Every neuron must be connected to other neurons, and our neuron constructor will handle connecting all the input neurons with the synapses, as follows:

public Neuron(IEnumerable<Neuron> inputNeurons) : this()
{
Ensure.That(inputNeurons).IsNotNull();

  foreach (var inputNeuron in inputNeurons)
  {
    var synapse = new Synapse(inputNeuron, this);
    inputNeuron?.OutputSynapses?.Add(synapse);
    InputSynapses?.Add(synapse);
  }
}