KurveilAI's newsletter let me know of new research by neuroscientists of the University of California Irvine, published in Neuron journal, 10 Sep 2009 issue, which suggests that memory exists even when you simply can't retrieve it.
Jeff Johnson of the UCI Center for the Neurobiology of Learning & Memory and colleagues discovered, using advanced brain imaging techniques, that a person's brain activity while remembering an event is very similar to when it was first experienced, even if specifics can't be recalled. Johnson says brain imaging shines a "searchlight" into the brain.
The work's summary states:
Episodic memory retrieval is thought to involve reinstatement of the neurocognitive processes engaged when an episode was encoded. Prior fMRI studies and computational models have suggested that reinstatement is limited to instances in which specific episodic details are recollected. We used multivoxel pattern-classification analyses of fMRI data to investigate how reinstatement is associated with different memory judgments, particularly those accompanied by recollection versus a feeling of familiarity (when recollection is absent). Classifiers were trained to distinguish between brain activity patterns associated with different encoding tasks and were subsequently applied to recognition-related fMRI data to determine the degree to which patterns were reinstated. Reinstatement was evident during both recollection- and familiarity-based judgments, providing clear evidence that reinstatement is not sufficient for eliciting a recollective experience. The findings are interpreted as support for a continuous, recollection-related neural signal that has been central to recent debate over the nature of recognition memory processes.J. Johnson's photo credit: Daniel A. Anderson/UCI Communications