Numbers for humans vary rather a lot. Some types of cells have up to 200,000 connections (Purkinje neurons) while others have very few. Thus talking about "the" number of synapses per neuron doesn't make much sense. It all depends on which type of neuron etc. you mean.
Anyway, when talking about a global brain average I most often see the number 1,000. For rat cortex (which is a bit different to mouse cortex in terms of thickness and density) I usually see the number 10,000 as the average (just for cortex, not the whole brain). Shane On 4/29/07, Matt Mahoney <[EMAIL PROTECTED]> wrote:
Does anyone know if the number of synapses per neuron (8000) for mouse cortical cells also apply to humans? This is the first time I have seen an estimate of this number. I believe the researchers based their mouse simulation on anatomical studies. --- "J. Storrs Hall, PhD." <[EMAIL PROTECTED]> wrote: > In case anyone is interested, some folks at IBM Almaden have run a > one-hemisphere mouse-brain simulation at the neuron level on a Blue Gene (in > > 0.1 real time): > > http://news.bbc.co.uk/2/hi/technology/6600965.stm > http://ieet.org/index.php/IEET/more/cascio20070425/ > http://www.modha.org/papers/rj10404.pdf which reads in gist: > > Neurobiologically realistic, large-scale cortical and sub-cortical > simulations > are bound to play a key role in computational neuroscience and its > applications to cognitive computing. One hemisphere of the mouse cortex has > roughly 8,000,000 neurons and 8,000 synapses per neuron. Modeling at this > scale imposes tremendous constraints on computation, communication, and > memory capacity of any computing platform. > We have designed and implemented a massively parallel cortical simulator > with > (a) phenomenological spiking neuron models; (b) spike-timing dependent > plasticity; and (c) axonal delays. > We deployed the simulator on a 4096-processor BlueGene/L supercomputer with > > 256 MB per CPU. We were able to represent 8,000,000 neurons (80% excitatory) > > and 6,300 synapses per neuron in the 1 TB main memory of the system. Using a > > synthetic pattern of neuronal interconnections, at a 1 ms resolution and an > average firing rate of 1 Hz, we were able to run 1s of model time in 10s of > real time! > > Josh > > ----- > This list is sponsored by AGIRI: http://www.agiri.org/email > To unsubscribe or change your options, please go to: > http://v2.listbox.com/member/?&; > -- Matt Mahoney, [EMAIL PROTECTED] ----- This list is sponsored by AGIRI: http://www.agiri.org/email To unsubscribe or change your options, please go to: http://v2.listbox.com/member/?&;
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