# Genetically determined connections

**URL:** <https://discourse.numenta.org/t/genetically-determined-connections/2050>\
**Category:** General Neuroscience\
**Tags:** neurons, neuroscience\
**Created:** [March 27, 2017, 7:21pm UTC](https://discourse.numenta.org/t/genetically-determined-connections/2050 "2017-03-27T19:21:37Z")\
**Posts on this page:** 1\
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**Author:** ![jakebruce](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.numenta.org/jakebruce/32/996_2.png) [@jakebruce](https://discourse.numenta.org/u/jakebruce)\
**Post date:** [March 27, 2017, 11:10pm UTC](https://discourse.numenta.org/t/genetically-determined-connections/2050/2 "2017-03-27T23:10:57Z")

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If you look at the original STDP paper (Bi & Poo 1998) and any paper that measures postsynaptic potentials, it’s pretty clear that synapses can be and often are weighted. They also come in a huge diversity of different sizes, and this has some relationship to the evoked synaptic potential. And this is true for pyramidal neurons too (Bi & Poo was hippocampal pyramids), it’s just that we don’t know whether or to what degree the weight matters, computationally.

You get a lot of power even just from binary weights as Numenta, Kanerva, etc have shown. So the weights may be a sort of epiphenomenon emerging from the need for a permanence value.

However, a great many computational neuroscience models of pretty much every part of the brain make a lot of use of graded synaptic weights, and they do appear to be present in the brain, so I’d be surprised if evolution didn’t find a use for them.

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