1. A neural network portion comprising a number N of hardware implemented pre-synaptic neurons capable each of firing an action potential, wherein N can be encoded in a word of n bits; the neural network portion being provided for, upon firing of a number F of hardware implemented pre-synaptic neurons in a predetermined period of time: if F.n<N, generating a message of a first type, the message comprising a unique address for each hardware implemented pre-synaptic neuron having fired in said predetermined period of time, each address being encoded as a word of n bits; and if F.n>N, generating a message of a second type, the message comprising N bits and being encoded in words of n bits, wherein each one of said N hardware implemented pre-synaptic neurons is represented by a unique bit, each bit having a first value if the hardware implemented pre-synaptic neuron represented by the bit has fired in said predetermined period of time, and a second value otherwise.