Tracking temporal response dynamics in the ventral striatum during social feedback in anorexia nervosa: A functional magnetic resonance imaging exploratory study.

OBJECTIVE: Research suggests abnormalities in reward-based processes in anorexia nervosa (AN). However, few studies have explored if such alterations might be associated with different temporal activation patterns. This study aims to characterize alterations in time-dependent processes in the ventral striatum (VS) during social feedback in AN using functional magnetic resonance imaging (fMRI). METHOD: Twenty women with restrictive-subtype AN and 20 age-matched healthy controls (HC) underwent a social judgment experimental fMRI task. Temporal VS hemodynamic responses were extracted in SPM for each participant and each social condition (acceptance/rejection). RESULTS: Compared with age-matched HC, patients with AN showed a significant time by group interaction of peak VS response throughout the task, with a progressive blunting of peak activation responses, accompanied by a progressive increase in baseline activity levels over time. DISCUSSION: The results suggest an attenuated response pattern to repetitive social rejection in the VS in patients with AN, together with a difficulty in returning to baseline. The information obtained from this study will guide future, design-specific studies to further explore alterations temporal dynamics.

[Neural bases of numerical processing and calculation]. / Bases neurales del procesamiento numérico y del cálculo.

AIM: To review the findings about neural correlates of number processing and arithmetic calculation, as well as the neuro-structural and neurofunctional imaging findings in patients with difficulties in this kind of abilities. DEVELOPMENT: The parietal lobe and specifically, the horizontal segment of the intraparietal sulcus, has become specialized in the internal representation of quantities, the abstract processing of magnitudes and the relation between them. On the other hand, the angular gyrus takes part in the verbal processing of certain tasks called arithmetical facts (for instance, multiplication tables and additions of small quantities). Prefrontal cortex, posterior part of temporal lobe, cingulate cortex and several subcortical regions are also involved in number processing. Empirical data have provided theoretical and anatomical models for number processing and calculation of which the Triple Code Model is currently the most accepted one. Moreover, implementation of neuroimaging techniques has demonstrated that patients who reported difficulties in numerical tasks show structural and functional involvement of the intraparietal sulcus. CONCLUSIONS: Neuroimaging techniques have allowed to specifying the neural basis of number processing and calculation. These findings can increase our knowledge of developmental dyscalculia and it's neuroanatomical and neurofunctional correlates. In the future, imaging and neuropsychological data could lead us to more accurate diagnosis methods and better educational programs, in order to improve numerical abilities of patients affected by dyscalculia.