Facts you read, hear, or study become memories through a process with three main steps. First comes acquisition: the moment you encounter a new piece of information. Each sensory experience activates a unique set of brain areas. In order to become lasting memories, these sensory experiences have to be consolidated by the hippocampus, influenced by the amygdala, which emphasizes experiences associated with strong emotions. The hippocampus then encodes memories, probably by strengthening synaptic connections stimulated during the original sensory experience. Once memory has been encoded, it can be remembered or retrieved later. Memories are stored all over the brain, and it's likely the prefrontal cortexthat signals for their retrieval. So how does stress affect each of these stages? In the first two stages, moderate stress can actually help experiences enter your memory. Your brain responds to stressful stimuli by releasing hormones known as corticosteroids, which activate a process of threat-detection and threat-response in the amygdala. The amygdala prompts your hippocampus to consolidate the stress-inducing experience into a memory. Meanwhile, the flood of corticosteroids from stress stimulates your hippocampus, also prompting memory consolidation. But even though some stress can be helpful, extreme and chronic stress can have the opposite effect.