The cognitive neuroscience of sleep: neuronal systems, consciousness and learning

116

Rapid eye movement (REM) sleep constitutes a distinct “third state” of consciousness, during which levels of brain activity are commensurate with wakefulness, but conscious awareness is radically transformed. To characterize the temporal and spatial features of this paradoxical state, we examined functional interactions between brain regions using fMRI resting-state connectivity methods. Supporting the view that the functional integrity of the default mode network (DMN) reflects “level of consciousness,” we observed functional uncoupling of the DMN during deep sleep and recoupling during REM sleep (similar to wakefulness). However, unlike either deep sleep or wakefulness, REM was characterized by a more widespread, temporally dynamic interaction between two major brain systems: unimodal sensorimotor areas and the higher-order association cortices (including the DMN), which normally regulate their activity. During REM, these two systems become anticorrelated and fluctuate rhythmically, in reciprocally alternating multisecond epochs with a frequency ranging from 0.1 to 0.01 Hz. This unique spatiotemporal pattern suggests a model for REM sleep that may be consistent with its role in dream formation and memory consolidation.

mentioning

confidence: 99%

Rhythmic alternating patterns of brain activity distinguish rapid eye movement sleep from other states of consciousness

Chow

Horovitz

Carr

et al. 2013

116

“…This double dissociation suggests that distinct mechanisms, enhancing different aspects of a procedural memory, can support off-line learning. The differential engagement of these mechanisms over day and overnight may be related to neurophysiological changes associated with sleep and wake (16). Alternatively, physiological factors associated with the circadian cycle may account for the differential off-line processing of skill over these intervals.…”

Section: Discussionmentioning

confidence: 99%

Off-line learning of motor skill memory: A double dissociation of goal and movement

Cohen

Pascual‐Leone²,

Press³

et al. 2005

230

264

Acquiring a new skill requires learning multiple aspects of a task simultaneously. For example, learning a piano sonata requires learning the musical notes and being able to implement this goal by learning the appropriate sequence of finger movements. After practice, skill continues to develop off-line during a period of consolidation. Here we show that different aspects of a procedural memory are processed separately during consolidation: Only the movement sequence is enhanced over the day; whereas only the goal is enhanced over a night of sleep. This double dissociation suggests that distinct systems, enhancing different aspects of a procedural memory, support improvements during consolidation. Consolidation is not a single process; instead, there are multiple routes to off-line learning, and the engagement of these distinct mechanisms is determined by when consolidation takes place. movement control ͉ procedural learning ͉ consolidation ͉ sleep C lassically, a distinction has been made between how a movement is performed and the spatial target or goal of the movement (1). For example, a pianist makes a series of finger movements to fulfill the goal of playing notes in a sonata. Enhanced knowledge of either the finger movements or the goal of these movements can produce an increase in skill (2-4). During practice, distinct mechanisms may be engaged to support the simultaneous acquisition of both components (5-7). Skill can also develop off-line, between practice sessions, during consolidation (8, 9). Skill enhancement during consolidation, like practice, may involve the simultaneous enhancement of both the goal and the movement. Alternatively, the principles operating during consolidation may differ from those during practice: Skill components may be enhanced separately. This result would imply that the mechanisms engaged simultaneously during practice are engaged separately during consolidation.It is possible to distinguish between the goal and the movement components of skill in a procedural sequence learning task (2). In the present experiment, participants acquired skill in the serial reaction time task (SRTT). In this task, a visual cue can appear at any one of four positions arranged horizontally on a computer screen (10). Each screen position corresponds to a button on a response box. A trial begins when a cue appears. The participant presses the appropriate response button, ending the trial, and after a short fixed delay, another cue is presented. Unbeknownst to the participant, the visual cues follow a specific spatial pattern that is learned as both a sequence of finger movements and as a sequence of response buttons to push, or goals (2-4). After training with one hand, these two skill components can be distinguished by probing skill with the untrained hand (Fig. 1). By switching hands, the same finger is no longer associated with the same response. So, although the same sequence of response buttons is required, this goal is achieved by using a different set of finger movements. Thus the goal remain...

“…The long postponed delay period (3 s) of our task allowed for the studying of delta-band oscillations. Another possibility is that delta oscillations have been considered of little functional relevance in cognition because they are consistently observed in SWS and during general anesthesia (23,29). There is no definitive evidence regarding the origin of delta activity in the brain, but several studies place the site of waking delta-band generation in the anterior medial Time-frequency plots show averaged LFP-LFP coherence over all sessions (n = 18) for simultaneously recorded cortical pairs.…”

Section: Discussionmentioning

confidence: 99%

“…Delta-band oscillations are typically associated with slow-wave sleep (SWS; ref. 23), but an important question is whether delta-band oscillations during SWS and waking states represent the same underlying phenomenon (24). Recent findings associated delta-band oscillations in individual cortical areas with attention (25).…”

mentioning

confidence: 99%

Coherent delta-band oscillations between cortical areas correlate with decision making

Nácher

Ledberg

Deco

et al. 2013

134

Coherent oscillations in the theta-to-gamma frequency range have been proposed as a mechanism that coordinates neural activity in large-scale cortical networks in sensory, motor, and cognitive tasks. Whether this mechanism also involves coherent oscillations at delta frequencies (1-4 Hz) is not known. Rather, delta oscillations have been associated with slow-wave sleep. Here, we show coherent oscillations in the delta frequency band between parietal and frontal cortices during the decision-making component of a somatosensory discrimination task. Importantly, the magnitude of this delta-band coherence is modulated by the different decision alternatives. Furthermore, during control conditions not requiring decision making, delta-band coherences are typically much reduced. Our work indicates an important role for synchronous activity in the delta frequency band when large-scale, distant cortical networks coordinate their neural activity during decision making.synchrony | low-frequency rhythm | brain circuits