National Brain Mapping Lab


General Questions

TDCS Section

  • 1
    How dose TDCS work?

    Mild current produced from the TDCS device primes the stimulated area for action without causing any neurons to fire electrical signals. Overall, this priming effect causes the neurons to become more likely to respond and communicate with other connected neurons within the stimulated area.

  • 2
    What kinds of studies are available?

    In this laboratory, electrical brain stimulation like TDCS, TACS, TRNS studies are doing. Also TCS compatible with MRI and EEG (up to 8 channels) are done.

  • 3
    What limitations are considered on TCS studies subject?

    Subjects can not participate in a TCS-experiment if one of the following applies:
    - They have cardiac pacemaker
    - They have intercranial electrodes, implanted defibrillators or any other prosthesis
    - pregnancy

  • 4
    Is TDCS safe?

    Yes, Side effects for TDCS are minimal. The most common side effects are tingling and itching at the stimulation site, and slight headaches during treatment.

  • 5
    Is it possible to do TCS with MRI?

    Yes, this device compatible with MRI.

EEG Section

  • 1
    What kinds of studies are available?

    In this laboratory, there are 32 & 64 channels bio-signal acquisition system, 32 channels wireless electrode cap and additional sensors. These can be used for studies in brain mapping field such as routine EEG, sleep EEG, evoked and event-related potentials recording, Brain-Computer Interface systems, neuro-marketing and other similar studies.

  • 2
    What limitations are considered for subjects on EEG experiments?

    If subject meet one of the given conditions, he (she) can’t participate in the experiment:
    - Head injury
    - Epilepsy (except the case study is concerned about epilepsy)
    - Be younger than 18 years old (In this case, the consent form must be read and signed by legal guardian
    - Having pacemaker or any electrical stimulator

  • 3
    Is Electroencephalography safe?

    There are no risks associated with an EEG. The test is painless and safe. The electrical activity of brain is recorded, but at no time any electrical current is put into subject’s body.

  • 4
    Is it possible to do EEG recording With MRI?

    Yes. A 64 channel EEG recording setup is available that is compatible with MRI and enables us to perform concurrent EEG recording with MRI.

  • 5
    What data is available for researcher after the experiment?

    The recorded data with bio-signal amplifier is available for further processing and analysis.

TMS Section

  • 1
    What is repetitive Transcranial Magnetic Stimulation (rTMS)?

    rTMS is an effective, non-invasive alternative for the large number of patients not responding to medication. rTMS does not require anesthesia – and is not to be confused with ECT (Electro Convulsive Therapy). The rTMS system delivers magnetic pulses to stimulate nerve cells in the part of the brain controlling the mood. The rapid change in the magnetic field induces a current, and if the current induced is of sufficient amplitude and duration, it will excite neurons.

  • 2
    What are the side-effects of rTMS?

    rTMS is well-tolerated and associated with few side-effects and only a small percentage of patients discontinue treatment because of these. The most common side-effect, which is reported in about half of patients treated with rTMS, is headaches. These are mild and generally diminish over the course of the treatment. Over-the-counter pain medication can be used to treat these headaches.
    About one third of patients may experience painful scalp sensations or facial twitching with rTMS pulses. These too tend to diminish over the course of treatment although adjustments can be made immediately in coil positioning and stimulation settings to reduce discomfort.
    The rTMS machine produces a loud noise and because of this earplugs are given to the patient to use during the treatment. However, some patients may still complain of hearing problems immediately following treatment. No evidence suggests these effects are permanent if earplugs are worn during the treatment.
    rTMS has not been associated with many of the side-effects caused by antidepressant medications, such as gastrointestinal upset, dry mouth, sexual dysfunction, weight gain, or sedation.
    The most serious risk of rTMS is seizures. However, the risk of a seizure is exceedingly low. At Johns Hopkins, we follow up-to-date safety guidelines that are designed to minimize the risk of seizures. While rTMS is a safe procedure, it is important to point out that because it is a new treatment, there may be unforeseeable risks that are not currently recognized.

  • 3
    Who cannot get rTMS?

    Patients with any type of non-removable metal in their heads (with the exception of braces or dental fillings), or within twelve inches of the coil should not receive rTMS. Failure to follow this rule could cause the object to heat up, move, or malfunction, and result in serious injury or death. The following is a list of metal implants that can prevent a patient from receiving rTMS:
    • Aneurysm clips or coils
    • Stents in the neck or brain
    • Implanted stimulators
    • Cardiac pacemakers or implantable cardioverter defibrillator (ICD)
    • Electrodes to monitor brain activity
    • Metallic implants in your ears and eyes
    • Shrapnel or bullet fragments in or near the head
    • Facial tattoos with metallic or magnetic-sensitive ink
    • Other metal devices or object implanted in or near the head

  • 4
    Is TMS Therapy uncomfortable?

    No, the most common side effect related to treatment was scalp discomfort during treatment sessions. This side effect was generally mild to moderate, and occurred less frequently after the first week of treatment.
    If necessary, you can treat this discomfort with an over-the-counter analgesic. If these side effects persist, your doctor can temporarily reduce the strength of the magnetic field pulses being administered in order to make treatment more comfortable.
    Less than 5% of patients treated with TMS Therapy system discontinued treatment due to side effects.

  • 5
    What happens during an rTMS procedure?

    For each rTMS session, the patient sits in a specially designed treatment chair, much like the kind used in a dentist’s office. Because rTMS uses magnetic pulses, before beginning a treatment, patients are asked to remove any magnetic-sensitive objects (such as jewelry, credit cards). Patients are required to wear earplugs during treatment for their comfort and hearing protection, as rTMS produces a loud clicking sound with each pulse, much like an MRI machine.
    During the first rTMS session, several measurements are made to ensure that the TMS coil will be properly positioned over the patient’s head. Once this is done, the TMS coil is suspended over the patient’s scalp. The TMS physician then measures the patient’s motor threshold, by administering several brief pulses. The motor threshold is the minimum amount of power necessary to make the patient’s thumb twitch, and varies from individual to individual. Measuring the motor threshold helps the physician personalize the treatment settings and determine the amount of energy required to stimulate brain cells.
    Once the motor threshold is determined, the coil is then brought forward so that it rests above the front region of the patient’s brain. Treatment is then commenced. During the treatment, patients will hear a series of clicking sounds and will feel a tapping sensation under the treatment coil.
    Succeeding treatment sessions do not require that the motor threshold be determined again, unless indicated otherwise, such as when changes in medications are made during the course of the treatment.

fNIRS Section

  • 1
    How dose fNIRS work?

    The NIRS device measures changes in light absorption and uses the modified Lambert Beer law to calculate changes in hemoglobin concentrations.

  • 2
    What kinds of studies are available?

    • Brain Oxygenation monitoring
    • Measures oxy-, deoxy-, and total hemoglobin concentration changes and optionally and tissue saturation index(TSI).

    • Quantitative analysis of brain functions
    • Concurrent fNIRS/MRI
    • Concurrent fNIRS/ other modalities

  • 3
    What values can I get from NIRS?

    Of course, to start with, the changes in concentration of oxy- and deoxyhemoglobin. If you add these up you will have the change in concentration of total hemoglobin. Total hemoglobin can be used to calculate blood volume and flow if the concentration of hemoglobin in blood is given. With the high sampling frequency of our devices you can accurately measure response time.

  • 4
    Is it possible to do fNIRS with MRI?

    Yes, this device compatible with MRI.

MRI Section افزودن پرسش و پاسخ