Histamine Could Boost Long-Term Memory

Histamine can improve long-term memory in both humans and mice, but might also hinder recall in people who already have good memories, study says.

AsianScientist (Jan. 15, 2019) – While histamine might be the bane of allergy sufferers, research from Japan shows that it could possibly help to improve long-term memory. These findings have been published in Biological Psychology.

Histamine is a neurotransmitter that not only affects the immune response but can also influence memory and acid levels in the stomach. Specialized receptors in different areas of the body regulate these different functions of histamine.

When a research team led by Professor Yuji Ikegaya of the University of Tokyo gave mice drugs that increase histamine levels, they found that the mice could recognize toys they had seen up to 28 days ago. Typically, mice forget about toys they have seen after three days.

Similarly, the researchers found that human subjects given a large dose of medication that increases the amount of histamine in the brain performed better on a long-term memory word association test. Participants with poor memories recognized more images correctly, while images that had been difficult to recall became easier for all participants to recognize.

However, taking the drug lowered scores of participants with good memories and images that had been easier to recall became slightly more difficult for all participants to recollect.

Ikegaya suggests that memory is a combination of a gradient system and a yes:no binary system. Information might be stored in the brain as a gradient, but nerves do not fire until they are above a particular threshold.

“You still have the memory, but you can’t access it unless it is above a particular threshold,” he explained.

The researchers suspect that the drug raises the histamine gradient to the point that the neurons involved in the latent memory reach the threshold level required to fire a signal and make us remember. However, for memories already over the threshold, extra histamine adds too much noise and excessive nerve signaling hinders recall.

The team is currently planning future studies to test how histamine levels might affect memory test results in older adults. Other studies will also examine how histamine might be involved in prospective memory, such as things we might write on reminder sticky notes to our future selves.

“To any students thinking about using this drug as a study aid, I must warn them to first always protect their health, and second to realize that we have not tested whether this drug helps anyone learn or memorize new things,” Ikegaya cautioned.

The article can be found at: Nomura et al. (2018) Central Histamine Boosts Perirhinal Cortex Activity and Restores Forgotten Object Memories.


Source: University of Tokyo; Photo: Pixabay.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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