It remains a dogma in cognitive neuroscience to separate human attention and memory into distinct modules and processes. Here we propose that brain rhythms reflect the embedded nature of these processes in the human brain, as evident from their shared neural signatures: gamma oscillations (30–90 Hz) reflect sensory information processing and activated neural representations (memory items). The theta rhythm (3–8 Hz) is a pacemaker of explicit control processes (central executive), structuring neural information processing, bit by bit, as reflected in the (...) theta-gamma code. By representing memory items in a sequential and time-compressed manner the theta-gamma code is hypothesized to solve key problems of neural computation: (1) attentional sampling (integrating and segregating information processing), (2) mnemonic updating (implementing Hebbian learning), and (3) predictive coding (advancing information processing ahead of the real time to guide behavior). In this framework, reduced alpha oscillations (8–14 Hz) reflect activated semantic networks, involved in both explicit and implicit mnemonic processes. Linking recent theoretical accounts and empirical insights on neural rhythms to the embedded-process model advances our understanding of the integrated nature of attention and memory – as the bedrock of human cognition. (shrink)

Sleep strengthens memories by repeatedly reactivating associated neuron ensembles. Our studies show that although long-term memory for a medium number of word-pairs benefits from sleep, a large number does not. This suggests an upper limit to the amount of information that has access to sleep-dependent declarative memory consolidation, which is possibly linked to the availability of reactivation opportunities. Due to competing processes of global forgetting that are active during sleep, we hypothesized that even larger amounts of information would enhance the (...) proportion of information that is actively forgotten during sleep. In the present study, we aimed to induce such forgetting by challenging the sleeping brain with vast amounts of to be remembered information. For this, 78 participants learned a very large number of 640 word-pairs interspersed with periods of quiet awake rest over the course of an entire day and then either slept or stayed awake during the night. Recall was tested after another night of regular sleep. Results revealed comparable retention rates between the sleep and wake groups. Although this null-effect can be reconciled with the concept of limited capacities available for sleep-dependent consolidation, it contradicts our hypothesis that sleep would increase forgetting compared to the wake group. Additional exploratory analyses relying on equivalence testing and Bayesian statistics reveal that there is evidence against sleep having a detrimental effect on the retention of declarative memory at high information loads. We argue that forgetting occurs in both wake and sleep states through different mechanisms, i.e., through increased interference and through global synaptic downscaling, respectively. Both of these processes might scale similarly with information load. (shrink)

Cognitive neuroscience aims to improve our understanding of aspects of human learning and performance by combining data acquired with the new brain imaging technologies with data acquired in cognitive psychology paradigms. Both neuroscience and psychology use the philosophical assumptions underpinning the natural sciences, namely the scientific method, whereby hypotheses are proposed and tested using quantitative approaches. The relevance of 'brain science' for the classroom has proved controversial with some educators, perhaps because of distrust of the applicability of so-called 'medical models' (...) to education. Nevertheless, the brain is the main organ of learning, and so a deeper understanding of the brain would appear highly relevant to education. Modern science is revealing the crucial role of biology in every aspect of human experience and performance. This does not mean that biology determines outcomes. Rather, there is a complex interplay between biology and environments. Improved knowledge about how the brain learns should assist educators in creating optimal learning environments. Neuroscience can also identify 'biomarkers' of educational risk, and provide new methodologies to test the effects of educational interventions. (shrink)

Cognitive neuroscience aims to improve our understanding of aspects of human learning and performance by combining data acquired with the new brain imaging technologies with data acquired in cognitive psychology paradigms. Both neuroscience and psychology use the philosophical assumptions underpinning the natural sciences, namely the scientific method, whereby hypotheses are proposed and tested using quantitative approaches. The relevance of ‘brain science’ for the classroom has proved controversial with some educators, perhaps because of distrust of the applicability of so-called ‘medical models’ (...) to education. Nevertheless, the brain is the main organ of learning, and so a deeper understanding of the brain would appear highly relevant to education. Modern science is revealing the crucial role of biology in every aspect of human experience and performance. This does not mean that biology determines outcomes. Rather, there is a complex interplay between biology and environments. Improved knowledge about how the brain learns should assist educators in creating optimal learning environments. Neuroscience can also identify ‘biomarkers’ of educational risk, and provide new methodologies to test the effects of educational interventions. (shrink)

Improvement in performance after the end of the training session, termed “Offline improvement,” has been shown in procedural learning tasks. We examined whether Offline improvement in learning a novel orthography depends on the type of reading instruction. Forty-eight adults received multisession training in reading nonsense words, written in an artificial script. Participants were trained in one of three conditions: alphabetical words preceded by direct letter instruction (Letter-Alph); alphabetical words with whole-word instruction (Word-Alph); and nonalphabetical (arbitrary) words with whole-word instruction (Word-Arb). (...) Offline improvement was found only for the Letter-Alph group. Moreover, correlation with a standardized measure of word reading ability showed that good readers trained in the Letter-Alph group exhibit greater Offline improvement, whereas good readers trained in the Word-Arb group showed greater Within-session improvement during training. These results suggest that different consolidation processes and learning mechanisms were involved in each group. We argue that providing a short block of direct letter instruction prior to training resulted in increased involvement of procedural learning mechanisms during training. (shrink)

Why do we sleep? Loosing consciousness makes us completely vulnerable to any dangers of the environment for a third of our life time and must therefore yield a critical evolutionary advantage. A likely core function of sleep is the regulation of neuronal plasticity. The absence of interfering conscious information processing sets the stage for the basic maintenance of synaptic homeostasis to the complex reorganization and consolidation of memories. However, the underlying neuronal mechanisms subserving these processes are still largely unknown. The (...) aim of this thesis is to further elucidate the essential role of sleep-specific neuronal oscillations in brain plasticity. In a multimodal neuroscientific approach, non-invasive imaging methods (EEG and fMRI) and brain stimulation techniques (TMS and tDCS) are combined in a series of empirical studies to investigate how slow oscillations and sleep spindles are influenced by and in turn mediate plastic changes in the sleeping brain. (shrink)