hide
Free keywords:
-
Abstract:
Introduction. While traditional models of systems memory consolidation postulate the reliance
of freshly encoded memories on the hippocampus, recent evidence in humans and animals has
shown that there are conditions under which the neocortex can rapidly acquire genuine memory
engrams. The current study investigates the idea of concurrent memory encoding in the entire
network, and specialized subsystems coding for different aspects of the memory.
Methods. 80 participants encoded the same abstract visual stimuli during fMRI scanning and
were instructed to either remember the detailed item-context combinations (DET) or to identify
conceptual categories (CEP). 24h later performance was tested in a categorization and an itemcontext
recognition task.
Results. CEP performed better in categorizing novel stimuli (t(78)=-6.91; p<0.001), whereas
DET had better memory for item-context combinations (t(78)=6.31; p<0.001). In both groups,
repetitions activated the precuneus, for exact items (p<0.05) as well as conceptual repetitions
(p<0.05). Contrasting the two groups, exact item repetition elicited higher bilateral activation
of the superior frontal gyrus (t=7.03; p<0.05), caudate and thalamus in DET (t=5.88; p<0.05),
and higher activation in visual cortex extending towards precuneus and fusiform gyrus (t=7.51;
p<0.05) in CEP. Comparing CEP with DET, activation in medial occipital cortex (t=6.83, p<0.05)
increased over category repetitions only in CEP.
Discussion. Our data suggest the precuneus as a hub for detailed as well as conceptual memory
representations. Additionally, differences in memory performance and neural differences between
the two groups indicate a functional specialization of neocortical and subcortical areas during
prioritized encoding of similar vs. differential features.
