  Our location in the Milky Way provides an exceptional opportunity to gain
insight on the galactic evolution processes, and complement the information
inferred from observations of external galaxies. Since the Milky Way is a
barred galaxy, the study of motions of individual stars in the bulge and disc
is useful to understand the role of the bar. The Gaia mission enables such
study by providing the most precise parallaxes and proper motions to date. In
this theoretical work, we explore the effects of the bar on the distribution of
higher-order moments --the skewness and kurtosis-- of the proper motions by
confronting two simulated galaxies, one with a bar and one nearly axisymmetric,
with observations from the latest Gaia data release (GaiaDR2). We introduce the
code ASGAIA to account for observational errors of Gaia in the kinematical
structures predicted by the numerical models. As a result, we find clear
imprints of the bar in the skewness distribution of the longitudinal proper
motion $\mu_\ell$ in GaiaDR2, as well as other features predicted for the next
Gaia data releases.
