Binary Neuron
This is a common type of activation function in neural networks. The activation level a of a binary node is set to an upper value u (set in the upper bound field) if the weighted input W plus a bias term b is greater than the threshold θ, and a lower value l (set in the lower bound field) otherwise:
This type of activation function is also referred to as a threshold function, and these units are sometimes called "linear threshold units."
Threshold
The value, denoted by θ above. This provides a simple model of the voltage potential that real neuron membranes must exceed in order to fire an action potential.
Bias
A fixed amount of input to this node, denoted by b above.