Abstract: Posttraumatic stress disorder (PTSD) is the only mental illness including startle response alteration in its diagnostic criteria. Compared to self-report, startle response measured in laboratory paradigm is associated more closely with overall symptom severity. There has been many research results on the neural mechanism of startle response in both humans and animals, making it possible to connect pre-clinical and clinical studies. At the beginning of using laboratory measurement of starlte response in PTSD clinical research, it has been mainly used as a specific indicator of hyperarousal symptoms, although it has not been firmly established the relation between startle alteration and overall symptoms yet. Recently, some new paradigms based on the theories of contextual anxiety or fear inhibition reveal the specific relationship of startle reflex and severity of PTSD symptom in particular contexts. The new progress in the application of startle response in PTSD will inspire and advance the discovery of pathological mechanism of PTSD and improvement of clinical diagnosis.

Key words: startle, posttraumatic stress disorder, contextual anxiety, fear inhibition