Some notes on doing a human brain in hardware.

There are about 109 bits in our DNA and some substantial part of that is to define our brain. The differences between human genomes is about 107 bits. We are a long way from knowing the map between DNA bits and the connectome. The connectome relates every synapse to two neurons and gives a little information about the synapse. There are about 011 neurons and 1014 synapses and our DNA merely provides statistical rules for generating the connectome. Presumably experience modifies our synapses and deletes some. I presume that the connectome is initially a product of out DNA and a random process. Identical twins probably have substantially different connectomes.

Scanning an adult brain yields about 1016 bits after reducing to a definition of a functional equivalent brain with the same experiences. Running such a brain takes perhaps 1016 synapse ops per second if we do not learn to power down inactive parts of the brain. Such powering down might bring this down to about 1014. A synapse op is receiving over an internal digital network a signal that says “add this 4 bit number to your accumulator”. The accumulator is associated with some neuron. Many times a second such messages are sent from the neuron conditioned on the accumulator and other things and addressed by information from the connectome.