Repetitive Transcranial Magnetic Stimulation, Visual Attention, Visual Cortical Plasticity
Conditions
Keywords
visual-evoked potentials, TMS, neuroplasticity
Brief summary
The goals of this study are to 1) use EEG steady-state visual evoked potentials as a noninvasive measure of the neuroplasticity induced by repetitive transcranial magnetic stimulation (rTMS), 2) use visual contrast detection paradigms as a behavioral measure of rTMS effects, and 3) to investigate how visual spatial attention augments or suppresses the neuroplastic impact of rTMS. Participants will observe visual stimuli on a screen while allocating their attention to different parts of the visual field and making responses when they observe changes in the visual stimuli. rTMS is performed to visual cortex using MRI-retinotopy neuronavigation. Then the visual task paradigm is performed again.
Interventions
DEVICErepetitive transcranial magnetic stimulation
Repetitive TMS targeted by neuronavigation to left lower visual field of primary visual cortex. Randomized to 10 Hz or 1 Hz on different treatment days. Stimulation at 110% of phosphene threshold, or 110% resting motor threshold if phosphenes not detectable. 1 Hz: 1000 pulses total over 1000 seconds. 10 Hz: 1000 pulses over 10 10 second pulse trains, with 50 second intertrain intervals
Sponsors
University of California, San Francisco
National Eye Institute (NEI)
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Masking description
Participant is blind to the rTMS target hemisphere, the rTMS stimulation parameters, and the objective of the study
Intervention model description
Cross-over: 1 Hz vs 10 Hz vs sham rTMS; stimulation to attended or unattended hemisphere
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
* Men and women, ages 18 to 65 * Must comprehend English well to ensure adequate comprehension of the EEG and TMS instructions, and of clinical scales * Left- or Right-handed * No current or history of neurological disorders * No seizure disorder or risk of seizures
Exclusion criteria
* Those with a contraindication for MRIs (e.g. implanted metal) * Any unstable medical condition * History of head trauma with loss of consciousness * History of seizures * Neurological or uncontrolled medical disease * Active substance abuse * Diagnosis of psychotic or bipolar disorder * Currently taking medications that substantially reduce seizure threshold (e.g., bupropion, olanzapine, chlorpromazine, lithium) * Currently pregnant or breastfeeding
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| post-rTMS change in ssVEP Response Amplitude | 60 minutes | Change in ssVEP contrast-response amplitude after rTMS |
| post-rTMS change in visual contrast perceptual sensitivity | 60 minutes | change in visual psychometric threshold across contrasts after rTMS |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORRyan Ash, MD, PhD
University of California, San Francisco
Outcome results
None listed