Phenomenology Life and Simplexity Jean-Luc Petit Université de Strasbourg.

Phenomenology Life and Simplexity

Jean-Luc PetitUniversité de Strasbourg

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Plan

1. “The complexity of reality”

2. Complexity – a threat to the living being

3. Simplexity: getting us out of predicament

4. Natural science and phenomenology

5. Constitution Theory a framework for simplexity

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Plan






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Palimpseste du Monastère de Ste Catherine, Mt Sinaï (IVe s)

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Stars cradle

Fly brain

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Reaction of Belousov-Zhabotinsky

Oxydoreduction of citric acid into a carbonic gas in which concentrations of bromate /bromure pass alternatively below and above a critical value under the influence of an autocatalytic coupling of states of the two substances, either oxidized or reduced.

Periodicity of colour changes observed by Boris Belousov in a study of metabolism of glucose (1950)

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Emergence in a network:u, v in same component because there is a path from u to v.

x, y in distinct components : no path.

If one adds m random connections between the n nodal points of the network, as soon as m goes beyond n/2, a giant component develops, until it encloses all the nodes.

An abstract mathematical model of the phase transitions and the appearance of structures out of chaos in dynamic physical or biological systems.

T. Bohman, Science 323 (2009)

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Complex System = not completely aleatory nor completely regular.

Brain: a mix of anatomical segregation and functional integration.

G. Tononi et al, TICS 2/12 (1998)

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Plan






A. Berthoz: « Nous vivons écartelés entre de nombreuses identités qui nous placent

dans un entrelacs de toiles d’araignées sociales et psychologiques … »

« L’homme d’aujourd’hui est un Thésée perdu dans un labyrinthe… »

13E. Rolls The Brain and Emotion (1999)

Thalamus

Striatum

Basal Ganglia

Cerebral Cortex

Cerebral Cortex

Globus

Pallidus

Substantia

Nigra

Subthalamic n.

Multiplicity of functional loops in the brain apparently incompatible with the stability of functioning of circuits

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Plan






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The inventary of simplex solutions

• F: 'X is an ingenious solution invented in the course of evolution to simplify (reduce the dimensions of) the problem posed by the complexity of the environment.'

• F is then the general formula for drawing up an inventory of the remarkable features of living organisms – but a list still does not amount to a theory.

• How does one get from a list to a Theory of simplexity?

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A tool-box of simplifying Principles

• 'A simplex process, Berthoz tells us, is a process regulated by several principles... This list of principles is designed to provide a framework, inevitably incomplete and debatable, for specifying the concept of simplexity (4)'.

• Only, this list knows no end: 'it is impossible to describe all the simplifying principles evolution has put in place: we discover more of them every day (73)'.

• In the end, no procedure can be excluded: 'Evolution seems to have used any means available, adopting unpredictable paths, utilizing all the tools that physics and chemistry made available, with the sole end in view of simplifying (38)'.

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Motor equivalence in gaze

We can move our gaze by moving the eyeor by moving the eye and the heador even by moving the whole body :

For that the gaze movement needs to be coded sufficiently generally to be realized by any part of the body.

The gaze movement is coded in a variable of velocity that is transformed in a signal of position according to the internal model controling the movement of the chosen limb.

A retinotopic model map where each neuron is represented by its receptive field:

The displacement of target in outer space is predicted by the change of activity in the map as a gaze-velocity signal is updated after the oculomotor command.No need of a higher cognitive spatial map to track the movement of targets in space.

Proc. Natl. Acad. Sci. USA, 88, 9653 (1991)

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Making a detour in tracking tasks: Instead of trying to continuously control the unpredictably changing position of a moving target Subjects intermittently minimize a composite variable s (a mixture of position, speed and acceleration) using a feedback (corrective) and feedforward (estimative) strategy in order to compensate for the unknown dynamics of the limbs-object system keeping it within the limits of one dimension.

The hand movement needed for that correction might be a simple ballistic movement with a stereotyped cinematic profile.

Biol. Cybern. 77, 381 (1997)

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Deciding where to look

Self-initiated (not externally cued) eye movements between alternatively possible targets rely on the prefrontal cortical areas of decision-making in behavior.

Decision condition: subjects are free to decide the direction of the forthcoming saccade.

Dorsolateral prefontal cortex active in decision condition not in case of imposed saccades.

Task:

fMRI results:

Neuroreport 18(12) (2007)

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Catching a falling ball thanks to an internal model of gravity:

The brain triggers hand movement based on the visual image of the object complemented by an implicit knowledge of the acceleration effect of gravity.

In the shuttle (0 g) the anticipatory movement occured earlier than on earth.

Prediction of movement is simplified by an internalization of laws of physics making possible to simulate moving objects in the world with the body.

Nature Neurosc. 4, 7 (2001)

---Lag of time-to-contact visual estimation (1g)---Precocious TTC based on internal model (0g)

Anticipatory biceps EMG response (0g)

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Head stabilization for top-down control of locomotion:

The task of coordinating the degrees of liberty of the limbs in walking is organized from the head not the feet.

The head is used as a mobile inertial platform freeing the body from the ground.

Head kinematics video recorded and reconstructed by computer (10 sj).

Exp. Brain Res (1990) 82, 97-106

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Different brain areas for egocentric and allocentric strategies in spatial location:

Orienting oneself in space supposes an ability to change point of view: from refering to oneself to taking an object or a landmark in the environment as frame of reference.

Egocentration activates a network including: parietal (1) occipital (2) and frontal (3, 4) areas.

Allocentration activates a partly different network including also occipito-temporal (7, 9) areas.

J Cogn. Neurosci. , 169 (2004)

Tasks : 1) Which garbage can is closer to you?2) Which can is closer to the red ball?3) Which can is closer to the front of palace?

Perspective taking : two mental imagery strategies for embodiment of the othera: Reflection Symmetry : A tilts on his left when B tilts on his right and vice versa as if A saw himself in a mirror. b: Rotation Symmetry : A tilts on his left when B tilts on his left as if disembodying and adopting B’s perspective.c: experimental setting: Subject on a ground trace in line with the rope of the acrobate.d: goniometer recording the tiltings of the bar.e: video of avatar acrobate tilting on his right (or left: f). Brain & Cognition (2009)

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Plan






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'Any science has to replace, or economize on, experience, by reproducing, or prefiguring, facts in the form of thoughts, such reproductions being more readily available than experience itself, and therefore capable of replacing the latter in many respects (452) ... Science can itself therefore be regarded as a minimal task, consisting in representing the facts in the most complete manner possible and with the least expenditure of thought (E. Mach, Die Mechanik in ihrer Entwickelung, 1883, 461)'.

'This would-be principle is nothing less than an attempt at an ultimately rational explanatory principle, the mere grouping together of an entire complex of evolutionary facts in advance of any ideal reduction to elementary facts and laws, and this whether or not any such reduction will ever be realizable (Husserl 1913, IX, §.55).'

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Formation of neuronal groups on the computer:

A: initial state of part (12 x 6) of a network of 144 excitatory cells and 2448 synaptic connections.

= cell

— = synaptic connection,

colors = strength of synaptic connection

B: state after hand surface stimulation (activation of 3x3 receptors) : formation of neuronal groups by reinforcing connections between neighboring cells and weakening connections between distant cells.

C: enlargement of B part including groups et ‡ :

Blue borders of weak connections protecting groups from encroachment by other groups.

Interface /‡ corresponds to the frontier between palm and back of hand.

J. Pearson et al., The J. of Neuroscience (1987)

A Dynamic Model of MorphogenesisThe cortical map of a hand simulated

27Recanzone et al., J. of Neurophysiology (1992)

Receptive Fields of 3b neurons located on trained hand(monkeys with improved performances)

3b RFs on controlateral hand

Plasticity of hand functional organization induced by stimulation

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///// : back of hand representation : loss of response

Median nerve transsection deprives the cortex of palm entries D1-D2

Stages of reorganization:(1) Silence of some cortical regions; new responses in back D1-D3;(2) Almost complete recovery of reactivity.

Buonomano & Merzenich, Annu. Rev. Neurosci., 21, (1998) / Merzenich et al., (1983).

3b

Hand functional reorganizationafter median nerve transsection

29Wall et al., J.Neuro. (1986)

1. A. areas 3b + 1 Parietal cortex. B normal topographic representation of hand in 3b. C. After median nerve transsection: loss of palm receptive fields + acquisition of back RF.

2. centers of palm receptive fields after nerve recovery (76j, 153j, 322j): re-innervation of median nerve territory: • RF unique (normal) ○ RF multiple (anomalous).

1.

2.

Plasticity of hand representations : Cortical Maps:

Cutaneous Receptive Fields:

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Maps of cutaneous receptive fieldsafter stimulation (normal/ abnormal)

A: before group formation • cell responsive to palm stimuli ○ cell responsive to dorsal stimuli (mixed cells unmarked)

B: after formation of groups: Most cells are of an exclusive type of response, mixed cells regrouping on the borders of network.

C: after repeated stimulation of one digit (X): Expansion of representation of digit palm (x 13,7) detrimental to adjacent digits and back of same digit representations.

D: after transsection of median nerve : Interruption of palm inputs of 2 digits safeguarding dorsal connections invasion of dorsal representations in regions initially dedicated to palm representations reactivity of some cells lost (black).

J. Pearson et al., The J. of Neuroscience, 1987

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Plan






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Jackendoff :

Projection

Projection

Conceptual Structure Computational Mind

Conceptual Structure Computational Mind

Projected World

Projected World

Gap

Real World

Information

Information

Information

Petitot :

Phenomenological World

Pheno-physical Real World

Geno-physical Real World

Schema of the dynamics of temporel field

ThingsProcessesMovements& durations-----------------Preconstituted/Constituted

Transcendent Objectsin objective Time Immanent Objects in phenomenologic time

Impressional Consciousness |Retentional Consciousness& Act (seizing the Now) | & Act (seizing the Now)-----------------------------------------------------------------------------------------Hyletic Datum [Now] Modification [Actual Now]

Retention

[…[[[Ur-Jetzt]Jetzt]Jetzt]…letzte Jetzt] = [Ur-Jetzt], [[Ur-Jetzt]Jetzt], [[[Ur-Jetzt]Jetzt]Jetzt], …

Originäre Zeitfeld: „Das Zeitfeld verschiebt sich gleichsam über die wahrgenommene und frisch erinnerte Bewegung und ihre objektive Zeit, ähnlich wie das Gesichtfeld über den objektiven Raum.“ (Vorlesungen über Zeitbewusstsein 1905 §.11)

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Présent

présent

présent

Distance temporelle

Modificationde passé

Saisie d’identitéImpressionoriginaire

Positions dans le temps objectif

Constitution d’objet temporel

Recouvrement

continu

présent

présent présentprésent

Associationsprimaires

Série des champs temporels

Rétention

Passé

« Cette saisie de présent est aux points de présent antérieurs comme le noyau à une queue de comète de rétentions. »

Husserl, 1905. 34

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„…nur muss man beständig denken, dass, was wir schon so objektiviert finden, erst als dieses Objektivierte konstituiert ist durch die Sinngebung der Erfahrung; sie als die konkrete Erfahrung, durch die ich den vertrauten Leib als Leib immerzu erfahre, gibt ihm diesen Sinn durch die wohleingeübte Vermöglichkeit des wechselseitig Betastenkönnens, wobei sich das gesamte Empfindungsfeld in Lokalisation verteilt auf die „Glieder“ des Leibkörpers in ihrer Phantomkonstitution und dadurch auf den ganzen Körper…Nun ist aber jedes Organ einerseits durch betasten taktuell konstituiert und die dabei fungierenden Kinästhesen, andererseits aber selbst konstituiert als wirklich oder möglicherweise tastendes, sodass wir immer und notwendig in ursprünglichster Tasterfahrung, die den Leib als Körper und als Leib ergibt, ein funktionelles Beieinander von tastendem und getasteten Organ finden, und mit der jeweils vermöglichen Umkehrung dass das getastete zum tastenden werden kann…Dadurch sind also auch die Partialkinästhesen möglicher Betastung verteilt auf die Leibglieder, ein jedes ist nicht nur konstituiert als betastbar, sondern als betastend, als Glied mit Kinästhesen, die in Freiheit in Gang gebracht werden können…Ist diese volle Konstitution erreicht, so wird es verständlich, dass der Leib ohne Besehen und Betasten, während er ausschließlich für aussendingliche haptische Konstitution fungiert, immerfort doch ganz lebendig bewusst ist und in seiner haptischen Anschaulichkeit bewusst zu machen ist; nämlich dass das immerfort erfüllte und in sich zu durchlaufende Tastfeld sowie die fest auf es verteilten Kinästhesen beständig sein taktuelles „Aussehen“ indizieren. Bei aller sinnlicher Erfahrung, so zunächst der visuellen, ist irgend welches Hapsis mit dabei, und auch mein Leib als ursprünglich haptisch konstituierter mit dabei…“ [ms D12III (1931), p. 18-20]

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Thank you!

Phenomenology Life and Simplexity Jean-Luc Petit Université de Strasbourg.

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Transcript of Phenomenology Life and Simplexity Jean-Luc Petit Université de Strasbourg.