  We study correlators of the global U(1) currents in holographic models which
involve N=4 SYM coupled to the finite density matter in the probe brane sector.
We find the spectral density associated with the longitudinal response to be
exhausted by the zero sound pole and argue that this could be consistent with
the behavior of Fermi liquid with vanishing Fermi velocity. However the
transversal response shows an unusual momentum independent behavior. Inclusion
of magnetic field leads to a gap in the dispersion relation for the zero sound
mode propagating in the plane of magnetic field. For small values of the
magnetic field B the gap in the spectrum scales linearly with B, which is
consistent with Kohn's theorem for nonrelativistic fermions with pairwise
interaction. We do not find signatures of multiple Landau levels expected in
Landau Fermi liquid theory. We also consider the influence of generic higher
derivative corrections on the form of the spectral function.
