METHODS AND APPARATUS FOR EFFECTUATING A LASTING CHANGE IN A NEURAL-FUNCTION OF A PATIENT
The following disclosure describes several methods and apparatus for intracranial electrical stimulation to treat or otherwise effectuate a change in neural-functions of a patient. The methods in accordance with the invention can be used to treat brain damage (e.g., stroke, trauma, etc.), brain disease (e.g., Alzheimer's, Pick's, Parkinson's, etc.), and/or brain disorders (e.g., epilepsy, depression, etc.). The methods in accordance with the invention can also be used to enhance neural-function of normal, healthy brains (e.g., learning, memory, etc.), or to control sensory functions (e.g., pain).
1 . A method of treating Parkinson's disease (PD) in a patient, comprising:
identifying a region within the brain of the patient exhibiting dysfunctional neuronal activity caused by PD in the patient;
implanting a stimulation lead within or adjacent to the identified region; and
electrically stimulating, through a plurality of electrodes of the stimulation lead, a population of neuronal tissue to treat PD in the patient, wherein (i) the stimulating repetitively applies, in a time sequence, electrical pulses through different electrodes of the plurality of electrodes to successively stimulate different neuron subpopulations within the population of neuronal tissue; (ii) at least a subset of the applied electrical pulses are provided at a subthreshold level that is sufficiently low to avoid overdriving a substantially majority of neurons of the population to depletion of neurotransmitters in the neurons of the population; and (iii) the applied electrical pulses causes entrainment of neuronal activity within respective subpopulations.
2 . The method of claim 1 wherein electrical pulses applied at a subthreshold level occur at a pulse amplitude level of 60% to 80% of a difference between an unstimulated resting potential of neurons and a threshold potential for direct stimulated action potential generation.
3 . The method of claim 1 wherein electrical pulses applied at a subthreshold level occur at a pulse amplitude level of approximately 10% of a difference between an unstimulated resting potential of neurons and a threshold potential for direct stimulated action potential generation.
4 . The method of claim 1 wherein the identifying comprises conducting an MRI scan of at least a portion of the patient's brain.
5 . The method of claim 1 wherein electrical pulses, applied to the different neuronal subpopulations, are repeated at a pulse rate with a range of 40 Hz to 200 Hz.
6 . The method of claim 1 wherein the successively stimulation of different neuron subpopulations within the population of neuronal tissue causes a rotational pattern of stimulation about the plurality of electrodes to occur.
7 . The method of claim 1 wherein the successively stimulation of different neuron subpopulations within the population of neuronal tissue causes alternating polarities of stimulation in different subpopulations of neurons.
8 . The method of claim 1 wherein the electrical pulses are biphasic pulses.
9 . The method of claim 1 wherein the electrical pulses are monophasic pulses.