Can you elaborate? In what way is the brain efficient in a sense that a transistor isn't?
The energy consumption of the brain is around 20W in an adult human.
Compare that to the multi hundred Watt consumption of the meager machine you're reading this on...
E.g. the functions of the first levels of the visual cortex is relatively well understood -- both from mapping the nerve connections and from copying the mechanism in computers.
There is a long time evolutionary pressure to conserve energy, all the way back to the evolution of nerves. (The brain use quite a lot of your total energy use, unless you're a non-mechanized lumberjack...)
Edit: The visual cortex might work differently than other parts of the brain (ask a researcher) because of speed demands, which otoh supports the point about energy efficiency.
1. The technique used to visualize synapses is awesome. 2. This quote about molecular switches comes out of nowhere. It's related but not really part of this study.
More importantly though the idea that these are switches and that there are way more of them than transistors in the world misses two important points.
1. Are the molecular switches relevant to the computation performed by the brain?
Only in so much as to build a transistor you need materials with certain specific properties, and to build a calcium channel you need proteins with certain specific responses to the environment. Comparing the computational unit of one to the building blocks of another isn't quite accurate.
2. Even if they were computationally relevant are they comprable in terms of key metrics like performance?
Two important things to remember about the brain are that its slow and very very efficient. Silicon logic on the other hand is very very fast and inefficient. Even if there were a thousand fold increase in the number of computational units assigned to the brain the processing speed of a modern transistor decimates synaptic level computation.