CoachNeurons do not touch. Where one fiber’s end meets the next cell lies a microscopic gap — the synapse. The electrical signal cannot jump it; instead the arriving fiber releases a chemical messenger into the gap, which crosses, docks on the far side, and — if enough arrives — starts the signal afresh in the next neuron. Electrical along the wire, chemical at every junction: the whole system alternates the two.
示例
Example 60.6 (The juggler’s synapses)
Remark 33.8’s juggler, explained at last: a month of practice conducted the same signals across the same junctions until those synapses strengthened — the routing that was laboriously weighed now runs pre-weighted. Skill is chemistry consolidated at the gaps; “practice makes permanent” is a statement about synapses.