Traditional lap pools are about 10 feet wide, though widths between 8 and 10 feet are common. (In competition pools, swim lanes are 2.5 meters wide, or about 8.2 feet.) You don't want to go too narrow with a lap pool.
The number of neurons in the brain varies dramatically from species to species. One estimate (published in 1988) puts the human brain at about 100 billion (10 11) neurons and 100 trillion (10 14) synapses.
the brain contains about 10^11 (100 billion) neurons. If we assume that the average neuron has 1,000 connections (not unreasonable), and that each of these connections stores one byte, then your figure of 100 terabytes is reasonable. So that's about one hundred thousand (100,000) gigabytes.