Amnesia (; ), 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. Essentially, amnesia is loss of memory. The memory can be either wholly or partially lost due to the extent of damage that was caused. There are two main types of amnesia:
retrograde amnesia and
anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory. Anterograde amnesia is the inability to transfer new information from the
short-term store into the
long-term store. People with this type of amnesia cannot remember things for long periods of time. These two types are not mutually exclusive. Both can occur within a patient at one time. Case studies, such as that of patient R.B., show that both types of amnesia can occur simultaneously. Case studies also show that amnesia is typically associated with damage to the medial temporal lobe. In addition, specific areas of the
hippocampus (the CA1 region) are involved with memory. Research has also shown that when areas of the
diencephalon are damaged, amnesia can occur. Recent studies have shown a correlation between
deficiency of RbAp48 protein and memory loss. Scientists were able to find that mice with damaged memory have a lower level of RbAp48 protein compared to normal, healthy mice. In people suffering with amnesia, the ability to recall
immediate information is still retained, and they may still be able to form new memories. However, a severe reduction in the ability to learn new material and retrieve old information can be observed. Patients can learn new procedural knowledge. In addition,
priming (both perceptual and conceptual) can assist amnesiacs in the learning of fresh
non-declarative knowledge. Amnesic patients also retain substantial intellectual, linguistic, and social skill despite profound impairments in the ability to recall specific information encountered in prior learning episodes.
