The neuron as an analog NOT digital system

x011 at Lehigh.EDU x011 at Lehigh.EDU
Thu Aug 10 12:25:59 EST 1995


In article <Pine.SGI.3.91.950808083330.11504C-100000 at golgi>, Joseph Strout <jstr
out at ucsd.edu> writes:
>On 8 Aug 1995, Marc Anton wrote:
>
>>      Though we tend to think of the neuron as essentially
>> a digital processor (with its on and off firings) it's really
>> closer to an analog processor with infinitely complex chemical
>> and electrical functions above and beyond anything capable with
>> digital reductionism.
>
>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.
This all-or-none action potential has bothered me.  Assuming submilisecond
processing then oscillation frequencies would be the main carriers if
information.  Then what function would the action potential serve?
I would speculate a fuse function or reset the cycle function.  I like
the reset the cycle idea.  Comments?  Ron Blue



More information about the Neur-sci mailing list