A recently published book claims that the amount of time we spend on the Internet is changing the very structure of our brains. Its thesis enough: Not only that the modern world's relentless informational overload is killing our capacity __for____ reflection, contemplation and patience, but that our online habits are also altering the way our brains are wired.
In the book, the author looks _(explicitly)_____ on such human inventions as the map and the clock and the _extent____ to which they influenced our essential models of thought. He argues that the Internet's multiplicity of stimuli and mass of information have _given_____ rise to hurried and distracted thinking. The author concludes that our ability to learn _anything_____ at all worthwhile has become superficial. Surprisingly very _little____ research has looked into the Internet's effect on the brain, but further research is __at___ hand and is investigating whether deep-thinking processes really are in danger of disappearing.
the whole paragraph has not been particulary well written and I am not sure about "explicitly", which is why I have put it in brackets.