Lecture 8 - Declarative memory (Cognitive Neuroscience, UU)

The hippocampus plays a big role in declarative memory: it is the ‘hub’ of memory.

Medial temporal lobe lesions lead to severe and global amnesia. Remote memories are spared after MTL lesions.

Within the hippocampus, there is spatial encoding by place cells.

• Relation memory theory
• Episodic memory theory

Recollection: hippocampus

Familiarity: perirhinal cortex

Three-process theory of medial temporal lobe functions:

1. Perirhinal cortex: object encoding
2. Parahippocampal cortex: spatial layout encoding
3. Hippocampus: fuses these aspects

Semantic knowledge in the brain:

• Sensory / functional theory
• Domain-specific theory

Semantic dementia: semantic memory loss due to dementia. Damage to the temporal cortex

[note: deze afbeelding uit het college is door de WorldSupporter redactie verwijderd wegens vermoedelijke inbreuk op het auteursrecht] 

Distributed-only view & Distributed-plus-hub view are two models of the cortical semantic network.

There is a lot of evidence for the distributed-plus-hub view.

Memories can become independent (outside of hippocampus).

How are retrieval memories reactivated and becoming available again? So how are episodic memories reactivated?

• Pair recall neurons reactivate the memory (increased activity)

Role prefrontal cortex --> different parts are active for semantic and phonological pairs of words.

Damage to frontal lobe lesions: source errors.

Multiple trace theory of consolidation: hippocampus is always involved, and has multiple memory traces  explanation of complete retrograde amnesia.

Memory is consolidated during sleep.

Filial imprinting – the formation (through learning) of an early social preference for the mother or another stimulus.

You need to sleep fairly soon after the learning experience for it to enhance memory.

Conclusions:

• Damage to the MTL causes amnesia: declarative memory
• Declarative memory involved episodic (HPC) and semantic memory (anterior temporal lobe).
• Three-process model of MTL
• Semantic memory is about concepts (hub)
• Involves a ‘hub’ in the anterior temporal lobe
• Frontal cortex is involved in memory encoding and retrieval
• Declarative memory is consolidated over time and involves sleep

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