Neurodynamics uses
the language of dynamical systems to describe brain function. So far in the
course we have looked at the consequences of viewing single neurons through the
prism supplied by harmonic oscillators. Now let’s look at what happens as we
view groups of tens of thousands of neurons under the same rubric
Over the past half-century, the Freeman laboratory has accumulated a
large volume of data and a correspondingly extensive interpretive
framework centered around an alternative perspective on brain
function, that of dynamical systems. The contents of consciousness, by
contrast, are seen as an inevitably sparse sample of events in the
perception-action cycle. The paper proceeds to an attempt to elucidate
the contents of this sparse sample.
Freeman (2005a ) established that local dynamics in rabbit and human
neocortex are scale-free, and that every skilled action involves all
cortex and basal ganglia in varying degree. Self-similarity from the
microscopic to the macroscopic levels of the cortex allows the cortex
to change state very quickly. Freeman (2002) introduces the notion of
a wave packet, amplitude modulation of which constitutes the
expression of knowledge, which is stored in synaptic modifications and
expressed by phase transitions. Freeman (op.cit., 517) also makes
the radical contention that we do not need independent access to the
external world for communication to occur; it is sufficient that the
internal meanings in speaker and hearer come transiently into
harmony.
The felt experience of consciousness is constrained by the fact that
the cortex operates discontinuously, with “shutter” states
interspersed with the generation of wave packets (Freeman 2007).
Moreover, while eschewing the technical apparatus of decoherence,
recent work has adopted quantum field theory (Freeman et al, 2006c) to
explain the phenomenon of anomalous dispersion in the brain. Just as
the vibration induced by a blow will reach the other side of a solid
object at a different time to the sound thereof, wave packets show
properties of transmission independent of neural impulse itself. In
fact, the brain behaves in ways not dissimilar to a boson.
Freeman (2005b) introduces several other leitmotiven. Globally
coherent brain activity may be an objective correlate of consciousness
through preafference. Preafference, in turn, enters once the more
veridical notion of circular causality is substituted for the
stimulus-response act.Briefly, once an action is lined up, the brain
prepares the system for the sensory consequences of this action in the
preafference process. The consequences for consciousness qua process
are enormous.
Essentially, Hume was right; there is no conscious will, but there
does exist a conscious “won't”. Agency as a concept needs to be
correspondingly attenuated; when the intending of an act presents
itself to consciousness, it is experienced as a cause; consciousness
of the consequences thereof are experienced as effects.
What is asserted, then, is that conscious states comprise a sparse
sample of the wave packets that embody motor commands, corollary
discharges, and pre-perceptions that we conceive as unconscious. Wave
packets embodying motor commands are the substratum for mathematical
and other abstract thought. Furthermore, focal consciousness samples
at far too slow a rate to give veridical access to the contents of
our cortices, and nature has gifted us various mechanisms to get
around this.
A talk by Professor
Walter Freeman of the University of California at Berkeley.
Given to the Foundations of Mind seminar at UC Berkeley
(http://FoundationsOfMind.org), organized by Sean O Nuallain. may be found at
Specifics of this paper
Walter states three precepts;
1. The only evidence for consciousness other than introspective is the
existence of group behavious and goal-directed such, particularly when
both attributes are combined in hunting;
2. Thus, it is speculated consciousness emerges around the Cambrian,
perhaps 500 million years ago;
3. Neuropil, generically considered, is the organ for consciousness
He summaries his viewpoint thus;
“Consciousness is a biological process that is sustained by
coordination of activity in many parts of the brain of a subject who
is engaged in an action of searching for information that it needs to
cope with its environment………My hypothesis is that the summary action
is expressed in a global field of synchronized oscillation, which will
shape the next action. My conjecture is that we experience this wave
packet as consciousness”
What follows is a highlighting of some salient points from his
presentation to the FoM group on 2 May 2014. This description has been
endorsed by Walter;
In the first place, it is worth noting that Walter's is a thoroughly
neurobiological account. While much of his vocabulary draws on his
considerable math and engineering background, he eschews the
cognitive and symbolic lexicon. Thus, there is no reference to
Grammars, to Piagetian formal operations, to phenomena/conscious
experience or the like; the goal is consistent with Occam's razor.
Thus, we find references to perception-action cycles, to phase
transitions, to attractors, and to the propagation of entities in
state-space. Methodologies recommended include diffusion tensor
imaging, nonequilibrium thermodynamics and much else that may seem
quaint only in a world in which it is assumed that since we have
mapped psychological predicates onto locations in the brain,
neuroscience is basically over, is it not?
It is significant, therefore, that even such ascesis allows
abstraction and generalization; recall of memories; spatial
delocalization and readout by downsampling the delocalized amplitude
modifications. Chomsky may not be name-checked but Merleau-Ponty will
be referenced.
It is accepted, in the other hand, that the animals transform the
stimulus while processing it and the beta and gamma waves carry
amplitude modifications indicating the animal's memories of past
states aimed at future states of the evolving agent . These may be
read out with diffusion tensor imaging.
The entorhinal cortex sens out a sparse but global signal which is the
basis for the individual expectation of the next action. Clearly,
consciousness will have as a signature a sparsely sampled version of
this signal.
A critical innovation is that knowledge is to be distinguished from
merer information partly by the “condensed state of the global
cortical neuropil”. For our purposes, perhaps the critical notion is
that the neocortex is a single organ with no glial barriers. This
allows a phase transition in which the entire cortex is sustaining a
fluctuation and this is the basis for awareness
References
Freeman WJ [2000] Neurodynamics: An Exploration of Mesoscopic Brain
Dynamics, London UK: Springer
Freeman, W. (2002) “How and why brains create meaning from sensory
information” International journal of bifurcation and chaos, Vol 14,
No 2 (2004), 515-530
Freeman WJ [2005a] A field-theoretic approach to understanding scale-free
neocortical dynamics
Biological Cybernetics 2005, 92/6: 350-359
Freeman WJ [2005b] William James on Consciousness, revisited. Chaos and
Complexity letters, 1 (1) : 17-43
Freeman WJ [2006a ] Origin, structure, and role of background EEG
activity. Part 4. Neural frame simulation. Clin. Neurophysiol. 117:
572-589.
Freeman WJ [2006b ] Scale-free neocortical dynamics. Encyc Comp Neurosci,
Izhikevich E [ed.].
http://www.scholarpedia.org/article/Scale-free_neocortical_dynamics
Freeman WJ [2007] Proposed cortical ‘shutter’ in cinematographic
perception. Ch. In: Neurodynamics of Cognition and Consciousness. Kozma R
and Perlovsky L [eds.]. New York: Soringer.
Freeman WJ, Vitiello G [2006c] Nonlinear brain dynamics as macroscopic
manifestation of underlying many-body field dynamics. Physics of Life
Reviews 3: 93-118.
Sean O Nuallain cinco de Maio 2014
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