Startle response

Startle response is a rapid, involuntary reaction to an unexpected stimulus. The response is a universal, defensive response to sudden or threatening stimuli, such as sudden noise or sharp movements, and is associated with negative affect. The startle response is a protective behavior designed to help the body prepare for fight or flight.

Physiology

The physiology of the startle response is complex, involving a number of different neurological pathways. The primary pathway involves the reticular formation in the brainstem, which receives sensory input and sends signals to the muscles involved in the startle response. This includes the facial muscles, skeletal muscles, and the cardiovascular system.

The startle response is also modulated by the limbic system, particularly the amygdala, which is involved in emotional processing. The amygdala can enhance the startle response when a person is in a state of heightened emotional arousal, such as fear or anxiety.

Clinical significance

The startle response can be exaggerated in a number of psychiatric disorders, including post-traumatic stress disorder (PTSD), anxiety disorders, and schizophrenia. An exaggerated startle response can also be a symptom of Startle syndrome, a rare genetic disorder.

In neurology, the startle response can be used as a diagnostic tool. A diminished or absent startle response can indicate damage to the reticular formation or other parts of the brain involved in the response.

See also

• Acoustic startle reflex
• Moro reflex
• Startle syndrome

References

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