1. Title page 2. Somatotroph 3. Periodic bursting 4. The model 5. Slow manifold 6. Bifurcation diagram 7. Overlay trajectory 8. The question 9. Phase-resetting 10. Manifold computations 11. Before animated 12. Before homoclinic 13. At homoclinic I 14. At homoclinic II 15. After animated 16. After homoclinic I 17. After homoclinic II 18. Summary		Summary Bursting in somatotroph cells Manifold computations possible in slow-fast systems Computations show that short perturbations in V do not work Mechanism understood mathematically Phase-resetting difficult experimentally Detailed prediction from model (to be) tested by experiments