
The hippocampus as a 'predictive map' - runesoerensen
https://deepmind.com/blog/hippocampus-predictive-map/
======
pizza
Relevant:

A compressed sensing perspective of hippocampal function (2014): _Hippocampus
is one of the most important information processing units in the brain. Input
from the cortex passes through convergent axon pathways to the downstream
hippocampal subregions and, after being appropriately processed, is fanned out
back to the cortex. Here, we review evidence of the hypothesis that
information flow and processing in the hippocampus complies with the
principles of Compressed Sensing (CS). The CS theory comprises a mathematical
framework that describes how and under which conditions, restricted sampling
of information (data set) can lead to condensed, yet concise, forms of the
initial, subsampled information entity (i.e., of the original data set). In
this work, hippocampus related regions and their respective circuitry are
presented as a CS-based system whose different components collaborate to
realize efficient memory encoding and decoding processes. This proposition
introduces a unifying mathematical framework for hippocampal function and
opens new avenues for exploring coding and decoding strategies in the brain._

[0]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4126371/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4126371/)

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mh-cx
Reading about rewards in AI context makes me wonder, why current AI only
focuses on the network topology aspect of natural intelligence.

What about the neurotransmitters like dopamine or serotonine? Could they (or
more specific: their effects) be key to an AI that feels more “natural“?

~~~
mh-cx
Downvoters please explain what's so stupid about my question.

~~~
pizza
I upvoted you, and I'm actually glad you asked the question despite downvotes.
I imagine those who did are of the opinion that essentially you're ascribing
too much function to the neurotransmitters themselves, as opposed to the
contexts in which the presence of the neurotransmitters are used as signals.

Take a look at this brain schematic here [0]. I vehemently disagree with some
of the presented-as-fact ideological aspects of the article, but the depiction
of neurotransmitters working differently in different brain regions is
illustrative.

i.e., a dopamine molecule does not already constitute a meaningful coordinate
system -- it doesn't have a meaning in and of itself, such as "the reward
molecule", or euphoria/"feel-good"/"addiction trap"/excitement molecule) in
the brain. Rather, the dopamine molecule has locally-interpreted semantics.

To make this more concrete with examples of different aspects of dopamine
alone:

\- "dopamine is known to encode the confidence level of motor predictions" \-
Scott Alexander, psychiatrist [1]

\- saturating the synaptic cleft between neurons with released (or non-
recycled) dopamine _is_ a part some euphoric processes (e.g. drugs, orgasm,
gambling) in the striatum negra

\- 'excess' (not a simple thing to determine for individuals imo) dopamine is
related with psychosis (not per se _causally_ ), and antipsychotics are often
designed to blunt dopamine transmission

However,

\- dopamine transmission is _also_ fundamentally necessary for muscle
movement, in the motor cortex

\- additionally, the conscious sensation of dopamine is highly dependent upon
the frequency of dopaminergic neuron spikes

\- Parkinson's disease is (iirc, said to be,) the result of the degeneration
of motor neurons; shakiness, problems sleeping;

What does that mean for AI? Well, if we want to go beyond network topology,
and start to use new varieties of component substrates, the individual types
of signals they represent must either a) be fairly meaningless outside of a
specific context or b) not be suited for learning from evidence and
generalization of data. Check out [2], [3], and [4] for more.

[0] [http://www.nationalgeographic.com/magazine/2017/09/the-
addic...](http://www.nationalgeographic.com/magazine/2017/09/the-addicted-
brain/)

[1] [http://slatestarcodex.com/2017/09/12/toward-a-predictive-
the...](http://slatestarcodex.com/2017/09/12/toward-a-predictive-theory-of-
depression/)

[2] [https://www.edge.org/conversation/stephen_wolfram-ai-the-
fut...](https://www.edge.org/conversation/stephen_wolfram-ai-the-future-of-
civilization) (not that i am a huge fan of wolfram :P)

[3] [https://www.edge.org/responses/what-scientific-concept-
would...](https://www.edge.org/responses/what-scientific-concept-would-
improve-everybodys-cognitive-toolkit), ctrl-f "biological"

[4] [https://en.wikipedia.org/wiki/Multi-
state_modeling_of_biomol...](https://en.wikipedia.org/wiki/Multi-
state_modeling_of_biomolecules)

~~~
chiggins
Not to derail this further, but your description of Parkinson's disease is
incorrect. Dopamine plays a role, but it isn't degeneration motor neurons
themselves. There are many effects, but the primary symptoms WRT motor control
are caused by death of dopaminergic neurons whose cell bodies reside in the
substantia nigra but innervate and regulate firing of corticostriatal pre-
motor pathways.

[0] I did my PhD on this

[1]
[https://en.wikipedia.org/wiki/Parkinson%27s_disease#Pathophy...](https://en.wikipedia.org/wiki/Parkinson%27s_disease#Pathophysiology)

[2]
[https://en.wikipedia.org/wiki/Nigrostriatal_pathway](https://en.wikipedia.org/wiki/Nigrostriatal_pathway)

~~~
pizza
TIL, thank you

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dontreact
I don't know how this theory fits in with patient H.M. who was still capable
of many types of learning and planning, despite having his entire hippocampus
removed.
[https://en.wikipedia.org/wiki/Henry_Molaison](https://en.wikipedia.org/wiki/Henry_Molaison)
At the least such a broad sweeping theory of how a brain region works should
address how it fits in with evidence with the most famous lesion (and deeply
studied) patient who did not have said brain area?

~~~
saurik
> "The researchers found, to their surprise, that half of H.M.'s hippocampus
> had survived the 1953 surgery..."

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eli_gottlieb
Hmmm. I'll need to read more closely later and make a real comment, but since
when did Gershman or anyone at DeepMind get on the predictive-coding train?

Nonetheless, this kind of algorithm sounds like exactly what I expect from a
predictive brain that cares fundamentally about trajectories.

~~~
mannigfaltig
What are your thoughts on this paper?

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m3kw9
Are the structure same throughout the areas where we think in general?
Otherwise there could be some sort of programming involved to get the brain to
think predictively

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shuma
Numenta have been doing this for many years now,
[https://numenta.com/](https://numenta.com/)

~~~
eli_gottlieb
Can you and others _please_ stop reading actual neuroscience and saying, "oh,
Numenta did this already"?

* Firstly, you're reading a _neuroscience_ paper. It's biology! Numenta is not biology.

* Secondly, Numenta makes a lot of big claims and then never publishes _anything_.

This has gotten as if we were responding, "Simpsons did it!" to jokes which,
in fact, _The Simpsons_ had never aired, based on the supposition that since
they once did a joke with vaguely similar vocabulary, it must have been the
same as _this_ joke.

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neurokim
This link should work for full text, final version, no paywall

[http://rdcu.be/wnSU](http://rdcu.be/wnSU)

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rayuela
Just $225 to read the actual paper... what a steal! If someone would so kindly
share that pdf on here I'd greatly appreciate it.

Nvm found it:
[https://www.biorxiv.org/content/early/2016/12/28/097170](https://www.biorxiv.org/content/early/2016/12/28/097170)

~~~
itschekkers
theres a website called sci-hub (which maybe illegal) that you can use to get
almost any paper in a STEM field, especially from major journals. you type
www.sci-hub.cc/ and then paste the DOI of the paper. it takes you straight to
the pdf!

~~~
SubiculumCode
Or you can contact the researcher, who are generally happy to share our
research via email. Or check their researchgate.

~~~
neurokim
Truth :) [https://rdcu.be/wnSU](https://rdcu.be/wnSU)

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gregatragenet3
It's too bad, their prior papers were generally open for anyone to read. These
new papers appear to be behind paywalls :(

~~~
pazimzadeh
Obligatory Sci-Hub link

[https://sci-hub.cc/https://www.nature.com/neuro/journal/vaop...](https://sci-
hub.cc/https://www.nature.com/neuro/journal/vaop/ncurrent/full/nn.4650.html)

