We demonstrate a spatial neuron that sums and regenerates electrical pulses in real time. The neuron uses a monolithic web of micro-transmission lines to propagate electrical pulses to a 'soma' where they are regenerated via quantum tunnelling amplification. The gain of the neuron follows a sigmoid curve similar to the one that controls the firing of real neurons. We report on the dependence of the regeneration threshold on bias parameters and obtain a good fit of the measured threshold by computing the stability diagram of the soma. The neuron is shown to regenerate coincident pulses with a timing sensitivity of 10 mu s compared to milliseconds for real neurons. The present design demonstrates that the physics underpinning analogue computation in biological neurons has an equivalent in modern semiconductor structures.