state of mich

Memory

April 19, 2012 by  


tufail alone

Once information has been encoded and stored in memory, it must be retrieved in order to be used. Memory retrieval is important in virtually every aspect of daily life, from remembering where you parked your car to learning new skills. There are many factors that can influence how memories are retrieved from long-term memory. In order to fully understand this process, it is important to learn more about exactly what retrieval is as well as the many factors that can impact how memories are retrieved.

1.    Short Term Memory is remembering something that you recently saw or heard. An example of short term memory is remembering the color of the car that just passed by you. Short term memory is very brief. It only lasts about 5 seconds. In order to remember the same information at a later time, your brain transfers this information from your Short Term Memory to Long Term Memory. Short Term Memory can be transferred to Long Term Memory by repeating the information, or visualizing it.

2.    Long Term Memory contains information that you have recorded in your brain in the past. An example of Long Term Memory is the gift you received for a birthday 5 years ago. Long term memory has no limit on capacity and can store vast amounts of information.

Although long term memory always remains intact, sometimes it may take longer to recall information.

Sometimes, it becomes very difficult to remember information. Difficulty results from growing older and health conditions.

Memory and Aging

As you get older, you may not be able to remember things as well as you did in your younger years. This is a natural part of aging.

Both long- and short- term memory are composed of three processes: encoding, storage, and retrieval. These processes take place in various locations in the brain, often simultaneously. Not much is known about the physiology of long-term memory, although scientists speculate that the hippocampus is involved in the creation of long-term memory. It is unclear where long-term memories are stored, although there is some evidence that a single memory may be broken down into various elements and stored in many places at once. As Irving Kupferman explains, “long-term memories are stored in multiple regions throughout the nervous system. (In other words, they are not localized but stored through circuitry)”. Furthermore, “reflexive and declarative memory formation may involve different circuits in the brain. Reflexive memory relies on the cerebellum and amygdala; formative, on the hippocampus and temporal lobes”.

Another area of dispute involves the generation of new proteins during long-term memory formation. “Though long-term memory has …been shown to require protein synthesis, it is not known for sure whether these newly synthesized proteins are used only in strengthening existing synapses or in growing new ones. Circumstantial evidence may point to new synapse formation in learning: it has been demonstrated that an enriched environment leads to denser dendrite growth in rats. Still however, the conclusive evidence that specific long-term memory formation relies on dendritic growth and structural synaptic changes has hitherto proven elusive”.

The Prefrontal Cortex–Site of Working Memory

Since the 1970’s, scientists have speculated that the prefrontal cortex, located in the forehead area of the brain, plays a central role in working memory. Experiments using PET scans and functional MRI on primates, coupled with observations of human brain injuries, point to the fact that “the prefrontal cortex always seems to be “busy” when target information is kept “in mind”. Writer Tim Beardsley explains, “with neural connections to almost all the areas of the brain that process sensory information, [the prefrontal cortex] is well situated to maintain a flexible store of information relevant to any task at hand”.

Neurologist Patricia Goldman-Rakic of Yale University has begun to map the various areas of the prefrontal cortex into various regions associated with the different senses. Her laboratory has found evidence that information about spatial location is confined to the sub-region of the prefrontal cortex, while processes related to visual appearance are in a separate area below that.

Short-term memory is the subject of various other arguments as well. “Short-term memory…may be either plastic or dynamic in nature, and this is still a matter of debate. In the plastic scenario, short-term memories are formed by brief changes in synaptic transmissions. In the dynamic theory, it may arise out of a reverberating feedback circuit, where a memory is held electrically within a loop. Thus, no physical changes are made, and synaptic connections are not modified. “ Long term memory, [on the other hand,] may be encoded by plastic changes in existing synapses”.

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