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Prefrontally mediated inhibition of memory systems in dissociative amnesia
Laura C Marsh1, Dace Apšvalka1, Hirokazu Kikuchi2
1MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK.
Psychological Medicine
|January 8, 2025
Summary
Generalized dissociative amnesia may involve prefrontal cortex inhibiting memory retrieval. Functional MRI (fMRI) in two patients showed right anterior dorsolateral prefrontal cortex (raDLPFC) suppressing hippocampal activity, consistent with retrieval suppression.
Area of Science:
- Cognitive Neuroscience
- Neuroimaging
- Psychiatry
Background:
- Mechanisms of generalized dissociative amnesia remain unclear.
- A leading theory proposes prefrontal cortex control inhibits memory retrieval.
- Cognitive neuroscience findings suggest a specific retrieval inhibition mechanism.
Purpose of the Study:
- To investigate the role of retrieval suppression in dissociative amnesia.
- To examine the neural basis of memory inhibition in dissociative amnesia.
- To test the hypothesis of prefrontal cortex modulating hippocampal activity.
Main Methods:
- fMRI data from two dissociative amnesia cases were analyzed.
- Neuroanatomical overlap was assessed between unrecognized stimuli and retrieval suppression tasks.
- Effective connectivity analyses explored the relationship between right anterior dorsolateral prefrontal cortex (raDLPFC) and hippocampus.
Main Results:
- Functional alignment observed between retrieval suppression regions and areas active during non-recognition of colleagues.
- Significant activation in raDLPFC and right ventrolateral prefrontal cortex, with deactivation in hippocampal and medial PFC regions.
- Dynamic causal modeling confirmed raDLPFC's modulatory role on the hippocampus, which resolved in one patient post-treatment but persisted in the other.
Conclusions:
- Findings support an inhibitory mechanism suppressing core memory regions.
- This suppression prevents the recognition of personally relevant stimuli in dissociative amnesia.
- The raDLPFC-hippocampus interaction is implicated in the pathophysiology of dissociative amnesia.
Keywords:
dissociative amnesiaeffective connectivitymemory inhibitionpsychogenic amnesiaretrieval stoppingretrieval suppressionMore Related Videos
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