  Radio jets can play multiple roles in the feedback loop by regulating the
accretion of the gas, by enhancing gas turbulence, and by driving gas outflows.
Numerical simulations are beginning to make detailed predictions about these
processes. Using high resolution VLBI observations we test these predictions by
studying how radio jets of different power and in different phases of evolution
affect the properties and kinematics of the surrounding HI gas. Consistent with
predictions, we find that young (or recently restarted) radio jets have
stronger impact as shown by the presence of HI outflows. The outflowing medium
is clumpy {with clouds of with sizes up to a few tens of pc and mass ~10^4
m_sun) already in the region close to the nucleus ($< 100$ pc), making the jet
interact strongly and shock the surrounding gas. We present a case of a
low-power jet where, as suggested by the simulations, the injection of energy
may produce an increase in the turbulence of the medium instead of an outflow.
