Retrograde Amnesia - Brain Structures

Brain Structures

The most commonly affected areas are associated with episodic and declarative memory such as the hippocampus, the diencephalon, and the temporal lobes.

• The hippocampus deals largely with memory consolidation, in particular episodic memory. Its main responsibility is making information go from short-term memories into long-term stores. Amnesic patients with damage to the hippocampus are able to demonstrate some degree of unimpaired semantic memory, despite loss of episodic memory, due to spared parahippocampal cortex.
• The diencephalon and the surrounding areas' role in memory is not well understood. However, this structure appears to be involved in episodic memory recall.
• The temporal lobes are essential for semantic and factual memory processing. Aside from helping to consolidate memory with the hippocampus, the temporal lobes are extremely important for semantic memory. Damage to this region of the brain can result in impaired organization and categorization of verbal material, disturbance of language comprehension, and impaired long-term memory. Right side lesions in particular, result in impaired recall of non-verbal material, such as music and drawings. Difficulties in studying this region of the brain extend to its duties in comprehension, naming objects, verbal memory, and other language functions.

Plasticity of the brain is when rewiring occurs because of brain damage, finding different neural pathways and not relying on the damaged structures. Thus, the brain can learn to be independent of the impaired hippocampus, but only to a certain extent. For example, older memories are consolidated over time and in various structures of the brain, including Wernicke's area and the neocortex, making retrieval through alternate pathways possible.