Amnesia (from Greek, meaning "forgetfulness"; from (a-), meaning "without", and (mnesis), meaning "memory"), also known as amnesic syndrome, is a deficit in memory caused by brain damage, disease, or psychological trauma. Amnesia can also be caused temporarily by the use of various sedatives and hypnotic drugs.
Short-term vs. long-term memory
Short-term memory is the information that a person is currently thinking about or is aware of. It is also called primary or active memory. Recent events and sensory data such as sounds are stored in short-term memory. Short-term memory often encompasses events over a period anywhere from 30 seconds to several days.
Because short-term memories need to be recalled for a lesser amount of time than long-term memories, the ability of the brain to store short-term items is more limited. According to "Memory Loss & the Brain," a newsletter from the Memory Disorders Project at Rutgers University, the brain can store anywhere from five to nine items. Long-term memory has much greater capacity and contains things such as fact, personal memories and the name of your third-grade teacher.
The different stages of memory are handled by different parts of the brain. Short-term memory is primarily takes place in the frontal lobe ofthe cerebral context. Then the information makes a stopover in the hippocampus and is then transferred to the areas of the cerebral cortex involved in language and perception for permanent storage.