  We conduct a thorough study of the persistent currents in a spin-orbit
coupled ${\alpha}-T_3$ pseudospin-1 fermionic quantum ring (QR) that smoothly
interpolates between graphene (${\alpha} = 0$, pseudospin-1/2) and a dice
lattice (${\alpha} = 1$, pseudospin-1). In particular, we have considered both
intrinsic spin-orbit coupling (ISOC) and Rashba spin-orbit coupling (RSOC) in
addition to an external magnetic field, and have systematically enumerated
their individual and combined effects on the charge, valley and the
spin-polarized persistent currents. The energy levels of the system comprise of
the conduction bands, valence bands, and flat bands which show non-monotonic
dependencies on the ring radius, R of the QR, in the sense that, for small R,
the energy levels vary as 1/R, while the variation is linear in R for large R.
The cases corresponding to zero magnetic fields are benchmarked with those for
finite external fields. Further, it is noted that the flat bands demonstrate
dispersive behavior, and hence can contribute to the transport properties only
when ISOC is non-zero. Moreover, the RSOC yields spin-split bands, thereby
contributing to the spin-resolved currents, together with distinct degeneracies
for different spin branches. The persistent currents in the charge, valley, and
spin sectors for each of these cases oscillate as a function of the magnetic
field with a period equal to the flux quantum, as they should be, and depend
upon the spin-orbit coupling terms. Further, we have explored the role played
by the parameter ${\alpha}$ in our entire analysis to ascertain the effect of
the flat bands.
