While neural circuits in FXS may be fundamentally intact, they are improperly tuned, which results in inflexibility in gaining certain types of knowledge.

‘Due to excessive dominance of the slow rhythm in FXS mice, these mice fail to learn new information that specifically contradicts what they initially learned.’

The study, co-authored with Dino Dvorak, a post-doctoral fellow in NYU's Center for Neural Science, focuses on the hippocampus. This part of the brain is crucial for memory, especially about space, which requires both encoding and remembering information. 




However, because the same neurons are active in both encoding and remembering, it's unknown what neural events control whether hippocampal neurons are encoding current experience into memory or recollecting information from memory. This dynamic is one of the keys to better understanding FXS, which impairs use of memory in multiple ways.
To explore this, first the scientists had to uncover an electrophysiological "signature of recollection" in hippocampus--a mapping that pinpointed whether these neurons are encoding current experience into memory or recollecting information from memory.
This resulted in two primary findings.
Specifically, they found that encoding and recollection are the result of a neural "tug-of-war" between two distinctive types of rhythmic neural synaptic activity within the hippocampus. Notably, encoding occurs when fast rhythmic activity overwhelms slower rhythmic activity; by contrast, recollection occurs when the slower rhythm dominates the medium rhythm.
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FXS hippocampus neurons are normal, and, as a result, FXS mice can learn and remember in the ways other mice do. However, due to excessive dominance of the slow rhythm in FXS mice, these mice fail to learn new information that specifically contradicts what they initially learned--in other words, the neural tug-of-war is too often won by the slower rhythm, preventing normal adaptive flexibility of cognitive function.
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Source-Eurekalert