A User's Guide to the Brain: Perception, Attention, and the Four Theaters of the Brain by John J. Ratey M. D

Author:John J. Ratey, M. D. [John J. Ratey, M. D.]
Language: eng
Format: epub
Tags: Psychology, Neuropsychology, Science, Life Sciences, Neuroscience, Cognitive Science
ISBN: 9780375701078
Google: DgiPDQAAQBAJ
Publisher: Knopf Doubleday Publishing Group
Published: 2002-01-08T05:00:00+00:00

SHORT-TERM VERSUS LONG-TERM MEMORY

AS WE ALL know, there is a difference between short-term and long-term memory. The former lasts for minutes or hours, and the latter for longer than a day. For certain memories, the time in between is used to consolidate them from less stable to more permanent forms.

Short-term memory is also referred to as “working memory” because it allows us to carry out the hundreds of tasks we busy ourselves with each day. Working memory gives continuity to what we’re aware of from one moment to the next. As noted in Chapter 3, it enables us to remember a phone number from the Yellow Pages long enough to dial it, and to keep track of the conversation we are having once it starts. It allows us to recall where we cut-and-pasted paragraph C while we are editing paragraph B in our draft book on the brain. Here I will permit an analogy to the computer—which otherwise is a dangerous exercise because a computer is far too simplistic a device when compared to the dynamic living organ inside one’s head. Short-term memory acts like a computer’s RAM: it holds the data we are working with at the moment, but loses them once the machine is turned off. Long-term memory acts like the computer’s hard disk: information is only put there when we hit “Save,” but once it’s put there it stays there so that we can access it again and again.

Short-term and long-term memory are easily distinguishable. The complex question is how short-term memories make the transition to long-term memories. Initial consolidation of a short-term memory occurs in only a few hours. But conversion to a long-term memory does not happen until the information has been sent by the cortex to the hippocampus. Research suggests that there is a special window in time during which the transition to long-term memory is possible. This window is essentially the time needed for neurons to synthesize the necessary proteins for LTP. An initial stimulation triggers a communication across the synapse between two nerve cells in the brain. Further stimulation then causes the cells to produce key proteins that bind to the synapse, cementing the memory in place. If LTP—and hence a memory—is to last for more than a few hours, proteins produced in the first neuron must find their way to specific synapses and bind to them, an event that changes the structure of the synapses and increases their sensitivity to an incoming signal. This may explain why we must repeat a list of words over and over in order to memorize them. It may also validate the role of REM sleep as a process for reliving new and old experiences so they become more permanently etched as long-term memories.

Very recent research with mice, flies, and Aplysia indicates that remembering something in the short term uses proteins that are already present in synapses. But to shift the memory into the long term, new proteins that reconfigure synapses are needed. The synthesis of

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