It seems natural to think that emotional experiences associated with a memory of a past event are new and present emotional states triggered by the remembered event. This common conception has nonetheless been challenged at the beginning of the 20th century by intellectuals who considered that emotions can be encoded and retrieved, and that emotional aspects linked to memories of the personal past need not necessary to be new emotional responses caused by the act of recollection. They called this specific (...) kind of memories “affective memories” and defended their existence. My aim here is to expound the historical background of this debate as well as the characterization and development of the notion of affective memory since its first inception. I aim to show that although the debate was left unresolved and the term disappeared from academy around 1930, many of the characterizations of the nature of emotions and memory done by the advocates of affective memory have reappeared in the scientific agenda and been further developed during the last decades. (shrink)

The structure of the brain and the nature of evolution suggest that, despite its uniqueness, language likely depends on brain systems that also subserve other functions. The declarative / procedural model claims that the mental lexicon of memorized word- specific knowledge depends on the largely temporal-lobe substrates of declarative memory, which underlies the storage and use of knowledge of facts and events. The mental grammar, which subserves the rule-governed combination of lexical items into complex representations, depends on a distinct neural (...) system. This system, which is composed of a network of specific frontal, basal - ganglia, parietal and cerebellar structures, underlies procedural memory, which supports the learning and execution of motor and cognitive skills, especially those involving sequences. The functions of the two brain systems, together with their anatomical, physiological and biochemical substrates, lead to specific claims and predictions regarding their roles in language. These predictions are compared with those of other neurocognitive models of language. Empirical evidence is presented from neuroimaging studies of normal language processing, and from developmental and adult- onset disorders. It is argued that this evidence supports the DP model. It is additionally proposed that “ language ” disorders, such as specific language impairment and non-fluent and fluent aphasia, may be profitably viewed as impairments primarily affecting one or the other brain system. Overall, the data suggest a new neurocognitive framework for the study of lexicon and grammar. (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)

Research in the neurosciences continues to provide evidence that sleep plays a role in the processes of learning and memory. There is less of a consensus, however, regarding the precise stages of memory development during which sleep is considered a requirement, simply favorable, or not important. This article begins with an overview of recent studies regarding sleep and learning, predominantly in the procedural memory domain, and is measured against our current understanding of the mechanisms that govern memory formation. Based on (...) these considerations, I offer a new neurocognitive framework of procedural learning, consisting first of acquisition, followed by two specific stages of consolidation, one involving a process of stabilization, the other involving enhancement, whereby delayed learning occurs. Psychophysiological evidence indicates that initial acquisition does not rely fundamentally on sleep. This also appears to be true for the stabilization phase of consolidation, with durable representations, resistant to interference, clearly developing in a successful manner during time awake (or just time, per se). In contrast, the consolidation stage, resulting in additional/enhanced learning in the absence of further rehearsal, does appear to rely on the process of sleep, with evidence for specific sleep-stage dependencies across the procedural domain. Evaluations at a molecular, cellular, and systems level currently offer several sleep specific candidates that could play a role in sleep-dependent learning. These include the upregulation of select plasticity-associated genes, increased protein synthesis, changes in neurotransmitter concentration, and specific electrical events in neuronal networks that modulate synaptic potentiation. Key Words: consolidation; enhancement; learning; memory; plasticity; sleep; stabilization. (shrink)

Walker's target article proposes a refinement of the well known two-stage model of memory formation to explain the positive effects of sleep on consolidation. After a first stage in which a labile memory representation is formed, a further stabilisation of the memory trace takes place in the second stage, which is dependent on (REM) sleep. Walker has refined the latter stage into a stage in which a consolidation-based enhancement occurs. It is not completely clear what consolidation-based enhancement implies and how (...) it can be dissociated from a stage for memory-stabilisation. A more serious consideration, however, is whether a second stage in memory consolidation that is solely dependent on sleep, is really necessary. The classical, passive, interference theory is able to explain adequately the findings related to the effects of sleep and memory, and can lead perhaps better to an understanding of the highly variable data in this field. (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)

High demands on cognitive functions in daily life call for an efficient memory system that reduces interference between memories and enables generalizations across similar events. By means of pattern separation, similar memories are stored as distinct, non-overlapping representations, whereas during pattern completion, previously stored memories are reactivated by partial environmental cues. These two functions are critically reliant on the hippocampus. Evidence from computational models, studies in rodents, as well as human data support the idea that pattern separation and completion are (...) mediated by the hippocampal dentate gyrus and CA3 regions. However, studies in humans lack information regarding mechanistic aspects of causality regarding the anatomical structures of the hippocampus and pattern separation and completion processes. The aim of this thesis was to elucidate the role of the human hippocampus and its subfield-specific contributions to pattern separation. We examined natural lesion models, by means of selective CA1 lesions during a transient global amnesia, and in a rare form of limbic encephalitis, where neurodegeneration preferentially shows in the dentate gyrus and CA3. The results showed that pattern separation measured by a mnemonic similarity task was best predicted by the volume of the dentate gyrus, whereas recognition memory was stronger associated with the volume of CA1. We also found a strong deficit in pattern separation associated with selective CA1 lesions. We then examined pattern separation performance after post-encoding sleep in healthy humans to clarify the neurobiological processes of memory consolidation. We demonstrated the relevance of hippocampal information processing during sleep in the stabilization of separated information. This might also suggest a link between pattern separation and completion processes during sleep-dependent memory consolidation. (shrink)

Why does symbolic communication in humans develop primarily in an oral medium, and how do theories of language origin explain this? Non-human primates, despite their ability to learn and use symbolic signs, do not develop symbols as in oral language. This partly owes to the lack of a direct cortico-motoneuron control of vocalizations in these species compared to humans. Yet such modality-related factors that can impinge on the rise of symbolic language are interpreted differently in two types of evolutionary storylines. (...) 1) Some theories posit that symbolic language originated in a gestural modality, as in “sign languages”. However, this overlooks work on emerging sign and spoken language showing that gestures and speech shape signs differently. 2) In modality-dependent theories, some emphasize the role of iconic sounds, though these lack the efficiency of arbitrary symbols. Other theorists suggest that ontogenesis serves to identify human-specific mechanisms underlying an evolutionary shift from pitch varying to orally-modulated vocalizations (babble). This shift creates numerous oral features that can support efficient symbolic associations. We illustrate this principle using a sound-picture association task with 40 learners who hear words in an unfamiliar language (Mandarin) with and without a filtering of oral features. Symbolic associations arise more rapidly and accurately for sounds containing oral features compared to sounds bearing only pitch features, an effect also reported in experiments with infants. The results imply that, beyond a competence to learn and use symbols, the rise of symbolic language rests on the types of signs that a modality of expression affords. (shrink)