Impulse (Star Trek: Enterprise)

In the Star Trek: Enterprise episode "Impulse" (season 3, episode 13), "impulse" refers specifically to a condition affecting the Vulcan crew of the Seleya, a Vulcan science vessel. The condition, contracted after an encounter with a previously unknown space anomaly, caused a neurological degeneration resulting in violent, aggressive behavior and a loss of higher cognitive functions. This state was initially mistaken for the Vulcan emotional disorder known as pon farr, leading to confusion among the Enterprise crew.

The "Impulse" infection fundamentally changed the Vulcans, known for their emotional control and logic, into something akin to zombies, driven by primitive instincts. The victims exhibited extreme strength, reduced language skills, and a desire to attack and infect others. The method of transmission appeared to be through physical contact, most likely through bites.

The Enterprise crew, led by Captain Archer, encountered the Seleya while searching for the Xindi weapon. The episode focuses on the crew's investigation of the deserted vessel, their discovery of the infected Vulcans, and their struggle to survive while avoiding infection and learning the cause of the outbreak. Doctor Phlox eventually identifies the condition and develops a cure, which is successfully administered to the remaining infected Vulcans.

The episode explores themes of fear, the fragility of logic, and the contrast between Vulcan emotional control and the primal aggression unleashed by the "Impulse" virus. The portrayal of Vulcans as mindless, violent creatures was a significant departure from established Star Trek canon and sparked debate among fans.