delanceyplace.com 6/30/10 - memory
In today's excerpt - how memory works:
"Many people wish their memory worked like a video recording. How handy would that be? Finding your car keys would simply be a matter of zipping back to the last time you had them and hitting 'play.' You would never miss an appointment or forget to pay a bill. You would remember everyone's birthday. You would ace every exam. Or so you might think. In fact, a memory like that would snare mostly useless data and mix them willy-nilly with the information you really needed. It would not let you prioritize or create the links between events that give them meaning. For the very few people who have true photographic recall -- eidetic memory, in the parlance of the field -- it is more burden than blessing.
"For most of us, memory is not like a video recording -- or a notebook, a photograph, a hard drive or any of the other common storage devices to which it has been compared. It is much more like a web of connections between people and things. Indeed, recent research has shown that some people who lose their memory also lose the ability to connect things to each other in their mind. And it is the connections that let us understand cause and effect, learn from our mistakes and anticipate the future. ...
"Learning and memory are not sequestered in their own storage banks, but are distributed across the entire cerebral cortex. ... The significance of these findings is profound. It means that memory is dispersed, forming in the regions of the brain responsible for language, vision, hearing, emotion and other functions. It means that learning and memory arise from changes in neurons as they connect to and communicate with other neurons. And it means that a small reminder can reactivate a network of neurons wired together in the course of registering an event, allowing you to experience the event anew. Remembering is reliving. ...
"The hippocampus [is] an essential mediator in [connecting neurons]. In a very small brain, every neuron might be connected to every other neuron. But a human brain that worked on this model would require that each of hundreds of billions of neurons be linked to every other neuron, an impossibly unwieldy configuration. The hippocampus solves this problem by serving as a kind of neural switchboard, connecting the distant cortical regions for language, vision and other abilities as synaptic networks take shape and create memories.
"[People with hippocampus damage] appear to have impairments that go well beyond the loss of memory creation. They also have severe difficulty imagining future events, living instead in a fragmented, disconnected reality. Recent studies show that imagining the future involves brain processes similar to, but distinct from, those involved in conjuring the past. We also tend to remember the people and events that resonate emotionally, which is why forgetting an anniversary is such an offense: it is fair evidence that the date is not as important as the ones we do remember. The discovery that memory is all about connections has revolutionary implications for education. It means that memory is integral to thought and that nothing we learn can stand in isolation; we sustain new learning only to the degree we can relate it to what we already know. ...
"The connections across the brain also help us conceive the future, as recent imaging studies have shown. Functional magnetic resonance imaging ... shows that a mosaic of brain areas similar to those involved in memory is active when participants imagine details of hypothetical or prospective events. ...
"[This] can sometimes cause us problems by altering our memories instead of augmenting them. ... Psychologist Elizabeth Loftus [has shown] how easy it is to create false memories of past events. In one study, participants watched a film of a car accident. Researchers asked some subjects how fast they thought the cars were going when they 'smashed into' each other and asked other subjects how fast the cars were going when they 'hit' each other. The subjects, who heard the word 'smashed' gave significantly higher estimates of the speed. In other experiments, subjects were fed incorrect information about an accident after watching the film; they might, for instance, be asked repeatedly whether a traffic light had turned yellow before the collision when in fact the light was green. Many then remembered a yellow light that never existed, which is why eyewitness testimony after police interrogation can be so unreliable."
|Anthony J. Greene|
|Scientific American Mind|