Neurology: Detailing the Process of Memory

The hippocampus is a region of the brain critical for establishing and retrieving long-term memories. A hotly debated topic in cognitive neuroscience is whether the hippocampus codes for memory strength (and is therefore mainly active for strong memories) or recollective experience (activity relates to retrieval of contextual information) during recognition. Thanks in part to findings from a TWRI-led study, this debate may finally be put to rest.

The study was led by Dr. Melanie Cohn in Dr. Mary Pat McAndrews’ lab. Participants were asked to study pairs of words (A-B). The team then used functional magnetic resonance imaging (fMRI) to assess hippocampal activity while participants performed a recognition task for the first member of the pairs (A) presented alone and then in the presence of their pair member (A-B). They asked participants to rate the degree of strength or familiarity of A words (i.e., certain-new to certain-old) and whether they were able to recollect the original study experience. Importantly, while other areas of the brain showed increased activation in relation to memory strength, activity in the hippocampus only increased when context was recollected.

Drs. Cohn and McAndrews explain, “Things can seem very familiar at first but you may not be sure why (missing context). Suddenly everything ‘makes sense’ because information becomes recollected with the right context and you now know why something is familiar to you. The hippocampus seems to be critical to this ‘conversion’ of one type of memory experience to the other.”

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