Why Neurons Have Thousands Of Synapses, A Theory Of Sequence Memory In Neocortex


Thank you @subutai for your response.


Hi @subutai,

what is active presynaptic cells?

“The matrices “delta D” are added to the current matrices of permanence values at every time step” means delta D will be added with matrix D, that is correct?

In part 5 of paper, eq( 6) is doing reinforcing and punishing, and eq(7) is do something like punishing, that is correct?


@Niki There are quite a few posts on the forum mentioning presynaptic cells. Our search page is quite good.


Thanks @rhyolight , I will check them.


If cell a connects to cell b (i.e. cell a forms a synapse onto cell b’s dendrite), then cell a is a presynaptic cell for cell b. Cell b will be a postsynaptic cell for cell a.

Yes. Delta D^d_ij will be added to D^d_ij

Yes, that’s right. Eq 7 is a much weaker punishment in case a cell was predicted but did not become active later.


Thank you for your reply @subutai.


Hi @subutai,

Are the three states “Active, predictive, and nonactive” mutually exclusive?


No, an HTM Neuron can be active and predictive at the same time.


I’ve just started reading the paper, however I’m wondering what operation is denoted by the slash in the graphic.

I think it would become obvious later on, but it’s important to me while I’m still at pages 3-4 to already know it.


It just denotes a linear operation, as opposed to a threshold. The proximal synapses (green) tend to have a linear impact on the cell body. In this paper, we focused almost completely on the blue context synapses and didn’t discuss the proximal ones too much.


Hi, I am new to HTM community.

Several years ago, I read the HTM whitepaper published in 2010. Is there any update on the theory between that and this paper, which is published in 2016?


Yes, see our latest paper: Why Does the Neocortex Have Layers and Columns, A Theory of Learning the 3D Structure of the World.


Thanks but I know there were some updates on the theory between the 2016 paper and the latest paper which is very interesting. I am asking what has changed between 2010 and 2016, because the following page says that the whitepaper is obsolete.