Can we use robotic augmentation limbs as flexibly as our natural limbs⁉️
🧨 Our new study, just out in @currentbiology.bsky.social, tested this using the Third Thumb @daniclode.bsky.social: a wearable robotic
extra thumb you control with your toes!
www.cell.com/current-biol... ‼️‼️
🚨Job alert🚨
The lab has up to *3 postdoc openings* for comp systems neuroscientists interested in describing and manipulating neural population dynamics mediating behaviour
This is part of a collaborative ARIA grant "4D precision control of cortical dynamics"
euraxess.ec.europa.eu/jobs/383909
Come join us at University of Toronto. We're hiring a Professor of computational cognitive neuroscience.
#neuroAI #compneuro jobs.utoronto.ca/job/Toronto-...
🦵We’re sure you’ve heard of phantom limbs - the sensation or pain felt in a limb that has been amputated. What if we told you that….
…the brain never forgets the missing limb?🧠
Longitudinal neuroimaging in three adults, followed before and up to 5 years after arm amputation, reveals that amputation does not trigger large-scale cortical reorganization
@hunterschone.bsky.social @cibaker.bsky.social @plasticity-lab.bsky.social
www.nature.com/articles/s41...
Phantom feelings in lost limbs present a puzzle for neuroscientists who were taught to believe that once a body part is amputated, another body part will creep into its spot on the brain’s map of the body.
A new imaging study undermines that theory. https://scim.ag/45SInZQ
Preprint out -- using intramuscular microelectrode arrays to detect residual motoneuron activity in tetraplegic spinal cord injury, and then using that activity for control
Credit to my other co-first authors Agnese Grison and Ciara Gibbs
1/n
www.medrxiv.org/content/10.1...
"primary somatosensory cortex stays remarkably constant even years after arm amputation. The study refutes foundational knowledge in the field of neuroscience that losing a limb results in a drastic reorganization of this region, the authors say." www.nature.com/articles/d41...
Thanks for the interest!
Dave is right that there are many studies that have mapped the phantom hand post-amputation.
However, the real novelty is ours is the first to offer data mapping the hand and lips before AND after amputation, offering a direct comparison between the maps before vs. after
Of course I stumble onto this paper right before I head to discuss post-injury remapping in my cog neuro lecture this morning www.nature.com/articles/s41... 🙃
Our longitudinal data confirms the maps are preserved. IMO, we need to stop chasing cortex and redirect our efforts to the periphery — the state of the nerve post-amputation, how to best reinnervate the nerve during surgery, the more likely driver of phantom pain
🧵3/3
jnnp.bmj.com/content/93/8...
The issue: clinical trial after clinical trial shows these therapies perform no better than placebos. Yet, these remain front-line treatments for phantom limb pain — essentially snake oil IMO sold under a neuroscience rationale that doesn’t hold up.
🧵2/3
You’re right—phantom limbs have always suggested the brain’s body map isn’t erased. The problem is the field went all-in on the idea that amputation causes reorganization. This has fueled decades of therapies (mirror box, VR, sensory discr. training) trying to “fix”supposedly broken brain maps
🧵1/3
Really delighted to announce that our paper is now out! We fMRI scanned patients both before amputation and after - allowing us to make direct comparisons.
We found that the cortical maps are extremely stable, almost unchanged - even 5 years after amputation!
Worth checking out: www.sciencedirect.com/science/arti...
They show that, irrespective of amputation, people (amputees and non-amputees) will report referred sensations at similar rates, by shaping their expectations. In other words, these effects are based on a suggestion bias, not remapping.
I don’t think phantom pain is at all associated with cortical body maps. I think the older studies put the entire phantom pain clinical field on a wild goose chase to fix broken body maps
I think we need to focus more on the peripheral nerve state post-amputation, ie procedures like TMR and RPNIs
We can only access the persistent ‘winner’ in humans because we can ask them to move their phantom fingers
We can perform this winner-takes-all analysis to replicate this supposed remapping, if we ignore the missing hand (red) and assign the territory to the next winner: lips (blue) or feet (green)
This does not mean that the monkeys’ brains forged new connections or that neurons changed their tuning because of the amputation, just that the region was already residually responsive to the adjacent fingers. You’re simply unmasking the adjacent digits, which you now assign to that territory.
They then assigned each cortical territory to the finger that elicited the greatest neuronal response when it was being touched, but because they could not touch the missing finger, the missing digit cannot be assigned any territory, because you can’t physically touch it.
Glad you found it interesting. Happy to explain! In the 1980s monkey experiments, researchers identified the animals’ somatosensory maps by recording from neurons, while simultaneously touching the animal’s remaining fingers with a glass probe after performing an amputation of a single finger
Two images of the same person side by side. On the left, the person is seated at a table, about to gift-wrap a small box. On the table is a roll of wrapping paper, the box and a pair of scissors. They are handling a sticky tape dispenser with two arms. On the right, the same individual, in the same set-up but now their left arm is missing.
Contrary to what many neuroscientists think: the brain holds a map of the body that remains unchanged even after a limb has been amputated: https://bit.ly/3UyFkRx
@mrccbu.bsky.social @pittdeptofmed.bsky.social @plasticity-lab.bsky.social @hunterschone.bsky.social 🧪 #PhantomLimb #Research
“This neural configuration before amputation remains after the amputation. And it’s not ‘use it or lose it,’” says John W. Krakauer.
By @avaskham.bsky.social
#neuroskyence
www.thetransmitter.org/plasticity/a...
Not to be a super fan. But, I talk about your study all the time. Beautiful work!
This is an incredible study and such important work. It also aligns with what we are seeing in the complimentary situation after stoke- rather than losing the peripheral limb, losing the central map.
pubmed.ncbi.nlm.nih.gov/34172735/
pubmed.ncbi.nlm.nih.gov/37940595/
Thanks so much Evan! Means a lot.
Thanks! All prosthesis use is reported in Supp. Table 1. There was minimal prosthesis use by 2/3 participants, only early post-surgery. Though, as it relates to reorganization, we’d argue prosthesis use is irrelevant to cortical reorganization, considering all participants show the same result.
Another amazing piece of work by @hunterschone.bsky.social
The only person I know that could have pulled off such a complicated project.
Really proud to be a part of it!
Thanks Jon!
