A report on Long-term memory, Episodic memory and Anterograde amnesia

The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation.

People with extensive, bilateral hippocampal damage may experience anterograde amnesia: the inability to form and retain new memories.

Over the years, three main ideas of hippocampal function have dominated the literature: response inhibition, episodic memory, and spatial cognition.

Explicit memory (or declarative memory) is one of the two main types of long-term human memory, the other of which is implicit memory.

Explicit memory can be divided into two categories: episodic memory, which stores specific personal experiences, and semantic memory, which stores factual information.

Guy Pearce plays an ex-insurance investigator suffering from severe anterograde amnesia caused by a head injury.

Declarative (denotative) or explicit memory is conscious memory divided into semantic memory (facts) and episodic memory (events).

The temporal lobe communicates with the hippocampus and plays a key role in the formation of explicit long-term memory modulated by the amygdala.

The medial temporal lobes include the hippocampi, which are essential for memory storage, therefore damage to this area can result in impairment in new memory formation leading to permanent or temporary anterograde amnesia.

There are two main types of amnesia: retrograde amnesia and anterograde amnesia.

Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store.

Retrograde amnesia is inability to recall memories before onset of amnesia. One may be able to encode new memories after the incident. Retrograde is usually caused by head trauma or brain damage to parts of the brain besides the hippocampus. The hippocampus is responsible for encoding new memory. Episodic memory is more likely to be affected than semantic memory. The damage is usually caused by head trauma, cerebrovascular accident, stroke, tumor, hypoxia, encephalitis, or chronic alcoholism. People with retrograde amnesia are more likely to remember general knowledge rather than specifics. Recent memories are less likely to be recovered, but older memories will be easier to recall due to strengthening over time. Retrograde amnesia is usually temporary and can be treated by exposing them to memories from the loss. Another type of consolidation (process by which memories become stable in the brain) occurs over much longer periods of time/days, weeks, months and years and likely involves transfer of information from the hippocampus to more permanent storage site in the cortex. The operation of this longer-term consolidation process is seen in the retrograde amnesia of patients with hippocampal damage who can recall memories from childhood relatively normally, but are impaired when recalling experiences that occurred just a few years prior to the time they became amnesic. (Kirwan et al.,2008)In the case of LSJ, her case shows that retrograde amnesia can affect many different parts of knowledge. LSJ was not able to remember things from her child or adult life. She was not able to remember things that most people pick up in everyday life such as logos or the names of common songs.

Systematic studies of anterograde amnesia started to emerge in the 1960s and 1970s.

Long-term memory, when discussed in the context of synaptic consolidation, is conventionally said to be memory that lasts for at least 24 hours.

Multiple trace theory (MTT) builds on the distinction between semantic memory and episodic memory and addresses perceived shortcomings of the standard model with respect to the dependency of the hippocampus.