Doha: Japanese researchers have identified a brain mechanism that may explain why people sometimes struggle to recall information they know, suggesting that temporary memory retrieval failures may result from changes in the brain's functional state rather than the loss of the memory itself.
According to Qatar News Agency, the study, led by researchers at Nagoya City University in collaboration with Hokkaido University and Kumamoto University, found that slow fluctuations in the activity of histamine-producing neurons influence how easily stored memories can be accessed. The findings were published in the journal Neuron.
"Our findings suggest that failure to recall is not always due to loss of the memory itself," said Professor Hiroshi Nomura of Nagoya City University. "Instead, the brain may sometimes be in a state in which a stored memory is difficult to access."
To investigate the mechanism, researchers trained mice to associate an audio cue with a sugar-water reward. They found that when histamine neuron activity was high immediately before the cue was presented, the animals were significantly more likely to retrieve the learned memory and respond accordingly. Memory-guided responses were about 40% higher during high-activity periods than during low-activity states.
The researchers also showed that suppressing histamine neuron activity reduced memory retrieval, while stimulating the neurons enhanced it, without affecting the animals' general movement, hearing, or responses to the reward itself.
Nomura said the findings could offer a possible explanation for everyday experiences such as the "tip-of-the-tongue" phenomenon, in which a person knows information but cannot immediately retrieve it. However, he stressed that the study did not directly examine human memory retrieval and that further research is needed to determine whether the same neural mechanism operates in people.
The researchers said future studies will explore whether similar histamine-dependent brain states influence other forms of memory and whether they contribute to age-related cognitive decline and neurological disorders.