Welcome to the Transcranial Direct Current Stimulation FAQ page! Compiled here are the questions most frequently presented to us by those interested in tDCS. We’ve tried our best to answer each question in a straightforward, yet comprehensive manner. We are continuously adding more questions, and updating our answers, to ensure this FAQ contains the most relevant up-to-date information as possible.
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FREQUENTLY ASKED QUESTIONS
Not to worry, we’ve got your back! While tDCS can be confusing at first, it’s really fairly simple and straight forward. First and foremost, we recommend that anyone interested in tDCS read through this FAQ page. We spent a significant amount of time researching and compiling these Q&A’s in hopes that it helps individuals like yourself in your quest to learn more about tDCS. We are always looking to improve this FAQ, so if you can’t find the answer to your question, please submit it at the bottom of this page!
Secondly, you may want to take a look at our “What is tDCS?” page. While you may find some of the information redundant, we’ve attempted to present information on tDCS in a more straight forward and easy to understand manner. Finally, we also recommend reading through Dr. Brent Williams Blog on tDCS, and if you’re looking for information on electrode placements, try TotaltDCS.com. This should get you well on your way to understanding more about tDCS.
*Please note that we do not take responsibility for content located on external websites.
The feelings experienced during a typical tDCS session can vary from individual to individual, and can be based on several factors such as as the montage (electrode placement) being used, level of current, and length of the session. The most common sensation associated with tDCS is a slight tingling, itching, or “warming” sensation felt at the source of the electrodes. This sensation can often be suppressed by applying additional saline solution, or by applying slight pressure to the sponge electrodes to help saturate the area. Adding additional saline solution usually requires stopping the session and removing the electrodes, however saline can be applied easily and comfortably during a tDCS session by using a saline solution applicator bottle.
In addition the the above, some individuals claim to experience a metallic taste in their mouth, but usually report it to be temporary and only during the start of the session. Sometimes it is possible to experience the appearance of a very flash of white light, however this is very rare and only possible if the device being used does not feature “ramping,” and the electrodes are positioned near the optical nerve (near the eyes). Almost all of the tDCS devices being produced by reputable companies feature this technology. The Brain Stimulator v3.0 features internal current stepping, which another form of ramping technology which results in an incredibly comfortable tDCS session.
Overall, most people describe tDCS as being a relatively positive experience, and some report not feeling anything at all!
For some related information, check out: Are there any side effects associated with tDCS?
Our goal is to produce tDCS devices of the highest quality standards, which operate with precision and guaranteed accuracy, therefore we do not include current meters in our products. Analog current meters are incredibly inefficient, and are only required for tDSC devices which do not have proper current control and management circuitry in place.
Our products include enhanced circuitry comprised of precision components, integrated circuits, and microprocessors (“smart” technology) which controls and monitors current levels several times a milliseconds. The design of our circuitry means that our products do not require a current meter to operate effectively.
However, tDCS devices which use basic, rudimentary circuitry, must include a current meter, as the user needs to consistently monitor and adjust the current flow.
Reported tDCS side effects are very few, and only experienced by a small number of the population. Some side effects associated with tDCS include a tingling or itching sensation during stimulation, a slightly metallic taste, and occasional redness at the site of the electrodes. Any redness usually fades away shortly after stimulation. An even smaller percentage of the population reports a slight headache as a tDCS side effect, however this also usually subsides shortly after the session is concluded. The most least reported tDCS side effect, which is usually attributed to improper use of electrodes or poorly assembled/prepared electrodes, is skin irritation. Sometimes this irritation can take the form of a small skin bump or lesion. However, it is important to note that even this side-effect is quite minor, and will fade away over a short period of time.
We found a great infographic on tDCS side effects located at tdcsbrainstorm.com, which shows that often most side effects can be attributed to the placebo effect. The results shown below depict that based on clinical trials, those individuals receiving “sham” stimulation (fake, no current) often reported the same symptoms at similar severity levels compared with those individuals receiving active stimulation (real tDCS).
Fisher Wallace produces products that are actually very different from The Brain Stimulator family of products. While our devices utilize tDCS (Transcranial Direct Current Stimulation), the Fisher Wallace Stimulator® utilizes tACS (Transcranial Alternating Current Stimulation). In all of the research we have completed on Transcranial Alternating Current Stimulation, it is our opinion that tACS has the potential to produce greater side effects than tDCS, in addition to having far far less scientific backing. Furthermore, Antal, Boros et al. (2008) found that tACS does not appear to create significant changes in cortical excitability. That being said, we do not dissuade customers from purchasing Fisher Wallace’s products, and in some cases will often recommend their products if we believe it is a better fit for the customer.
It is important to note, that while most people believe that the Fisher Wallace Stimulator® is FDA Approved, this is not the case. The Fisher Wallace Stimulator® is only FDA Cleared, which is quite different from approval. While much progress has been made over the years to gain approval, there are currently no CES (Cranial Electrotherapy Stimulation) devices that have received FDA Approval. The Brain Stimulator is neither FDA Cleared, nor Approved. The reason for this is because The Brain Stimulator is not a medical device, and is not recommended for use in medical applications.
YES! Our products use the exact same technology (tDCS) as the Halo Sport headphones! The only real difference between The Brain Stimulator and Halo Sport (other than price!), is The Brain Stimulator provides the user with the flexibility to position the electrodes in multiple arrangements. The incredible thing about tDCS is that different electrode placements (referred to as “montages”) can produce different results. The Halo Sport headphones utilize fixed electrodes, which are located on the headphone’s bar, placing them directly over the primary motor cortex. While this may be convenient for those who wish to use tDCS for solely for muscle memory, this limits the user and prevents them from exploring other placement positions. We took a different approach and manufactured The Brain Stimulator with free standing electrodes which can be placed anywhere the user desires.
From the very beginning, we have always maintained the belief that the customer should be allowed to use tDCS in any manner they so choose, and that to limit the customer, would be to limit self exploration and creativity.
We manufacture all our tDCS devices in sunny Southern California. Additionally, the majority of the resale products we carry, such as Amrex Sponge Electrodes, are manufactured in California as well! If it’s not made in California, it’s made somewhere else in the United States. If it’s not made in the United States, WE DON’T CARRY IT.
Working with domestic companies not only provides us with the ability to build close working relationships with our vendors, but also includes unmatched benefits such as faster shipping and restocking times, and the ability to closely manage our quality control processes. Doing business with local vendors has been an integral part of our value proposition from day one, and helps differentiate us from our competitors. The ability to walk through the door of any number of our local vendors, shake their hand and sit down across the table from them, is something incredibly invaluable.
By choosing to work with and purchase from domestic companies, we’re doing are part to help to create jobs right here in United States. Additionally, we do all of our order fulfillment in house, so every purchase gets shipped straight to you from our California offices. Furthermore, we’re working hard to expand our International business, and hope to start opening up overseas shipping facilities in the near future. In the meantime, we offer several International shipping options from inexpensive to expedited delivery.
The technology in our devices actually doesn’t utilize Frequency. Frequency is the number of occurrences of a repeating event, within a specified unit of time. Hertz is a unit of Frequency used in the International System of Units to represent one cycle per second. Hertz is often used to measure Alternating Current. In the field of Cranial Electrical Stimulation, Alternating Current is used in tACS devices (Transcranial Alternating Current Stimulation). Devices such as ours that utilize tDCS (Transcranial Direct Current Stimulation) utilize Direct Current, which is essentially the opposite of Alternating Current, in that it doesn’t oscillate (or repeat) and remains consistent.
Scientific research findings suggest that tDCS causes polarity-dependent alterations in cortical excitability and activity. In other words, of the two electrodes (the positive Anode & the negative Cathode), Anodal stimulation increases cortical excitability, while Cathodal stimulation decreases cortical excitability. These changes in cortical excitability are most likely initiated through respective depolarization and hyper-polarization of the underlying neurons. It appears that this effect can be attributed to a sub-threshold modulation of resting membrane potential, which can persist even after stimulation. In simpler terms, tDCS does not actually cause neurons to fire, but instead increases the likelihood of them firing, by increasing “neuronal excitability”.
We recommend using Alkaline disposable 9V batteries for use in our tDCS devices. Alkaline 9V batteries are the standard, over-the-counter batteries which can be purchased at almost any store that carries batteries. Common brands include Duracell, Energizer, Rayovac and others. Out of the various brands of Alkaline 9V batteries available, we personally recommend Duracell’s Procell brand Alkaline 9V Batteries. This is the only battery that we personally use, and the only battery that we stock in our online store. There are several different factors why we recommend this type and brand of battery such as longevity, reliability, power, and affordability. More information on Duracell Procell 9V batteries can be found on the product’s listing page.
Regardless of the brand of battery you choose, we strongly recommend not using rechargeable batteries for tDCS. One reason for this is that these batteries are rarely charge to the full 9-volts, which prevents the user from effectively engaging in tDCS montages where electrodes are father apart. Essentially, the higher the voltage, the more effective the battery is at passing current over farther distances.
These flashes of light are quite common when using transcranial electrical stimulation, and are known as phosphenes. Usually this will happen when an electrode is placed near the eye, and is a result of current running across optic nerves. While it may seem scary at first, this phenomenon has been recognized and studied by the scientific community and is understood to be a harmless side-effect of tDCS. Phosphenes can be reduced or even prevented completely by moving the electrodes further away from the eyes. More can be read about TES and Phosphenes in this PubMed Article.
We no longer recommend using self-adhesive electrodes with tDCS. The reason we do not recommend self-adhesive is due to the fact that they do not conduct current as well, or as evenly as sponge electrodes. Due to the way self-adhesive Electrodes are manufactured, there’s often a high potential for current to collect, or concentrate, on a specific location on the electrode’s surface. This concentration of current creates what’s known as a “Hot Spot,” causing high current density which can result in an uncomfortable session, or even skin irritation. While Hot Spots do not always happen, sponge electrodes are by far the safest and most effective option for use with tDCS. Additionally, you can further practice “safe-tDCS” by always using an electrode positioning headband(s) (we offer small and large tDCS headbands), to ensure that the entire electrode makes contact with the targeted area.
For best results, we recommend you replace your sponges every two weeks, or after 7 tDCS sessions. Replacement sponges can be found in packs of 10 in our online store. Over time, the sponges within Amrex electrodes can grow brittle and crumble, crack, or split causing an uneven distribution of current. Worn-out sponges can cause an uncomfortable tDCS session, with increased tingling, itching, and sometimes stinging sensations occurring. A good way to tell if your sponges need replacing is if soaking them with saline solution becomes more difficult, if they start to display a darker/brownish color, or begin feeling “stale.” More importantly, if your tDCS sessions become uncomfortable, or you start to notice sensations that maybe you didn’t before, this is also a good sign that your sponges may need replacing. You can find 10-packs of replacement sponge inserts for both the 3×3″ Amrex Electrodes and the 2×2″ Amrex Electrodes through our online store.
Essentially the main difference between the 3×3″ Sponge Electrodes and the 2×2″ Sponge Electrodes is the size of the electrode pad and the area they cover. They both are constructed in exactly the same way, with the same materials and use the same Amrex electrode cables and adapters. The 3×3″ electrodes will cover a broader area, while the 2×2″ will cover a slightly smaller, more condensed area. Essentially the 2×2″ sponge electrodes will stimulate a more targeted area, while the 3×3″ have more of a generalized effect on the area being stimulated. Additionally, because of the larger surface area, the 3×3″ size generally provides a more comfortable session with fewer negative side effects. Due to these facts, the 3×3″ size sponge electrodes are far more popular than their 2×2″ counterpart.
While saline solution is not strictly required for use with sponge electrodes, it is recommended. Plain water will work in helping the sponge to pass current, just not as well as saline solution. Water in and of itself is a very poor conductor of current. So in using just water, you’re essentially asking the sponge alone to work to pass current to the targeted area. By adding salt to plain water (saline solution), the electricity is able to actually jump from molecule to molecule through the solution, providing a better connection. In using a sponge well soaked with saline solution, the current encounters the least amount of resistance, providing the most effective, and most comfortable tDCS experience.
It’s actually fairly common for individuals using well soaked sponge electrodes to not feel much of anything when engaging in tDCS. Sometimes you may notice a sensation when first turning on the device, which may fade away over the course of the session. This is due to the cells in your body aligning to allow the current to pass through with less resistance. Additionally, we’ve found that over time the body becomes less sensitive to the feelings associated with tDCS. If you’ve been using tDCS for some time and no longer feel anything, even when replacing the battery, it’s very possible that you’ve just become used to the sensations. We can assure you that there is little to no possibility that your device has “gone bad” as we have individuals who have been using our products for years and still experience all of the wonderful effects that can be associated with tDCS.
If you’re still suspicious that maybe your device isn’t producing current, there’s a simple way that you can test to ensure current is flowing. Install a new battery in your device and remove any electrodes or adapters from the electrode lead wires. While this next part may sound a little weird, it’s completely harmless. Turn the device on and to the lowest setting, and lightly lick the two electrode leads with your tongue. You should feel a slight tingle on your tongue (less than the sensation of licking a 9 volt battery, if you ever did that as a kid).
What are some other types of transcranial stimulation? tCS, tACS, tRNS, TENS, CES, TMS & ETC Defined.
tCS – Transcranial Current Stimulation or tES – Transcranial Electrical Stimulation
tCS or tES (used interchangeably) is often used to describe any therapy in which electricity is applied on or through the cranium. In comparison to all of the types of cranial stimulation listed below, it is generally understood by most that tDCS is safer, more comfortable, easier to engage in, more affordable, and will often produce a more robust response. However it is important to note that new theories and opinions on the different forms of tCS/tES are being developed on an ongoing basis
tACS – Transcranial Alternating Current Stimulation
tACS is a form of tCS where the transcranial stimulation currents are time dependent with a sinusoidal shape (as in AC current). Amplitude, frequency and relative phases across stimulation electrodes can be controlled. tACS stimulation may provide a powerful way to couple to the oscillatory behavior of the brain, which is at present an active research field in basic and clinical Neuroscience.
tRNS – Transcranial Random Noise Stimulation
tRNS is a type of tCS where the stimulation current is varied randomly. Unlike tDCS, tRNS has been recently introduced and there is little experience with its use. However, it appears as if its main effects are excitatory.
TENS – Transcutaneous Electrical Nerve Stimulation
Usually used in muscle therapy and not intended for use on the cranium. Transcutaneous is defined as existing, applied, or measure across the depth of the skin.
CES – Cranial Electrotherapy Stimulation
Applies a small, pulsed (AC) electric current across a patient’s head to treat anxiety, depression, insomnia and chronic pain. The term CES is often used interchangeably with tACS to refer to the same type of device.
TMS – Transcranial Magnetic Stimulation
Utilizes magnetic fields to stimulate nerve cells in the brain, and is usually used to treat depression in patients where other therapies have proven ineffective. TMS can be very particular and should only be performed by a qualified technician. To learn more about TMS and rTMS (Repetitive Transcranial Magnetic Stimulation), check out our Brain Stimulation Comparison page.
ECT – Electroconvulsive therapy, or “shock therapy”
Made familiar to the public through a scene in the 1975 film, One Flew Over the Cuckoo’s Nest. ECT utilizes a current incredibly larger than most forms of cranial electrical stimulation (around 600-1000 milliamps), and is applied to the entire brain, often via the temples. This form of therapy usually results in a controlled grand mal seizure and must be done under general anesthesia. Because ECT produces significant side effects, including memory loss and confusion, it is only used for patients with severe, treatment-resistant depression, and even then it is used as a last result measure. To learn more about ECT, check out our Brain Stimulation Comparison page.
A fantastic comparison of tDCS, tACS, tRNS, and tACS can be found in the July 2014 book, The Stimulated Brain – Cognitive Enhancement Using Non-Invasive Brain Stimulation (Page 38, Figure 2.1) edited by Roi Cohen Kadosh.
As a company policy, we do not provide advice on the use of The Brain Stimulator for specific applications. Additionally, we do not provide advice on the placement of electrodes. Everyone’s individual situation and tDCS desires are different, and therefore we cannot advise to that detail. Furthermore, we are often asked if The Brain Stimulator can help with certain medical issues. It is important to note that The Brain Stimulator is in no way a medical device and is not intended for, nor claims to diagnose, assist, treat, cure, or prevent any medical condition or ailment whatsoever. It’s essential that those interested in tDCS do their own research and come to their own conclusions on how they wish to use tDCS.
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