How much energy does a neuron use for information processing as opposed to just surviving?
http://quantum-mind.co.uk/anaesthetics-and-brain-energy/

About 80% of the brain’s energy consumption is devoted to neuronal firing with only 20% involved in maintenance activity.

The energy for firing is mainly supplied by glia and astrocytes, the maintenance of the neuron itself is done mainly by the cellular machinery in the neuron.