Yohan John 🤖🧠

Computational Neuroscientist

Reseach Assistant Professor at Boston University

I make biological neural network models of cognitive-emotional interaction in the limbic system. I'm also interested in philosophy of mind, emergence, and phenomenology.

Also, I sometimes dabble in mathematical concepts that are way over my head. :P

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npub1x2cj24s4axzg70nkx995vrf8ltdfd7gyy6gvvt4dhc6uuapzw0hst2jjtg

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DrYohanJohn_at_fediscience.org@mostr.pub

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nprofile1qqsr9vf92c27npy08emrzj6xp5nl4k5klyzzdyxx96kmudwwws388mcpz4mhxue69uhhyetvv9ujumt0wd68ytnsw43qg6l84e

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npub1x2cj24s4axzg70nkx995vrf8ltdfd7gyy6gvvt4dhc6uuapzw0hst2jjtg

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Last Notes

2024-08-15 21:22:02

There is a huge difference between modeling 𝘥𝘢𝘵𝘢 and modeling a 𝘱𝘩𝘦𝘯𝘰𝘮𝘦𝘯𝘰𝘯.
The success of AI/ML means that the former is eclipsing the latter in neuroscience, and I imagine in many other fields.

2024-05-15 12:02:46

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@npub13hn…fzrs
Ooh this looks excellent. Thanks!

2024-05-14 19:05:22

Every once in a while I come across a behavioral task (typically in rodents or monkeys) that is far more interesting than the accompanying analysis of neural correlates. It would be nice to read a historical survey of task design: the ingenuity of task design seems underappreciated.

2024-05-14 11:54:32

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@npub1w6d…ytvx
That makes sense!
But unique events don't even really have well-defined variances, no?
I'll have a look at the paper anyway. Thanks!

2024-05-13 20:00:57

Roko's decision theory won't save you. :P
(This sort of thing only convinces me that single-event probabilities might turn out to be meaningless.)
https://fediscience.org/system/media_attachments/files/112/435/557/550/981/406/original/17eefef57e9f6217.png

2024-05-08 20:05:39

Revisiting the topic of Up and Down states in striatal spiny projection neurons after ages. Anyone have a good reference (or unpublished pet theory) on the functions they might enable for basal ganglia circuits?
http://www.scholarpedia.org/article/Up_and_down_states

2024-05-08 12:48:02

Good article on a very tricky subject: to what extent do our tentative attempts at classification enter into feedback loops with an individual's personality and sense of identity?
https://www.newyorker.com/magazine/2024/05/13/why-were-turning-psychiatric-labels-into-identities

2024-05-05 13:45:45

“Even a potato in a dark cellar has a certain low cunning about him which serves him in excellent stead. He knows perfectly well what he wants and how to get it."
Just read Samuel Butler's 'Book of the Machines', from 1872 (!). Brilliant. And funny!
https://en.m.wikipedia.org/wiki/Darwin_among_the_Machines

2024-05-05 13:42:06

“Even a potato in a dark cellar has a certain low cunning about him which serves him in excellent stead. He knows perfectly well what he wants and how to get it."
Just read Samuel Butler's 'Book of the Machines', from 187llq a (!). Brilliant. And funny!
https://en.m.wikipedia.org/wiki/Darwin_among_the_Machines

2024-05-03 20:47:17

"Thus the CMB temperature fluctuations look like Chladni patterns resulting from a complicated three-dimensional drumhead that vibrated for 380 000 years."
- Jean-Pierre Luminet, physicist
https://arxiv.org/abs/0704.3374

2024-05-01 03:27:39

I just finished "Death's End", the last book in Liu Cixin's 'Three Body Problem' series. I'll grant that there are plenty of flaws... but what a stunning achievement it is. As vast and inspiring (and cold!) as the cosmos itself.

2024-04-24 19:28:33

"... an author's failure to produce a readable book is not ipso facto a failure to produce a good book — the history of philosophy bears witness to this..."
https://www.jstor.org/stable/3489148

2024-04-23 19:46:42

Today I was introduced to the Dempster-Shafer theory, and the broader notion of generalization of probability beyond single events to sets.
This book on the topic seems quite interesting.
https://link.springer.com/book/10.1007/978-3-030-63153-6

2024-04-13 21:34:56

Great article on the elusive beauty in cricket batting technique.
(Paywalled, sadly.)
https://fediscience.org/system/media_attachments/files/112/266/057/793/269/780/original/d1f9e0d8df982cae.png

2024-04-08 20:14:13

"And all that is now
And all that is gone
And all that's to come
And everything under the sun is in tune, but..."
https://fediscience.org/system/media_attachments/files/112/237/428/819/867/431/original/805874749c57bf85.jpeg

2024-04-02 19:22:56

I regularly come across (and commit) typos that suggest an incomplete process of syntactic metamorphosis.

2024-03-31 18:41:24

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@npub1xkw…7jwu
Happy Easter!
Legacy had a big impact on me, growing up. I watch it every few years now. Every time I get something else out of it.

2024-03-27 17:39:14

I keep coming across "deflationary" accounts in philosophy.
Where are the inflationary accounts? :P

2024-03-27 00:56:39

Cooperative competition happens in so many ways.
"When synapses strengthen, they release a virus-like particle that weakens the surrounding cells’ connections, the new work shows."
https://www.thetransmitter.org/synaptic-plasticity/neurons-making-memories-shush-their-neighbors/

2024-03-21 21:35:44

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@npub18j2…q9qz
As it turns out I saw a talk by DiCaglio and read a bit of that book. I had forgotten about it!

2024-03-21 21:16:37

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@npub18j2…q9qz
Both sound cool! Thanks!

2024-03-21 20:09:15

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@npub1k92…lfa9
It was a zoom session. Luiz advertised it here.

2024-03-21 18:06:42

How seriously should we take "levels" of reality? I mean the parcellation of the universe into, say, the the particle level, the chemical level, the cellular level, the organism, individual level, the social/ecological level etc?
Do levels interpenetrate?
Are these metaphysical matters or just pragmatic ones?
Stimulated by the great session on mental disorders just completed, hosted by @npub1ary…md4c , featuring Anneli Jefferson, @npub1qe8…4vky , @npub1skv…aky3 Alexey Tolchinky & @npub19un…gacg

2024-03-08 21:35:51

Fast synaptic learning is pretty amazing: it seems to require only very sparse firing (both in terms of percentage of cells firing and in terms of firing rate), but it can lead to very long-term changes.
Piette et al 2020. Engrams of Fast Learning. https://doi.org/10.3389/fncel.2020.575915
#Neuroscience
https://fediscience.org/system/media_attachments/files/112/062/218/238/566/605/original/5021a8f28d52ed14.png
https://fediscience.org/system/media_attachments/files/112/062/218/237/839/741/original/893c4345c3f5d837.jpeg

2024-03-03 17:36:43

Dune 2 was definitely a masterpiece. Arty, eerie, monumental.

2024-02-27 20:34:07

I can't be the only neuroscientist who thinks of this every time they see the word 'brainstem'.
Narf.
https://www.youtube.com/watch?v=snO68aJTOpM

2024-01-24 20:38:47

"Reason has always existed, but not always in a reasonable form."
- Karl Marx

2024-01-22 21:16:05

"However, when similar flight paths are compared across conditions, the stability of the hippocampal code persists."
Doesn't this mean that "place cell" is a misnomer (for such firing patterns)? They're really "place+trajectory" cells. Shouldn't a "true" place cell be path-invariant?
Credit-assigning on such invariant reps is presumably needed somewhere in the system in order to drive flexible navigation, no?
https://www.nature.com/articles/s41586-022-04560-0
#Neuroscience

2023-12-05 03:23:07

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@npub1zn5…rsnd
Makes sense. But the learning is slow right?

2023-12-04 22:16:14

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@npub1xkw…7jwu
What counts as resolving a competition?
A winner-take-all network involves lateral inhibition, and often positive feedback too. That allows one winning neuron (or ensemble) to remain active and the competitors to be suppressed.

2023-12-04 20:59:21

Most models that implement neural competition seem to use inhibition to achieve competition among neurons/ensembles.
What other plausible mechanisms for neural competition are there?

2023-08-09 19:19:06

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@npub1skv…aky3 @npub1t64…u4j0
The nice thing about this paper is that it shows how top-down causation might even occur within physics. Can physics violate the laws of physics? :)