Developmental changes in the engagement of episodic retrieval processes and their relationship with working memory during the period of middle childhood.

We examined the development of children’s engagement of the episodic retrieval processes of recollection and familiarity and their relationship with working memory (WM). Ninety-six children (24 in four groups aged 8, 9, 10, and 11 years) and 24 adults performed an episodic memory (EM) task involving old/new, remember/know (R/K), and source memory judgements and numerous WM tasks that assessed verbal and spatial components of WM and delayed short-term memory (STM). Developmental changes were observed in EM with younger children (8-, 9-, 10-year-olds) making fewer remember responses than 11-year-olds and adults while 11-year-olds did not differ from adults. Only children aged 10 years plus showed a relationship between EM and WM. EM was related to verbal executive WM in 10- and 11-year-old children suggesting that children at this stage use verbal strategies to aid EM. In contrast, EM was related to spatial executive WM in adults. The engagement of episodic retrieval processes appears to be selectively related to executive components of verbal and spatial WM, the pattern of which differs in children and adults

Working memory constellations

Evidence is presented that supports the view that most models of short-term memory cannot account for the flexibility of the primary memory system. It is argued that the working memory model outlined by Baddeley and Hitch (1974) is, however, a potentially adequate model. Working memory, in this thesis, is depicted as a system that assembles 'constellations' consisting of the central executive and one or more sub-systems. This view suggests a formulation that is considerably more complex than the 1974 model. The empirical studies examine the role of the visuo-spatial scratch pad in the formation and maintenance of working memory constellations. It is concluded from these studies that the scratch pad is independent of the articulatory loop but is usually coupled to the central executive except during maintenance rehearsal. Furthermore, it can be used concurrently with the articulatory loop to process spatial aspects of highly verbal tasks. However a constellation consisting of the executive, the loop and the scratch pad is vulnerable to a wider range of interference effects than a simpler constellation. Paivio (1971) suggested that 'dual coding' leads to better memory performance, however, this is only the case when no distractors are present. The final two chapters present some speculations on how working memory research might proceed in the future. It is concluded that the current trend towards collecting convergent evidence and the emphasis on testing theory in applied situations should give us insights into memory that were not available to Ebbinghaus and other early memory researchers

Are forwards and backwards digit recall the same? A dual task study of digit recall

There is some debate surrounding the cognitive resources underlying backwards digit recall. Some researchers consider it to differ from forwards digit recall due to the involvement of executive control, while others suggest that backwards recall involves visuo-spatial resources. Five experiments therefore investigated the role of executive-attentional and visuo-spatial resources in both forwards and backwards digit recall. In the first, participants completed visuo-spatial 0-back and 2-back tasks during the encoding of information to be remembered. The concurrent tasks did not differentially disrupt performance on backwards digit recall relative to forwards digit recall. Experiment 2 shifted concurrent load to the recall phase instead, and in this case revealed a larger effect of both tasks on backwards recall relative to forwards recall, suggesting that backwards recall may draw on additional resources during the recall phase and that these resources are visuo-spatial in nature. Experiments 3 and 4 then further investigated the role of visual processes in forwards and backwards recall using dynamic visual noise (DVN). In Experiment 3 DVN was presented during encoding of information to be remembered, and had no effect upon performance. However, in Experiment 4 it was presented during the recall phase, and the results provided evidence of a role for visual imagery in backwards digit recall. These results were replicated in Experiment 5 in which the same list length was used for forwards and backwards recall tasks. The findings are discussed in terms of both theoretical and practical implications

Network based statistical analysis detects changes induced by continuous theta-burst stimulation on brain activity at rest

We combined continuous theta-burst stimulation (cTBS) and resting state (RS)-fMRI approaches to investigate changes in functional connectivity (FC) induced by right dorsolateral prefrontal cortex (DLPFC)-cTBS at rest in a group of healthy subjects. Seed-based fMRI analysis revealed a specific pattern of correlation between the right prefrontal cortex and several brain regions: based on these results, we defined a 29-node network to assess changes in each network connection before and after, respectively, DLPFC-cTBS and sham sessions. A decrease of correlation between the right prefrontal cortex and right parietal cortex (Brodmann areas 46 and 40, respectively) was detected after cTBS, while no significant result was found when analyzing sham-session data. To our knowledge, this is the first study that demonstrates within-subject changes in FC induced by cTBS applied on prefrontal area. The possibility to induce selective changes in a specific region without interfering with functionally correlated area could have several implications for the study of functional properties of the brain, and for the emerging therapeutic strategies based on transcranial stimulation

The role of domain-specific practice, handedness and starting age in chess

The respective roles of the environment and innate talent have been a recurrent question for research into expertise. This paper investigates markers of talent, environment, and critical period for the acquisition of expert performance in chess. Argentinian chessplayers (N = 104), ranging from weak amateurs to grandmasters, filled in a questionnaire measuring variables including individual and group practice, starting age, and handedness. The study reaffirms the importance of practice for reaching high levels of performance, but also indicates a large variability, the slower player needing eight times more practice to reach master level than the faster. Additional results show a correlation between skill and starting age, and indicate that players are more likely to be mixed-handed than individuals in the general population; however, there was no correlation between handedness and skill within the chess sample. Together, these results suggest that practice is a necessary but not sufficient condition for the acquisition of expertise, that some additional factors may differentiate between chessplayers and non-chessplayers, and that the starting age of practice is important

The brain decade in debate: I. Neurobiology of learning and memory

This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed.University of Bristol Department of PsychologyUniversidade Federal de São Paulo (UNIFESP) Departamento de PsicobiologiaUniversity of California Center for Neurobiology of Learning and Memory Department of Neurobiology and BehaviorUniversity of California Neuropsychiatric InstituteUniversidade Federal do Rio Grande do Sul Instituto de Biociências Departamento de BioquímicaUniversity of Edinburgh Department of NeuroscienceUniversity of Arizona Department of PsychologyNorthwestern UniversityUniversidade de São Paulo Instituto de Biociências Departamento de FisiologiaUniversidade Federal do Paraná Departamento de Farmacologia Laboratório de Fisiologia e Farmacologia do Sistema Nervoso CentralUNIFESP, Depto. de PsicobiologiaSciEL