Try this:
x = linspace(0,1, 250); % Create Data
y = 5+randn(size(x)); % Create Data
figure(1)
plot(x, y)
hold on
VLX = repmat(x(60:60:end), 2, 1); % Vertical Line ‘x’ Locations
VLY = repmat(ylim, size(VLX,2), 1)'; % Vertical Line ‘y’
plot(VLX, VLY, 'LineWidth', 1.5)
hold off
