[Neuro] Brain-Brain Interface with tDCS like stimulation

Grant Taylor grantstaylor at gmail.com
Tue Aug 6 16:56:48 UTC 2013

Yes, great point about FUS actually triggering the firing of neurons while
tDCS shifts the threshold of natural firing. That was something I hadn't
considered, but I imagine it would be the difference between the two
systems that has the biggest impact on how both are utilized in
research/clinical/BCI applications.

On Mon, Aug 5, 2013 at 9:37 PM, John Withers <jwithers at reddagger.org> wrote:

> Grant,
> I think it depends on the context we are talking about. They both look
> sorta the same. But I think that view can easily gloss over the fact that
> these are fundamentally different technologies, both in presumed mechanisms
> of action and in practice.
> And in the caveat area, I have used and experimented with TDCS pretty
> extensively, built out units, and actively consult with companies on this.
> However, I have never touched an ultrasound device (so many fun things in
> neuro bioengineering right now, so little time) and only follow the
> research the same as you.
> TDCS only works at essentially the cortical surface. There are some claims
> of a magic AC stimulation device that presumably goes deeper safely, but I
> along with a lot of people find this a questionable claim and the only
> papers on the Fischer device I have seen are authored by the guy who helped
> them build it out. Most likely these claims were simply for patent purposes
> to differentiate in an area with plenty of prior art.
> Ultrasound can be targeted at deep brain structures.
> You already hit on spatial resolution.
> TDCS also won't fire neurons per se. It provides a comparatively weak bias
> to fire compared to ultrasound since ultrasound is apparently producing
> repeatable gross motor movement in response to stimulation.
> And I do think it is important, if obvious, to really just keep in mind
> that these aren't really varieties of the same thing. To me this is like
> the fact that TDCS is showing very good preliminary results in helping
> alleviate the worst symptoms of some forms of depression. So do certain
> medications. There are different tradeoffs in both cases and we would never
> want to think of these two interventions in anything approaching the same
> way and wouldn't.
> I think there is a lot more chance to make that mistake casually with two
> things that are both electronic black boxes to most folks, have some
> overlapping use cases, and both are about applying stimulation through the
> skull. Yet they have different mechanisms of action, capabilities and as
> time goes on we might find much different sets of dangers.
> j
> On 08/05/2013 02:14 PM, Grant Taylor wrote:
>> Hey John, I agree with the majority of your post, but just wanted to make
>> two comments:
>> First, in reference to Kevin's original question: from my understanding
>> (quick credentials: I have a PhD in applied experimental psychology and
>> have experience with various brain measurement techniques, but have never
>> actually used tDCS or FUS, so I wouldn't consider myself an expert on these
>> methods) I would say that focused ultrasound is, in fact, quite similar to
>> transcranial direct current stimulation. Although the two methods use
>> different mediums (oscillating mechanical pressure from ultrasound vs.
>> low-level electrical stimulation from tDCS), they both have the same
>> impact: generalized excitation or inhibition of some localized brain
>> region. That is, they are both manipulating the firing threshold of the
>> neurons within a specific region. You are definitely correct that neither
>> phenomenon is very well understood in terms of exactly how they cause this
>> excitation/inhibition, so there are still many questions to be answered,
>> but from a practical standpoint they can both be used for generally the
>> same purposes, so I think that makes them pretty similar. From what I can
>> tell the biggest differences between the two seems to be that tDCS is
>> easier to implement, but FUS has better spatial resolution (it can be used
>> to manipulate more specific brain regions than tDCS).
>> For more information on FUS, see the section titled "Potential mechanisms
>> behind the observed neuromodulation" in this paper by the same lead author:
>> http://www.ncbi.nlm.nih.gov/**pmc/articles/PMC3342684/<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3342684/>
>>  Second, it's a bit off-topic, but you mentioned that the source was an
>> "odd publication", so I just wanted to mention that you are right, but PLOS
>> ONE is "odd" in a great way. PLOS ONE is an open-access journal, so all of
>> their published articles are available for free to everyone, but they still
>> maintain the same level of peer-reviewed scrutiny as other reputable
>> journals. This journal, and other similar open-access publications, are
>> leading the fight against the paywalls perpetuated by traditional
>> publishers, and have the potential to help disseminate scientific findings
>> to a much broader audience (here's a more detailed explanation <
>> http://theconversation.com/**the-great-publishing-swindle-**
>> the-high-price-of-academic-**knowledge-6667<http://theconversation.com/the-great-publishing-swindle-the-high-price-of-academic-knowledge-6667>>).
>> I think this movement is directly in line with the Noisebridge philosophy,
>> so I wanted to take this opportunity to spread their message.
>> I definitely agree with your point about this just being an
>> attention-grabbing study. There's no real benefit in combining these two
>> technologies together, especially when we still know so little about the
>> individual components. This is an interesting technical demonstration, not
>> a scientific development.
>> Sorry this ended up way longer than I anticipated. If you actually read
>> all of this, then congratulations! you must have a longer-than-average
>> attention span.
>> -Grant
>> On Sun, Aug 4, 2013 at 3:08 PM, John Withers <jwithers at reddagger.org<mailto:
>> jwithers at reddagger.org**>> wrote:
>>     On 08/04/2013 04:00 AM, Kevin Schiesser wrote:
>>         Is focused ultrasound similar to transcranial direct current
>>         stimulation?
>>         See
>>         http://www.plosone.org/**article/info:doi/10.1371/**
>> journal.pone.0060410<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060410>
>>         for info on BBI.
>>         __
>>     Probably not. Neither phenomena is all that well understood (TDCS
>>     only looks that way until you dig far enough down to get to the
>>     "then the magic happens" part. We know what it does, but not
>>     really why it should do that).
>>     And this seems kinda an odd publication to me unless I am missing
>>     something, which is possible.
>>     Brain wave entrainment is a well understood phenomenon. Unless I
>>     am deeply missing something here, that's all the trigger is. Look
>>     at a strobe in a certain frequency range, certain of your
>>     brainwaves tend to sync with it. This is the same thing that
>>     Mitch's flashy glasses do. Hooking an eeg trigger to that isn't
>>     breaking new ground. And it is enormously limited, it is a single
>>     channel.
>>     Ditto stimulating motor movement in mice using ultrasound techniques.
>>     Putting both of them together to create "BCI" seems like nothing
>>     but trying to make a sexy headline.
>>     Although, it would be cool to do in a space just for the fun of
>>     it, yeah.
>>     j
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