Pali and Echo Phenomena: Symptoms of Persistence and Perseveration.

Some neurological or psychiatric positive, productive symptoms are an abnormal persistence of a sensorial feeling or abnormal repetition of a motor, behavioral or cognitive process corresponding to a perseverative symptom. Palinopsia, palinacousis, and related sensorial symptoms have been described. Verbal and motor symptoms include echolalia, palilalia, echopraxia, and motor perseveration. Cognitive disorders induce perseverative behavior, perseverative thinking, including palipsychism, flashbulb memories, and reduplicative paramnesia (also known as "palimnesia") and many related perseverative symptoms. We propose a review of physiological phenomena and pathological symptoms involving these perseverative or repetitive characteristics and discuss the potential mechanisms and neural network involved in this productive semiology.