Correspondence between biology and software implementation of theory

[rhyolight]

If you have not read it: Why Neurons Have Thousands Of Synapses, A Theory Of Sequence Memory In Neocortex.

@david.pfx

• the input from the encoder to SP corresponds to synapses between afferent (sensory) axons and distinct mini-column neurons

Remember many encoders can contribute to the input to the SP. The SP’s relationship to this input consist of proximal dendrites. The axons of the input may not be sensory, they may come from another population of neocortical cells. Minicolumn receptive fields are enforced by inhibitory neurons.

@david.pfx

• the SDR output from the SP corresponds to the activation of pyramidal neurons, one neuron per bit, and each in a distinct mini-column

No, the output of the SP are the active minicolumns, not individual pyramidal neurons. The output representation of the SP is an SDR where each bit represents a minicolumn.

@david.pfx

• the cells per column used by TM correspond to distinct neurons within each mini-column

Yes. The TM operates within the confines described by the SP. They are the same sheet of cells, but two simultaneously occurring processes. We define them differently in code because it is easier to understand the two distinct processes separately.

@david.pfx

So the hotgym example would involve 1462 input axons and synapses, 1638 mini-columns and 13 cells in each mini-column? Of those 21,294 neurones about 133 would be activated on each datum (sparsity 0.0063)?

There are several hot gym examples. The numbers you’re quoting don’t look right. We usually use 2048 minicolumns, like this. This is a parameter to the SP in all cases. Same with the number of cells in each minicolumn, which is a TM parameter like this. It is usually set to 16 or 32. It is not calculated, it is manually set.