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materiały pomocnicze dla przedstawiania poglądów autora w trakcie dyskusji w grupie dyskusyjnej "nauka". Strona została utworzona przez uczestnika dyskusji.: andrew.wader |
| Strona w
trakcie opracowywania. Obecnie zawiera ona
jedynie kilka ilustracji, które trudno jest
zamieścić w tekście wypowiedzi zamieszczanych na forum. 
Fig. 1.
Two
kinds
of connections
reach
so called 'object neurons'. One of them,
going from the side of hypothalamus and
amygdale
is active in the case
of emotional arousal and take part in the
consolidation of
the long- term memory
traces. The second
connection constitutes
the oscillating loop, which cause that the
evoked mental image is
aroused
for the time necessary for the
action
of the
working memory.
Fig. 2
The
nature of the mental imaginary. A mental
image is recalled
from the memory,
when the activation oscillate down and
back to the top of the hierarchical structure
owing to so called
recurrent axons. Three layers of the hierarchical structure of
neurons integrating sensory information,
for instance - in the visual pathways. The
traces of long term memory are
consolidated under the influence
of connections
from hypothalamus and amygdale (A).
There are
consolidated through two
mappings:
weights of receiving, ascending synapses
(s10, s11,
s12) and
synaptic
weights of
reproducing connections (s1, s2,
s3).
The second,
cortico – hippocampal
loop (B) is necessary for temporary
recalling of
the mental image. The activation of
the object neuron by this
indexing loop causes the recurrent
reactivation of
neurons
in lower layers. The doted line indicate
the pathways of repetitive circulations of
stimuli in the upper layers of the
hierarchical structure, what is the essence of
mental
imaginary. The object neuron can be activated also from
the side of speech area (C).
Mental imagery is the essence of
episodic memory, short term memory
and is used for working memory activity.
Rys. xxx (18) Poglądowa ilustracja sposobu pojmowania najbardziej ogólnych zasad działania mózgu, wg dotychczasowych, klasycznych koncepcji. Przeważnie zakłada się, iż mózg reaguje na bodźce i podejmuje jakieś działania. Owszem uwzględnia się, że podjęcie tych działań zależy od emocji (podwzgórza i zasobów pamięciowych).
Rysunek zamieszczam aby ułatwić przedstawienie nowej koncepcji sformułowanej przez Lou et.al. i inne grupy badawcze. Według tych autorów.:
{ Organizm (mózg) ma wmontowaną apriorycznie – istotę (motor) świadomości - która polega na zapewnieniu krążenia bodźców (impulsów ) pomiędzy wzgórzem a korą mózgową.Istota świadomości polegałaby, w "najgłębszej warstwie znaczeniowej" na zapewnieniu rekurencji .. nawracającym krążeniu impulsów… Zaprojektowanie istoty świadomej wymagałoby więc, po pierwsze zbudowania obwodów, które są w stanie wpaść w oscylacje podstawowe .. Takie drgające jądro mózgu to podstawa.. Dopiero potem można mówić od procesach bardziej szczegółowych – co jest tłumaczeniem stwierdzenia Lou et al.:
["..Two opposing views have prevailed in the
discussion on whether the neural activity in the
brain needs to be triggered by sensory
stimulation, or rather is an internal state of
the brain. In the former view the nervous system
is organized as a set of complex neuronal
connectivity patterns triggered into action by
the outside world [23]; accordingly, behavior is
fundamentally the resultant of the external
world. In contrast, the latter line of thought
sees the workings of the brain as mainly
intrinsically generated neuronal activity, with
sensory inputs acting as modifiers of such
intrinsic activity [24], [25]…"] }
Dla ponownego poruszenia tematu o tym jak dochodzi do stanu iż na wzgórku aksonu są generowane spick'i -zamieszczam przy okazji jeszcze trzy inne rysunki.:
Poniżej zamieszam tekst pracy o charakterze General Commentary. Prace takie przyjmuje do druku pismo.: "Frontiers of neural circuits"
How
to understand coordination
of
neural oscillatory
networks.
A
commentary on
Whitman J.C and her colleagues already in the
abstract of their paper propose to “
explore the arrangements by which these low- and
high-frequency oscillations work in concert,
coordinating neural activity into whole-brain
functional networks” (Whitman et al, 2013). They
entitle second
chapter of their paper as.: “
Orchestration: Networks Formed from Multiple
Frequencies of Oscillations”.
The
authors conclude that the oscillations of
different frequencies coordinate cognitive
processes taking place in the distant
regions of the brain, however they don't provide
description of neural circuits that carry this
out. It seems, that the authors
should
clarify first the
most basic issues why during periods of
the deep sleep we record on the surface of the
skull the slow waves,
it means
slow oscillations from the interval of
delta and theta range
and during wakefulness
much faster oscillations in the gamma
band. The paper doesn't present theoretical model enabling
the intuitive understanding why in wakefulness
the frequency of oscillations increase. The
notion proposed by authors
of a "network formed from multiple
frequencies of oscillations" probably should be
an extension of this basic intuitive model of
coordinating
mechanism of recurrent resonance.
Formulation of
the model of
neural mechanism coordinating
oscillatory networks depends on whether
we
recognize the assumption of some
researchers involved in investigation of
neural oscillatory activity that
the thalamo- cortical oscillations are
essential
for
any action of the brain and for emergence
of self – consciousness (Lou et al, 2011; Llinas,
1998). Whitman J.C and her colleagues don’t
refer to these authors therefore we
should mention their main ideas.
Lou et al. links the retrieval from autobiographic memory with a very
basic process of recurrent thalamo - cortical
oscillations. The authors used
magneto-encephalography and so called Granger
causality analysis to test if specific
autobiographic memory retrieval may enhance recurrent interaction between higher order, modality
non-specific brain regions and thalamus. The
obtained
results
inclined them to considerations of two
main opposing visions of organization of the
brain and the mechanisms underlying the
phenomenon of consciousness. According to the
classic understanding
brain responds to external stimuli. It
means that the nervous system is organized as a
set of complex neuronal connectivity patterns
triggered into action by the outside world and
that
behavior is fundamentally the resultant
of the external world. They are inclined however
to opt for a different option
formulated previously (Llinas, 1991,
1998). They argue that the work
of the brain is
mainly a intrinsically generated neuronal
activity, with sensory inputs acting as
modifiers of such intrinsic activity.
Understanding
of
oscillatory networks
requires
in my opinion also the comprehension of
circuitry
realizing mental imaginary. Early data obtained by means of neurological findings and afterwards by neural imaging confirmed that "the visual imaginary and visual perceptions rely on the same neural substrate" (Farah, 1989; Decety, 1995; Bartolomeo, 2008; Deslaar, 2008). A very important phenomenon essential for understanding the nature of mental imagery are the oscillation between neurons of the upper and lower layers of hierarchical structures realizing perceptions.
The importance of top - down pathways for mental
imaginary is recognized
since several years (Mesulam, 2008,
Gilbert 2007,
Fietta 2011) . These oscillations are
temporary sustained
by loops
existing
between neurons in CA1 layers of hippocampus and cerebral cortex (Poch and
Campo, 2011).
I try to summarize the mentioned data about
(a) the basic thalamo – cortical
oscillations and (b) the structures realizing
mental imagery on the fig. 1.
This intuitive scheme makes clear why the
additional frequences occur when object neurons
are aroused by external
stimuli or by running of
working memory. In this perspective
different patterns of cortical oscillations
result from the kinds of aroused functional
networks.
References
Bartolomeo, P. (2008).
The
neural correlates of visual mental imagery: an
ongoing debate.
Daselaar, S.M., Rice, H.J., Greenberg D.L.,
Cabeza R. , LaBar KS, Rubin DC. (2008).
The
Decety, J.,
Jeannerod, M.H. (1995). Imaginary and its
neurological substrate. Rev. Neurol. 151,
474 –479 Farah, M.J. (1989).
The neural basis of mental imagery.
Trends. Neurosci.12,
395-359.
Fietta P, Fietta P. (2012).
Cognition: neurobiological correlates and
dynamics.
Theor. Biol. Forum.
105,
87-108.
Gilbert, C.D., Sigman, M. (2007).
Brain
states: top-down influences in sensory
processing.
Llinás, R., Paré, D. (1991).
Of
dreaming and wakefulness.
Neuroscience.
44, 521-35. Llinás, R., Ribary, U., Contreras, D., Pedroarena, C. (1998). The neuronal basis for consciousness. Philos Trans R Soc Lond B Biol Sci. 353, 1841-1849.
Lou, H.C., Joensson, M., Biermann-Ruben, K.,
Schnitzler, A., Østergaard, L., Kjaer, T.W.,
Gross, J. (2011). Recurrent activity in higher
order, modality non-specific brain regions: A
Granger causality analysis of autobiographic
memory retrieval.
PLoS One.
, 6(7):e22286.
Mesulam, M. (2008).
Representation, inference, and transcendent
encoding in neurocognitive networks of the human
brain. Ann.
Neurol.
64,
367-378. doi: 10.1002/ana.21534.
Poch, C., Campo, P. (2012).
Neocortical-hippocampal dynamics of
working memory in healthy and diseased brain
states based on functional connectivity. Whitman, J.C., Ward, L.M., Woodward, T.S. (2013). Patterns of Cortical Oscillations Organize Neural Activity into Whole-Brain Functional Networks Evident in the fMRI BOLD Signal. Fron. Hum. Neurosci.7:80. doi: 10.3389/fnhum.2013.00080.
Legend for
fig. 1.
Intuitive and symbolic depiction of
some layers of the hierarchical structure
of neurons integrating sensory information and
of
tree coordinating networks.
The
traces of long term memory are consolidated
under the influence
of connections from hypothalamus and
amygdale (A).
The cortico – hippocampal loop
participate in recalling of
mental images (B). The activation of
object neuron by these
indexing loops causes the recurrent
reactivation of
neurons in lower layers. When the neuron
of a known object is stimulated, for instance
from the side of speech area (C) next the
activation returns – by recurrent
axons or generally by reproductive
pathways – to lower levels of the hierarchical
structure. The dotted line indicate the pathways
of repetitive circulations of stimuli in the
upper layers of the hierarchical structure
during the mental imaginary. Mental imagery is
essential
for the episodic memory, short term
memory
and
working memory activity. These processes
and sensory impulses stimulate also
further the thalamo – cortical loops, what
increase the frequency of oscillations.
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andrewwader@gmail.com |
