This was an interesting project!
You will probably have to experiment to get exactly the effect you want, but this will get you going:
% Create Data —
t = linspace(10,34); % ‘t’ (ms)
y = [20+5*sin(2*pi*3*t/24)+2*randn(1,100); 60+5*cos(2*pi*3*t/24)+2*randn(1,100)];
figure(1)
plot(t, y)
hold on
plot([12; 12], [-40; -20], '-k', [12; 22], [-40; -40], '-k', 'LineWidth', 2)
hold off
axis([[10 34] -60 140])
text(11.8,-30, '10 mA', 'HorizontalAlignment','right')
text(17,-45, '10 ms', 'HorizontalAlignment','center')
% set(gca, 'XTick', [10:2:34], 'XTickLabel', {[] 12:2:32 []}) % Used temporarily to get the ‘text’ positions correct
set(gca, 'Visible', 'off')
Produces:
