Awareness of Knowledge or Awareness of Processing? Implications for Sleep-Related Memory Consolidation

The present study assessed the effects of awareness at encoding on off-line learning during sleep. A new framework is suggested according to which two aspects of awareness are distinguished: awareness of task information, and awareness of task processing. The number reduction task (NRT) was employed because it has two levels of organization, an overt one based on explicit knowledge of task instructions, and a covert one based on hidden abstract regularities of task structure (implicit knowledge). Each level can be processed consciously (explicitly) or non-consciously (implicitly). Different performance parameters were defined to evaluate changes between two sessions for each of the four conditions of awareness arising from whether explicit or implicit task information was processed explicitly or implicitly. In two groups of subjects, the interval between the pre-sleep and post-sleep sessions was filled either with early-night sleep, rich in slow wave sleep (SWS), or late-night sleep, rich in rapid eye movement (REM) sleep. Results show that implicit processing of explicit information was improved in the post-sleep relative to the pre-sleep session only in the early-night group. Independently of sleep stage, changes between sessions occurred for explicit processing of implicit information only in those subjects who gained insight into the task regularity after sleep. It is concluded that SWS but not REM sleep specifically supports gains in computational skills for the processing of information that was accessible by consciousness before sleep

Developmental changes in the theta response system: a single-sweep analysis

Recently, increased interest was focused on the EEG frequency responses in the theta (4-7 Hz) range because of their association with stimulus information processing. However, it is not known whether the event-related theta response depends on the development of the spontaneous theta activity and how it varies with age in children. In the present study, a single-sweep analysis was applied to assess the developmental changes in the event-related EEG theta activity. Auditory passive, oddball target, and standard event-related potentials (ERPs) were recorded at Fz, Cz, and Pz from 50 children aged 6-11 years and 10 young adults. Theta responses were analyzed in two time windows of the post-stimulus epochs for three single-sweep parameters: amplitude, phase-locking with stimulus, and enhancement relative to prestimulus activity. For all three types of stimuli adults had theta responses with lower amplitude, higher enhancement, and stronger phase-locking than those of children. Unlike adults, no reliable differences between the early and late theta response were found for children. Significant developmental changes were observed for theta response amplitude that decreased and phase-locking of early theta responses that increased with advancing age. These findings indicate that the theta component of the auditory ERP differs remarkably between children and adults and undergoes developmental alterations, possibly reflecting specific differences in stimulus information processing

The sleeping brain and the neural basis of emotions

In addition to active wake, emotions are generated and experienced in a variety of functionally different states such as those of sleep, during which external stimulation and cognitive control are lacking. The neural basis of emotions can be specified by regarding the multitude of emotion-related brain states, as well as the distinct neuro- and psychodynamic stages (generation and regulation) of emotional experienc

Lateral-torsional Buckling of Ferritic Stainless Steel Beams in Case of Fire

audience: researcherThis work presents a numerical study of the behaviour of ferritic stainless steel Ibeams subjected to lateral-torsional buckling and compares the obtained results with the beam design curves of Eurocode 3. New formulae, for the lateraltorsional buckling, that approximate better the real behaviour of ferritic stainless steel structural elements in case of fire are proposed. These new formulae were based on numerical simulations using the program SAFIR, which was modified to take into account the material properties of the stainless steel