The neuron as an analog NOT digital system

Marc Anton ma2 at delta1.deltanet.com
Wed Aug 9 03:38:02 EST 1995


Joseph Strout (jstrout at ucsd.edu) wrote:

: I don't think anyone involved in neuroscience treats real neurons as 
: purely digital processors, as you suggest.  There are at least two 
: reasons why you may have gotten this impression:

: 1. Action potentials (neuron "spikes") are indeed all-or-none over most 
: connections.  They are transmitted as a regenerative wave of potential.  
: If the signal is too weak, it will quickly die and not travel far at 
: all.  If it is just strong enough, it will be regenerated at each point 
: and will propagate to the synapse.  If the signal was very strong, the 
: result is exactly the same.  (There can be a *little* variance in action 
: potential amplitude and shape, but not much.)  However, the real 
: processing in neurons takes place in the dendrites and soma, where inputs 
: from various synapses at various times are combined.  This is a complex, 
: nonlinear, and analog function of space and time, and this is widely 
: recognized.

: 2. Some researchers work with abstract "artificial neural networks" whose 
: structure and operation are inspired by real neurons.  Some of these may 
: be digital (indeed, they are almost always implemented on a digital 
: computer).  But these are only cartoon sketches of real neurons, leaving 
: out nearly all the complexity and detail found in a biological system, 
: while retaining the bare minimum of properties capable of supporting the 
: complex behavior of interest.  And again, I think any researcher in the 
: field would readily acknowledge this.

That's pretty much what I was reffering to, however, I do
acknowledge that, in the specific fields of the neural sciences,
the limitations of AI's attemts to model the neuron are probably
recognized, but many in the fields of AI and philosophy
take a quantum leap and over-estimate
the simplistic neural models and then to on to make rash
speculations that they constitute a basis for
higher and real intelligence, not to mention all
the qualities we call human.
 
It's the nature of analytic science (the prevalent science
of our day in age) to see or break-down the elements
of knowing into quanta elements, and it's very tempting
to stretch this into a "digital" understanding of 
the world.   All I'm saying is the neuron, intelligence, humanity,
the world, the universe, etc...all the objects of study
in sciences, are all "reduced" as a show of the measure
and limit of our own analytical understanding; we are
far from engendering levels of understanding and intelligence
anywhere near what we're capable of were we to let go of
our stubborn insistance on this reductionism.
 
We have to realize that, though digital models are clean and 
neat, they leave out a lot, all the perceived trash, the 
randomness, and convoluted information pouring out of analog
systems, are part and parcel of the complex world we live in.
To over-simplify this is to delude ourselves, it's to not admit
the fact that we must look to other ways of understanding and 
knowledge above and beyond that available with today's paradigms
of..."digital reductionism?".

-Marc



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