A common understanding of long term memory storage among researchers in the concept of engrams. Engrams are patterns of neurons connected through activation at the same time. A unique pattern of such a neural network is referred to as an engram. [Shenk, 2000]

Information comes into brain as pattern of nerve cell activity, lasting seconds or less. Most is not, but some is permanently stored and saved within the same regions of brain and can be reactivated later. To do this, some nerve cell connections are strengthened, while others may be weakened. ("How Your Brain Remembers," 2000)

Do Engrams Make Sense?

Yes! The concept of engrams explains many phenomenon.

1. Why memory cues work. The more neurons activated that were activated at the time of the memory, the more likely the entire memory is to be activated.
2. Why people experience the "tip of the tongue " phenomenon. These engrams, "memory constellations," overlap with and trigger one another [Shenk, 2000].

Can they be located?

These memories, stored as engrams, are not located in any "Memory Bank" in one special location in the brain. Rather they are spread out throughout the brain, a concept called equipotentiability.[McAleer, 1985 .p.22]

Canadian surgeon Wilder Penfield thought he had found engrams in the 1920's and 1930's. He performed surgery on patients with severe epilepsy. He stimulated the brain cells most likely to cause the people's epilepsy with a tiny electric current. His patients stayed awake during the operation, so that they could tell him when they were about to have an epileptic attack. This would be how he would find the diseased cells and remove them. When he stimulated some of his patients in the area of the limbic system , many reported experiencing flashbacks. Exciting as his discovery was, only 40 out of 1,132 people on whom Penfield performed this operation reported specific, detailed memories. Some heard music, or voices. Some didn't report any such experience. (Yount, 1996, p. 39)