Declarative/explicit memory: the medial temporal lobe memory system

• Animal models of amnesia

What brain systems support memory, and what specific functions do they support?

Where are memories stored? Is there an engram?

What parts of the medial temporal lobe are important for memory?

To what extent does recognition memory impairment occur in amnesia, and in particular, does recognition memory impairment ordinarily occur after damage limited to the hippocampal region?

What is the specific contribution of perirhinal cortex to visual recognition memory (perceptual, mnemonic, or both)?

Why does the recognition memory performance of amnesic patients benefit from extended study time?

Do nondeclarative memory phenomena, such as priming or category learning, influence recognition memory?

Does the hippocampus play a time-limited role in the storage of information?

How do the effects of bilateral medial temporal lobe lesions and unilateral temporal lobectomy differ?

Which medial temporal lobe structures are necessary and sufficient for object recognition memory?

Which medial temporal lobe structures contribute to object association memory?

Is the medial temporal lobe a functionally homogeneous neural network?

Which medial temporal lobe structure is critical for linking object, event, or place information with affective valence?

What parts of the medial temporal lobe are important for declarative memory?

Anterograde amnesia is the inability to recall or recognize information that was processes after the brain insult. Anterograde amnesia affects memory for personal as well as public facts and events.

Retrograde amnesia is the inability to recall or recognize information that was processes prior to the brain insult. Retrograde amnesia affects memory for personal as well as public facts and events.

Chronic global amnesia is a deficit in explicit memory (e.g., recall and recognition of facts and events) that manifests itself in everyday life. A key feature is a lack of continuity from day to day. The anterograde amnesia prevails irrespective of the kind of material to be remembered and the modality of presentation. It often occurs in the absence of other cognitive deficits, and in the face of preserved implicit memory (e.g., skill learning and repetition priming). The purity and severity of the explicit memory impairment varies from patient to patient. Some degree of retrograde amnesia usually accompanies the anterograde amnesia.

Would these rats be impaired on tests other than repetition of the original learning even? Could they exploit their representation in novel situations? FX rats used a different form of memory representation than SH rats. How did their memory representations differ?

• Constant condition: While not preventing a relational representation, these conditions allow the formation of a simple association between an individual set of cues and the behavior reinforced by successful escape.

• Variable-start condition: Rats are reinforced for multiple trajectories toward multiple-stimulus complexes. Successful navigation would seem impossible without taking into account the relations among the varying visual perspectives and swim trajectories.

Relational processing and flexibility are the hallmarks of memory dependent on the hippocampal system.

In rats, is the hippocampus specialized for spatial memory or does it mediate a general memory function as it does in humans?

Non-spatial declarative processing depends specifically on the hippocampus in animals as it does in humans.