MIT neuroscientists have published new research that provides insight into how working memory functions in the brain. Working memory refers to the ability to hold information in mind for a short period of time, such as recalling a password or phone number long enough to input it into a device. The study, published in PLOS Computational Biology, compared measurements of brain cell activity in an animal performing a working memory task with the output of computer models representing two theories of the underlying mechanism for holding information in mind.
The first theory suggests that memory is maintained by neurons remaining persistently active, while the second theory proposes that a network of neurons stores the information by making short-lived changes in the pattern of their connections, or synapses. The results of the study strongly favored the latter theory, with the versions of the computer models that allowed for synapses to transiently change connections producing neural activity patterns that closely resembled what was observed in the real brains of the animals being tested.
According to senior author Earl K. Miller, the idea that brain cells maintain memories by being constantly “on” may be simpler, but it does not accurately reflect the complexity and flexibility of thought that can arise from intermittent neural activity supported by short-term synaptic plasticity. “You need these kinds of mechanisms to give working memory activity the freedom it needs to be flexible,” Miller said. “If working memory was just sustained activity alone, it would be as simple as a light switch. But working memory is as complex and dynamic as our thoughts.”
The research suggests that the mechanisms behind working memory are more nuanced than previously thought, and have important implications for understanding the brain’s functions and potential treatments for mental health disorders.