Educators educating Educators

Jul 23

L-T Memory Happens Here

How long before a short-term memory becomes a long-term memory?

Work with the famous patient H.M. yields some insights into this topic. As a result of H.M. surgery to relieve the effects of epileptic seizures, he not only lost the ability to convert experiences into short-term memory but also the ability to recall past experiences. He had what is referred to as retrograde amnesia, a loss of memory of the past.

But how far back could he remember? Was his long-term memory completely gone? Researchers questioned H.M. about events that occurred within three to seven of his surgery, with no recall. But when questioned about events in his early childhood, H.M. had perfect recall of those experiences. Upon further investigation, it was determined that his long-term memory was intact up to the eleventh year before his surgery.

The ramifications of this research are critically important for educators. As you recall from his surgery, H.M. lost his hippocampus during surgery, the region of the brain involved in converting short-term memories into longer-term memories. If the hippocampus was involved in all memory activities, its complete removal should destroy all memory abilities, thereby wiping his memory clean. But, as illustrated above, this does not happen.

John Medina explains that, “ the hippocampus holds on to a newly formed memory trace for years, not days, not months, and even a decade or more. System consolidation, that process of transforming a labile memory into a durable one, can take years to complete. During that time, the memory is not stable.”

So if long-term memory is not stored in the hippocampus, where is it stored? It is stored in the same place in the cortex as it was stored as an initial short-term memory. Again we look to Medina for an explanation of this phenomena, “Declarative memories appear to be terminally stored in the same cortical systems involved in the initial processing of the stimulus. In other words, the final resting place is also the region that served as the initial starting place. The only separation is time, not location.”

As a summary, let’s examine the neural relation between the hippocampus and cortex as they control the formation of memories.

The cortex and the hippocampus are in continuous conversation and are essentially involved in memory formation and operate in unison to turn short-term memories into long-term memories.

1. Long-term memories occur from accumulations of synaptic changes in the cortex as a result of multiple reinstatements of the memory.

2. These reinstatements are directed by the hippocampus, perhaps for years.

3. Eventually the memory becomes permanent in the hippocampus, and this newer, more stable memory is eventually stored in the cortex.

4. Retrieval mechanisms may reconstruct the original pattern of neurons recruited during the first moments of learning.

This research has huge implication for educators. It may take ten years before the multiplication tables are moved from short-term storage in the hippocampus to long-term memory in the cortex. Or what about the time and effort necessary to store in the cortex the elementary language arts curriculum?

Educators are dedicated professionals and truly have demanding jobs. As educators, we are “brain surgeons” since we actually change the brains of our students. But we must be engaging, creative, and persistent because it might take ten years before our job of developing long-term memory is completed.


In case you get bored with the lazy days of summer and want to get a jump preparing for the coming school year, I added to Stuff4Educators a section called How to Study Better based on research from Harvard Medical School that highlights four science-backed ways towards better learning (Hint: drop the highlighter). Additionally, I posted a YouTube video under exercise from the Dana Foundation that won the Northwest Emmy award called Exercise and the Brain that explores the benefits of exercise on the brain and learning. Finally, some books that I have read this past year and found to be stimulating are listed.