Stages of nonsymbolic number processing in occipitoparietal cortex disentangled by fMRI adaptation

The neurobiological mechanisms of nonsymbolic number processing in humans are still unclear. Computational modeling proposed three successive stages: first, the spatial location of objects is stored in an object location map; second, this information is transformed into a numerical summation code; third, this summation code is transformed to a number-selective code. Here, we used fMRI-adaptation to identify these three stages and their relative anatomical location. By presenting the same number of dots on the same locations in the visual field, we adapted neurons of human volunteers. Occasionally, deviants with the same number of dots at different locations or different numbers of dots at the same location were shown. By orthogonal number and location factors in the deviants, we were able to calculate three independent contrasts, each sensitive to one of the stages. We found an occipitoparietal gradient for nonsymbolic number processing: the activation of the object location map was found in the inferior occipital gyrus. The summation coding map exhibited a nonlinear pattern of activation, with first increasing and then decreasing activation, and most activity in the middle occipital gyrus. Finally, the number-selective code became more pronounced in the superior parietal lobe. In summary, we disentangled the three stages of nonsymbolic number processing predicted by computational modeling and demonstrated that they constitute a pathway along the occipitoparietal processing stream

Image Aquisition Order and Input Order of BOLD-fMRI Data for Slice Time Correction in fMRI Data Processing Tools

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Processing of quantitative information, investigated with fMRI.

Ever since the discovery of the ‘number neurons’, the neural representation of quantity in the brain has been thought of as a number-selective coding system. In such a system, the neuron is activated by a specific quantity but numerically close quantities also activate the neuron. Recent fMRI studies also confirmed the existence of a number-selective system in humans. Several computational modelling studies predicted a number-sensitive coding stage as a necessary preceding stage to the number-selective neurons (Verguts & Fias, 2004). In this coding scheme, the coding is analogous to the number it represents. This can be implemented by neurons that respond monotonically to number (e.g., more strongly for larger numbers). Recently, the biological reality of such a system has been demonstrated by use of single-cell recording, in the lateral intraparietal area (LIP) of the macaque monkey. In this thesis, we searched for evidence of number-sensitive coding in humans. Using a priming paradigm, we found behavioural evidence for a number-sensitive system in humans for small non-symbolic numerosities (1 to 5). Using event-related fMRI, we showed number-sensitive activation in the human LIP area in the same number range. Remarkably, we could not extend these results for larger numerosities (2 to 64). Whereas the lack of results in the behavioural priming experiment could be due to an insensitivity of the method, this was not a plausible explanation in the fMRI experiment, as the activity measured in human LIP significantly decreased for numerosities larger than 8. We therefore concluded that the number-sensitive system is liable to a capacity limit for higher numerosities, which could be caused by the use of lateral inhibition. We further suggest that the implementation of this lateral inhibition is dependent on the particular task set, and that the capacity limit is not present (or less stringent) when numerosity is not behaviourally relevant. This could explain the finding of number-sensitive neurons for larger numerosities in monkeys. Finally, we suggest that a different mechanism is employed when numerical value of large numerosities is relevant. This leads to the conclusion that dot patterns in the small and large number range are processed differently

What do politicians think of the common consolidated corporate tax base? A Belgian case study

This paper analyzes the views of Belgian politicians on the Common Consolidated Corporate Tax Base (CCCTB), an ambitious project to harmonize corporate taxation in the EU. Applying case study methodology, the results show that most politicians were proponents of this new tax system. During the discussions in several political institutions, the politicians referred to the macro-economic impact, the legal certainty and their party’s view to found their opinion. Besides several agreements, certain aspects of CCCTB like the optionality and the applied tax rate involved clear differences in view between left and right-wing politicians, which could hamper a political agreement on CCCTB

Number Processing Pathways in Human Parietal Cortex

Numerous studies have identified the intraparietal sulcus (IPS) as an area critically involved in numerical processing. IPS neurons in macaques are tuned to a preferred numerosity, hence neurally coding numerosity in a number-selective way. Neuroimaging studies in humans have demonstrated number-selective processing in the anterior parts of the IPS. Nevertheless, the processes that convert visual input into a number-selective neural code remain unknown. Computational studies have suggested that a neural coding stage that is sensitive, but not selective to number, precedes number-selective coding when processing nonsymbolic quantities but not when processing symbolic quantities. In Experiment 1, we used functional magnetic resonance imaging to localize number-sensitive areas in the human brain by searching for areas exhibiting increasing activation with increasing number, carefully controlling for nonnumerical parameters. An area in posterior superior parietal cortex was identified as a substrate for the intermediate number-sensitive steps required for processing nonsymbolic quantities. In Experiment 2, the interpretation of Experiment 1 was confirmed with a connectivity analysis showing that a shared number-selective representation in IPS is reached through different pathways for symbolic versus nonsymbolic quantities. The preferred pathway for processing nonsymbolic quantities included the number-sensitive area in superior parietal cortex, whereas the pathway for processing symbolic quantities did not

The effect of a multidisciplinary weight loss program on renal circadian rhythm in obese adolescents

Adolescent obesity is a serious health problem associated with many comorbidities. Obesity-related alterations in circadian rhythm have been described for nocturnal blood pressure and for metabolic functions. We believe renal circadian rhythm is also disrupted in obesity, though this has not yet been investigated. This study aimed to examine renal circadian rhythm in obese adolescents before and after weight loss. In 34 obese adolescents (median age 15.7 years) participating in a residential weight loss program, renal function profiles and blood samples were collected at baseline, after 7 months, and again after 12 months of therapy. The program consisted of dietary restriction, increased physical activity, and psychological support. The program led to a median weight loss of 24 kg and a reduction in blood pressure. Initially, lower diurnal free water clearance (- 1.08 (- 1.40-- 0.79) mL/min) was noticed compared with nocturnal values (0.75 (- 0.89-- 0.64) mL/min). After weight loss, normalization of this inverse rhythm was observed (day - 1.24 (- 1.44-1.05) mL/min and night - 0.98 (- 1.09-- 0.83) mL/min). A clear circadian rhythm in diuresis rate and in renal clearance of creatinine, solutes, sodium, and potassium was seen at all time points. Furthermore, we observed a significant increase in sodium clearance. Before weight loss, daytime sodium clearance was 0.72 mL/min (0.59-0.77) and nighttime clearance was 0.46 mL/min (0.41-0.51). After weight loss, daytime clearance increased to 0.99 mL/min (0.85-1.17) and nighttime clearance increased to 0.78 mL/min (0.64-0.93). Conclusion: In obese adolescents, lower diurnal free water clearance was observed compared with nocturnal values. Weight loss led to a normalization of this inverse rhythm, suggesting a recovery of the anti-diuretic hormone activity. Both before and after weight loss, clear circadian rhythm of diuresis rate and renal clearance of creatinine, solutes, sodium, and potassium was observed.What is Known:center dot Obesity-related alterations in circadian rhythm have been described for nocturnal blood pressure and for metabolic functions. We believe renal circadian rhythm is disrupted in obesity, though this has not been investigated yet.What is New:center dot In obese adolescents, an inverse circadian rhythm of free water clearance was observed, with higher nighttime free water clearance compared with daytime values. Weight loss led to a normalization of this inverse rhythm, suggesting a recovery of the anti-diuretic hormone activity.center dot Circadian rhythm in diuresis rate and in the renal clearance of creatinine, solutes, sodium, and potassium was preserved in obese adolescents and did not change after weight loss

Development of surgical site infections despite perioperative antimicrobial therapy in two dogs

Surgical site infections (SSI) are common complications with a prevalence of 0.8 to 18%. Many risk factors, such as patient, environmental and treatment factors can contribute to the development of SSI. Two dogs that developed a SSI after forelimb amputation are discussed. The first dog was presented with an open comminuted intra-articular fracture of the right elbow. The second dog was diagnosed with a soft-tissue sarcoma at the right elbow. Perioperative cefazolin was administered in both patients. Only in the first patient, antimicrobial therapy was continued in the postoperative period. Both dogs developed an SSI within four to five days postoperatively. Yet, prophylactic antimicrobials can help to prevent SSI, provided that the correct antimicrobial is used at the correct dose, at the right time and given IV. Factors, such as hypothermia, violating the Halsted's principles and the number of people present in the theater may increase the risk of SSI. Besides the meticulous use of antimicrobials, perioperative management is thus also important in SSI prevention