# Defect synapse in spatial pooler

**URL:** <https://discourse.numenta.org/t/defect-synapse-in-spatial-pooler/5723>\
**Category:** Numenta Theory\
**Created:** [April 2, 2019, 6:22am UTC](https://discourse.numenta.org/t/defect-synapse-in-spatial-pooler/5723 "2019-04-02T06:22:10Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rodi](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.numenta.org/rodi/32/3720_2.png) [@Rodi](https://discourse.numenta.org/u/Rodi)\
**Post date:** [April 2, 2019, 6:22am UTC](https://discourse.numenta.org/t/defect-synapse-in-spatial-pooler/5723/1 "2019-04-02T06:22:11Z")

</div>

Hi everyone

Can you tell me what happen if i consider defective synapse in spatial pooler?

it seems like this figure. some connections are outside of receptive field and some inside.  
a synapse is called as defect off if it always disconnected even training. otherwise, if a synapse is celled as defect on if it always connected even training.

. ![2019-04-02_15-06-42](https://canada1.discourse-cdn.com/flex030/uploads/numenta/original/2X/d/db064ec631a50d66adef30c349b226731a42f04f.png)

---

<div class="post-metadata">

**Author:** ![Bitking](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.numenta.org/bitking/32/3099_2.png) [@Bitking](https://discourse.numenta.org/u/Bitking)\
**Post date:** [April 2, 2019, 12:40pm UTC](https://discourse.numenta.org/t/defect-synapse-in-spatial-pooler/5723/2 "2019-04-02T12:40:26Z")

</div>

By definition - the gray box **is** the receptive field.  
There should not be any connections to the input space outside of this area.

The discussion in this post may help with your question:

> [@What does "the receptive field center" mean in SP?](https://discourse.numenta.org/t/what-does-the-receptive-field-center-mean-in-sp/4872):
>
> [QQ%E6%88%AA%E5%9B%BE20181102152138] Sorry for disturbing. I’m reading the paper The HTM Spatial Pooler—A Neocortical Algorithm for Online Sparse Distributed Coding by Cui. While confused that in the part of fault Tolerance, it discuss the “receptive field center” with respectively showing the picture above. What does the “receptive field center” mean?

---

<div class="post-metadata">

**Author:** ![rhyolight](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.numenta.org/rhyolight/32/3922_2.png) [@rhyolight](https://discourse.numenta.org/u/rhyolight)\
**Post date:** [April 2, 2019, 4:07pm UTC](https://discourse.numenta.org/t/defect-synapse-in-spatial-pooler/5723/3 "2019-04-02T16:07:32Z")

</div>

The Spatial Pooling process is resistant to synapse failure. If proximal synapses fail, the system will generalize and performance does not degrade much. [This video explains how SDRs enable this behavior](https://youtu.be/ZDgCdWTuIzc?t=578).