  We present sub-arcsecond, Multi-Element Radio Linked Interferometer (MERLIN)
observations of the decimetre radio continuum structure and neutral hydrogen
(HI) absorption from the nuclear region of the starburst galaxy NGC 4194 (the
Medusa Merger). The continuum structure of the central kiloparsec of the Medusa
has been imaged, revealing a pair of compact radio components surrounded by
more diffuse, weak radio emission. Using the constraints provided by these
observations and those within the literature we conclude that the majority of
this radio emission is related to the ongoing star-formation in this merger
system.
  With these observations we also trace deep HI absorption across the detected
radio continuum structure. The absorbing HI gas structure exhibits large
variations in column densities. The largest column densities are found toward
the south of the nuclear radio continuum, co-spatial with both a nuclear dust
lane and peaks in $^{12}$CO (1->0) emission. The dynamics of the HI absorption,
which are consistent with lower resolution $^{12}$CO emission observations,
trace a shallow north-south velocity gradient of ~320km/s/kpc. This gradient is
interpreted as part of a rotating gas structure within the nuclear region. The
HI and CO velocity structure, in conjunction with the observed gas column
densities and distribution, is further discussed in the context of the fuelling
and gas physics of the ongoing starburst within the centre of this merger.
