Modulation of Spontaneous Cortical Activity by tDCS: BRAIN Initiative I

An emerging neurological tool, called transcranial Direct Current Stimulation (tDCS), has
recently been shown to safely and effectively enhance cognition in healthy individuals, as
well as reduce key symptomatology in disorders such as stroke and depression, with only
negligible side effects. tDCS delivers low-amplitude current to the scalp using small
electrodes and part of this current passes through the skull and modulates neural activity in
the underlying brain region. How this tiny amount of electric current acts to improve
cognitive function and reduce symptoms (e.g., motor impairments in stroke patients with a
lesion in motor brain areas) is currently unknown, although many investigators across the
world are now working on this problem. Magnetoencephalography (MEG) offers a unique view of
neural function, as it can delineate changes in active brain regions with excellent temporal
resolution (< 1 ms) and high spatial accuracy (2-3 mm). MEG non-invasively measures the
magnetic fields that emanate from active neocortical cells. The potential of the MEG
technique to precisely monitor the neural effects of tDCS shows extreme promise, but to date
the method has been rarely utilized in this area.

Under this protocol, Modulation of Spontaneous Cortical Activity by tDCS: BRAIN Initiative I,
approximately 124 participants will provide written informed consent, undergo cognitive and
behavioral testing and a structural MRI during a single visit, and then return several weeks
later (2-4 weeks) to complete a short tDCS session followed by a MEG recording (i.e., after
tDCS). Most participants will return for two more visits, each separated by 2-4 weeks, that
include a tDCS session followed by a MEG recording (i.e., 4 total visits). The three tDCS-MEG
visits will be identical except that the nature of the stimulation (e.g., location,
amplitude, direction/polarity) will be different.

Inclusion Criteria:

- Informed consent obtained from the participant.

- Age: 19-35 years of age at enrollment or 55-72 years of age at enrollment.

- Gender: males and females included.

- Right-handed based on the Edinburgh Handedness Inventory

- Cognitive functioning: IQ of 85 - 115 on the Wechsler Adult Intelligence Scale-Revised

- Ability to complete the questionnaires in English, as not all the neuropsychological
tests and questionnaires have been validated in other languages.

Exclusion Criteria:

- Current use of the following medications: psychotropic medications or other
medications with significant CNS effects (e.g., antipsychotics, psychostimulants,
anticonvulsants, alpha-agonists, adrenergic blockers, lithium, and sedating
antihistamines), or other excluded medication.

- Current psychiatric diagnosis based on the Mini-International Neuropsychiatric
Interview (MINI) and/or the adult attention-deficit/hyperactivity disorder (ADHD)
diagnostic interview.

- Current substance abuse or substance dependence at any time.

- The presence of a known neurological disorder or any major medical illness or injury
impacting neurological/psychiatric function (e.g., diabetes, epilepsy, cerebral palsy,
traumatic brain injury, significant environmental/toxic injury, neurodegenerative
disorder, past meningitis/encephalitis).

- General medical conditions: any major medical conditions that would interfere with
involvement in the study or may affect CNS function as judged by the investigative
team.

- History of clinically-significant head trauma.

- Pregnancy

- Any other condition that, in the opinion of the investigator, is a contraindication to
participation

- The presence of any ferrous metal implant, including orthodonture, which may interfere
with the MEG data acquisition and/or be anMRI safety concern.

- Inability to correct visual acuity to 20/20 with corrective lenses (we can correct
from +5 to -6 diopters in .5 diopter steps, separately for each eye, with non-magnetic
corrective lenses in the laboratory).