  Recent experiments find that the pseudogap phase of the high-T$_{c}$ cuprates
ends suddenly at an electron doping $x^{*}$ when the Fermi surface change its
shape from hole-like to electron-like. In this short note, we argue that the
antiferromagnetic(AF) spin correlation of the system should drop abruptly at
the same doping. At the same time, we argue that the critical behavior observed
at $x^{*}$ in the specific heat measurement should be attributed to the strong
renormalization of the quasiparticle excitation in the anti-nodal region by the
critical AF spin fluctuation. This picture also predicts that any
pseudogap-like spectral feature related to AF scattering in the electron-doped
cuprates should terminate at the doping level when the Fermi surface becomes
tangent to the boundary of AF Brillouin zone. Recent ARPES measurement on the
electron-doped cuprate Nd$_{2-x}$Ce$_{x}$CuO$_{4}$ seems to be consistent with
such a prediction.
