Dr's Casebook: Memory function is the job of the seahorse-shaped organ

The hippocampus is a seahorse-shaped organ within the brain. Photo: Getty ImagesThe hippocampus is a seahorse-shaped organ within the brain. Photo: Getty Images
The hippocampus is a seahorse-shaped organ within the brain. Photo: Getty Images
I’ve been thinking about heroes recently and I wonder if there’s someone that you particularly admire, maybe from the world of sport or entertainment?

While walking with friends in the Derbyshire Dales recently I saw that one had a little tattoo in the shape of a seahorse on her shoulder. I asked why she had chosen that particular subject for a tattoo: “Ah, because it brings back memories,” she replied.

I was just intrigued because there is a seahorse shaped organ within the brain and its job is very much to do with memory function.

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I spent a lot of time researching the hippocampus when I was writing a book on dementia, and I found it such a fascinating part of the brain that I keep an eye on any new research done on it.

Fascinatingly, the latest research suggests that there are marked differences in gene activity in the anterior and posterior parts of this little organ.

But first a little neuro-anatomy:

The brain is made up of three main parts, which reflect the development of the brain up the evolutionary tree.

The midbrain is the part that controls emotions and stores memories. Nowadays we mainly refer to it as the “limbic system”.

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This consists of several parts, of which the hippocampus is a very important component.

It is shaped a little like a seahorse, hence its name, which comes from the Greek “hippos” meaning horse and “kampos”, meaning sea-monster.

In biology, hippocampus is the genus for the seahorse.

The latest research suggests that it functions as two halves, which have different roles.

The anterior part seems to be more important for mood and emotion.

The posterior part is more to do with cognitive indexing.

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By studying the hippocampus from patients who had to have them removed to treat epilepsy, scientists were able to look at gene activity throughout the organ.

They found that genes associated with mood disorders, such as bipolar disorder, tended to be more active in the anterior hippocampus.

On the other hand, genes associated with cognitive disorders, such as autism spectrum disorder, tended to be more active in the posterior hippocampus.

This may have important significance in targeting future drug development for these different conditions.

We already know that the hippocampus is also involved in navigation and orientation.

Since my friend had a good sense of direction I just told her that her hippocampus was a good choice.

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