Neural correlates of retrieval of declarative memories modulated by the reconsolidation process
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2019
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Abstract
Consolidated memories can return to a labile state if they are reactivated by unpredictable
reminders. To persist, active memories must be re-stabilized through a process known as
reconsolidation. Although there is consistent behavioral evidence about this process in humans, the
retrieval process of reconsolidated memories remains poorly understood. In this context, one
fundamental question is whether the same or different neurophysiological mechanisms are involved in
retrieval of consolidated and reconsolidated memories. Because it has been demonstrated that the
exposure to the reconsolidation process may restructure and strengthen memories, we hypothesized
distinct neurophysiological patterns reflecting enhanced recollective processes during retrieval of
reconsolidated memories. Moreover, we hypothesized that the administration of an amnesic agent
during reconsolidation, such as a new learning, can reverse these neurophysiological changes. To test
it, consolidated and reconsolidated declarative memories (and memories whose reconsolidation
process was interfered) (i.e., picture-word pairs) were evaluated in humans in an old/new associative
recall task while the brain activity and the pupillary response were recorded using
electroencephalography and eyetracking. Our results showed that retrieval of reconsolidated
memories elicits specific patterns of brain activation, characterized by an earlier peak latency of the
parietal ERP old/new effect compared to memories that were consolidated or whose reconsolidation
process was disrupted by a new learning. Moreover, our results demonstrated that only retrieval of reconsolidated memories is associated to a late reversed mid-frontal effect. Complementarily,
reactivated memories showed an earlier peak latency of the pupil old/new effect compared to nonreactivated memories. Based on these results, we argue that partially distinct brain mechanisms –
presumably associated to enhanced recollective processes - support retrieval of reconsolidated
declarative memories.
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Tesis (Ph.D. in Neuroscience)--Pontificia Universidad Católica de Chile, 2019