The Shallows: What the Internet is Doing to Our Brains

by Nicholas Carr

Every time we perform a task or experience a sensation, whether physical or mental, a set of neurons in our brains is activated. If they’re in proximity, these neurons join together through the exchange of synaptic neurotransmitters like the amino acid glutamate.18 As the same experience is repeated, the synaptic links between the neurons grow stronger and more plentiful through both physiological changes, such as the release of higher concentrations of neurotransmitters, and anatomical ones, such as the generation of new neurons or the growth of new synaptic terminals on existing axons and dendrites. Synaptic links can also weaken in response to experiences, again as a result of physiological and anatomical alterations. What we learn as we live is embedded in the ever-changing cellular connections inside our heads. The chains of linked neurons form our minds’ true “vital paths.” Today, scientists sum up the essential dynamic of neuroplasticity with a saying known as Hebb’s rule: “Cells that fire together wire together.”