There is no better sign of true love than to finish each other’s sentences, and now a new study has explained the science behind this universal sign of affection. According to the research conducted by a team from the University of California, Berkeley, when you either finish your spouse's sentences or answer a fill-in-the-blank question, you are engaging the hippocampus, the same part of your brain associated with memory storage.

In order to find these results, scientists recorded neuronal activity using electrodes inserted into the hippocampus of 12 epileptic patients as they heard fill-in-the-blank sentences with an obvious answer. They then recorded information from only the non-epileptic hemisphere. Results showed that in 10 of the 12 subjects, only constrained sentences – those with a single obvious answer – caused a burst of synchronized theta waves in the hippocampus, which also happens when it makes a memory association.

As the fill-in-the-blank sentences became more challenging and had more than one obvious answer, the hippocampus became more active as it attempted to predict what would happen.

"The hippocampus started building up rhythmic theta activity that is linked to memory access and memory processing," study co-author, Robert Knight explained, as reported by Medical Xpress.

Although its not entirely clear as to why the hippocampus is used when retrieving fill-in words, one theory is that when one of these associated neurons is triggered, all those vibrating with the same frequency fire simultaneously, giving us recall of related memories. For example, according to Medical Xpress, the smell of an orange triggers a picture in the mind of the look of an orange, along with any positive or negative emotions connected with oranges.

In addition, this same mechanism is what we would use when trying to fill in the words of a spouse or loved one. The new findings could open up a whole new area of study with intracranial recordings to probe details of the connection between language and memory. According to Knight, the research also shows a sentence is not a static thing, but evolves in time,

“It is a real-time part of our language system, not a slave to the language system," he said.

Source: Piai V, Anderson KL, Lin JJ, Dewar C, et al. Direct brain recordings reveal hippocampal rhythm underpinnings of language processing. PNAS . 2016

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