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.
It is estimated that there are up to 100 billion neurons in the human brain. It is likely that there are more neurons in the human body than any other cell type. many neurons are in the brain others are in tracts or organised pathways within the brain and spinal cord.