We study temperature modulated synchronization phenomena in the Morris-Lecar (ML) models with synaptic couplings. Little has been known about the thermal effects on synchronization in a real nervous system. Dynamical mechanisms on such synchronization are investigated by linear stability analysis with phase descriptions for the ML type, in order to understand the effects of temperature on the phase response curve (PRC). We find two types of PRC shape modulation induced by changes in temperature that depend on an injected current amplitude: (1) the PRC shape switch between the type-I and type-II, and (2) the almost unchanged appearance of a type-II PRC. A large variety of synchronization is demonstrated with these changes in the PRC shapes.