Taste and smell receptors are specific sensors.
Your brain extends to the tip of your fingers, nose, scattered around your skin and the tip of your toe in the form of the peripheral nervous system (PNS). The PNS rich in sensors which perform computations on the spot.
Silicon systems consume roughly 10^-9 - 10^-11 joules per operation and the brain consumes about 10^-15 - 10^-19 joules of per operation. Therefore, the carbon based systems are at least a million times more energy efficient than their silicon counterparts.
Fan out is the number of other components that a circuit element is directly connected to. Its a shorthand of how powerful or parallel a device can be. Logic gates in silicon systems can have a maximum fan out of about 10. Carbon based system can have more than 10,000 per element.