Does the bias of an artificial neuron adjust or remain constant during training?
Neurons values are something like this

$N_i = w_{i1}x_{i1} + w_{i2}x_{i2} + ... + w_{in}x_{in} + b_i$

the bias is $b$ here

but it also can be written like  

$N_i = w_{i0} + w_{i1}x_{i1} + w_{i2}x_{i2} + ... + w_{in}x_{in}$

where bias is $w_{i0}$

it is the weight of index 0

when mentioned weights in optimization it is by default include bias