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Background Using EEG based neurofeedback (NF), the activity of the brain is modulated directly and, therefore, the cortical substrates of cognitive functions themselves. In the present study, we investigated the ability of stroke patients to control their own brain activity via NF and evaluated specific effects of different NF protocols on cognition, in particular recovery of memory. Methods N = 17 stroke patients received up to ten sessions of either SMR (N = 11, 12–15 Hz) or Upper Alpha (N = 6, e.g. 10–12 Hz) NF training. N = 7 stroke patients received treatment as usual as control condition. Furthermore, N = 40 healthy controls performed NF training as well. To evaluate the NF training outcome, a test battery assessing different cognitive functions was performed before and after NF training. Results About 70 % of both patients and controls achieved distinct gains in NF performance leading to improvements in verbal short- and long-term memory, independent of the used NF protocol. The SMR patient group showed specific improvements in visuo-spatial short-term memory performance, whereas the Upper Alpha patient group specifically improved their working memory performance. NF training effects were even stronger than effects of traditional cognitive training methods in stroke patients. NF training showed no effects on other cognitive functions than memory. Conclusions Post-stroke victims with memory deficits could benefit from NF training as much as healthy controls. The used NF training protocols (SMR, Upper Alpha) had specific as well as unspecific effects on memory. Hence, NF might offer an effective cognitive rehabilitation tool improving memory deficits of stroke survivors.

The approximate number system (ANS) has been consistently found to be associated with math achievement. However, little is known about the interactions between the different instantiations of the ANS and in how many ways they are related to exact calculation. In a cross-sectional design, we investigated the relationship between three measures of ANS acuity (non-symbolic comparison, non-symbolic estimation and non-symbolic addition), their cross-sectional trajectories and specific contributions to exact calculation. Children with mathematical difficulties (MD) and typically achieving (TA) controls attending the first six years of formal schooling participated in the study. The MD group exhibited impairments in multiple instantiations of the ANS compared to their TA peers. The ANS acuity measured by all three tasks positively correlated with age in TA children, while no correlation was found between non-symbolic comparison and age in the MD group. The measures of ANS acuity significantly correlated with each other, reflecting at least in part a common numerosity code. Crucially, we found that non-symbolic estimation partially and non-symbolic addition fully mediated the effects of non-symbolic comparison in exact calculation.

Proceedings of the 6th International Brain-Computer Interface Conference 2014

Proceedings of the 6th International Brain-Computer Interface Conference 2014

Magnitude processing is one of the most central cognitive mechanisms that underlie persistent mathematics difficulties. No consensus has yet been reached about whether these difficulties can be predominantly attributed to deficits in symbolic or nonsymbolic magnitude processing. To investigate this issue, we assessed symbolic and nonsymbolic magnitude representations in children with low or typical achievement in school mathematics. Response latencies and the distance effect were comparable between groups in both symbolic and nonsymbolic tasks. The results indicated that both typical and low achievers were able to access magnitude representation via symbolic and nonsymbolic processing. However, low achievers presented higher error rates than typical achievers, especially in the nonsymbolic task. Furthermore, measures of nonsymbolic magnitude explained individual differences in school mathematics better than measures of symbolic magnitude when considering all of the children together. When examining the groups separately, symbolic magnitude representation explained differences in school mathematics in low achievers but not in typical achievers. These results suggest that symbolic magnitude is more relevant to solving arithmetic problems when mathematics achievement is particularly low. In contrast, individual differences in nonsymbolic processing appear to be related to mathematics achievement in a more general manner.

Background: Recently it was suggested that the carry effect observed in addition involves both categorical and continuous processing characteristics. Methods: In the present study, we aimed at identifying the specific neural correlates associated with processing either categorical or continuous aspects of the carry effect in an fMRI study on multi-digit addition.Results: In line with our expectations, we observed two distinct parts of the fronto-parietal network subserving numerical cognition to be associated with either one of these two characteristics. On the one hand, the categorical aspect of the carry effect was associated with left-hemispheric language areas and the basal ganglia probably reflecting increased demands on procedural and problem solving processes. Complementarily, the continuous aspect of the carry effect was associated with increased intraparietal activation indicating increasing demands on magnitude processing as well as place-value integration with increasing unit sum. Conclusions: In summary, the findings suggest representations and processes underlying the carry effect in multi-digit addition to be more complex and interactive than assumed previously. (VLID)2201183

An association of numbers and space (SNARC effect) has been examined in an ever growing literature. In the present quantitative meta-analysis, 46 studies with a total of 106 experiments and 2,206 participants were examined. Deeper number magnitude processing determined by task, stimulus and participants characteristics was associated with a stronger SNARC effect. In magnitude classification tasks the SNARC effect assumed consistently a categorical shape. Furthermore, the SNARC effect was found to increase with age from childhood to elderly age. No specific difference in the size of the SNARC effect was observed due to the explicit use of imagery strategies that could not be explained by increased reaction times. In general, these results corroborate the predictions by the dual-route model of the SNARC effect regarding the activation of number magnitude representation and suggest that automaticity may play a role in the development of the association of numbers and space across the lifespan.

Number magnitude is assumed to be encoded in an analog visuo-spatial frame, which resembles a left-to-right oriented and logarithmically compressed mental number line. Some authors have suggested that also the semantic representation of multidigit numbers can be described by their location on the mental number line. However, more recent behavioural studies suggest that units and decades may be represented complementarily in separate cognitive bins of information. In this dissertation the semantic number representation of one- and two-digit Arabic numbers is examined. The empirical investigations are divided in two parts. The first part concerns activation of semantic number magnitude and its association with spatial processing. In three behavioural studies the spatial nature of the mental number line is examined. In Study 1 the congruity between the mental number line and response location is tested. In Study 2 the congruity between the mental number line and stimulus location is investigated, and in Study 3 the abstractness of number magnitude. The second part of the dissertation is dedicated to cognitive and neurophysiologic correlates of two-digit semantic number processing. In two behavioural Studies 4 and 5 and a combined behavioural/functional magnetic resonance tomography (fMRI) Study 6 the semantic representation of units and decades is explored by means of the unit decade compatibility effect. In Study 4 the influence of different semantic relations on behavioural responses of normal participants is investigated. In Study 5 the influence of reading and segmentation abilities on the semantic representation of units and decades is examined in adult semi-illiterates, and in the fMRI Study 6 the neural correlates of unit and decade representations. Two main conclusions may be drawn from our investigations. First, Semantic number processing seems to be represented in a visuo-spatial code, which shares cognitive resources and interacts with other spatial representations. Second, the mental number line does not provide a comprehensive model for all features of multi-digit semantic number processing. Two-digit semantic number processing activates separate unit and decade representations besides the analog representation of number magnitude.

A memória de trabalho pode ser concebida em termos de sistemas de armazenamento ou por meio de modelos processuais ou dinâmicos. Nós adaptamos, para uso com a população brasileira, uma bateria de testes baseada em um modelo que divide a memória de trabalho em três aspectos: eficiência ou velocidade de processamento, armazenamento temporário e coordenação de operações. O exame das características psicométricas do instrumento, aplicado em 832 participantes de diversas faixas etárias e níveis educacionais, revelou sua adequação para uso em nosso meio, preservando as características do procedimento original e mostrando coeficientes aceitáveis de fidedignidade e de validade. O desempenho nos testes se correlacionou com o desempenho em testes de função executiva e de inteligência fluida, mas não se correlacionou com testes de memória associativa episódica. O programa de pesquisa deve continuar com o exame da utilidade clínica da BAMT-UFMG em neuropsicologia. Working memory may be conceived in terms of storing systems or by means of models of dynamic processes. We adapted a working memory assessment procedure based on a process model for use in Brazil. The model conceives working memory as three interrelated aspects: processing speed or efficiency, temporary storage and coordinative capacity. Results with 832 participants of several ages and educational levels indicate that the procedure is adequate to be used in our cultural environment, preserving the original characteristics and displaying acceptable reliability and validity characteristics. Working memory performance correlated with measures of executive function and fluid intelligence but not with measures of associative episodic memory. This research program will be pursued further examining the clinical neuropsychological usefulness of the BAMT-UFMG.