It is fascinating following our expanding knowledge of the workings of the brain with the use of functional MRI over the past 10-15 years. fMRI has provided an extraordinary view of brain function and enabled a wide range of remarkable discoveries. As this research proliferates, it promises many more new insights, with a multitude of applications.
Particularly interesting has been the growing understanding of memory formation and retrieval. Expanding on this knowledge and taking it to the next level, a recent study by neuroscientists and artificial intelligence researchers at DeepMind, Otto von Guericke University Magdeburg and the German Centre for Neurodegenerative Diseases shows how the human brain connects individual – or episodic – memories to solve problems and draw new insights.
The researchers proposed a novel brain mechanism that would allow retrieved memories to trigger the retrieval of other, related memories.
There have been many studies of episodic memories which advance the theory that they are stored as separate memory traces in a brain region called the hippocampus. Taking this as standard knowledge, the researchers’ new theory explores an anatomical connection that loops out of the hippocampus to the neighbouring entorhinal cortex but then passes back in to the hippocampus. It is this recurrent connection, the researchers thought, that allows memories retrieved from the hippocampus to trigger the retrieval of further, multiple linked memories.
To test the theory the researchers used a 7 Tesla fMRI to scan brain activation in 26 male and female study participants as they performed a task that required them to draw insights across separate events using a series of paired images. Their results are published in the September 2018 issue of Neuron.
Part of the study involved the development of a technique where they were able to separate out the parts of the entorhinal cortex that provide the input to the hippocampus, which allowed them to precisely measure the patterns of activation in the hippocampus to distinguish input and output separately.
Their resulting data showed that when the hippocampus retrieves a memory, it doesn’t simply pass it to the rest of the brain, but instead recirculates the activation back into the hippocampus, triggering the retrieval of other related memories.
They say their results preserve the best of both worlds – you preserve the ability to remember individual episodic experiences by keeping them separate, while at the same time allowing related memories to be combined on the fly at the point of retrieval.
In addition, they reckon this understanding could be replicated in Artificial Intelligence systems so they will have a greater capacity for rapidly solving novel problems.
What’s next?