Canonum De Ius Cogitatum
Canons of Cognitive Law
II. Mind (PSY)
2.4 Concepts of Sensation
Article 34 - Impulse
Canon 929 (link)
An Impulse is similar to instinct in that it is triggered by a strong emotional source either sensed externally or internally and is involuntary. However, unlike instinct, Impulse does not imply a physical reaction but a cognitive one.
Canon 931 (link)
The lack of use of an instinct will see it devolve into an Impulse.
Canon 933 (link)
Over time, the absence of reference to an impulse means even an Impulse may be forgotten.