  We revisit the dynamics of the curvaton in detail taking account of effects
from thermal environment, effective potential and decay/dissipation rate for
general field values and couplings. We also consider the curvature perturbation
generated through combinations of various effects: large scale modulation of
the oscillation epoch, the effective dissipation rate and the timing at which
the equation of state changes. In particular, we find that it tends to be
difficult to explain the observed curvature perturbation by the curvaton
mechanism without producing too large non-Gaussianity if the curvaton energy
density is dissipated through thermal effects. Therefore, the interaction
between the curvaton and light elements in the thermal plasma should be
suppressed in order for the curvaton to survive the thermal dissipation.
