Dear Alex and colleagues,
Thanks for the opportunity to ad a few lines on signaling matters. I
would not discard any organizational aspect of signaling pathways. I
have put below a diagram that approaches the dynamics of some major
ones.Your analogy with mobile phones would be right, provided that
conversations were mixed, that a number of receivers were just random,
and that a component of "experience information" would be entered too
--I think it can apply to the dynamics of second messengers, where
multitudes of microevents and pathways may be integrated via lots of
feedbacks (See the box in the figure below). Symmetry is a big word
concerning the organization of pathways in the construction of
multicellular development... opposed paths, tipping points, collective
(populational) symmetry breakings, massive feedbacks, etc.
By the way, when we commented days ago on Tononi's phi, both from John
Collier and myself, the idea was to consider it as applied to the
closure of meaning episodes in language. How "getting" the meaning of
some linguistic episode (eg, a joke) provokes a sudden change of
transient connectivity between areas...
Apart from meaning, it may also be interesting that there seems to be a
strong asymmetry in between the incoming / outgoing information
flows--the "social info loops" around. In most human organizations, the
ratio is in between 3 and 4. It means that you and me are ordered by
upper levels in around 80 % of our exchanges, while what we send upwards
becomes a meager 20 %. It is from a statistics on business communication
metrics. The generalization is far from direct, but maybe it would occur
in the cells too--amazingly there is very little literature on cellular
"signal emission".
Anyhow, how the whole ascending and descending info flows give raise to
all the varieties of organizational complexity is a fascinating problem,
All the best--Pedro
*Figure 6: Prototypical signaling pathways of multicellularity.*From
left to right, a stimulus in the intercellular space binds to a
transmembrane receptor (sensor) on its extracellular domain. Upon
binding, the receptor undergoes a transient modification of its
cytoplasmic domain; this effect triggers a transient modification of a
series of proteins in the cell, each one acting as an intermediate in
the signal transduction pathway (signal processing), with characteristic
hierarchies of protein kinases and second messengers. The last
components are actuators or effectors that activate or inhibit proteins
and channels that control several cellular functions, notably gene
expression by means of transcriptional switches that may interact with
several coactivator partners. The whole biochemical changes produced in
the cell represent the response to the received signal —its /molecular
meaning/.
El 26/04/2016 a las 10:10, Alex Hankey escribió:
Dear Pedro,
Thank you for the comments on my presentation, and particularly for
reminding us all that life transmits information of many different
kinds by very specific and selective processes in chemical signally
molecules.
I must confess that I had assumed that such kinds of signals could be
considered special cases of digital information analogous to the codes
transmitted by a digital signalling tower in a mobile telephone
network, where the initial code has to name the device that the rest
of that message section is meant to receive.
In mobile phone systems, individual devices are sent information by
identifiers. If we have a nervous system working with several
neurotransmitters, or a cell signalling system working with a number
of cytokines, each with a specific regulatory influence / purpose, are
these individual items not performing in ways that are covered by the
usual combination of Wiener and Shannon, and therefore in principle
understood, and AS YOU SPECIFICALLY POINT OUT, with no particular
"experience" component.
I wonder whether the material I transmitted made the following point
succinctly / precisely enough:
David Chalmers specifically hypothesized that 'experience information'
(my terminology) mst have a double aspect, and that the 'loop' arising
from criticality specifically fulfils his hypothesis in a new and
potent way.
(The material contains so many points that this, to my mind, really
significant one may have got buried.)
Thank you also for appreciating the amplification of Tononi's
contribution
(Tononi, I personally regard as of real significance). The internal
loop creates
the internal coherence that is required to form the 'integrated
information'.
I have a suspicion that the following propositions are probably correct:
a. any information structure that is truly 'non-reductive'
(Chalmers requirement 3) must possess long range coherence.
b. any information structure with long-range coherence will be a form
of integrated information.
c. Hence Chalmers requirement 3 in fact specifies integrative information.
This sequence a, b, c simplifies what those writing in the 1990's were
saying:
they were in fact setting equivalent requirements on the form of
'experience information'
(though Tononi undoubtedly thought he was saying something different,
as did those who followed up on his work, and Chalmers did not realize
that Tononi's proposal was equivaent to the point that he had proposed.
Anyone's thoughts on this would be very much appreciated,
All best wishes,
Alex
--
-------------------------------------------------
Pedro C. Marijuán
Grupo de Bioinformación / Bioinformation Group
Instituto Aragonés de Ciencias de la Salud
Centro de Investigación Biomédica de Aragón (CIBA)
Avda. San Juan Bosco, 13, planta X
50009 Zaragoza, Spain
Tfno. +34 976 71 3526 (& 6818)
pcmarijuan.i...@aragon.es
http://sites.google.com/site/pedrocmarijuan/
-------------------------------------------------
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