));
gex = zeros (1, length(timeframe));
V(1) = -70;
gex(1) = 0;
gCS = 0;
dTime_LTP = 0; %a variable that increases with time, and resets to zero anytime t is a number in t_US
dTime_LTD = 0; % a variable that increases with time, and resets to zero anytime V(t) > -54

for t = 1 : length(timeframe) -1
    gex(t + 1) = (gex(t) * exp (-dTime/Tex)); %normal formula for gex
    if ismember( t, t_CS)
        dTime_LTP = 0; %resets to zero because t is a t_CS
        gCS = gCS + (A_LTD * exp(-dTime_LTD/ 35)); 
        if gCS < 0
            gCS = 0;
        end
    end
    if V(t)> -54
        dTime_LTD = 0;
        gCS = gCS + (A_LTP * exp(-dTime_LTP/ 25));
        if gCS > 1.2
            gCS = 1.2;
        end
    end
    if ismember(t, t_US)
        gex(t) = gex(t) + 1.2;
    end
    if ismember( t, t_CS)
        gex(t) = gex(t)+ gCS;
    end
    %series of functions that lead up to the parameters I use to calculate V(t+1)
    V(t+1) = E + ((V(t) - E)* exp(- dTime/ timeConst));
    dTime_LTP = dTime_LTP + dTime; %increases with time as we go round the loop
    dTime_LTD = dTime_LTD + dTime;
end

[Achin Gupta]

Hi Temi,

Have you considered the updates on gex(t) if multiple conditions are true? For example if V(t) > -54 and ismember(t, t_US), both hold true, then gex(t) will get multiple updates. Is that what you intend to do ?

Also, the if condition with "if V(t)> -54", do you intend to fix the gCS=1.2 after updating it as gCS = gCS + (A_LTP * exp(-dTime_LTP/ 25)).

I have an uncomfortable feeling about the order of your updates overall. Please let me know your thoughts on this.

Looking forward to hearing from you.

[Temi O]

Hi Achin,

Thanks.

Q: Have you considered the updates on gex(t) if multiple conditions are true? For example if V(t) > -54 and ismember(t, t_US), both hold true, then gex(t) will get multiple updates. Is that what you intend to do ?

A: The t in V(t) > -54 can be any number, it does not have to be a number in t_CS.

Q: Also, the if condition with "if V(t)> -54", do you intend to fix the gCS=1.2 after updating it as gCS = gCS + (A_LTP * exp(-dTime_LTP/ 25)).

A: No, my intention is to say if gCS from that calculation is greater than 1.2, then gCS should be 1.2 at that t. It could change after the loop is completed.

[Achin Gupta]

Okay.

I recommend running your code on paper and see if it behaves the way you want it to. I say that because multiple if conditions, as you have placed, can easily do unintended actions on participating variables.

In your place, I would make sure that my variables get updated as I want them to. Or I would use elseif to make the variable updates more predictable.

Best.

[Temi O]

Thanks. I'm kind of teaching myself how to use MATLAB and I try to write my codes like I would do on paper but it does not work out as I expect. For example, a much simpler code below:

spikeMat is a vector that has the values of either 0 or 1.

I am trying to say that anytime spikeMat(t) = 1, then fac_P(t) at timepoint t should increase by this formula: fac_P(t)= fac_P(t)+ (0.1 * ( 1 - fac_P(t))).

Then fac_P(t+1) should be :

fac_P(t+1)= facResting_P0 + ((fac_P(t)- facResting_P0) * exp(-dTime/fac_timeConst));

After this, the value of fac_P should not change till the next time spikeMat(t) = 1

dTime = 10^-3;
time = 0: dTime: 1;
fac_P = zeros(1, length(time));
fac_P(1) = 0;
facResting_P0 = 0;
fac_timeConst= 0.1;
for t = 1: length(time)-1
    [spikeMat] = poissonSpikeGen(10^-3, 100, 1, 1); %a function that I created elsewhere
    t_spike = find( spikeMat== 1);
    if ismember(t, t_spike)
        fac_P(t)= fac_P(t)+ (0.1 * ( 1 - fac_P(t)));
        fac_P(t+1)= facResting_P0 + ((fac_P(t)- facResting_P0) * exp(-dTime/fac_timeConst));
    end
    fac_P(t + 1) =  fac_P(t);
end