Distinct influence of inter- versus intra-trial feedback on the brain response to subsequent feedback: Evidence from event-related potentials.

Substantial evidence indicates that feedback processing not only varies with the valence of feedback, but is also highly dependent on contextual factors. Even so, the influence of prior outcome history on current outcome evaluation is far from clear. To investigate this issue, we conducted two event-related potential (ERP) experiments using a modified gambling task whereby each trial was associated with two consequences. In experiment 1, two instances of feedback indicated participant performance on two dimensions of a single decision, within a trial. In experiment 2, participants made two decisions in each trial, and then received two instances of feedback. We examined the feedback-related negativity (FRN) as an index of feedback processing. When both instances of feedback were relevant to the same trial (intra-trial), the FRN to the second was affected by the valence of the immediately previous feedback: The FRN was amplified to losses following wins. This was observed in both experiment 1 and experiment 2. When two instances of feedback were relevant to two different trials (inter-trial), the effect of immediately previous feedback on the FRN was inconsistent. In experiment 1 there was no effect of feedback from the previous trial on the FRN. However, in Experiment 2 there was an effect of inter-trial feedback on the FRN that was opposite to the effect of intra-trial feedback: The FRN was amplified when losses followed losses. Taken together, the findings suggest that the neural systems involved in reward processing dynamically and continuously integrate preceding feedback for the evaluation of present feedback.

A novel Fontan Y-graft for interrupted inferior vena cava and azygos continuation.

OBJECTIVES: To evaluate the hemodynamicdynamic advantage of a new Fontan surgical template that is intended for complex single-ventricle patients with interrupted inferior vena cava-azygos and hemi-azygos continuation. The new technique has emerged from a comprehensive pre-surgical simulation campaign conducted to facilitate a balanced hepatic flow and somatic Fontan pathway growth after Kawashima procedure. METHODS: For 9 patients, aged 2 to18 years, majority having poor preoperative oxygen saturation, a pre-surgical computational fluid dynamics customization is conducted. Both the traditional Fontan pathways and the proposed novel Y-graft templates are considered. Numerical model was validated against in vivo phase-contrast magnetic resonance imaging data and in vitro experiments. RESULTS: The proposed template is selected and executed for 6 out of the 9 patients based on its predicted superior hemodynamic performance. Pre-surgical simulations performed for this cohort indicated that flow from the hepatic veins (HEP) do not reach to the desired lung. The novel Y-graft template, customized via a right- or left-sided displacement of the total cavopulmonary connection anastomosis location resulted a drastic increase in HEP flow to the desired lung. Orientation of HEP to azygos direct shunt is found to be important as it can alter the flow pattern from 38% in the caudally located direct shunt to 3% in the cranial configuration with significantly reversed flow. The postoperative measurements prove that oxygen saturation increased significantly (P-value = 0.00009) to normal levels in 1 year follow-up. CONCLUSIONS: The new Y-graft template, if customized for the individual patient, is a viable alternative to the traditional surgical pathways. This template addresses the competing hemodynamic design factors of low physiological venous pressure, high postoperative oxygen saturation, low energy loss and balanced hepatic growth factor distribution possibly assuring adequate lung development. DATE AND NUMBER OF IRB APPROVAL: 25 October 2019, 280011928-604.01.01.

Number of Trials Necessary to Apply Analysis Within the Framework of the Uncontrolled Manifold Hypothesis at Different Levels of Hierarchical Synergy Control.

The uncontrolled manifold hypothesis is a method used to quantify motor synergies, defined as a specific central nervous system organization that maintains the task-specific stability of motor actions. The UCM allows for inter-trial variance analysis between consecutive trials. However, despite the large body of literature within this framework, there is no report on the number of movement repetitions required for reliable results. Based on the hypothetical hierarchical control of motor synergies, this study aims to determine the minimum number of trials necessary to achieve a good to excellent level of reliability. Thirteen young, healthy participants performed fifteen bilateral isometric contractions of elbow flexion when visual feedback was provided. The force and electromyography data were recorded to investigate synergies at different levels of hierarchical control. The intraclass correlation coefficient was used to determine the reliability of the variance indices. Based on the obtained results, at least twelve trials are required to analyze the inter-trial variance in both force and muscle synergies within the UCM framework.