Whenever something bad happens to us, brain systems responsible for mediating emotions kick in to prevent it from happening again. When we get stung by a wasp, the association between pain and wasps is encoded in the region of the brain called the amygdala, which connects simple stimuli with basic emotions.
But the brain does more than simple associations; it also encodes lots of other stimuli that are less directly connected with the harmful event—things like the place where we got stung or the wasps’ nest in a nearby tree. These are combined into complex emotional models of potentially threatening circumstances.
Till now, we didn’t know exactly how these models are built. But we’re beginning to understand how it’s done.
Emotional complexity
“Decades of work has revealed how simple forms of emotional learning occurs—how sensory stimuli are paired with aversive events,” says Joshua Johansen, a team director at the Neural Circuitry of Learning and Memory at RIKEN Center for Brain Science in Tokyo. But Johansen says that these decades didn’t bring much progress in treating psychiatric conditions like anxiety and trauma-related disorders. “We thought if we could get a handle of more complex emotional processes and understand their mechanisms, we may be able to provide relief for patients with conditions like that,” Johansen claims.
To make it happen, his team performed experiments designed to trigger complex emotional processes in rats while closely monitoring their brains.
Johansen and Xiaowei Gu, his co-author and colleague at RIKEN, started by dividing the rats into two groups. The first “paired” group of rats was conditioned to associate an image with a sound. The second “unpaired” group watched the same image and listened to the same sound, but not at the same time. This prevented the rats from making an association.