Memory Loss

Fig - Memory Loss

Definition:
Memory is the mental process of retaining and recalling information or experiences. Our memories help us retrieve information from a year ago or moments earlier. Memory loss is unusual forgetfulness that can be caused by brain damage due to disease or injury, or it can be caused by severe emotional trauma.

Types of Memory

No one structure or location in the brain is responsible for memory. Rather, memory is a complex process. The brain uses different processes to store memories of what you see, hear, feel, smell, and taste. There appear to be three phases involved in memory:

Sensory Memory
In this stage, your senses hold on to information very briefly. This sensory information is then processed by the brain and stored into short-term memory.

Short-Term Memory
Short-term memory consists of what you have in mind at the moment. The amount of information that can be stored in short-term memory is limited. The information can be kept in this storage for only a short period of time (30 seconds or less). Because the amount of information that can be held in short-term memory is limited, much of the information in this storage system is lost, discarded, or ignored. If you are not able to hold on to information for a few seconds, you probably will not be able to remember the information several hours or days later. Information in short-term memory is then processed and transferred to long-term storage.

Long-Term Memory
Long-term memory has the capacity to hold a large amount of information. Information can be stored in long-term memory from 30 seconds to a lifetime. Memories from yesterday and from childhood are stored in long-term memory.

Common Causes

The following are common causes for memory loss:

Fig - Functions of the Cerebral Hemispheres
  • Aging
  • Alzheimer's disease
  • Neurodegenerative illness
  • Head trauma or injury
  • Hysteria often accompanied by confusion
  • Seizures
  • General anesthetics such as halothane, isoflurane, and fentanyl
  • Alcoholism
  • Stroke or transient ischemic attack (TIA)
  • Transient global amnesia
  • Drugs such as barbiturates or benzodiazepines
  • Electroconvulsive therapy (especially if prolonged)
  • Temporal lobe brain surgery
  • Brain masses (caused by tumors or infection)
  • Herpes encephalitis
  • Other brain infections
  • Depression

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