Hi dudes,
Rico wrote:
Re: It has been suggested that a deeper principle of organization may be a map of the statistical correlations in the behavioral repertoire, rather than a map of body parts. wowzers! : 0
...Why not both? Looking at how the brain works, it IS likely to be so... why build a whole extra network when there's a perfectly good one already sitting there? : )
Re:Taking the PMC as an example: It turns on and that leads to certain muscular contractions and thus movement. But now is it the type of cells that are found in the PMC that make them unique, or is it their function (connection)?
There are different kinds of brain cells and also different 'layers' they can inhabit. Some 'specialized' cells, such as mirror neurons, and pyramidal neurons, are found in various different networks, some others (like Purkinje cells in the cerebellum) are unique to an individual network. Some 'unusual cells' are in small clusters, some dotted about, some in fairly large groups. We also have to be somewhat cautious in this area, as so much work is still going on and a cell-type we may have thought unique to an area may later be discovered elsewhere. This is a side effect of living through a time of rapid discovery. : ) See the date on this, for example:
http://www.nature.com/neuro/journal/v16 … .3466.html
Also, sometimes the 'unusual' structures appear at the latter end of processing (for example neuromuscular junctions are in the muscles, not the brain) and it is they that furnish the fine-tuning of motion, translated from basic signals.
Re: More generally, is a network in the NH model made of specific types of cells?
No, most cells are pretty similar. But some networks may have their own 'specialist' cells and some contain 'specialist cells' also found in other networks. The type of cells a network has is going to reflect its processing tasks. Apparently, only the Cerebellum needs Purkinje cells, but several different areas must need mirror neurons.
Re: What physical qualities gives each network its uniqueness?
This is a great question...because we start off thinking: the types of receptors on the surface of cells will differ according to what neurotransmitters it can receive, and the types of transmitter a cell is able to make will affect its internal structure (eg, a given cell will not need to make vesicles to store a transmitter it isn't going to make). However, since much behavior is dictated by location (one can transplant a cell and it will start to change what transmitters it deals with, to better match its neighbors), these 'individuality' markers cannot said to be permanent qualities of cellular architecture. Cells seem to be 'shape shifters', and stem cells are the ultimate shape shifters.
Individual brain cells, much like individual people and our genome, appear to be changeable and dynamic according to their context.
This is quite irritating for researchers, who generally prefer things to stay as they are long enough to be measured and categorized. Dynamic phenomena are a notorious pain to keep track of (witness weather forecasting) LOL : )
What's more, whole cell populations change all the time through plasticity -this week I have x number of mirror neurons in my hippo, next week that number will be more (if I've used it wisely) or less (if I've used it wrongly or haven't used it at all.)
'Maintenance' & repair cells (such as glia) also play a big part in changes within and across networks.
Re: Perhaps you will say that networks are totally arbitrary. That the model is useful but is totally not the territory.
Not totally arbitrary because they do furnish us with a model based on a concrete foundation in the same way the standard model for physics can be deduced from (abstracted from) concrete factors. Such models ARE predictive, so there is a gateway to further learning via model-dependant realism.
Re: But still, the PMC runs movement of the body. From an NH perspective, the movement of the body entails all six network functions.
These two statements are mutually contradictive... The second one is closer to true (remove the word 'functions'). “The PMC is recruited for motion”, or “ the PMC modulates movement of the body” is a more accurate way of presenting the first. And we can of course 'take over' this function by waving a TMS coil over the PMC and watching the body jerk around randomly (great fun at parties).
Re: Are you sure that time mass weight etc, exhist? Outside of Network 3s imagination?
This is the rerun of the concept: “if a tree falls in the forest, and there's nobody there to hear it, does it make a noise?” -Do the laws of physics allow predictions about reality? Yes they do. Do we experience everything as zeroes and ones? Yes we do. Did I create this world in VR last tuesday and all our memories are false? Probably not. We have to decide what we believe is reality, based on the actual evidence available to our minds. In that sense scientists are here to catalogue what 'appears' to be going on. Questioning whether reality IS actually going on is for philosophers, spiritual explorations and LSD trips, somewhat outside the realm of the kind of research on which we base tutorials. : )
Best,
AR
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