As the Fifth Doctor explained, the nervous system was a delicate network of logic junctions, called synapses. (TV: Castrovalva [+]Christopher H. Bidmead, Doctor Who season 19 (BBC1, 1982).)
As a Time Lord, the Eleventh Doctor's nervous system was hyperconductive. (TV: Nightmare in Silver [+]Neil Gaiman, Doctor Who series 7 (BBC One|BBC One]], 2013).)
The Third Doctor speculated that the Nestene creature in Channing's tank was a kind of brain or nervous system, humanly speaking. (TV: Spearhead from Space [+]Robert Holmes, Doctor Who season 7 (BBC1, 1970).)
Sutekh said he could shred the Fourth Doctor's nervous system into fibres and draw the pain out for centuries. (TV: Pyramids of Mars [+]Stephen Harris, Doctor Who season 13 (BBC1, 1975).)
Mehendri Solon required the head from a species with a central nervous system to complete Morbius' body. (TV: The Brain of Morbius [+]Robin Bland, Doctor Who season 13 (BBC1, 1976).)
The Hoothi infected other creatures, usually having better control over ones with more complex nervous systems. (PROSE: Love and War [+]Paul Cornell, Virgin New Adventures (Virgin Books, 1992).) The Sild tapped into the nervous systems of their hosts to control them. (PROSE: Harvest of Time [+]Alastair Reynolds, (informally) BBC Books past Doctor novels (BBC Books, 2013).)
After the Boneless killed Forrest, they performed an exploratory dissection of her nervous system and left a two-dimensional print of it on a wall. (TV: Flatline [+]Jamie Mathieson, Doctor Who series 8 (BBC One, 2014).)
Remote wore receivers in their ears which broadcast media signals directly into their nervous systems. (PROSE: The Shadows of Avalon [+]Paul Cornell, BBC Eighth Doctor Adventures (BBC Books, 2000)., The Book of the War [+]Lawrence Miles, et al., Faction Paradox novels (Mad Norwegian Press, 2002).)