Imaging studies of the brain have revealed the different areas involved in the processes of
learning and reasoning. However, the specific role these regions play in these processes,
or if stimulating these areas can improve these processes is unknown.
Researchers would like to use repetitive transcranial stimulation (rTMS) to better
understand the roles of individual brain regions on the processes of learning and reasoning.
Repetitive transcranial magnetic stimulation (rTMS) involves the placement of a cooled
electromagnet with a figure-eight coil on the patient's scalp, and rapidly turning on and
off the magnetic flux. This permits non-invasive, relatively localized stimulation of the
surface of the brain (cerebral cortex). The effect of magnetic stimulation varies,
depending upon the location, intensity and frequency of the magnetic pulses.
The purpose of this study is to use rTMS to help determine the roles of different brain
regions in the development of implicit learning of motor sequences and analogic reasoning.
In addition, researchers hope to evaluate if stimulation of these regions speeds up the
process of learning or analogic reasoning.
The human frontal cortex subserves a number of psychological processes including those
necessary for adequate implicit learning of visuomotor sequences and analogical reasoning.
1. Implicit learning is a form of procedural learning indicated by behavioral improvement
without awareness of a repeated stimulus structure that leads to improved performance.
This type of learning has been associated with activation of the primary motor cortex
(M1) in neuroimaging studies. While neuroimaging studies contributed to identify this
region, they do not provide information about its relative role in the process of
implicit learning. Is activity in this region necessary for implicit learning to
occur? Is it possible that "energizing" this region using subthreshold transcranial
magnetic stimulation can accelerate the implicit phase of learning? The purpose of
this protocol is to transiently stimulate focally M1 and dorsolateral prefrontal cortex
during acquisition of implicit learning and evaluate the effects on reaction times and
accuracy of performance. We plan to study a group of normal volunteers, and three
groups of patients who demonstrate impaired visuomotor procedural learning tasks:
those with Parkinson's disease, cerebellar disease, and focal frontal lesions. The
result expected from this study is an advanced understanding of the role that the motor
cortex and dorsolateral prefrontal cortex plays in implicit learning in health and
disease. Additionally, we expect to be able to shorten the implicit phase of learning
by rTMS particularly in the patient groups that exhibit abnormal procedural learning.
2. Analogical reasoning requires that subjects adequately process different forms of
information and then perform a mapping process that allows them to recognize the
similarity between two or more forms of information. Evidence has been provided that
indicates this process of analogical mapping is subserved by the frontal cortex. We
plan to study a group of normal volunteers, and three groups of patients who
demonstrate impaired performance on tests of analogical reasoning and problem-solving:
those with Parkinson's disease, frontal lobe dementia, and focal frontal lesions. We
predict that subthreshold rTMS will facilitate analogical reasoning by promoting the
activation of established or novel neural activation patterns that represents the
actual mapping and decision processes required for analogical reasoning. Additionally,
we expect to facilitate response times and accuracy in analogical mapping in those
patients that exhibit abnormal analogical reasoning performance.
Right handed normal volunteers (18-65 years old).
Patients with Parkinson's disease off medication.
Patients with cerebellar deficits.
Patients with frontal lobe lesions.
Patients with frontal lobe dementia.
Subjects with personal or family history of seizures or other neurological disorders.
Volunteers or patients with severe coronary artery disease.
Metal in the cranium except mouth.
Increased intracranial pressure as evaluated by clinical means.
Intake of neuroleptics.