Role of Sleep in Formation of Relational Associative Memory

Abstract

Relational memory, the ability to make and remember associations between objects, is an essential component of mammalian reasoning. In relational memory tasks, it has been shown that periods of offline processing, such as sleep, are critical to making indirect associations. To understand biophysical mechanisms behind the role of sleep in improving relational memory, we developed a model of the thalamocortical network to test how slow-wave sleep affects performance on an unordered relational memory task. First, the model was trained in the awake state on a paired associate inference task, in which the model learned to recall direct associations. After a period of subsequent slow-wave sleep, the model developed the ability to recall indirect associations. We found that replay, during sleep, of memory patterns learned in awake increased synaptic connectivity between neurons representing the item that was overlapping between tasks and neurons representing the unlinked items of the different tasks; this forms an attractor that enables indirect memory recall. Our study predicts that overlapping items between indirectly associated tasks are essential for relational memory, and sleep can reactivate pathways to and from overlapping items to the unlinked objects to strengthen these pathways and form new relational memories.

Augmenting hippocampal–prefrontal neuronal synchrony during sleep enhances memory consolidation in humans

“…Paired associative learning (PAL) has previously shown to be sensitive to the effect of sleep 1 , 40 , 77 – 79 . We adapted the task for participants to make it relatively short (20 min for the learning phase, 5–10 min for the retrieval phase), and based on visual stimuli (vPAL; see also ref.…”

Tau pathology leads to lonely non-traveling slow waves that mediate human memory impairment

“…All statistical comparisons were carried out using the Pingouin Python package for statistical analysis 66 . All correlations reported are Pearson correlations unless stated otherwise.…”

“…Paired associative learning (PAL) had been previously proven sensitive to the effect of sleep [65][66][67][68][69] and especially familiarity was previously shown to be sensitive to pathological aging 24,25 .…”

Sleep and quiet wakefulness signify an idling brain hub for creative insights

“…Participants who received sufficient nocturnal sleep after training gained better insights about hidden rules than participants who were forced to stay awake [33]. A recent thalamocortical network model-based report suggested that awake learning was replayed in slow waves of NREM, leading to drawing indirect associations within a transitive inference task, and a correlation was present between the number of slow waves and the improvement in forming the associations [44]. Additionally, a recent study on both humans and rodents revealed that awake hippocampal coactivations, specifically during sharp wave ripples, represent a mnemonic shortcut for nesting inference relationships [45].…”