up:: The Brain A part of the Limbic system.

The amygdala are two clusters of nuclei. It governs the fight or light response to a perceived or imagined fear.

They have a primary role in processing of memory, decision-making and emotional responses (including fear, anxiety and aggression).

Sensory input (going through the Thalamus) goes straight to the Amygdala before being processed to the Occipital lobe (visually) or Temporal lobe (auditory). That’s why you jump first before actually seeing what the danger is.