Neural correlates of stimulus response and stimulus outcome shifting in healthy participants and MS patients

Introduction

Adaptation to changing situations can be mediated by two strategies: (1) Evaluation of a response and (2) Evaluation of outcome values in relation to objects. Previous studies indicate that response shifting is associated with a network comprising the left frontal cortex and parietal cortex connected by the superior longitudinal fascicle, whereas outcome evaluation is associated with a network consisting of the orbitofrontal cortex, amygdala and uncinate fascicle. However, these studies rarely compared both kinds of adaptation directly and existing fMRI studies with healthy subjects are not informative about the role of the two fiber systems.

Methods

We analyzed stimulus response shifting and stimulus outcome shifting in two studies, one fMRI-study on healthy participants and one study on patients with MS involving structural MRI (Diffusion Tensor Imaging, Voxel Based Morphometry, Ventricular volumetry). Two tasks were used, identical in presentation but different in instruction, controlling for effects of lower level processing. In the SRS task, participants had to perform a “Go” or “NoGo” response depending on a stimulus change: if the stimulus remained the same, they had to continue with the former type of response, if it changed they had to adapt their response pattern. In the SOS task they had to perform a “Go” response only if the presented stimulus corresponded to that of an internal alternating series.

Results

fMRI findings showed that SRS is related to a bilateral parietal-premotor network. In the left hemisphere the prefrontal cortex was also involved. SOS was lateralized to the right hemisphere, particularly to the anterior temporal pole and amygdala, and the inferior parietal cortex. MS patients impaired on this task suffered from lesions in the right uncinate fascicle and showed an enlarged right frontal lateral ventricle.

Conclusion

With physically identical tasks, a functional neuronal segregation can be demonstrated for stimulus response shifting (bilateral activations with a focus in the left prefrontal cortex) and stimulus outcome shifting (right anterior temporal lobe and right supramarginal gyrus).     

To adjust or not adjust: Nonparametric effect sizes,confidence intervals,and real-world meaning

ObjectivesThe main objectives of this article are to: (a) investigate if there are any meaningful differences between adjusted and unadjusted effect sizes (b) compare the outcomes from parametric and non-parametric effect sizes to determine if the potential differences might influence the interpretation of results, (c) discuss the importance of reporting confidence intervals in research, and discuss how to interpret effect sizes in terms of practical real-world meaning.DesignReview.MethodA review of how to estimate and interpret various effect sizes was conducted. Hypothetical examples were then used to exemplify the issues stated in the objectives.ResultsThe results from the hypothetical research designs showed that: (a) there is a substantial difference between adjusted and non-adjusted effect sizes especially in studies with small sample sizes, and (b) there are differences in outcomes between the parametric and non-parametric effect size formulas that may affect interpretations of results.ConclusionsThe different hypothetical examples in this article clearly demonstrate the importance of treating data in ways that minimize potential biases and the central issues of how to discuss the meaningfulness of effect sizes in research.     

Our world is more than physics: a constructive – critical comment on the current science and theology debate

“Critical realism” is one of the most important positions in the current science and theology debate. An analysis of its origin and meaning leads to the question if this position mostly propagated by physicist-theologians could miss an intrinsic feature of the personal dimension of reality. A deeper meaning of the personal dimension sets human science apart. Taking into account social science's insight that persons responsible for their conclusions and actions drive the process of science, the moral dimension of science has to be emphasized. To integrate these aspects into a coherent position, a more differentiated epistemological model is needed. The solution proposed in this paper is to modify critical realism to constructive-critical realism. Theologically interpreted, constructive-critical realism remembers humankind's purpose to shape nature in cooperation with God and with the means of culture toward increasing realization of freedom in relationship. The argument is widely influenced by an analysis of the works of John Polkinghorne.     

Alternative-based thresholding with application to presurgical fMRI

Functional magnetic reasonance imaging (fMRI) plays an important role in pre-surgical planning for patients with resectable brain lesions such as tumors. With appropriately designed tasks, the results of fMRI studies can guide resection, thereby preserving vital brain tissue. The mass univariate approach to fMRI data analysis consists of performing a statistical test in each voxel, which is used to classify voxels as either active or inactive—that is, related, or not, to the task of interest. In cognitive neuroscience, the focus is on controlling the rate of false positives while accounting for the severe multiple testing problem of searching the brain for activations. However, stringent control of false positives is accompanied by a risk of false negatives, which can be detrimental, particularly in clinical settings where false negatives may lead to surgical resection of vital brain tissue. Consequently, for clinical applications, we argue for a testing procedure with a stronger focus on preventing false negatives. We present a thresholding procedure that incorporates information on false positives and false negatives. We combine two measures of significance for each voxel: a classical p-value, which reflects evidence against the null hypothesis of no activation, and an alternative p-value, which reflects evidence against activation of a prespecified size. This results in a layered statistical map for the brain. One layer marks voxels exhibiting strong evidence against the traditional null hypothesis, while a second layer marks voxels where activation cannot be confidently excluded. The third layer marks voxels where the presence of activation can be rejected.     

Medication for Complex Posttraumatic Disorders

Treatment guidelines and reviews of outcome studies agree that drugs are valuable for moderation of irrational moods and impulsivity that interfere with thoughtfulness and cooperativeness. As such, they empower patients to make good use of psychotherapy for mastery of the risk of betrayal in intimate relationships, which is the typical recurrent traumatic event in complex posttraumatic disorders. Psychotherapy, for its part, has demonstrated correction and lasting remission of disorder in the aftermath of certain kinds of single trauma and promises further development to achieve similar efficacy for complex posttraumatic disorders. This article summarizes the strengths and limitations of each class of psychiatric drugs. It explains how the natural course of complex posttraumatic disorders greatly contaminates observations of medication efficacy and fosters unrealistic expectations for drug development.     

Altruism in adolescents and young adults: validation of an instrument to measure generative altruism with structural equation modeling

Aim of this study was to develop and test a research instrument to measure generative and functional altruism in adolescents/young adults. In an anonymous questionnaire survey using standardised questionnaires, 873 students were recruited in academic high schools and professional schools. The 7-item Generative Altruism Scale (GALS), which includes affective and behavioural elements, correlated with relevant external measures that correspond with the underlying construct. Confirmatory factor analysis proved an acceptable model fit with characteristics of χ² [df = 14, N = 846] = 129.946, p < .001, CFI = .91, AIC = 157.946, and SRMR = .048. Female and male students differed significantly with respect to altruism scores (F = 25.5; p < .0001). The GALS could be used for empirical studies analysing the connection between altruism and the development of ethical values and prosocial behaviour. Particularly, compassion as an intrinsic motivator could be fostered in appropriate education programmes.     

Temporal buffering and visual capacity: The time course of object formation underlies capacity limits in visual cognition

Capacity limits are a hallmark of visual cognition. The upper boundary of our ability to individuate and remember objects is well known but—despite its central role in visual information processing—not well understood. Here, we investigated the role of temporal limits in the perceptual processes of forming “object files.” Specifically, we examined the two fundamental mechanisms of object file formation—individuation and identification—by selectively interfering with visual processing by using forward and backward masking with variable stimulus onset asynchronies. While target detection was almost unaffected by these two types of masking, they showed distinct effects on the two different stages of object formation. Forward “integration” masking selectively impaired object individuation, whereas backward “interruption” masking only affected identification and the consolidation of information into visual working memory. We therefore conclude that the inherent temporal dynamics of visual information processing are an essential component in creating the capacity limits in object individuation and visual working memory.     

Cognitive functions of gamma-band activity: memory match and utilization

Oscillatory neural activity in the gamma frequency range (>30Hz) has been shown to accompany a wide variety of cognitive processes. So far, there has been limited success in assigning a unitary basic function to these oscillations, and critics have raised the argument that they could just be an epiphenomenon of neural processing. We propose a new framework that relates gamma oscillations observed in human, as well as in animal, experiments to two underlying processes: the comparison of memory contents with stimulus-related information and the utilization of signals derived from this comparison. This model attempts to explain early gamma-band responses in terms of the match between bottom-up and top-down information. Furthermore, it assumes that late gamma-band activity reflects the readout and utilization of the information resulting from this match.