The present invention concerns an apparatus for treating neurological disorders comprising (i) at least one electrode implantable in the brain of a patient and (ii) a processing and stimulation device connected to the at least one electrode, wherein the processing and stimulation device comprises (a) at least one stimulation module adapted to generate a stimulation signal to be sent to the at least one electrode, the stimulation signal being characterised by a plurality of parameters, (b) at least one acquisition module of a signal characteristic of cerebral activity coming from the brain of the patient adapted to determine its power in at least one frequency band, and (c) at least one control module of at least one parameter of the stimulation signal as a function of the power of the signal characteristic of cerebral activity acquired, based on a transfer function having a saturating trend, wherein the transfer function is such as to set the at least one parameter (Va, Vd, Vf) of the stimulation signal (Vstim) differently dependent on a plurality of power ranges, by keeping the at least one parameter within a predetermined stimulation range ([Vi_HighThreshold； Vi_LowThreshold]) with i=a,d,f.
