The startle response is a brainstem reflectory reaction (reflex) that serves to protect the back of the neck (whole-body startle) and the eyes (eyeblink) and facilitates escape from sudden stimuli. It is found across the lifespan of many species. An individual’s emotional state may lead to a variety of responses. The acoustic startle reflex is thought to be caused by an auditory stimulus greater than 80 decibels.
The anterior cingulate cortex in the brain is largely thought to be the main area associated with emotional response and awareness, which can contribute to the way an individual reacts to a startle inducing stimuli. Along with the anterior cingulate cortex, the amygdala and the hippocampus are known to have implications in this reflex. The amygdala is known to have a role in the ‘fight or flight’ response, and the hippocampus functions to form memories of the stimulus and the emotions associated with it.
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