Everyday human behavior is guided and shaped by the search for rewards. This includes eating tasty meals, drinking something refreshing, sexual activity and nurturing children. Many of these behaviors are needed for survival. But in some instances, this search for rewards can pose a significant threat to survival.
People rely on memories of rewards to function and survive. Associated with positive experiences, these memories provide context for evaluating present and future choices. For example, if foods high in sugar are associated with a positive experience, this can reinforce the behavior of eating the food that provided the reward. Similarly, a flavorful meal at a specific restaurant increases the likelihood you’ll become a returning costumer.
A deeper understanding of how reward memories work and interact with each other is critical to informing the choices you make and to treating disorders where seeking rewards has become problematic. Eliminating all reward seeking would negatively affect behaviors essential for survival, such as eating and reproducing. But if you can specifically target reward memories linked to different drugs, this could help reduce their abuse.
I am a behavioral neuroscientist studying addiction, and my team is interested in how reward memories are formed and processed in the brain. We study how memories linked to natural rewards such as food, water and sex differ from those linked with rewards from drugs such as fentanyl and cocaine.
Understanding the differences between these types of rewards and how memories of different drugs interact may lead to more effective treatments for addiction.
What is memory?
To study reward memories, it is important to understand the neurobiology of memory, or how the brain remembers things.
In 1904, evolutionary zoologist Richard Semon introduced the term engram to describe the physical representation of a memory – also called its trace – that forms in the brain after an experience. Later, psychologist Donald Hebb hypothesized that interconnected brain cells that are active at the same time during an experience form a physical ensemble that make up a memory.
In the past decade, neuroscientists have developed new tools that support the idea that neuronal ensembles, or small populations of brain cells that are activated at the same time, are likely the physical representation of memory. How new memories recruit neurons into ensembles is not fully understood, but the plasticity of neurons – their ability to change their connections with each other – seems to play a major role.
Memories are physically stored in your brain.
Research on neuronal ensembles has transformed how scientists understand learning and memory. Researchers can now create artificial memories, activate positive memories to counteract negative feelings, and alter how memories are linked. All these experiments on altering…