Fig. 4.

Event related time courses for each of the four sequence types plotted alongside the haemodynamic response function (HRF) obtained using the default parameters in SPM5. In all cases there was a more rapid decline from peak response in the empirically derived response functions than in the canonical HRF. In addition, the spin echo data showed a shorter peak latency in V1 and M1. For clarity of display, the canonical HRF function has been arbitrarily scaled to have a peak response 10% greater than the maximum height of the empirically derived event related time courses.