This study investigated whether near-infrared spectroscopy (NIRS) can be used to measure the processing of arithmetic problems in school children. Another aim was to assess whether distinct formats of such problems would lead to different neural processing. Two large samples of school children from different age groups were examined while calculating or reading arithmetic problems that were either presented in numeric or in word format. As expected, we found that, compared to reading, calculation resulted in greater average oxygenation in parietal and posterior frontal regions. Neither format nor age had a significant effect on brain oxygenation. We were able to demonstrate that NIRS measurements can readily be conducted with children and in school settings, which is an indication for the ecological validity of this measurement technique.

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.

Scientific collaboration between neuroscience and mathematics education has mostly focused on brain imaging trying to inform education. This study aims at meeting expectations of both research fields, thus enhancing the ecological validity. We investigated the influence of age, mathematical competency, and task characteristics (format, complexity) on students' arithmetic performance. Based on behavioral data from a pilot study (n = 73), arithmetic tasks were chosen for a subsequent investigation (n = 90), in which parietal brain activation was measured with near-infrared spectroscopy. Substantial group differences in calculation time were observed. While task characteristics influenced arithmetic performance in both age groups, this influence was much smaller for grade 8 students. However, parietal brain activation during calculation was not affected by age, mathematical competency, or task characteristics. Limitations of the experimental design and general problems of applying imaging methods to the school context are discussed.

The current standard for molecular profiling of colorectal cancer (CRC) is using resected or biopsied tissue specimens. However, they are limited regarding sampling frequency, representation of tumor heterogeneity, and sampling can expose patients to adverse side effects. The analysis of cell-free DNA (cfDNA) from blood plasma, which is part of a liquid biopsy, is minimally invasive and in principle enables detection of all tumor-specific mutations. Here, we analyzed cfDNA originating from nucleus and mitochondria and investigated their characteristics and mutation status in a cohort of 18 CRC patients and 10 healthy controls using targeted next-generation sequencing (NGS) and digital PCR. Longitudinal analyses of nuclear cfDNA level and size during chemotherapy revealed a decreasing cfDNA content and a shift from short to long fragments, indicating an appropriate therapy response, while shortened cfDNAs and increased cfDNA content corresponded with tumor recurrence. Comparative NGS analysis of nuclear tissue and plasma DNA demonstrated a good patient-level concordance and cfDNA revealed additional variants in three of the cases. Analysis of mitochondrial cfDNA surprisingly revealed a higher plasma copy number in healthy subjects than in CRC patients. These results highlight the potential clinical utility of liquid biopsies in routine diagnostics and surveillance of CRC patients as complementation to tissue biopsies or as an attractive alternative in cases where tissue biopsies are risky or the quantity/quality does not allow testing.

Different components of body image processing seem to be reflected by different neural mechanisms. A core symptom of Anorexia nervosa (AN) is a disturbance of body image with correlates found on a neural level. The present study focusses at the neural processing of visual body stimuli of different weight categories in adolescent and adult AN patients. Method 33 adolescents aged 12-18 years (15 AN patients, 18 control participants) and 36 adult women (19 AN patients, 17 control participants) underwent functional magnetic resonance imaging (fMRI) while performing a perceptive and an affective body image task involving photographic stimuli of women belonging to different BMI categories. ResultsDifferential effects on activation depending on the BMI of the women shown in the pictures were found in frontal brain regions, the thalamus, caudate and the fusiform gyrus. Group effects differentiating between AN patients and control participants were seen mainly in the caudate and insula. DiscussionDuring a perceptive task, diminished activation of regions involved in perceptive and evaluative functions as well as emotional reasoning was seen in AN. During evaluation of the neural processing in an affective task there was a tendency towards activation differences reflecting reduced ability of size estimation and impaired integration of visual and body perception with emotions..