Little is known about the neurophysiological mechanisms underlying the human sleep-wake cycle. Using intracranial electrodes in humans, we investigated changes in topographic distribution of gamma power and local- and long-range gamma EEG coherence in neocortex and hippocampus during different cerebral states. We report significantly greater variability in gamma power across cortical regions du...

The present review analyzes sensory processing during sleep and wakefulness from a single neuronal viewpoint. Our premises are that processing changes throughout the sleep– wakefulness cycle may be at least partially evidenced in single neurons by (a) changes in the discharge rate and firing pattern of the response to sound, (b) changes in the phase locking of the response to the hippocampal th...

Maximum Entropy models can be inferred from large data-sets to uncover how local interactions generate collective dynamics. Here, we employ such models to investigate the characteristics of neurons recorded by multielectrode arrays in the cortex of human and monkey throughout states of wakefulness and sleep. Taking advantage of the separation of excitatory and inhibitory types, we construct a m...

Sleep and wakefulness are functions of the central nervous system (CNS) that are altered in numerous psychiatric disorders. Interestingly, Marcos José Salgado published in 1727 his book which is considered the first book of Physiology in the American continent and entitled “Cursus Medicus Mexicanus” (Figure 1) that suggests the use of drugs to regulate brain functions and their therapeutic acti...

Ring chromosome 20 [r(20)] syndrome is a chromosomal disorder characterized by epilepsy and intellectual disability. Distinctive electroclinical features and wakefulness EEG patterns have been described. The EEG features of sleep have not yet been evaluated. We studied the pattern of sleep in six patients aged 2-59 years who underwent at least one polysomnographic recording. Their sleep pattern...

Prolonged wakefulness alters cortical excitability, which is essential for proper brain function and cognition. However, besides prior wakefulness, brain function and cognition are also affected by circadian rhythmicity. Whether the regulation of cognition involves a circadian impact on cortical excitability is unknown. Here, we assessed cortical excitability from scalp electroencephalography (...

Evidence on sleep-dependent benefits for episodic memory remains elusive. Furthermore we know little about age-related changes on the effects of sleep on episodic memory. The study we report is the first to compare the effects of sleep on episodic memories in younger and older adults. Memories of stories and personal events were assessed following a retention interval that included sleep and fo...

A widely accepted view is that wakefulness is a state in which the entire cortical mantle is persistently activated, and therefore desynchronized. Consequently, the EEG is dominated by low-amplitude, high-frequency fluctuations. This view is currently under revision because the 1-4 Hz delta rhythm is often evident during "quiet" wakefulness in rodents and nonhuman primates. Here we used intracr...

Sleep enhances generalization in adults, but this has not been examined in toddlers. This study examined the impact of napping versus wakefulness on the generalization of word learning in toddlers when the contextual background changes during learning. Thirty 2.5-year-old children (M = 32.94, SE = 0.46) learned labels for novel categories of objects, presented on different contextual background...