This research project will test two highly controversial and scantily researched hypotheses in the neuropscience of memory:
- that the extended hippocampal system (EHS) is always needed for recollective processes, as opposed to familiarity, regardless of memory age;
- that under certain conditions, the neocortex can support new declarative learning independently of the EHS.
These contradict the prevailing view that all remote memories are independent of the hippocampus, and that the neocortex cannot support new declarative learning. Patients with specific EHS lesions and patients with extensive Medial Temporal Lobe (MTL) lesions will be tested on recognition memory of personal events, using Remember/Know (RK) distinctions, Receiver Operating Characteristic (ROC) curves, and Process Dissociation Paradigms (PDP).
PDP and ROC have never been used to study remote memory, and only they can provide objective measures of recollection/familiarity. It is expected that EHS patients will show a specific deficit on recollection, regardless of memory age, whereas MTL patients will show deficits on both components. Neuroimaging of patients and healthy controls will provide converging evidence for the distinct role of the EHS in recollection, regardless of memory age.
To test patients' ability to acquire new declarative information, a Fast Mapping (FM) paradigm derived from the developmental literature on the acquisition of language will be used. FM allows children to acquire large amounts of associative information, presumably capitalizing on neocortical plasticity and independently of the EHS.
If residual neocortical plasticity underlies amnesic patients' observed ability to learn new semantic information, then they should also succeed on FM tasks. Neuroimaging will confirm that FM learning is independent of the EHS. The results of this project will have far reaching implications for memory theory and memory rehabilitation.
Call for proposal
See other projects for this call