This continues where last week’s post left off. Time for some (mad?) science…
Today’s Menu
Supercharging problem-solving with TES
Enhancing memory with deep-brain stimulation
Indirect avenues of boosting cognition
Direct Stimulation of the Brain
There are a variety of different ways to stimulate the brain, which (like recording methods) can be grouped into invasive and noninvasive modalities. Invasive methods, as the name implies, involve implantation directly into the brain, generally requiring surgery.
Noninvasive techniques do not require surgery and thus are more easily (and safely) deployed.
Noninvasive Methods
The most common noninvasive stimulation techniques are transcranial electrical stimulation (TES, TCS, T[D/A]CS) and transcranial magnetic stimulation (TMS). The names are fairly self-explanatory: TES consists of applying small (mA) current, direct or alternating, directly to the scalp, with the intent of stimulating or inhibiting certain regions of the brain. As TES is cheap and easy to configure, it has been the subject of extensive research, with studies of its cognitive effects still published regularly.
TMS involves the use of stronger currents through coils in contact with a patient’s scalp to create a magnetic field, through which one can induce (via the ever-handy Faraday's Law) corresponding current flows in the sub-scalp cortical tissue. TMS features a high temporal resolution but a low spatial resolution, and it is far bulkier than most TES setups.
There are other methods of noninvasive stimulation, like focused ultrasound (FUS), which relies on low-intensity ultrasound pulsations to produce reversible excitation or inhibition of neurons. But they aren’t yet as well-developed as variants of TES and TMS, so we’ll leave them for now.
TES and the Nine Dots of Doom
Consider the famed nine-dot problem, in which a player must connect dots in a 3-by-3 grid with only four lines, without visiting a dot twice. If you haven’t done this before, stop scrolling and try it.
If you’re like most folks, you won’t figure it out—in fact, most never solve the problem even when given hints, and most forget the solution after being told it.
The two solution methods seem simple in retrospect:
Only one of those works in the limit of dots as vanishing points, but both are suitably creative and literally require “thinking outside of the box.”
Why, exactly, is this so hard to do? Some researchers blame inbuilt human pattern-matching, a “mental set effect” we trot out when solving problems: we tend to apply solution methods we’re already aware of, and struggle where novelty is required. It’s thought that this filtration by known patterns happens in the left hemisphere of the brain—more specifically, the left anterior temporal lobe (ATL), associated with pattern-driven cognition, while its contralateral counterpart, the right ATL, plays a role in insight and novel meaning.
The idea to leverage TES against the nine-dot problem was born when some researchers noted an increase in problem-solving ability among patients with lesions in the left ATL. They sought to mimic this inhibition of the left ATL not by brain damage (good luck getting that approved), but by non-invasive stimulation, and to excite the right ATL while they were at it. Their hypothesis:
inhibition to the left ATL can lead to a cognitive style that is less influenced by mental templates and that the right ATL may be associated with insight or novel meaning. (Chi & Snyder)
They called their method L-R+ stimulation, denoting left-ATL inhibition and right-ATL excitation: they applied ~2mA currents for ~10min, thought to affect hemispheric dominance for up to an hour. The result: none of the study’s 22 participants could solve the problem pre-stimulation; but after ten minutes of stimulation, over 40% of the group solved it.
The same authors found success stimulating problem-solving ability in other contexts, yielding similarly suggestive results:
Now, there’s nuance to these works (and context surrounding them: other studies, assiduous lit reviews) that I’ll get into later. But, on its face, this is incredible: the difference between an unsolvable problem and a solved one can be as simple as a few milliamps of current, applied in the right place. As with cognitive-load monitoring, it’s easy to see an even more exciting future: if these are the low-hanging fruit, what will we gain from a maturing understanding of the anterior temporal lobe and finer-grain manipulation via (perhaps) optogenetic methods? And (of course) there are other regions to modulate, and interactions between regions, and higher-level neural dynamics we don’t yet understand… it’s incredible what we can grasp at now, in the lowly present, with some principled fiddling.
Invasive Methods
Sometimes, there’s just no way around it: you have to stick an electrode in someone’s brain. For these situations we have deep-brain stimulation (DBS), an eminently invasive technique that enjoys wide adoption outside of augmented cognition—for example, for the treatment of epilepsy, or the mitigation of L-DOPA-induced dyskinesia in Parkinson’s patients. But it has also found use in augmenting cognition, most often through enhancing varieties of memory. (Caveat: the invasive nature of DBS means its populations under study often have some sort of neurological pathology—worth keeping in mind to contextualize its results.)
Deep-Brain Memory Boosts
Let’s pluck one study from the mire: DBS applied to targets in the hippocampal and entorhinal regions of seven epileptic subjects while they learned locations within a novel virtual environment. (I know: more virtual mazes? It’s easier than trapping people in real mazes, I guess.) It was observed that stimulation of the entorhinal region produced a significant reduction in excess path length (relative to paths learned without stimulation), connoting an improvement in spatial memory:
No such effect was observed for hippocampal stimulation (which has, elsewhere, been documented to impair spatial memory)—pity the poor hippocampal subjects who spent twice the time wandering, thanks to science!
Indirect Stimulation of the Brain
This is something else I’ll only touch, as I’m planning to return to it later. Most cognitive augmentations are not the stuff of electrodes or prodding currents: they are life experiences, interfacing through our faculties of sensation and perception.
There is a profound body of work, for example, suggesting multilingualism—most commonly bilingualism—carries a kaleidoscope of cognitive benefits, ranging from the delay of neurodegenerative disease, to increased IQ, to enhanced attention and cognitive flexibility.
There is also some incredible work linking psychedelics to increased neuroplasticity, though that will prove quite the thorny deep-dive, awash with biochemistry (mTOR upregulation, etc.) and, of course, hallucinogen hijinks.
Conclusions (If Any)
How would you live differently, if you were more creative, or if you were simply smarter? How would work change if you could ramp your IQ as you might overclock a CPU, or toggle intense creativity when convenient? These are the sorts of unrealistic, unreasonable questions that work in augmented cognition might just end up answering. (To say nothing of the vast potential for therapeutics: sometimes augmenting cognition simply means restoring it.)