  It is widely assumed that neural activity related to synchronous rhythms of
large portions of neurons in specific locations of the brain is responsible for
the pathology manifested in patients' uncontrolled tremor and other similar
diseases. To model such systems Hindmarsh-Rose (HR) oscillators are considered
as appropriate as they mimic the qualitative behaviour of neuronal firing. Here
we consider a large number of identical HR-oscillators interacting through the
mean field created by the corresponding components of all oscillators.
Introducing additional coupling by feedback of Pyragas type, proportional to
the difference between the current value of the mean-field and its value some
time in the past, Rosenblum and Pikovsky (Phys. Rev. E 70, 041904, 2004)
demonstrated that the desirable desynchronization could be achieved with
appropriate set of parameters for the system. Following our experience with
stabilization of unstable steady states in dynamical systems, we show that by
introducing a variable delay, desynchronization is obtainable for much wider
range of parameters and that at the same time it becomes more pronounced.
