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. Several embodiments of methods in accordance with the invention are
directed toward enhancing or otherwise inducing a lasting change in neural activity
to effectuate a particular neural-function. Such lasting change in neural activity
is defined as "neuroplasticity." 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). Certain embodiments of methods in
accordance with the invention electrically stimulate the brain at a stimulation
site where neuroplasticity is occurring. The stimulation site may be different
than the region in the brain where neural activity is typically present to perform
the particular neural function according to the functional organization of the
brain. In one embodiment in which neuroplasticity related to the neural-function
occurs in the brain, the method can include identifying the location where such
neuroplasticity is present. In an alternative embodiment in which neuroplasticity
is not occurring in the brain, an alternative aspect is to induce neuroplasticity
at a stimulation site where it is expected to occur. Several embodiments of these
methods that are expected to produce a lasting effect on the intended neural activity
at the stimulation site use electrical pulses that increase the resting membrane
potential of neurons at the stimulation site to a subthreshold level.