If you’d asked me a short few weeks ago whether I thought neurogenesis in humans continued throughout their lifetime (as so often the topic comes up in the most casual of conversations), I’d have, with 100 percent confidence, said “yes.”
That’s right friends, strangers, guy in that chair over there… Today, we’re talking about one of my favorite subjects! Brains.
Recently, I found out that adult hippocampal neurogenesis (AHN) in humans might not, in fact, be a real thing.1 This is shocking! So then I wondered: Could we potentially use brain computer interface (BCI) as an artificial neurogenesis therapy for individuals suffering the effects of neurodegenerative diseases—such as Alzheimer’s—psychiatric disorders, and age-related cognitive dysfunctions?
But what is AHN, why is it important, and how does BCI fit in?
The Importance of Adult Hippocampal Neurogenesis in Humans
Neurogenesis is basically what it sounds like—the birth of new neurons. It starts in the womb and may continue until about 13 years of age2 or until death. Adult neurogenesis (what we’re focused on) has been corroborated in mice, songbirds, and non-human primates. While there is considerable evidence of adult neurogenesis in humans, this is where things get dicey. The methodology currently used isn’t ideal. For example:
- Carbon dating cells can be mislabel wherein dying cells are labeled as dividing cells, giving a false positive for neurogenesis, and protein markers can mislabel cell types (glia for neuron)1
- Studies don’t particularly account for cellular degradation in post-mortem samples, nor for cognitive health of the doner before death, which can lead to erroneous findings1
The extreme variation in findings in similar methodologies used is another head scratcher. This is why proving AHN in humans is so difficult. Finding a reliable way to measure potential AHN in real-time in living subjects via imaging seems to be the way to go but has thus far not been available.
Anyway, based on both animal and (contentious) human studies, adult neurogenesis is thought to take place in two areas of the brain: the subventricular zone, and the dentate gyrus of the hippocampus. AHN is thought to be responsible for things like learning, memory retention, and spatial memory (which is the ability to navigate your environment and remember how to get to the grocery store).
Now… neurodegenerative diseases, psychiatric disorders, and age-related cognitive dysfunctions all have something in common: in both human studies, and in studies1 using animal models in which it’s been shown AHN is present, those with the abovementioned ailments all showed decreased neurogenesis. Based on this, we could hypothesize that human AHN therapies could provide symptom alleviation (or potential condition improvement) in such conditions as depression, Alzheimer’s, and age-related memory loss. According to ADULT NEUROGENESIS IN HUMANS: A Review of Basic Concepts, History, Current Research, and Clinical Implications:
- “Consecutive animal model studies have indicated the potential of neurogenesis-based targets in drug development for depression due to the implied role that neurogenesis plays in the mechanisms of actions of many antidepressant drugs.
- “A neurogenic drug […] was found to reduce severity of the symptoms in patients with major depressive disorder (MDD) compared to placebo, but the robustness of the results was limited by small sample size and skewed test-control distribution of the study…
- “Metformin—[an FDA-approved] drug for the treatment of Type 2 diabetes—was reported to induce neurogenesis in a rat model and in human neuronal cell cultures, but no clinical trials have been conducted to support these results. Prolonged treatment with this drug in humans with diabetes, however, was found to have an antidepressant effect and appeared to protect patients from cognitive decline.”1
If AHN in humans eventually is proven, endogenous cell replacement or neuronal progenitor/stem cell transplant therapies could be a viable source of treatment.6 However, regardless of the existence of AHN in humans, prevention of cognitive decline is a noteworthy effort. But what about alternate treatment solutions in the absence of AHN in humans?
BCI as a Treatment for Cognitive Disorders
BCI has been growing in popularity for some time and has been applied to both clinical and practical use for decades: cochlear implants, the Utah array, deep brain stimulation. But it seems that a lot of BCI solutions, and even studies, tend toward mobility vs cognition. For instance, BCI studies in stroke patients primarily focus on mobile rehabilitation; however, one study3 found a link between motor, cognitive, and emotion functions that revealed promising evidence of the benefits of BCI in treating post-stroke cognitive impairments (PSCI). I want to point something important out here: BCI mobility rehabilitation has yielded very good results for patients; however, patients with a certain percent of PSCI can’t participate in this type of rehabilitation. Your brain must be able to send, receive, and decode signals for BCI to work, which is why cognitive rehabilitation is so important.
Part of what led to studying BCI in PSCI is that since the “effects of BCI-based neurofeedback training have been seen to improve certain cognitive functions in neurodevelopmental and neurodegenerative conditions such as [ADHD] and mild cognitive impairment (MCI) in elderly subjects, respectively, it is therefore also likely to generalise to other dysfunctions, including PSCI.” While more research is needed in this area, the foundation has undeniably been set. BCI could potentially act as a treatment in cognitive and some psychological disorders.
A Look at Current BCI Projects
There are multiple companies in the BCI industry, though most seem focused on entertainment and mobility. For example, NextMind’s Dev Kit is a very cool product available for consumer purchase that allows individuals to interact with the digital world in a hands-free manner. I recommend watching the launch talk—very cool. While the Dev Kit is geared mostly toward entertainment—video games, interacting with the TV, and such—being able to move and communicate through digital space offers a lot of benefits for mobility- and speech-impaired individuals.
Kernel’s Flux, however, is a different beast. According to their website, “Kernel Flux is a turnkey magnetoencephalography (MEG) platform based on optically-pumped magnetometers (OPMs), which provides real-time access to the intricate brain activity underlying functions such as arousal, emotion, attention, memory, and learning.” It’s a tool that’s been used in studies to help determine areas of the brain affected by such conditions as Parkinson’s4 and mild MCI5 related to dementia of Alzheimer’s type (DAT). The conclusion of the latter study found that “MEG functional connectivity may be an ideal candidate biomarker for early, presymptomatic detection of the neuropathology of DAT, and for identifying MCI-patients at high risk of having DAT.”
If Kernel is providing the means of early detection in neurodegenerative diseases and conditions linked with cognitive decline, is it possible that same tool can be used to detect AHN in humans? And more importantly, if AHN isn’t really real, who is going to step up to the plate with BCI focused on the treatment of neurodegenerative diseases? Elon Musk? Heh. Wait…
Could Neuralink Produce a Synthetic Neurogenesis Therapy?
Neuralinkan elon musk company is working on cutting edge BCI technology. They’ve created an implant that uses tiny threads inserted into the brain to receive neuronal signals. The implant amplifies the signals, then converts them to digital code which is sent via Bluetooth to a mobile app. The threads can also send signals to stimulate neurons and identify some neurons by shape.
While Neuralink’s initial goal is to facilitate digital communication and interaction in paralysis patients, they’re ultimately hoping for potential restoration of motor function in said patients, treatment of cognitive and psychological disorders, restoration of vision, and more. I highly recommend watching the launch of N1 for a look at the science and engineering behind all of it, and I recommend watching the progress update to get a look at the Link and its specs. It. Is. Very cool. But what does it have to do with neurogenesis?
Well, “Progressive degeneration of specific neuronal types and deterioration of local neuronal circuitry are the hallmarks of degenerative neurological diseases, such as [Parkinson’s, Alzheimer’s, Huntington’s, and ALS].”6 Identification of these specific neuronal types is key in any neurogenesis therapy (kinda like gene therapy!), whether transplanting genetically engineered cells into target regions of the brain or using software programed to mimic specific neuronal signals in place of lost or damaged neurons.
Because Neuralink’s device can send, decode, and receive signals and identify neurons, and because we know specific neurons related to specific neurodegenerative diseases (i.e. Huntington’s degrades striatal medium spiny and cortical neurons), I opine that, yes, Neuralink’s device could definitely act as a synthetic type of neurogenesis therapy. There’s obviously an extreme amount of data that would have to be collected though, given that two of the same type of neuron in a person’s brain giving the same directive (or “action potential”) can do so in two different ways, and this varies from person to person. Neuralink’s data processing ability is pretty remarkable and quite robust, and since it’s already individually tuned (so to speak), it’s essentially made to be a target therapy.
Furthermore, with the ability to process so much data simultaneously, the Link could additionally help identify neurons or neural circuitry affected by neurological disorders or damage to provide effective treatment therapy. It could also help with schizophrenia, wherein erroneous information processing due to abnormal dendritic branching and synaptic connections could be corrected or overwritten.1
There’s an exceptional amount of potential with this device and, while it might sound like science fiction, it seems more to me like it’ll be reality within the next 10-20 years given where technology is at now and the rate of progress.
Whew! It took a long time, but we got there. Now, enjoy a Macaque playing Pong with his brain.
1 ADULT NEUROGENESIS IN HUMANS: A Review of Basic Concepts, History, Current Research, and Clinical Implications
2 The controversy of adult hippocampal neurogenesis in humans: suggesting a resolution and way forward
3 BCI for stroke rehabilitation: motor and beyond
4 Hypersynchrony despite pathologically reduced beta oscillations in patients with Parkinson’s disease: a pharmaco-magnetoencephalography study
5 A multicenter study of the early detection of synaptic dysfunction in Mild Cognitive Impairment using Magnetoencephalography-derived functional connectivity
6 Neurogenesis as a potential therapeutic strategy for neurodegenerative diseases