  We investigate the phase response properties of the Hindmarsh-Rose model of
neuronal bursting using burst phase response curves (BPRCs) computed with an
infinitesimal perturbation approximation and by direct simulation of synaptic
input. The resulting BPRCs have a significantly more complicated structure than
the usual Type I and Type II PRCs of spiking neuronal models, and they exhibit
highly timing-sensitive changes in the number of spikes per burst that lead to
large magnitude phase responses. We use fast-slow dissection and isochron
calculations to analyze the phase response dynamics in both weak and strong
perturbation regimes.
