The memory system
Memory is considered to be a three-part system that consists of: sensory memory, short term memory and long term memory. Sensory memory is the earliest stage of memory where new information can only last for about three-tenths of a second. It refers to what is seen, heard and felt in the present and allows perceptions such as visual patterns, sounds or touches to linger for a brief moment after the stimulation is over. If this information is not selected and transferred into the short term memory, it fades away.
Short Term Memory
Short term memory, also known as working memory only lasts for seconds or occasionally minutes. Although short term memory is quickly forgotten, most people can hold five to nine items, such as numbers, at one time but the amount of information that can be stored can vary. Another characteristic that prevents short term memory as a permanent information store is concentration. Concentration is needed when trying to remember a certain piece of information. By switching focus to something else or carry out another mental activity completely wipes out the information previously held in the short term memory. The mechanism of rehearsal allows information to be passed from the short term memory to long term memory. The more often an item occurs in the short term memory, the more likely it is to be transferred into the long term memory.
Long Term Memory
The third part of the system, long term memory contrasts with sensory memory and short term memory in that information can be stored for extended periods of time and has virtually unlimited capacity and can store unlimited amounts of information indefinitely. Long term memory allows a person to remember events that may have happened years before and takes place through permanent chemical or structural changes in the nerve cells which are caused by patterns of electrical activity within the cells. The longer an electrical pattern relating to a particular memory is, the stronger the chemical or structural basis of the memory become.
“Forgetting”
There are several possible explanations as to why something that has been stored in long term memory has been forgotten. One possibility is retrieval failure. As people grow older, the memory traces fade over time meaning that the physical changes that form the synapses decay. (see figure 1.4) Another theory known as the interference theory suggests the possibility of taking in and storing new memories that interferes with the ones already recorded. A third possibility is that the process of retrieval breaks down. In other words, the brain cannot find the pathways that lead to a stored memory. Many begin to experience this breakdown in their 20s and tend to get worse when they reach their 50s. Your synapses are reinforced and cells make stronger connections with each other. But as you begin to age, these synapses begin to falter, which begins to affect how easily you can retrieve your memories. In addition, some parts of the brain essential to memory are highly vulnerable to aging.
Causes of memory loss
Other things can happen to your brain to speed up this decline. For example, you may have inherited some unhealthy genes, been exposed to poisons or perhaps too much alcohol and smoked too much. As you age physical changes in the brain can make it hard more difficult to remember efficiently. The good news though, is that memory loss and dementia are inevitable.
Anything that affects the cognition, the process of thinking, learning and remembering, can affect memory. Medications like anti depressants and sleeping pills can interfere with memory as well as alcohol and drug use as they change the chemicals in the brain. Stress, which leads to lack of sleep and depression is common with aging. People with head injuries and any other infections may experience memory problems as well. Amnesia is the loss of the ability to memorise information or recall information stored in the memory and is thought to be due to damage to the neural pathways in the brain that control memory. Amnesia usually affects long term memories than short term memories. Possible causes of this disorder include: head injury, disorders such as Alzheimer’s disease, infections and thiamine deficiency in alcoholics.
Memory is the ability to store, retain and retrieve information. When there is some damage to the part of the brain that performs these functions then that is when memory loss can occur. Memory loss is a symptom where a person experiences an unusual level of forgetfulness and inability to recall past events. For a very long time, humans have tried to understand what memory is, how it works and why it goes wrong. It is an important part of what makes us truly human, and yet it is still one of the most elusive and misunderstood of human attributes.
Bibliography
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