Neuron Output

The output of a neuron is a spike, or “action potential”, which propagates along the

axon. The axon leaves the cell body and almost always splits in two. One branch travels horizontally making many connections with other cells nearby. The other branch projects to other layers of cells or elsewhere in the brain. In the image of the neuron above, the axon was not visible. We added a line and two arrows to represent that axon.

Although the actual output of a neuron is always a spike, there are different views on how to interpret this. The predominant view (especially in regards to the neocortex) is that the rate of spikes is what matters. Therefore the output of a cell can be viewed as a scalar value.

Some neurons also exhibit a “bursting” behavior, a short and fast series of a few spikes that are different than the regular spiking pattern.

The above description of a neuron is intended to give a brief introduction to neurons. It focuses on attributes that correspond to features of HTM cells and

leaves out many details. Not all the features just described are universally accepted. We include them because they are necessary for our models. What is known about

neurons could easily fill several books, and active research on neurons continues today.