Scent is the only sense that is directly linked to the memory and emotional learning centers of the brain, says  Rachel Herz , a neuroscientist at Brown University and an expert on the psychological science of smell. 

What are the smells you remember that even in memory make you stop a moment and breathe deeply, or that make your heart beat more vigorously, your palms ache for what’s been lost? Write these down. Write as quickly as you can, seeing how one smell leads to another. What kinds of images, memories, or stories might arise from this sensory trigger?

Things that you can taste, touch, hear, and smell also provide additional context that can act as memory triggers,