Throughout the history of mathematics, concepts of number and space have been tightly intertwined. We tested the hypothesis that cortical circuits for spatial attention contribute to mental arithmetic. We trained a multivariate classifier to infer the direction of an eye movement, left or right, from the brain activation measured in posterior parietal cortex. Without further training, the classifier then generalized to an arithmetic task. Its left versus right classification could be used to sort out subtraction versus addition trials, whether performed with symbols or with sets of dots. These findings are consistent with the suggestion that mental arithmetic co-opts parietal circuitry associated with spatial coding.

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Offering a decision aid increases the number of patients who prefer conservative or less invasive treatment options. As decision aids improve patient knowledge and lower decisional conflict without raising anxiety levels, they have a place in surgery to help surgeons and patients achieve well-considered and shared treatment decisions.

Human cognition is characterized by severe capacity limits: we can accurately track, enumerate, or hold in mind only a small number of items at a time. It remains debated whether capacity limitations across tasks are determined by a common system. Here we measure brain activation of adult subjects performing either a visual short-term memory (vSTM) task consisting of holding in mind precise information about the orientation and position of a variable number of items, or an enumeration task consisting of assessing the number of items in those sets. We show that task-specific capacity limits (three to four items in enumeration and two to three in vSTM) are neurally reflected in the activity of the posterior parietal cortex (PPC): an identical set of voxels in this region, commonly activated during the two tasks, changed its overall response profile reflecting task-specific capacity limitations. These results, replicated in a second experiment, were further supported by multivariate pattern analysis in which we could decode the number of items presented over a larger range during enumeration than during vSTM. Finally, we simulated our results with a computational model of PPC using a saliency map architecture in which the level of mutual inhibition between nodes gives rise to capacity limitations and reflects the task-dependent precision with which objects need to be encoded (high precision for vSTM, lower precision for enumeration). Together, our work supports the existence of a common, flexible system underlying capacity limits across tasks in PPC that may take the form of a saliency map.

The current study provides a generalizable account of the anatomo-functional associations as well as the connectivity of representational codes underlying numerical processing as suggested by the triple code model (TCM) of numerical cognition. By evaluating the neural networks subserving numerical cognition in two specific and substantially different numerical tasks with regard to both grey matter localizations as well as white matter tracts we (1) considered the possibility of additional memory-related cortex areas crucial for arithmetic fact retrieval (e.g., the hippocampus); (2) specified the functional involvement of prefrontal areas in number magnitude processing, and, finally; (3) identified the connections between these anatomo-functional instantiations of the representations involved in number magnitude processing and arithmetic fact retrieval employing probabilistic fiber tracking. The resulting amendments to the TCM are summarized in a schematic update, and ideas concerning the possible functional interplay between number magnitude processing and arithmetic fact retrieval are discussed.

The operational momentum (OM) effect describes a systematic bias in estimating the outcomes of simple addition and subtraction problems. Outcomes of addition problems are overestimated while outcomes of subtraction problems are underestimated. The origin of OM remains debated. First, a flawed uncompression of numerical information during the course of mental arithmetic is supposed to cause OM due to linear arithmetic operations on a compressed magnitude code. Second, attentional shifts along the mental number line are thought to cause OM. A third hypothesis explains OM in 9-month olds by a cognitive heuristic of accepting more (less) than the original operand in addition (subtraction) problems. The current study attempts to disentangle these alternatives and systematically examines potential determinants of OM, such as reading fluency which has been found to modulate numerical–spatial associations. A group of 32 6- and 7-year-old children was tested in non-symbolic addition and subtraction problems, in which they had to choose the correct outcome from an array of several possible outcomes. Reading capacity was assessed for half of the children while attentional measures were assessed in the other half. Thirty-two adults were tested with the identical paradigm to validate its potential of revealing OM. Children (and adults) were readily able to solve the problems. We replicated previous findings of OM in the adults group. Using a Bayesian framework we observed an inverse OM effect in children, i.e., larger overestimations for subtraction compared to addition. A significant correlation between children’s level of attentional control and their propensity to exhibit OM was observed. The observed pattern of results, in particular the inverse OM in children is hard to reconcile with the previously proposed theoretical frameworks. The observed link between OM and the attentional system might be interpreted as evidence partially supporting the attentional shift hypothesis.

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BackgroundEvidence-based surgery (EBS) is stressed to increase efficiency and health care quality, but not all surgeons and surgical nurses use EBS in clinical practice. To define future tailor-made interventions to improve evidence-based behavior, the aim of this study was to determine the attitude and awareness among surgeons and surgical nurses as to the paradigm of EBS and the barriers experienced when practicing EBS.MethodsIn this cross-sectional study, surgeons and surgical nurses at a university hospital in Amsterdam were invited to complete the BARRIERS scale and McColl et al. questionnaire. An evidence quiz was composed for the surgeons.ResultsResponse rates were 67% (29/43) for surgeons and 60% (73/122) for nurses. Attitudes toward EBS were positive. Among the surgeons, 90% were familiar with EBS terms, whereas only 40% of the nurses were. Common barriers for surgeons were conflicting results (79%, 23/29) and the methodologic inadequacy of research reports (73%, 21/29); and for nurses they were unawareness of EBS (67%, 49/73) and unclear reported research (59%, 43/73). Only about half of the convincing evidence presented in the quiz was actually applied.ConclusionsSurgeons have a positive attitude toward EBS and are familiar with EBS terminology, but conflicting results and methodologic shortcomings of research reports are major barriers to practicing EBS. Continual confrontations with available evidence through frequent critical appraisal meetings or grand rounds and using more aggregate sources of evidence are advocated. Nurses can probably benefit from EBS training focusing on basic skills. Finally, collaboration is needed among surgeons and nurses with the same zest about EBS.