Neural pathways were the channel within a nervous system for neural signals or neurons to be sent between the brain and other parts of a humanoid. Damage to one's neural pathway could lead to severe neurological damage and even death.
An illegal procedure called accelerated critical neural pathway formation affected neural pathways and generally resulted in increased intelligence, but with high likelihood of dramatic and often unpredictable side effects on the personality of the patient. (DS9: "Doctor Bashir, I Presume")
Ribosome infusions could help treat extreme cell damage caused by early neural pathway degeneration. In 2366, Doctor Beverly Crusher attempted to convince Lieutenant Worf to agree to a ribosome infusion to treat the Romulan Patahk. (TNG: "The Enemy")
Benjamin Sisko suffered unusual neural pathway activity in 2373, following exposure to a plasma burst. The condition was associated with odd synaptic potentials and post-neural shock syndrome, and also with a series of prophetic visions. Sisko suffered severe headaches and, eventually, life threatening depolarization of his central nervous system. The condition was corrected by a neuropolaric induction. He suffered a temporary relapse in 2374. (DS9: "Rapture", "Far Beyond the Stars")