Tuesday, March 10, 2009
Scientists Watch Brain Networks Rewire Themselves
 Filed under: in the news...


Researchers from the Max Planck Institute for Biological Cybernetics
used an MRI machine to visualize how large parts of the brain
automatically reorganize themselves through a process called long-
term
potentiation (LTP). (Long-term potentiation is a process thought to
be
involved in learning, and also in seizures.) Using experimental
stimulation of nerve cells in the hippocampus, researchers were able
to trigger whole groups of neurons to reorganize their network
structure and functionality.


From a Max Planck Society statement:


Scientists refer to the characteristic whereby synapses, nerve cells
or entire areas of the brain change depending on their use as
neuronal
plasticity. It is a fundamental mechanism for learning and memory
processes. The explanation of this phenomenon in neuronal networks
with shared synapses reaches as far back as the postulate of Hebbian
learning proposed by psychologist Donald Olding Hebb in 1949: when a
nerve cell A permanently and repeatedly stimulates another nerve cell
B, the synapse is altered in such a way that the signal transmission
becomes more efficient. The membrane potential in the recipient
neuron
increases as a result. This learning process, whose duration can
range
from a few minutes to an entire lifetime, was intensively researched
in the hippocampus.
A large number of studies have since shown that the hippocampus plays
an important role in memory capacity and spatial orientation in
animals and humans. Like the cortex, the hippocampus consists of
millions of nerve cells that are linked via synapses. The nerve cells
communicate with each other through so-called "action potentials":
electrical impulses that are sent from the transmitter cells to the
recipient cells. If these action potentials become more frequent,
faster or better coordinated, the signal transmission between the
cells may be strengthened, resulting in a process called long-term
potentiatation [sic] (LTP), whereby the transmission of the signal is
strengthened permanently. The mechanism behind this process is seen
as
the basis of learning.


Although the effects of long-term potentiation within the hippocampus
have long been known, up to now it was unclear how synaptic changes
in
this structure can influence the activities of entire neuronal
networks outside the hippocampus, for example cortical networks. The
scientists working with Nikos Logothetis, Director at the Max Planck
Institute for Biological Cybernetics, have researched this phenomenon
systematically for the first time. What is special about their study
is the way in which it combines different methods: while the MRI
scanner provides images of the blood flow in the brain and,
therefore,
an indirect measure of the activity of large neuronal networks,
electrodes in the brain measure the action potentials directly, and
therefore the strength of the nerve conduction. It emerged from the
experiments that the reinforcement of the stimulation transmission
generated in this way was maintained following experimental
stimulation. "We succeeded in demonstrating long-term reorganization
in nerve networks based on altered activity in the synapses,"
explains
Dr. Santiago Canals. The changes were reflected in better
communication between the brain hemispheres and the strengthening of
networks in the limbic system and cortex. While the cortex is
responsible for, among other things, sensory perception and movement,
the limbic system processes emotions and is partly responsible for
the
emergence




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Me    View profile
  More options May 4, 5:49 pm

Newsgroups: soc.culture.usa
From: Me <agnesche...@gmail.com>
Date: Mon, 4 May 2009 14:49:46 -0700 (PDT)
Local: Mon, May 4 2009 5:49 pm
Subject: Re: Facts againt transplanting brains
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On May 4, 5:48 pm, Me <agnesche...@gmail.com> wrote:


- Hide quoted text -
- Show quoted text -

Tuesday, March 10, 2009
Scientists Watch Brain Networks Rewire Themselves
 Filed under: in the news...

Researchers from the Max Planck Institute for Biological Cybernetics
used an MRI machine to visualize how large parts of the brain
automatically reorganize themselves through a process called long-term
potentiation (LTP). (Long-term potentiation is a process thought to be
involved in learning, and also in seizures.) Using experimental
stimulation of nerve cells in the hippocampus, researchers were able
to trigger whole groups of neurons to reorganize their network
structure and functionality.

From a Max Planck Society statement:

Scientists refer to the characteristic whereby synapses, nerve cells
or entire areas of the brain change depending on their use as neuronal
plasticity. It is a fundamental mechanism for learning and memory
processes. The explanation of this phenomenon in neuronal networks
with shared synapses reaches as far back as the postulate of Hebbian
learning proposed by psychologist Donald Olding Hebb in 1949: when a
nerve cell A permanently and repeatedly stimulates another nerve cell
B, the synapse is altered in such a way that the signal transmission
becomes more efficient. The membrane potential in the recipient neuron
increases as a result. This learning process, whose duration can range
from a few minutes to an entire lifetime, was intensively researched
in the hippocampus.
A large number of studies have since shown that the hippocampus plays
an important role in memory capacity and spatial orientation in
animals and humans. Like the cortex, the hippocampus consists of
millions of nerve cells that are linked via synapses. The nerve cells
communicate with each other through so-called "action potentials":
electrical impulses that are sent from the transmitter cells to the
recipient cells. If these action potentials become more frequent,
faster or better coordinated, the signal transmission between the
cells may be strengthened, resulting in a process called long-term
potentiatation [sic] (LTP), whereby the transmission of the signal is
strengthened permanently. The mechanism behind this process is seen as
the basis of learning.

Although the effects of long-term potentiation within the hippocampus
have long been known, up to now it was unclear how synaptic changes in
this structure can influence the activities of entire neuronal
networks outside the hippocampus, for example cortical networks. The
scientists working with Nikos Logothetis, Director at the Max Planck
Institute for Biological Cybernetics, have researched this phenomenon
systematically for the first time. What is special about their study
is the way in which it combines different methods: while the MRI
scanner provides images of the blood flow in the brain and, therefore,
an indirect measure of the activity of large neuronal networks,
electrodes in the brain measure the action potentials directly, and
therefore the strength of the nerve conduction. It emerged from the
experiments that the reinforcement of the stimulation transmission
generated in this way was maintained following experimental
stimulation. "We succeeded in demonstrating long-term reorganization
in nerve networks based on altered activity in the synapses," explains
Dr. Santiago Canals. The changes were reflected in better
communication between the brain hemispheres and the strengthening of
networks in the limbic system and cortex. While the cortex is
responsible for, among other things, sensory perception and movement,
the limbic system processes emotions and is partly responsible for the
emergence

Contact: Wendy Leopold
w-leop...@northwestern.edu
847-491-4890
Northwestern University

Brain networks change according to cognitive task
EVANSTON, Ill. -- - Using a newly released method to analyze
functional
magnetic resonance imaging (fMRI), Northwestern University
researchers
have demonstrated that the interconnections between different parts
of
the brain are dynamic and not static. This and other findings answer
longstanding debates about how brain networks operate to solve
different cognitive tasks. They are presented in the current (June 1)
issue of the Journal of Neuroscience.
Equally important, the researchers discovered that the brain region
that performed the integration of information shifted depending on
the
task their subjects performed. In this study, the subjects were
assigned two language tasks. In both, subjects were asked to read
individual words and then make a spelling or rhyming judgment.


"We found that one network takes different configurations depending
on
the goal of the task," said Tali Bitan, primary author of "Shifts of
Effective Connectivity Within a Language Network during Rhyming and
Spelling."


A post-doctoral fellow in the department of communication sciences
and
disorders, Bitan worked with Associate Professor James Booth of the
same department and M-Marsel Mesulam, director of the Cognitive
Neurology and Alzheimer's Disease Center in Northwestern's Feinberg
School of Medicine.


Mesulam, who was among the first scientists to predict the existence
of convergence zones within interconnected brain networks, said the
study presents "the clearest and most convincing evidence to date" of
the dynamics in effective connectivity.


To better understand dynamic effective connectivity, Mesulam compares
the brain networks to a network of highways connecting different
parts
of a city. The highway is static. No matter how heavy the traffic
load, it always has the same number of lanes. In the brain, there is
a
dynamic change that allows certain pathways to preferentially
facilitate the demands of a given cognitive task. The brain highway
in
effect "adds lanes" to accommodate the requirements of the particular
task.


Depending on the goal of the task -- whether subjects were asked to
make an orthographic (spelling) judgment or a phonological (rhyming)
judgment – the Northwestern researchers found that different
convergence zones in the network were involved in the task.


"The existence and the identity of convergence zones -- areas in which
information from multiple sources meets in the brain -- have been
debated since they were proposed in the late 20th century," said
Bitan. "Now, with new techniques to analyze brain imaging data, we
can
examine the specific role played by different brain regions in the
network that are required for any cognitive task. These techniques
examining effective connectivity enable us to learn how the brain
changes its interconnectivity according to the task at hand."


The Northwestern researchers also propose to explain the role of each
brain region as it interacts within a complex network to achieve a
specific cognitive goal.


The conventional method for analyzing fMRI data, which can only show
which brain regions are active in a given task, showed two brain
regions that were specifically active for each of the studied tasks:
the lateral temporal cortex (LTC) for the rhyming task and the
intraparietal sulcus (IPS) for the spelling task.


In addition to the task-specific regions, the inferior frontal gyrus
(IFG) and the fusiform gyrus (FG) were engaged by both tasks. Dynamic
Causal Modeling, the new method examining the influences between
brain
regions, indicates that each task preferentially strengthened the
influences converging on the task specific regions (LTC for rhyming,
IPS for spelling). This finding suggests that task specific regions
serve as convergence zones that integrate information from other
parts
of the brain.


The results also show that switching between tasks -- in this case
between rhyming and spelling -- led to changes in the influence of
the
IFG on the task specific regions. This finding suggests the IFG plays
a pivotal role in "making" task specific regions more or less
sensitive, depending on the task.


"Previous studies showed that the IFG is active in many different
language tasks and suggested that the IFG was involved not only in
the
integration process but also in control of other brain regions,"
Bitan
said. "Our study corroborates the role of the IFG in modulating other
brain regions. In contrast, however, it shows that the integration
process is done primarily in the task-specific regions."


In the 19th and early 20th century, scientists with a
"localizationist" approach postulated that discrete brain regions
were
associated with specific functions of language and memory. By the end
of the 20th century, a "connectionist" view stressing the importance
of interconnected networks became the consensus.


The research presented in the Journal of Neuroscience effectively
sets
the stage for further development in our understanding of
neuroscience. In their article, the Northwestern scientists provide
evidence of the ways in which different cognitive goals are achieved
from the interaction between different brain regions.


In addition to Bitan, Booth and Mesulam, co-authors of the article
are
Janet Choy and Douglas Burman of Northwestern's communication
sciences
and disorders department and Darren Gitelman, associate professor of
neuology at Northwestern University Feinberg School of Medicine.

...........
  More options May 4, 6:05 pm

Newsgroups: soc.culture.usa
From: Me <agnesche...@gmail.com>
......

Presence of supression does not please me as a most powerfrul factor
taht will bring on the SCIENCE REVOLUTION
only, but is this wanderful forum of fast scienec exchange from the
best centers in the coutry.


THE STRUCTURALIST BGIAS DID NOT SAVE TEH NETWORKS - THEY WERE
UNDERUSED AT ONE TIME
BRAIN NETWORKS ARE FUNCTIONAL UNITS - NOTHING THATC  AN BE DETENCTED
BY PUTTING THE ELECTRODES IN
THEY CONGREGATE ON THE TASK; AS A MATTER OF FACT THE ORIGINALLY
PUBLISHED HILGARD BRAIN NETWORKS
WERE HYPOTHETICAL.
WHAT OCCURS IS TAHT BRAIN DELEGATES F8UNCTIONAL NETWORKS TAHT CAN
SOLIDIFY IN THE CENTERS.
THAT SI NOT EVEN NEW IN FORMATION BUT IS BEARING ON THE FACT THAT IS
BETETR TO TRIM AND STIMULATE
OWN  BRAIN network and evelop centers
THAN TO TAKE ON FOREIGN TISSUE AS BRAINTISSUE fast renews ( since it
is onlkt a function inthe first instance)


/I have several heart centers in brain and no palpitations /


On May 4, 5:49 pm, Me <agnesche...@gmail.com> wrote:



- Hide quoted text -
- Show quoted text -

On May 4, 5:48 pm, Me <agnesche...@gmail.com> wrote:

> Tuesday, March 10, 2009
> Scientists Watch Brain Networks Rewire Themselves
>  Filed under: in the news...

> Researchers from the Max Planck Institute for Biological Cybernetics
> used an MRI machine to visualize how large parts of the brain
> automatically reorganize themselves through a process called long-term
> potentiation (LTP). (Long-term potentiation is a process thought to be
> involved in learning, and also in seizures.) Using experimental
> stimulation of nerve cells in the hippocampus, researchers were able
> to trigger whole groups of neurons to reorganize their network
> structure and functionality.

> From a Max Planck Society statement:

> Scientists refer to the characteristic whereby synapses, nerve cells
> or entire areas of the brain change depending on their use as neuronal
> plasticity. It is a fundamental mechanism for learning and memory
> processes. The explanation of this phenomenon in neuronal networks
> with shared synapses reaches as far back as the postulate of Hebbian
> learning proposed by psychologist Donald Olding Hebb in 1949: when a
> nerve cell A permanently and repeatedly stimulates another nerve cell
> B, the synapse is altered in such a way that the signal transmission
> becomes more efficient. The membrane potential in the recipient neuron
> increases as a result. This learning process, whose duration can range
> from a few minutes to an entire lifetime, was intensively researched
> in the hippocampus.
> A large number of studies have since shown that the hippocampus plays
> an important role in memory capacity and spatial orientation in
> animals and humans. Like the cortex, the hippocampus consists of
> millions of nerve cells that are linked via synapses. The nerve cells
> communicate with each other through so-called "action potentials":
> electrical impulses that are sent from the transmitter cells to the
> recipient cells. If these action potentials become more frequent,
> faster or better coordinated, the signal transmission between the
> cells may be strengthened, resulting in a process called long-term
> potentiatation [sic] (LTP), whereby the transmission of the signal is
> strengthened permanently. The mechanism behind this process is seen as
> the basis of learning.

> Although the effects of long-term potentiation within the hippocampus
> have long been known, up to now it was unclear how synaptic changes in
> this structure can influence the activities of entire neuronal
> networks outside the hippocampus, for example cortical networks. The
> scientists working with Nikos Logothetis, Director at the Max Planck
> Institute for Biological Cybernetics, have researched this phenomenon
> systematically for the first time. What is special about their study
> is the way in which it combines different methods: while the MRI
> scanner provides images of the blood flow in the brain and, therefore,
> an indirect measure of the activity of large neuronal networks,
> electrodes in the brain measure the action potentials directly, and
> therefore the strength of the nerve conduction. It emerged from the
> experiments that the reinforcement of the stimulation transmission
> generated in this way was maintained following experimental
> stimulation. "We succeeded in demonstrating long-term reorganization
> in nerve networks based on altered activity in the synapses," explains
> Dr. Santiago Canals. The changes were reflected in better
> communication between the brain hemispheres and the strengthening of
> networks in the limbic system and cortex. While the cortex is
> responsible for, among other things, sensory perception and movement,
> the limbic system processes emotions and is partly responsible for the
> emergence

Contact: Wendy Leopold
w-leop...@northwestern.edu
847-491-4890
Northwestern University

Brain networks change according to cognitive task
EVANSTON, Ill. -- - Using a newly released method to analyze functional
magnetic resonance imaging (fMRI), Northwestern University researchers
have demonstrated that the interconnections between different parts of
the brain are dynamic and not static. This and other findings answer
longstanding debates about how brain networks operate to solve
different cognitive tasks. They are presented in the current (June 1)
issue of the Journal of Neuroscience.
Equally important, the researchers discovered that the brain region
that performed the integration of information shifted depending on the
task their subjects performed. In this study, the subjects were
assigned two language tasks. In both, subjects were asked to read
individual words and then make a spelling or rhyming judgment.

"We found that one network takes different configurations depending on
the goal of the task," said Tali Bitan, primary author of "Shifts of
Effective Connectivity Within a Language Network during Rhyming and
Spelling."

A post-doctoral fellow in the department of communication sciences and
disorders, Bitan worked with Associate Professor James Booth of the
same department and M-Marsel Mesulam, director of the Cognitive
Neurology and Alzheimer's Disease Center in Northwestern's Feinberg
School of Medicine.

Mesulam, who was among the first scientists to predict the existence
of convergence zones within interconnected brain networks, said the
study presents "the clearest and most convincing evidence to date" of
the dynamics in effective connectivity.

To better understand dynamic effective connectivity, Mesulam compares
the brain networks to a network of highways connecting different parts
of a city. The highway is static. No matter how heavy the traffic
load, it always has the same number of lanes. In the brain, there is a
dynamic change that allows certain pathways to preferentially
facilitate the demands of a given cognitive task. The brain highway in
effect "adds lanes" to accommodate the requirements of the particular
task.

Depending on the goal of the task -- whether subjects were asked to
make an orthographic (spelling) judgment or a phonological (rhyming)
judgment – the Northwestern researchers found that different
convergence zones in the network were involved in the task.

"The existence and the identity of convergence zones -- areas in which
information from multiple sources meets in the brain -- have been
debated since they were proposed in the late 20th century," said
Bitan. "Now, with new techniques to analyze brain imaging data, we can
examine the specific role played by different brain regions in the
network that are required for any cognitive task. These techniques
examining effective connectivity enable us to learn how the brain
changes its interconnectivity according to the task at hand."

The Northwestern researchers also propose to explain the role of each
brain region as it interacts within a complex network to achieve a
specific cognitive goal.

The conventional method for analyzing fMRI data, which can only show
which brain regions are active in a given task, showed two brain
regions that were specifically active for each of the studied tasks:
the lateral temporal cortex (LTC) for the rhyming task and the
intraparietal sulcus (IPS) for the spelling task.

In addition to the task-specific regions, the inferior frontal gyrus
(IFG) and the fusiform gyrus (FG) were engaged by both tasks. Dynamic
Causal Modeling, the new method examining the influences between brain
regions, indicates that each task preferentially strengthened the
influences converging on the task specific regions (LTC for rhyming,
IPS for spelling). This finding suggests that task specific regions
serve as convergence zones that integrate information from other parts
of the brain.

The results also show that switching between tasks -- in this case
between rhyming and spelling -- led to changes in the influence of the
IFG on the task specific regions. This finding suggests the IFG plays
a pivotal role in "making" task specific regions more or less
sensitive, depending on the task.

"Previous studies showed that the IFG is active in many different
language tasks and suggested that the IFG was involved not only in the
integration process but also in control of other brain regions," Bitan
said. "Our study corroborates the role of the IFG in modulating other
brain regions. In contrast, however, it shows that the integration
process is done primarily in the task-specific regions."

In the 19th and early 20th century, scientists with a
"localizationist" approach postulated that discrete brain regions were
associated with specific functions of language and memory. By the end
of the 20th century, a "connectionist" view stressing the importance
of interconnected networks

....