function [presyn_I_Na_present_thistrial]=presyn_I_Na_checker(stim_indices,presyn_trace,presyn_pulse_duration,trial)
%this uses the method from bump_counter, viz., converting values to 1 or 0 based on being greater or less than the preceding value, respectively
%the number of consecutive decreases then increases are used to determine whether there was in fact I_Na
%this yes/no is returned for each presynaptic pulse

consecutive_ups=2;
consecutive_downs=2;

sodium_current_present=[];
for i=1:length(stim_indices)
    current_trace=presyn_trace(stim_indices(i):stim_indices(i)+(presyn_pulse_duration-1));
            
	%convert to binary -- 1 means that bin is greater than the bin after it, 0 means it is less than the bin after it (if equal to bin after it?)
    fromstart=current_trace(1:end-1);
	tofinish=current_trace(2:end);
	does_it_dip_then_rise=fromstart>tofinish;
		
	%determine if there is a dip-then-rise;  if so, this is taken to be sodium current
	spotter=0;
	for k=consecutive_downs+1:length(does_it_dip_then_rise)-consecutive_ups
        if all(does_it_dip_then_rise(k-consecutive_downs:k-1))
            if ~any(does_it_dip_then_rise(k:k+(consecutive_ups-1)))
                spotter=1;
                break
            end
        end
	end
    %if ~spotter, figure, plot(current_trace), title('no sodium current'), disp(strcat('Trial #',num2str(trial),'Pulse #',num2str(i))),error('s'), end
	    
    sodium_current_present=[sodium_current_present; spotter];
end
presyn_I_Na_present_thistrial=sodium_current_present;