Amnesia Flashcards
Why do people with Korsakoff’s syndrome get amnesia?
Because alcohol damages thiamine, which damaged mammillary bodies.
Where was patient RB’s damage?
In CA1 of the HPC. He had anterograde amnesia.
Where was HM’s damage?
He had bilateral removal of the MTL, thus the HPC. He had anterograde amnesia.
Where was patient YR’s damage?
CO2 poisoning reduced his hippocampal volume by half, and he had anterograde amnesia.
What do we know about semantic memory in patients with HPC damage?
A study of 5 patients found anterograde amnesia for both semantic and the usual episodic memory.
What do we know about semantic memory in patients with developmental amnesia?
Semantic memory seems to be spared. This implicates the neocortex.
What is the process of memory formation in the HPC?
Memories are consolidated into the neocortex over time, eventually becoming independent of the HPC and MTL. Perseveration being interrupted, leads to amnesia. This might be to do with sleep – ‘replay’ of memories transferring from HPC –> neocortex in SWS.
What evidence is there for the role of the HPC in memory formation?
Amnesiacs have better memory the further back in time the event was. This is because the longer ago the event, the more likely it if fully transferred to the neocortex, and thus HPC removal/damage does not impair memory.
What is multiple trace theory?
MTT suggests that episodic memories are never fully consolidated from the HPC, because every time the trace is replayed, it is slightly different.
However MTT suggests that episodic memories have some resilience against damage, because of this repetition and rehearsal. Semantic memories become independent of the HPC over time under MTT.
Are people with amnesia susceptible to priming?
Yes! They have no recollection of having been primed, but do show normal priming response (e.g. same as controls in word stem completion tasks). This suggests priming is not supported by the HPC or MTL.
Can people with amnesia be conditioned?
Yes! Again, they show normal conditioning response but have no memory of having been conditioned. This is true of motor learning also (i.e. no memory of learning motor action, but can perform it as if normal).
What happens to recognition memory in amnesia?
Recognition (but not recall) is retained when the cortex surrounding the HPC is undamaged – this suggests that HPC is not vital for recognition, but the cortex might be.
