Young brain develops activity peaks while it is still growing

November 7, 2012
Image of simulated growth of a network out of 10,000 neurons.

After a short period of growth, cultured networks of neurons regularly exhibit major activity in the absence of external stimulation. These "bursts" are entirely related to growth. At this stage, they have little to do with learning behaviour, as the network is still too young to sustain a process of memory formation. This has now for the first time been simulated for networks ranging in size from 10,000 to 50,000 neurons. The simulations provide insight into the role of the growth process in initial activity. Researchers at the University of Twente's MIRA Institute recently published details of this work in PLOS ONE.

"Isolated" , which have yet to form any interconnections, soon put out cell extensions (axons and dendrites) that connect them to other neurons. The resultant network starts to show signs of activity after just one week. The researchers made these observations in networks that they had cultured from neurons extracted from the brains of young . These cells were grown in culture dishes whose bases had been fitted with . Here, the network grows in a single plane, as far as possible. If it were to grow "upwards" (3D), it would be difficult to determine what was actually being measured. After a week, observations show that the neurons have become active and that they start to "fire". This activity can be seen to pass through the entire network in the form of a "burst".

Images of cultured neurons on an array of electrodes.

The question was whether these bursts might be related to the development of a long-term memory, by a process of synapse strengthening. This process of begins to develop after three weeks. Now, for the first time, substantial computer capacity has been used to simulate larger networks (10,000-50,000 neurons). This showed that the bursts really do arise during the first few weeks of growth. The simulations reveal a between the growth of the network and the occurrence of the first bursts, which is in line with the observations. The burst runs through the network like a wave, at enormous speed. As in the experiments, no external stimulation was applied to the network. However, the simulations do include certain types of neurons that act as "pacemakers" by initiating a process. This corresponds to what happens in reality.

A realistic model that simultaneously calculates both growth and activity provides a better picture of the workings of a "brain" of limited size. Bursts are the expression of coordinated action in networks. They are generally seen as building blocks of human brain function. If coordination between networks is disrupted, bursts can degenerate into total discharges of the type seen in abnormalities such as strokes or epileptic seizures. One particularly exciting research question being explored by Prof. Wim Rutten's group is whether artificially cultured brains could be linked to robots, for example, as they learn more efficiently than any existing algorithms. The use of reliable simulations will also help to reduce the number of experiments involving living neural networks.

Explore further: How connections in the brain must change to form memories could help to develop artificial cognitive computers

More information: The article entitled "Growth dynamics explain the development of spatiotemporal burst activity of young cultured neuronal networks in detail" by Taras Gritsun, Joost le Feber and Wim Rutten, has been published in PLOS ONE, Volume 7, Issue 9.

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6 comments

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Tausch
3 / 5 (1) Nov 10, 2012
All (living) cells are active.
All (living) cells grow.
Bursts are the expression of coordinated action in networks.


'Coordination' implies an ability or the acquisition of this ability before the bursts.

Where and when is 'coordination' learned in the absent of external stimulus?
What determines the timing of the bursts?

These "bursts" are entirely related to growth. At this stage, they have little to do with learning behaviour, as the network is still too young to sustain a process of memory formation.


I disagree.
You used the word 'coordination'. All coordination requires bookmarking location first.
'Bookmarking' of location is memory.

[q}"Isolated" neurons, which have yet to form any interconnections, soon put out cell extensions (axons and dendrites) that connect them to other neurons.

'put out extensions' is growth.
Does this qualify as 'burst activity' as well?

Tausch
3 / 5 (1) Nov 10, 2012
'Bookmarking' of the presence of other cells (ignoring 'location') is also memory.
210
not rated yet Nov 11, 2012
@Tausch

Okay, these guys/researchers, have shown a bit of their logic and work..and their links, ok...where is your research? Your book? Please show proof, diagrams, pictures just as they have for your line of thinking...this is only fair and right.

word-to-ya-muthas
Tausch
not rated yet Nov 11, 2012
This is a science news site. Those are my comments. Their 'logic' is flawed. 'Cosmetic' flaws. Their basic premise is unscathed.

Their important observation is uncontested in neuroscience:
..cultured networks of neurons regularly exhibit major activity in the absence of external stimulation...


So what if they drew the false conclusion from this observation?
(That the activity has nothing to do with learning or memory.)

From my line of reasoning if you separate growth from memory at the very beginning of conception you will find re-introducing learning and memory at later point in time impossible and inconsistent.

The pathway for learning and memory:
"All this work fits well into the framework and provides a molecular explanation for how estrogen facilitates learning and memory," Baudry said. "We now know the cascade of events that takes place: estrogen to MAP kinase to calpain to actin polymerization to glutamate receptors."

Read more at: http://phys.org/n...75.html#
Tausch
not rated yet Nov 11, 2012
There you have have it. In one small paragraph. See above link. The entire pathway. For learning and memory:

Estrogen > MAP kinase > calpain > actin polymerization > glutamate receptors

The components of that pathway are synonymous to regularly re-occurring MAJOR ACTIVITY, learning, memory AND growth WITHOUT external stimulus! And right there from the word 'go' (conception)

No need to reinvent the neuroscience wheel!!
Tausch
not rated yet Nov 11, 2012
I expect to published my related research:
The origin of human languages.

A direct link between the mechanical and biochemical processes.
All of Chomsky's approaches to any language is intractable.
Pinkerton is no better. Müll.

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