Motor learning promotes regionally-specific spindle-slow wave coupled cerebral memory reactivation.

Sleep is essential for the optimal consolidation of newly acquired memories. This study examines the neurophysiological processes underlying memory consolidation during sleep, via reactivation. Here, we investigated the impact of slow wave - spindle (SW-SP) coupling on regionally-task-specific brain reactivations following motor sequence learning.

Spindle-slow wave coupling and problem-solving skills: impact of age.

We examined how aging affects the role of sleep in the consolidation of newly learned cognitive strategies. Forty healthy young adults (20-35 years) and 30 healthy older adults (60-85 years) were included. Participants were trained on the Tower of Hanoi (ToH) task, then, half of each age group were assigned to either the 90-minute nap condition, or stayed awake, before retesting.

Eye movements during phasic versus tonic rapid eye movement sleep are biomarkers of dissociable electroencephalogram processes for the consolidation of novel problem-solving skills.

The hallmark eye movement (EM) bursts that occur during rapid eye movement (REM) sleep are markers of consolidation for procedural memory involving novel cognitive strategies and problem-solving skills. Examination of the brain activity associated with EMs during REM sleep might elucidate the processes involved in memory consolidation, and may uncover the functional significance of REM sleep and EMs themselves. Participants performed a REM-dependent, novel procedural problem-solving task (i.

Functional differences in cerebral activation between slow wave-coupled and uncoupled sleep spindles.

Spindles are often temporally coupled to slow waves (SW). These SW-spindle complexes have been implicated in memory consolidation that involves transfer of information from the hippocampus to the neocortex. However, spindles and SW, which are characteristic of NREM sleep, can occur as part of this complex, or in isolation.

Brain activations time locked to slow wave-coupled sleep spindles correlates with intellectual abilities.

Sleep spindles (SP) are one of the few known electrophysiological neuronal biomarkers of interindividual differences in cognitive abilities and aptitudes. Recent simultaneous electroencephalography with functional magnetic resonance imaging (EEG-fMRI) studies suggest that the magnitude of the activation of brain regions recruited during spontaneous spindle events is specifically related to Reasoning abilities. However, it is not known if the relationship with cognitive abilities differs between uncoupled spindles, uncoupled slow waves (SW), and coupled SW-SP complexes, nor have the functional-neuroanatomical substrates that support this relationship been identified.

Stability of neural encoding moderates the contribution of sleep and repeated testing to memory consolidation.

There is evidence suggesting that online consolidation during retrieval-mediated learning interacts with offline consolidation during subsequent sleep to transform memory. Here we investigate whether this interaction persists when retrieval-mediated learning follows post-training sleep and whether the direction of this interaction is conditioned by the quality of encoding resulting from manipulation of the amount of sleep on the previous night. The quality of encoding was determined by computing the degree of similarity between EEG-activity patterns across restudy of face pairs in two groups of young participants, one who slept the last 4 h of the pre-training night, and another who slept 8 h.

Weakly encoded memories due to acute sleep restriction can be rescued after one night of recovery sleep.

Sleep is thought to play a complementary role in human memory processing: sleep loss impairs the formation of new memories during the following awake period and, conversely, normal sleep promotes the strengthening of the already encoded memories. However, whether sleep can strengthen deteriorated memories caused by insufficient sleep remains unknown. Here, we showed that sleep restriction in a group of participants caused a reduction in the stability of EEG activity patterns across multiple encoding of the same event during awake, compared with a group of participants that got a full night's sleep.

Damage of the temporal lobe and APOE status determine neural compensation in mild cognitive impairment.

In mild cognitive impairment (MCI), the APOE4 genotype is associated with accelerated memory decline, likely due to the impact of neuropathology on main cerebral networks required for successful memory retrieval and/or to decreased capacity for recruiting secondary networks that might compensate for that brain damage. Here, we tested this hypothesis in twenty-six healthy older adults and thirty-four MCI patients, of which sixteen were APOE4 carriers. Compared to controls, MCI showed hippocampal volume reduction, cortical thinning in frontal, temporal and parietal regions, and dysfunctional EEG oscillations across fronto-temporal networks.