human_brain

Mass of 1-2 kg in adult. so about 2% of body weight. Consumes 20% of oxygen, 25% glucose, and 15% blood flow.
Mass at birth = .2*Mass of adult brain.

Cortex (thinking part) has

for rat
for chimps
for humans. about 1mm depth. in cortex. About in human cortex.
Human genome is about 1 meter of DNA with 1 base pair/3.8 Angstroms. so about 2 bits/base pair so . Maximum. (actually there is alot of redundancy). So memory can't be stored in DNA.
Cortex develops in response to stimulus.

Explosion in cortex size due to limited increase in genome length:

Cortex evolution is recent, about the last 3 million years.

cortex function:

neuron components: cell body~20 micron diameter, axon 1 micron radius, 2 cm long, dendrites 1 micron radius 2 mm long. So total axon length = . Surface area is axon dominated= .
old view: axons = output devices (electrically active), dendrites = input devices (electrically passive). Pulse length of 1 msec in axon. Frequency varies alot. Pulse strength of about .1 volts.
new view: dendrites do some operations on input. Effective multiplication of rapidly stimulated dendrite. Also an effective division.
synapses connect axons to dendrites. Distance of 50 angstroms across junction. = about .1 msec to cross. Connections can be excitatory (glutamate=MSG) or inhibitory (gaba).

Power requirements

Assume v pulses/second. Then . Unmylenated axons have . Membranes have a dielectric constant of about 6.