9 ms·

Seems pretty cool. I've heard great things about deep brain stimulation and how it is the SOTA for many neurological disorders. It has actual experiments in h

by qrian 3y ago

Seems pretty cool. I've heard great things about deep brain stimulation and how it is the SOTA for many neurological disorders. It has actual experiments in humans instead of rodents. And the humans are healthy adults too! So it ticks all boxes for me as an amature enthusiast for a potential 'enhance my cognition' method. I wonder, where the catch?

nomadpenguin 3y ago
The catch with deep brain stimulation currently is that it's only SOTA for implanted electrodes, meaning it's incredibly expensive, and while DBS implantation is very safe for a brain surgery, it's still a brain surgery. tTIS is very investigational and neuromodulatory focused ultrasound is still quite a bit away from clinical applications. (Ablative focused ultrasound is FDA approved, but that's only for very specific indications.) There's also the Brainsway H series TMS coils that claim to stimulate deep structures, but the activation of large amounts of cortical tissue makes the claim a little hard to verify.
deleted 3y ago
[deleted]
m3kw9 3y ago
There’s always a catch even when you exercise there is a catch somewhere
mattkrause 3y ago
The catch is that the effects of tTIS are very, very weak--even compared to other forms of non-invasive brain stimulation--and while it does do something to the brain, the proposed mechanism is probably not quite right. Some of the authors' earlier work in rodents painted a really exciting picture of directly driving neuronal activity from outside the brain. However, that data came from an animal with a small, smooth brain and the stimulation was actually delivered onto the skull (rather than the skin). Thus, they could make electric fields of ~400 V/m in their animals, whereas fields of ~1 V/m are about all you can expect from non-invasive (i.e., scalp) electrical stimulation of an awake, healthy human (at least one that you want to keep healthy!). We recently did some experiments with macaques receiving tTIS through the scalp, which are much more similar to humans. It could shift the timing of individual neurons' ongoing activity, but not directly force them to spike. It generally wasn't strong enough to impose new rhythms on the brain, just muck up existing ones. This isn't nothing--"mistimed" neural activity is involved in lots of diseases and ways to fix that might be very valuable--but it's very different fro the dominant story. Here are our results, if you want to read more: https://www.biorxiv.org/content/10.1101/2023.09.25.559340v1 https://www.biorxiv.org/content/10.1101/2023.09.25.559340v1
- blufuz 3y ago
  Your experiment in macaques is a really important test for such a new method, but do you think that the difference in stimulation protocol could be meaningful? In their paper they used a theta burst stimulation protocol (3 100 hz pulses 200ms apart) which has been very effective with TMS and has been shown to affect neuronal plasticity. Maybe 10 hz tACS-like stimulation is more about spike timing than plasticity?
- noduerme 3y ago
  Just wondering, if you take a wide beam approach to stimulating the brain with electricity, doesn't that sort of just reamplify whatever is going on in the circuitry and/or activate whatever's already latently there? How's this any better than a line of coke or six cups of coffee?
  - Staple_Diet 3y ago
    Yes to your first question, or at least that's where most literature leans. In brain stimulation research the terms online and offline refer to whether stim is delivered concurrently with a task (online) or before/after a task (offline). Generally greater benefits are seen in studies that repeatedly pair brain stim concurrently with a task over several sessions, but of course many methodological factors (intensity, duration, electrode location) and individual factors (brain morphology, neurochemical concentration levels) can influence the outcome. With your second question; brain stimulation is reasoned to be less addictive than those substances, and of course less selective in its effect. Furthermore the studies that report positive benefits can show these benefits lasting almost 24h following a single stimulation session....however, having done my doctorate on this technology I can tell you it is definitely no panacea, and lately many critiques of this type of intervention have been published.
    - mattkrause 3y ago
      I would (slightly) disagree with that. The hope is often to enhance whatever's already going on in the brain--and this is a sensible goal because there's often less neural synchrony in some diseases (e.g, schizophrenia) or situations (e.g., memory lapses). However, the brain has its own internal dynamics--and they're complicated! You can 't just blithely write a new thing on top of them and expect it to work. In our experiments, doing so often backfires: stimulating at 5 Hz often makes makes cells already firing at 5 Hz act less rhythmically, not more. The reason is that the brain's oscillations drift in frequency and abruptly reset, so they "compete" with the imposed oscillation. This is a pretty well-studied phenomeon in other contexts (e.g., sloshing in rocket fuel tanks or nearby pipes cancelling each other in organs). TI is exciting because you could potentially sense what's going on and adjust the stimulation accordingly, but we've got a lot of work to go.

by qrian 3y ago

nomadpenguin 3y ago

The catch with deep brain stimulation currently is that it's only SOTA for implanted electrodes, meaning it's incredibly expensive, and while DBS implantation is very safe for a brain surgery, it's still a brain surgery. tTIS is very investigational and neuromodulatory focused ultrasound is still quite a bit away from clinical applications. (Ablative focused ultrasound is FDA approved, but that's only for very specific indications.) There's also the Brainsway H series TMS coils that claim to stimulate deep structures, but the activation of large amounts of cortical tissue makes the claim a little hard to verify.

deleted 3y ago

[deleted]

m3kw9 3y ago

There’s always a catch even when you exercise there is a catch somewhere

mattkrause 3y ago

The catch is that the effects of tTIS are very, very weak--even compared to other forms of non-invasive brain stimulation--and while it does do something to the brain, the proposed mechanism is probably not quite right. Some of the authors' earlier work in rodents painted a really exciting picture of directly driving neuronal activity from outside the brain. However, that data came from an animal with a small, smooth brain and the stimulation was actually delivered onto the skull (rather than the skin). Thus, they could make electric fields of ~400 V/m in their animals, whereas fields of ~1 V/m are about all you can expect from non-invasive (i.e., scalp) electrical stimulation of an awake, healthy human (at least one that you want to keep healthy!). We recently did some experiments with macaques receiving tTIS through the scalp, which are much more similar to humans. It could shift the timing of individual neurons' ongoing activity, but not directly force them to spike. It generally wasn't strong enough to impose new rhythms on the brain, just muck up existing ones. This isn't nothing--"mistimed" neural activity is involved in lots of diseases and ways to fix that might be very valuable--but it's very different fro the dominant story. Here are our results, if you want to read more: https://www.biorxiv.org/content/10.1101/2023.09.25.559340v1 https://www.biorxiv.org/content/10.1101/2023.09.25.559340v1

blufuz 3y ago
Your experiment in macaques is a really important test for such a new method, but do you think that the difference in stimulation protocol could be meaningful? In their paper they used a theta burst stimulation protocol (3 100 hz pulses 200ms apart) which has been very effective with TMS and has been shown to affect neuronal plasticity. Maybe 10 hz tACS-like stimulation is more about spike timing than plasticity?
noduerme 3y ago
Just wondering, if you take a wide beam approach to stimulating the brain with electricity, doesn't that sort of just reamplify whatever is going on in the circuitry and/or activate whatever's already latently there? How's this any better than a line of coke or six cups of coffee?
- Staple_Diet 3y ago
  Yes to your first question, or at least that's where most literature leans. In brain stimulation research the terms online and offline refer to whether stim is delivered concurrently with a task (online) or before/after a task (offline). Generally greater benefits are seen in studies that repeatedly pair brain stim concurrently with a task over several sessions, but of course many methodological factors (intensity, duration, electrode location) and individual factors (brain morphology, neurochemical concentration levels) can influence the outcome. With your second question; brain stimulation is reasoned to be less addictive than those substances, and of course less selective in its effect. Furthermore the studies that report positive benefits can show these benefits lasting almost 24h following a single stimulation session....however, having done my doctorate on this technology I can tell you it is definitely no panacea, and lately many critiques of this type of intervention have been published.
  - mattkrause 3y ago
    I would (slightly) disagree with that. The hope is often to enhance whatever's already going on in the brain--and this is a sensible goal because there's often less neural synchrony in some diseases (e.g, schizophrenia) or situations (e.g., memory lapses). However, the brain has its own internal dynamics--and they're complicated! You can 't just blithely write a new thing on top of them and expect it to work. In our experiments, doing so often backfires: stimulating at 5 Hz often makes makes cells already firing at 5 Hz act less rhythmically, not more. The reason is that the brain's oscillations drift in frequency and abruptly reset, so they "compete" with the imposed oscillation. This is a pretty well-studied phenomeon in other contexts (e.g., sloshing in rocket fuel tanks or nearby pipes cancelling each other in organs). TI is exciting because you could potentially sense what's going on and adjust the stimulation accordingly, but we've got a lot of work to go.