brain, spinal cord, and nerve disorders
Amnesia
Introduction
Amnesia is total or partial loss of the ability to recall experiences or events that happened in the preceding few seconds, in the preceding few days, further back in time, or after the event that caused the amnesia. Because many areas of the brain are involved in memory, damage almost anywhere in the brain can cause amnesia. How amnesia is caused is only partly understood. How long memory loss lasts depends on the severity of the damage that caused it. Doctors evaluate memory loss by asking simple questions and doing formal tests of memory. The cause of memory loss is treated if possible. Memory loss can be classified as follows: Retrograde:Amnesia for the events before the event that caused the amnesia Anterograde:Amnesia for the events after the event that caused the amnesia Sense-specific:Amnesia for events processed by one sense, such as hearing Memory loss involves facts more commonly than learned skills. How far back in time memories are lost varies from a few seconds before the amnesia occurred to a few days, to further back in time, affecting more distant past (remote, or long-term) memories. Processing of memories involves the following: Taking in new information (registration) Linking new information with memories already stored in the brain, with mental pictures, or with other things that can help with retrieval (encoding) Recalling the memory (retrieval) The brain’s mechanisms for storing information and recalling it from memory are located primarily in the Temporal Lobe Damage and Emotions originating from the limbic system can influence the storing of memories and their retrieval. The limbic system includes parts of the cerebrum and some structures deep within the brain. Areas that are responsible for alertness and awareness in the brain stem also contribute to memory. 