The Hippocampus: More than Space, More than Time; More than “Maps” & What Meets the Eye

 

Well, what can we say? Bravo.  It’s about time!!

It’s very late at night, too late to be writing..around 2 AM…and certainly too late to be typing..but we just came across the publication which has aroused us to the point of more than being awake at this late, late time but having to put down our thoughts in this blog.

We’ve long been lamenting the failure to deal with this general nature of the “mapping” of the hippocampus for years now.

We have regularly insisted, hoping for such an experiment to arise, that “episodic memory recall” and ‘navigation through mazes” are both actually manifestations of the same underlying ‘traveling’ through different dimensional domains.

So Bravo!! Truly and let’s look at  how the press on this research tumbles out, as almost sheer poetry to our ears:

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The Hippocampus Maps More Than Space

“The hippocampus and the neighboring entorhinal cortex are well known for their striking ability to map space”

 “But new research published in Nature suggests a much broader function. The study, from Simons Collaboration on the Global Brain director David Tank and his collaborators, found that cells in this area can also map sound”.

(this notion of the ‘map” is unfortunate…and ironically they are extending the less than adequate spatial map concept, without clarifying what a “map might truly, really be, to now try to speak to us of  a map-related narrative for the sound task performance.)

“As we described in a story published in December 2016, Dmitriy Aronov, first author on the study, trained rats to use a joystick to move through a sort of sound maze — a defined sequence of frequencies. :

 The researchers discovered a set of cells that act very much like place cells, which fire when the animal is in a specific location. These ‘sound cells’ fire when the animal hears a specific tone.

Apparently in a  December, 2016, it was noted in apiece by the same authors:

“The findings point to a more general function of the hippocampus — it’s representing the whole experience,” says Aronov,   “Anatomically, it makes no sense for the hippocampus to be only about space, because it receives information from everywhere in the brain.”

There is more here though to feast our thoughts upon. The publication itself is even more entlightening

Mapping of a non-spatial dimension by the hippocampal–entorhinal circuit

Those who have followed this page must recognize, we have ardently and perhaps too passionately at times pushed for the hippocampus being the central hub and key to what we casually call ‘experience’.

Here we see now that the researchers have to recast their idea of the place cells and indeed the grids which relate to those place cells

And we all, along with the researchers,  must now appreciate that the hippocampus can only be understood in terms of some broader and more interesting notion of experience. As we note down below that in turn requires that they have more to go by in defining experience than something like the rather nutty Thomas Nagel notion of ‘how it feels like to be a bat”

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And that revised and upgraded notion of experience more properly in synchrony with Darwinian logic..rather than every day shopping mall talk.. is something we have tried to pass along…and will comment upon down below.

“From pressing the lever to traversing the frequency to receiving the reward and starting a new trial — there is a sequence of activation throughout the entire period of behavior,” Tank says. The sequence probably represents not just sound but other aspects of the task as well, perhaps even abstract concepts”

The authors state (ironically we hope) that they  discovered a set of cells that act very much like place cells, which fire when the animal is in a specific location. These ‘sound cells’ fire when the animal hears a specific tone.”  The quotes are theirs (thankfully)

But of course this conclusion must be drawn since they discover that the cells that do the navigation in spatial task overlap considerably wit those which provide guidance in the sound related tasks:

“Neurons involved in this representation overlapped with the known spatial cell types in the circuit, such as place cells and grid cells.

These results suggest that common circuit mechanisms in the hippocampal–entorhinal system are used to represent diverse behavioral tasks, possibly supporting cognitive processes beyond spatial navigation”

empathy_brain

Clearly , we applaud as they come to the point here in realizing that ‘spatial firing” of various cells in a circuit controlled pattern cannot be deemed just “spatial firing” but must be indicative of something more.

“‘Spatial firing is often considered to be one specific example of a ‘cognitive map’—a general representation of relationships between cognitive entities?

Of course we must agree with them that  “the firing of hippocampal cells is modulated not only by location, but also by non-spatial variables, including sensory, behavioral and internal parameters”

“These entities ,they remark , seeking to get beyond t the unfortunate, Moser based interpretation of spatial navigation as an allocentrically determined mapping process, ” can correspond to different locations, but can also be distinct stimuli or even abstract concepts”

They are here recognizing that the rats sequence of behavior is determined by a serious organization via the hippocampus but not in terms of either ‘places” or of “sound”..but in terms of internally unfolding sequences or series of their own movements/behaviors/and indeed, the unfolding of what we say, along with them (for now) is ’experience”.

We repeat: they say,

 ““The findings point to a more general function of the hippocampus — it’s representing the whole EXPERIENCE,

They note that as the rats experience the task of sound performance

“Critically, spatial and non-spatial representations are produced by the same neuronal population, suggesting a common circuit mechanism for encoding fundamentally different kinds of information across tasks.”

 “Our results therefore suggest that the well-known spatial patterns in the hippocampal–entorhinal circuit may be a consequence of the continuous nature of the relevant task variables (for example, location) rather than the ‘territory”, just as the same neurons and the same circuit cannot be reflective of the ‘territory of sounds” either.

Those who have been following this page must recognize several hauntingly reminiscent themes that we have been striking for a couple of years all coming to a crescendo her in this study….
For one thing, they now realize that the notion of a ‘map” is not at all what it seems to be..a pictorial rendering of an external space…that the definition of a ‘map” properly has nothing at all to do with the ‘Territory’ that is being navigated with the help of the map. Of course, the “map is not the territory” as we are so used to hearing. But it is NOTHING like the territory at all.

 

subway-spiderBut that a far more general function is readily apparent to those who look at what a “map” truly is.  An analysis of what a map truly is shows unequivocally that it is not at all “pictorial” ..even in degree of accuracy of not. But that a map is an encoding of the possibilities of the users movement horizons and the characteristics and limitations of the user and not the territory.

If you consider many maps of which you and I are aware…whether road maps, or subway maps, or train maps, or airplane maps, or pedestrian maps, they show us not “what IS out there”, but they show what we can or cannot do or expect do by nature of the “vehicle” which is doing the moving, whether road maps or train maps…or whichever sort of map it is…the map is a reflection of the possibilities, the rules for movement which are imposed on us by limitation of the vehicle which moves us and not by the terrain per se.

As is said at the end of the article:

“Our observations lead to an intriguing conjecture that in more complex tasks (for example, those containing memory-guided decision points), the hippocampal–entorhinal system might similarly represent arbitrary behavioral states.”

We can begin to suspect something going astray here when we are hit with the word ‘arbitrary”.  Something is going on that we know we are not going to like as much as the rest of the research.

olfactory-relays-2

Unfortunately we soon enough come to an aspect of that lurking problem, though just a problem of epistemology and mathematics that can easily be resolved.

That cloud shows itself clearly when they come to discussing the idea of interpreting their observations in terms of continuous dimensions that seemingly all might involve hippocampul-entorhinal cortical circuitry.”

“Finally,’ they state,” recent functional MRI studies have suggested that cognitive spaces defined by continuous dimensions are represented by the human hippocampal–entorhinal system”how-to-remember-things-with-method-of-loci

“One interpretation of these findings is that any arbitrary continuous variables that are relevant to an animal can be represented by the hippocampal–entorhinal activity using a common circuit mechanism.”

 In this framework, task performance activates a sequence of neural activity, in which firing fields are elicited parametrically with progress through behavior.  Neighboring and partially overlapping fields therefore represent the order and adjacency of behavioral states.

This could be useful for linking events in episodic memory and for planning future actions (for example, via simulated continuous neural sequences ?

We have repeatedly written about how the ‘place cells” are not truly depiction of “place” and that the Mosers and Nadel both misunderstood seriously the nature of Poincare’s explanation of how creatures like us..and even those not just like us…manage to give themselves a “space” frame in which to operate…to position themselves….and to gauge how much further they must go  till satisfaction.

We should recall that Poincare, one of the greatest geniuses of the past couple of centuries of mathematics was dismissed as a naive “conventionalist” by many include Nadel and O’Keefe in their 1978 seminal work on the hippocampus, when he pointed out that space was nothing more than an extension of the organism’s movements and its awareness of the possibilities of those movements into what he called a “group” (a mathematical structure) of displacements “in “that space.

So space was not for him a container for objects..but a “containment of the movement possibilities of the organism”  Of course he was presaging the role of the hippocampus. But it was though preposterous that the geometry of space, so clearly real and natural to our intuition should be “constructed” somehow from the movements of the organism. He was thus dismissed as denying the absolute validity of Euclidean spacetime by many including the founders of the exploration of the hippocampus.

'They tested some brain boosting pills on me and now I'm selling maps. Want to buy one?'

And of late we have commented extensively on the manner in which modern physics down to the latest quantum physics has shown us that “the reality out there beyond us” if we choose to use that term “reality” is not at all “continuous” but is more properly “discrete”

The lessons of physics have been that the nice and cozy Euclidean/Newtonian world of events organized in continuous space and time, with points in space lined nicely side by side (with no gaps between even infinitesimal ones) and in time that is composed of point-like “instants” one immediately rushing after the last one..continuously…is an illusion that we all intuitively slipped into but which was truly a matter of own “construction”.

It was not a matter of a Grand Deceiver of the sort which Descartes worried about or some evil force imprinting us with a false belief.  On the contrary as Poincare and later Piaget pointed out the notions derived from our own movements and behaviors as we were in some way unknown to them aware of the mathematical grouping of those movements…

Continuous space time and it soothing cozy causality….arises from that kind of universe were the products of our own construction. To us that means they were the products of our own brains, of course

drawing

Therefore, when we hear about the current researchers seeking to interpret the hippocampus in its splendid job performance as doing what it sort of, kind of has to do when dealing with continuous realms of ‘experience’, we do not respond with the same applause as for the overall findings.experience 1

On the contrary what this research must present to us is the even more interesting question of just how is it that the continuous realm of space and time trajectories…with its immediately emergent causation is generated by the hippocampus…and not that this world is “objectively out there’ only to be mirrored by that little segment of our brains.

experience 2

The continuous and space time situation “experience” that we all have in the context of which events seem to so naturally arise must be constructed by the hippocampus. Certainly if we lend any credence to our physics…for those who like to speak in terms of ‘reality” and “objectively real events”…then we have to admit that the discrete is prior both logically and chronologically to the continuous, don’t we.

This then is the marvel of the hippocampus.

 

Experience is truly its domain and bailiwick, we agree with the researchers. But it is what ‘makes’ that experience, manufactures it, as it were, on the fly, each moment of every day. And that is what must explored.  Much more than merely   how it reflects and seeks to cope with continuous realms which are presumably out there in the noumena of the universe, but, on the other hand, how it presents the rat, and all of us and the researchers with this transform of the ‘discrete’ into continuous ‘experience” that allows us to continue navigating whichever way we go.

Experience is therefore the last item on our agenda for today.  Followers know very well how much we rant and rave and fulminate about the need for understanding that ‘experience’ is not some simply awareness of something beyond our eyes and ears, that is not a “perceptual event or occurrence”, but it is something that we must look at when we consider ourselves as “observers’ of that experience, whether in rats, or our subject or patients, or in ourselves as we do what is known as “introspecting” as an ongoing construction.

The Hippocampus does not organize life  for our “selves’ by “mapping” experience into  a continuous space time that the self travels through, a ” out there for us”,  rather,  it constitutes “experience” via space and time constructions as a unifying framework with “self” as a point of origin at its center of all coordinates. 

Surely the hippocampus has to be directly involved as the major actor in that ongoing drama…if not the producer and director of the script of life.

However, in order to properly view that on-going construction and generation of “experience” by the hippocampus entorhinal circuitry as it relates to and ‘revs up” the rest of our brain during it moment to moment guidance of our movements and behaviors. we need a model and a way of speaking about this that does not settle into the metaphors that have led to this long and weary historical misinterpretation of the “self’ and the ‘experience” which is part of it.

For that, again we have urged readers to consider the use of a proper Darwinian manner of speaking about this marvelous ongoing construction of our lives.  And that too is present in numerous posts here on our page.

At any rate, we should say “Bravo” at long last.  And leave the reader with one more footnote that we all should consider  We have noted that the authors of this research likely have gotten the relation between the hippocampal-entorhinal circuit in its role in the brain’s overall functioning and the continuity of experience backwards.

We have insisted upon that primacy of the discrete over the illusion of continuity…with the backing of a century of physics and philosophy research.  And now we wish to urge consideration of even more: That the production of   the continuity of experience” is manifest in the very key and so controversial and elusive notion of ‘self’.

This odd index of our lives and our experience is precisely that aspect of our experience which does not produce “continuity” but, in contrast,  is the embodiment of that continuity depending upon the operation of the hippocampal/entorhinal circuit.

The Jamesian flowing continuous self is very much what emerges as the vehicle of the navigation of that circuit whose trajectory is shaped by it.  Whether it is the rather fancified ‘self” of the man or woman in the street or the simpler rudiment that allows the rat to ‘know’ something like ‘HERE is where I ‘am NOW”.. just as every GPS voice or floor map in a shopping mall tells us.

experience

This ‘self’ is the consequence of the continuous construction of experience by the hippocampus entorhinal circuit.  it is not the generator of experience by being an observer of the real universe around it. On the contrary..the self is a locus in the intersection of the continuity of time and the continuity of space…which is here shown to be the work of our brains.

Now does this mean that we are merely saying that the “self “ is not at all ‘real” . That it is a figment of our imaginations.  A delusion suffered by those of us, like me, who are not ardent materialists? No, it does not.

center-of-gravity-centroidThe reader should ask themselves, whether the “center of gravity” of an object in that intuitive Euclidean/Newtonian world of our innocence prior to this century is “real” or is it not’

Surely the “self” is that center which we “calculate” via our hippocampal-entorhinal circuit that has meaning only in the course of …but very much in the course of…those storms and forces of experience.

We may or may not focus on this aspect of the notion of experience but it is spoken of very much as if it is a force which determines our course in life and our destiny.  This does not mean that we consider it to be an actual ontologically situated “force”, anymore than Darwin considered “natural selection” to have been a real force operating in evolutionary time and space.  Yet the use of the term “force” for both “natural selection” and ‘experience” is not coincidental.

As an antidote to the popular misuse of the term “experience” as some sort of simplistic, instantaneous sensory ‘input’ of ‘information” to some “computational inner system”, we urge taking a look at the way the term has been used by  a few folks who do know about language use.  To us, one can almost take each statement and transpose it into a statement about “natural selection” and the survival and progress of “species’.

Dennett

The “Self “which is the other side of the coin of ‘experience”…or much as the “mind’s eye is to metaphorical visual field of experience”.. is a center of the storm (an eye of the hurricane outside)

Surely there is no such point or place to which we can really point.  Yet, we speak about objects in that continuous spacetime and we  engage in calculations of
their trajectories, either past or future.  And it works out rather well.

The “center of gravity” some might say is just “in our minds”. But, it surely is “real” in the sense that its use is vital and at the heart of the continuous space time framework in which our speaking of the motion and life of the object takes place.

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So it is then with the notion of ‘self’ as it can only be defined in terms of its “use” and its usefulness as the embodiment of the calculation of a continuous space time and its fascinating consequence of causation.  Surely, it, the self” is the very embodiment of the impossibility of the ‘action at a distance” that comes with a continuous space time frame and its quaint notion of causation. IT does the “causing” that is associated with the expression of “will”, and it is the product of it’s “experience” as it impacts upon the ‘self’.

It is as real as its use in every second and every minute of our navigation through life, whether through a maze or through our world.

We should note that we have not yet commented in full on the interesting aspect of the ‘proof” of the non -simplicity of the “mapping’ of the hippocampus by means of its role in the experiencing and ordering of our experience of the phenomenon of sound.

Here we have before us the interesting  occurrence in one dimension instead of three dimensions….and how that suggests that here we have the archetypal four dimensional manifold being produced by the hippocampal-entorhinal circuit relates to this picture.  But we have only rather hastily began to sketch this picture  tonight.

We promise there is more to unravel here…much more than meets the eye and that requires the ear to help make sense of any kind of ‘map” of any kind…and the nature of sound is quite as primordial as the nature of movement and indeed sound and sound making is an extension of movement so it would not be surprising that the hippocampus was pressed into service to help us make sense of our experience of sounds just as it helps us make sense of our experience of movements.

Isn’t it quite natural to ask ourselves whether some integration of these two navigational guides of these two varieties of experience isn’t also a a job of the hippocampus…or do we believe that all the serious work of living and deciding how to live takes place in the pre frontal cortex…rather than down below in the highly lateralized hippocampus…where both sound and motion may be “mapped” (excuse the word) together to help shape each others pathways of choice.

But we have to save that for another day.

loosing_and_finding
We leave the reader with the closing lines of the above research that perhaps the reader will ponder in the context of rather effusive remarks above:

“This could be useful for linking events in episodic memory and for planning future actions  (for example, via simulated continuous neural sequences ).

Spatially localized place and grid codes might therefore be a manifestation of a general circuit mechanism for encoding sequential relationships between behaviorally relevant events.

This view suggests a role for these cell types in supporting not only spatial navigation, but cognitive processes in general.”

Amen !!!!

PS: We’ll no doubt come back to this page tomorrow morning (or more likely afternoon) and put in some details and links and references and those dozens of earlier blogs and posts to which we refer above…..and, quite possibly, fulminate a while longer tomorrow.  Which is after all “another day”.

One of our favorite quote is from the poet Borges<

Time is the substance I am made of. Time is a river which sweeps me along, but I am the river; it is a tiger which destroys me, but I am the tiger; it is a fire which consumes me, but I am the fire.”

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