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An overview is presented of the literature dealing with sleep-like motility and concomitant neuronal activity patterns throughout the life cycle in vertebrates, ectothermic as well as endothermic. Spontaneous, periodically modulated, neurogenic bursts of non-purposive movements are a universal feature of larval and prenatal behavior, which in endothermic animals (i.e. birds and mammals) continue to occur periodically throughout life. Since the entire body musculature is involved in ever-shifting combinations, it is proposed that these spontaneously active periods be designated as 'rapid-BODY-movement' (RBM) sleep. The term 'rapid-EYE-movement (REM) sleep', characterized by attenuated muscle contractions and reduced tonus, can then be reserved for sleep at later stages of development. Mature stages of development in which sustained muscle atonia is combined with 'paradoxical arousal' of cortical neuronal firing patterns indisputably represent the evolutionarily most recent aspect of REM sleep, but more research with ectothermic vertebrates, such as fish, amphibians and reptiles, is needed before it can be concluded (as many prematurely have) that RBM is absent in these species. Evidence suggests a link between RBM sleep in early development and the clinical condition known as 'REM sleep behavior disorder (RBD)', which is characterized by the resurgence of periodic bouts of quasi-fetal motility that closely resemble RBM sleep. Early developmental neuromotor risk factors for RBD in humans also point to a relationship between RBM sleep and RBD. [ABSTRACT FROM AUTHOR]

Neural correlations during a cognitive task are central to study brain information processing and computation. However, they have been poorly analyzed due to the difficulty of recording simultaneous single neurons during task performance. In the present work, we quantified neural directional correlations using spike trains that were simultaneously recorded in sensory, premotor, and motor cortical areas of two monkeys during a somatosensory discrimination task. Upon modeling spike trains as binary time series, we used a nonparametric Bayesian method to estimate pairwise directional correlations between many pairs of neurons throughout different stages of the task, namely, perception, working memory, decision making, and motor report. We find that solving the task involves feedforward and feedback correlation paths linking sensory and motor areas during certain task intervals. Specifically, information is communicated by task-driven neural correlations that are significantly delayed across secondary somatosensory cortex, premotor, and motor areas when decision making takes place. Crucially, when sensory comparison is no longer requested for task performance, a major proportion of directional correlations consistently vanish across all cortical areas. [ABSTRACT FROM AUTHOR]

Extracellular action potentials were recorded from developing dissociated rat neocortical networks continuously for up to 49 days in vitro using planar multielectrode arrays. Spontaneous neuronal activity emerged toward the end of the first week in vitro and from then on exhibited periods of elevated firing rates, lasting for a few days up to weeks, which were largely uncorrelated among different recording sites. On a time scale of seconds to minutes, network activity typically displayed an ongoing repetition of distinctive firing patterns, including short episodes of synchronous firing at many sites (network bursts). Network bursts were highly variable in their individual spatio-temporal firing patterns but showed a remarkably stable underlying probabilistic structure (obtained by summing consecutive bursts) on a time scale of hours. On still longer time scales, network bursts evolved gradually, with a significant broadening (to about 2 s) in the third week in vitro, followed by a drastic shortening after about one month in vitro. Bursts at this age were characterized by highly synchronized onsets reaching peak firing levels within less than ca. 60 ms. This pattern persisted for the rest of the culture period. Throughout the recording period, active sites showed highly persistent temporal relationships within network bursts. These longitudinal recordings of network firing have, thus, brought to light a reproducible pattern of complex changes in spontaneous firing dynamics of bursts during the development of isolated cortical neurons into synaptically interconnected networks. [ABSTRACT FROM AUTHOR]

Neural correlations during a cognitive task are central to study brain information processing and computation. However, they have been poorly analyzed due to the difficulty of recording simultaneous single neurons during task performance. In the present work, we quantified neural directional correlations using spike trains that were simultaneously recorded in sensory, premotor, and motor cortical areas of two monkeys during a somatosensory discrimination task. Upon modeling spike trains as binary time series, we used a nonparametric Bayesian method to estimate pairwise directional correlations between many pairs of neurons throughout different stages of the task, namely, perception, working memory, decision making, and motor report. We find that solving the task involves feedforward and feedback correlation paths linking sensory and motor areas during certain task intervals. Specifically, information is communicated by task-driven neural correlations that are significantly delayed across secondary somatosensory cortex, premotor, and motor areas when decision making takes place. Crucially, when sensory comparison is no longer requested for task performance, a major proportion of directional correlations consistently vanish across all cortical areas.