Apparatus for treating neurological disorders comprising - at least one electrode implantable in the brain of a patient and - a processing and stimulation device connected to the at least one electrode, wherein the processing and stimulation device comprises - at least one stimulation module adapted to generate a stimulation signal (V stim) to be sent to the at least one electrode, the stimulation signal (V stim) being characterised by a plurality of parameters (V a, V d, V f), - at least one acquisition module of a signal characteristic of cerebral activity coming from the brain of the patient adapted to determine its power (P BF) in at least one frequency band, and - at least one control module of at least one parameter (V a, V d, V f) of the stimulation signal (V stim) as a function of the power (P BF) 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 said at least one parameter (V a, V d, V f) of the stimulation signal (V stim) differently dependent on a plurality of power ranges, by keeping the at least one parameter (V a, V d, V f) within a predetermined stimulation range ([V i _ HighThreshold;V i_LowThreshold]) with i = a,d,f, characterised in that the transfer function with saturating trend based on a plurality of power ranges is a piecewise function, placing the stimulation parameter equal to a first value (V i2) of the stimulation parameter for powers of the signal acquired above a first power limit value and placing the stimulation parameter equal to a second value (V i1) of the stimulation parameter for powers of the signal acquired below a second power limit value according to the following law: sat U P BF = { V i 2 per P BF ≥ P BF 2 U i P BF per P BF 2 > P BF > P BF 1 V i 1 per P BF ≤ P BF 1 with V i1 and V i2 alternatively set equal to the minimum value V i_LowThreshold and to the maximum value V i_HighThreshold of a stimulation parameter V i, P BF2 and P BF1 equal, respectively, to a maximum limit value and a minimum limit value of the saturation ranges of the stimulation parameter V i and U i (P BF) being a law of variability of the stimulation parameter V i outside the saturation ranges. - at least one electrode implantable in the brain of a patient and - a processing and stimulation device connected to the at least one electrode, wherein the processing and stimulation device comprises - at least one stimulation module adapted to generate a stimulation signal (V stim) to be sent to the at least one electrode, the stimulation signal (V stim) being characterised by a plurality of parameters (V a, V d, V f), - at least one acquisition module of a signal characteristic of cerebral activity coming from the brain of the patient adapted to determine its power (P BF) in at least one frequency band, and - at least one control module of at least one parameter (V a, V d, V f) of the stimulation signal (V stim) as a function of the power (P BF) 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 said at least one parameter (V a, V d, V f) of the stimulation signal (V stim) differently dependent on a plurality of power ranges, by keeping the at least one parameter (V a, V d, V f) within a predetermined stimulation range ([V i _ HighThreshold;V i_LowThreshold]) with i = a,d,f,