Here's what happens:

1. Stimulus detection: Our senses (e.g., visual, auditory, tactile) detect the stimulus, which is then transmitted to the brain.

2. Amygdala activation: The amygdala receives this information and rapidly processes it for emotional significance. This process is thought to occur in a matter of milliseconds.

3. Emotional appraisal: The amygdala sends signals to other brain regions, such as the prefrontal cortex (PFC) and anterior cingulate cortex (ACC), which help evaluate the emotional relevance of the stimulus. This appraisal process involves assessing factors like familiarity, valence (pleasantness or unpleasantness), and novelty.

4. Emotion generation: The PFC and ACC, along with other brain regions, generate an emotional response based on the appraisal outcome. For example, if the stimulus is perceived as threatening, the amygdala may trigger a fear response, which can lead to increased heart rate, blood pressure, and other physiological changes.

5. Neurotransmitter release: The emotional response is further amplified by the release of neurotransmitters like dopamine, serotonin, and norepinephrine, which modulate the intensity and duration of the emotional experience.

In terms of what you can do to better understand this process, I suggest:

1. Practice mindfulness: Regular mindfulness practice can help increase awareness of your emotional responses and reduce reactivity.

2. Recognize patterns: Pay attention to recurring stimuli that trigger strong emotions in yourself or others. This can provide valuable insights into the underlying mechanisms driving these responses.

3. Emotional regulation strategies: Develop techniques like deep breathing, progressive muscle relaxation, or cognitive reappraisal to manage emotional intensity and duration.

4. Neuroimaging studies: Explore neuroimaging research on emotion processing in humans, which can provide a deeper understanding of the neural correlates of emotional experience.

By grasping the intricacies of brain processing underlying sudden emotional responses, you'll be better equipped to navigate your own emotions and develop effective strategies for managing them.