Dear Bassam:

"Neural" includes neurons and glia.

The concept of "plasticity" as the strengthening of synapses apply only to neurons, because the astroglial network does not have synapses (astrocytes communicate by means of gap junctions). 

Neuron-astrocyte interactions is a new, integrative field in neuroscience. There are some models attempting to interpret this interacting system. Vera Maura has done a good job of understanding these complex interactions using the retina as a model of the whole brain.

I have built a model in which neurons execute cognitive operations (processing sensory signals, selective attention, memory, motor control), while the astroglial network instantiates feelings (all kinds of feelings - from basic sensations as hunger and thirst to perceptual 'qualia' as the feel of color, sound, taste, smell, also emotional feelings as joy and sadness and social feelings as love and hate).

In this model, neurons induce hydro-ionic waves in brain tissue, having the astroglial network as the master hub that propagates the small waves to the whole system and allow their interferences. For instance, when we are facing dangerous situations the amygdala triggers a wave of fear in brain/body tissue. The feeling of fear is not inside the amygdala, but in the living tissue, having astrocytes as the master hub that broadcasts it to the whole brain and body.

Constructive interferences in the astroglial network produce global waves that instantiate feelings; these waves feed back on the neurons and modulate their activity. The feedback of astrocytes on neurons is part of the neural plasticity phenomenon. According to the model, the wave of feeling reinforce the neuronal patterns that feel good, and depress the patterns that feel bad. There are several well known mechanisms that execute this modulation, for the details please read the paper below.

Article Astrocytes and Human Cognition: Modeling information integra...

Yes, in the retina for example, dark and light adaptation are accompanied by changes in extracellular potassium activity.That´is attributed to Mueller cells, the macroglia of retinas. Remember that retinas have a tremendous range of excitability of 6 log units.

In retinas the tissue at the neuropil will fight a low concentration of calcium (from 1 to 0,1 mEq/l) for minutes before it beguins to fall reaching 0,6 mEq/l after +- 7 minutes.

Look at my publication list for details

Dear Bassam:

"Neural" includes neurons and glia.

The concept of "plasticity" as the strengthening of synapses apply only to neurons, because the astroglial network does not have synapses (astrocytes communicate by means of gap junctions). 

Neuron-astrocyte interactions is a new, integrative field in neuroscience. There are some models attempting to interpret this interacting system. Vera Maura has done a good job of understanding these complex interactions using the retina as a model of the whole brain.

I have built a model in which neurons execute cognitive operations (processing sensory signals, selective attention, memory, motor control), while the astroglial network instantiates feelings (all kinds of feelings - from basic sensations as hunger and thirst to perceptual 'qualia' as the feel of color, sound, taste, smell, also emotional feelings as joy and sadness and social feelings as love and hate).

In this model, neurons induce hydro-ionic waves in brain tissue, having the astroglial network as the master hub that propagates the small waves to the whole system and allow their interferences. For instance, when we are facing dangerous situations the amygdala triggers a wave of fear in brain/body tissue. The feeling of fear is not inside the amygdala, but in the living tissue, having astrocytes as the master hub that broadcasts it to the whole brain and body.

Constructive interferences in the astroglial network produce global waves that instantiate feelings; these waves feed back on the neurons and modulate their activity. The feedback of astrocytes on neurons is part of the neural plasticity phenomenon. According to the model, the wave of feeling reinforce the neuronal patterns that feel good, and depress the patterns that feel bad. There are several well known mechanisms that execute this modulation, for the details please read the paper below.

Article Astrocytes and Human Cognition: Modeling information integra...

i am so proud that you both answer my question...

i am so luck that i  disccus with scientists like you 

i appreciate your answers...

actually my question is based on the fact that synaptic plasticity is basis of learning and memory ... i want to paraphrase my question: if synaptic plasticity definition was the ability of synapses to strengthen or weaken over time in response to decrease or increase in their  activities 

if we consider now that astrocytes in their activities are able to change their morphology , the number of synapses, the functional domain they form, the gap junction between them, and the network they form ...if these are all dynamics ....

why we dont consider that learning and memory is also based on astrcoytes ...

if   they change over time and space....temporally and spatially ...

so the local hub and the master hub is the basis of this plasticity...and calcium is the core player? i mean its another basis of learning and memory in addition to synaptic plasticity. 

note : i ask because i dont know ....

i PERSONALLY LIKE THEHYPOTHESYS OF AHARON KATCHALSKY AND  EBEHARD NEUMANN (1971-2) that high mental functions are linked to the polyelectrolite gel between glia and neurons.  This supramolecular structure has dynamic states.That it can store a kind of long term memory has been experimentally demonstrated in 1977 (discussed in the more recent paper, last section)

So in this  case someone can suggest that there is two types of plasticity in the CNS:

First type: low level plasticity ... its synaptic  plasticity in small ensembles  of tripartite synapses

Second type : high level plasticity  its astrocytic plasticity.(LTP) and long term memory 

In both cases calcium is the message where the contents are encoded and transmited as intercellular and at high level operating system they decode and store

or its like hardware  and software

Dear Bassam, you asked: "so the local hub and the master hub is the basis of this plasticity...and calcium is the core player? i mean its another basis of learning and memory in addition to synaptic plasticity"

Alfredo: No, the calcium wave in astrocytes and in brain tissue is not the "basis" of learning and memory. In my model, learning and memory are cognitive functions executed by the neuronal network, The astroglial calcium wave modulates these processes; for instance, you are more likely to remember conscious experiences accompained by stronger feelings. The feeling wave generated in astrocytes reinforces the learning process, but the learning process and memory formation occur in neurons.

The calcium ions that enter neurons through NMDA channels and binds with calmodulin activate:

a) the calmodulin-dependent kinases that

b) activate signal transduction pathways and transcription factors that

c) control the expression of genes that release growth factors that

d) induce the growth of dendrites and axon terminals of the synapses (neuronal connections) involved in the processing of the information, which

e) are reactivated when the memory is consciously recalled.

Thanks professor, your paper anyway was one of my inspiration to model astrocytic network in artificial intelligence,. Still I need a lot of reading to capture the whole picture , and I appreciate your answers to me with Vera Maura... And I am still under the happiness feeling that you answered my question... I need to send you my ideas of my framework in your email ...if you have time to direct me... I appreciate your help so much. With regards.

Yes, please send me your ideas and I will try to help!

Instead of an answer, I have a question for you: do you think that POst tetanic potentition and LTP are the same or different events?

My e-mail is [email protected]