Whew! It Was My Dentate Gyrus, Not My Entorhinal Cortex

“Tip-of-the-tongue syndrome is, as most know, age-linked. It is believed that older folk suffer a gradual loss in the power of the brain’s transmission system, possibly because of white matter decay. This loss of power necessitates the activation of more transmission lines to achieve any given word or fact recall. Ergo, the irritating delay, and the fear that the memory is going.” Sanford Rose

Dolors & Sense

By Sanford Rose

KISSIMMEE Florida—(Weekly Hubris)—11/25/2013—I couldn’t remember the word.

The word for French Protestants exiled after the revocation of the Edict of Nantes in 1685.

But I read 17^th-century history all the time. I am enamored of 17^th-century history.

Lately, of course, I’ve been reading more early 20^th-century history.

Macaulay, the doyen of historians of the 17^th century, apparently feels jilted, fearful of being supplanted by Luigi Albertini, the author of a magisterial work on the origins of World War I.

Still, not to remember the word! Is this Macaulay’s jealous revenge?

Is he who chronicled so eloquently the century of Newton saying: “You are straying from my balanced cadences to dwell in the dissonant forests of that Italian fact-mongerer. A pox on your memory of my beloved century”?

Then I remembered: Huguenots, of course.

The recall process took me 15 minutes.

That I forgot suggests a failure in one part of my hippocampus, a part of the brain that is associated with memory encoding and consolidation.

That I remembered suggests that it is not the most important part.

Tip-of-the-tongue syndrome is, as most know, age-linked. It is believed that older folk suffer a gradual loss in the power of the brain’s transmission system, possibly because of white matter decay. This loss of power necessitates the activation of more transmission lines to achieve any given word or fact recall. Ergo, the irritating delay, and the fear that the memory is going.

But if the extra lines can in fact be recruited within a reasonable period of time, the decay is very likely confined to the part of the hippocampus dubbed the dentate gyrus.

It has not penetrated to the more pivotal entorhinal cortex. Decay in this area is highly correlated with Alzheimer’s Disease.

Fortunately, we can replace neurons in various parts of the hippocampus, though we may not be able to reverse AD.

The brain remakes itself throughout adult life, provided we nourish it properly.

The success of brain rebuilding, or neurogenesis, depends essentially on an on-going tug of war within the individual neuron between two chemicals, cortisol, a byproduct of physiological and psychological stress manufactured in the adrenal glands, and brain-derived neurotrophic factor (BDNF), a protein manufactured, counterintuitively, throughout the body. The former kills neurons, while the latter encourages their growth.

Helping BDNF to triumph over nerve-killing cortisol in turn depends on lifestyle changes that emphasize adequate exercise and the cultivation of new learning experiences.

Hitting the bicycle as well as the history books may therefore be the best ways to delay the damage to the dentate gyrus that confines words to our tongue tips.

Provided, of course, that we can mollify Macaulay.