It introduces basic concepts in neuroscience and then elaborates on the field of connectomics, that is, how to scan, decode, compare, and understand patterns in brain connectivity.

That said, Seung emphasizes that these size correlations only show up for large samples and cannot necessarily predict what will happen in any individual's brain.

Seung discusses theories of memory formation, including basic Hebbian plasticity and the more speculative neural Darwinism.

Seung reviews the history of mapping the Caenorhabditis elegans connectome by Sydney Brenner and colleagues, published in 1986.

He says this might often coincide with Brodmann's or Cajal's divisions, but if we ultimately care about connectivity, Seung's classification would be most directly relevant.

Seung examines how connectomics may in the future help identify neurological problems before they become serious and inform development of drugs or gene therapies for connectopathies.

[further explanation needed] Seung examines the efforts of the Alcor Life Extension Foundation to offer some chance of immortality by cryonics.

He compares preservation in liquid nitrogen with a plastination approach that, unlike Alcor's method, requires "no special maintenance".

[2] Terry Sejnowski echoed this sentiment about the book's style: "With the first-person flavour of James Watson's Double Helix—an account of how DNA's structure was discovered—Connectome gives a sense of the excitement on the cutting edge of neuroscience.

"[3] Susan Okie affirms that "Seung is a clear, lively writer who chooses vivid examples," though she expresses skepticism about the "science-fiction fantasy that, one day, a human being's connectome could be simulated and 'uploaded' onto a computer".

Other possible problems may arise from "Faults in synaptic transmission and in processes inside neurons and the glial cells that support them".