Precise display time measurement in JavaScript for web-based experiments.

Conducting research via the Internet is a formidable and ever-increasingly popular option for behavioral scientists. However, it is widely acknowledged that web-browsers are not optimized for research: In particular, the timing of display changes (e.g., a stimulus appearing on the screen), still leaves room for improvement. So far, the typically recommended best (or least bad) timing method has been a single (RAF) JavaScript function call within which one would give the display command and obtain the time of that display change. In our Study 1, we assessed two alternatives: Calling the RAF twice consecutively, or calling the RAF during a continually ongoing independent loop of recursive RAF calls. While the former has shown little or no improvement as compared to single RAF calls, with the latter we significantly and substantially improved overall precision, and achieved practically faultless precision in most practical cases. Our two basic methods for effecting display changes, plain text change and color filling, proved equally efficient. In Study 2, we reassessed the "RAF loop" timing method with image elements in combination with three different display methods: We found that the precision remained high when using either or changes - while drawing on a element consistently led to comparatively lower precision. We recommend the "RAF loop" display timing method for improved precision in future studies, and or changes when using image stimuli. We publicly share the easy-to-use code for this method, exactly as employed in our studies.

Dynamic Causal Modeling of the Prefrontal/Amygdala Network During Processing of Emotional Faces.

Introduction: The importance of the amygdala/medial orbitofrontal cortex (OFC) network during processing of emotional stimuli, emotional faces in particular, is well established. This premise is supported by converging evidence from animal models, human neuroanatomical results, and neuroimaging studies. However, there is missing evidence from human brain connectivity studies that the OFC and no other prefrontal brain areas such as the dorsolateral prefrontal cortex (DLPFC) or ventrolateral prefrontal cortex (VLPFC) are responsible for amygdala regulation in the functional context of emotional face stimuli. Methods: Dynamic causal modeling of ultrahigh-field functional magnetic resonance imaging data acquired at 7 Tesla in 38 healthy subjects and a well-established paradigm for emotional face processing were used to assess the central role of the OFC to provide empirical validation for the assumed network architecture. Results: Using Bayesian model selection, it is demonstrated that indeed the OFC, and not the VLPFC and the DLPFC, downregulates amygdala activation during the emotion discrimination task. In addition, Bayesian model averaging group results were rigorously tested using bootstrapping, further corroborating these findings and providing an estimator for robustness and optimal sample sizes. Discussion: While it is true that VLPFC and DLPFC are relevant for the processing of emotional faces and are connected to the OFC, the OFC appears to be a central hub for the prefrontal/amygdala interaction. Impact statement Using dynamic causal modeling (DCM), abnormal effective connectivity in the orbitofrontal cortex (OFC)/amygdala network has been repeatedly observed in the pathophysiology of psychiatric disorders. However, it has to be considered that these findings are all based on the a priori assumption of the OFC being the central area for prefrontal control regulating amygdala activation. This is particularly important, as DCM results conditionally depend on the underlying model space used for model selection. Using Bayesian model comparison methods, it is shown that the OFC (and not the dorsolateral prefrontal cortex or ventrolateral prefrontal cortex) engages in amygdala downregulation in the context emotional face processing.

Facial responses of adult humans during the anticipation and consumption of touch and food rewards.

Whether cognitive, motivational and hedonic aspects of reward anticipation and consumption can be reliably assessed with explicit and implicit measures, and if different motivational (decision utility) and hedonic (experienced utility) processes get recruited by distinct reward types, remain partly unsolved questions that are relevant for theories of social and non-social decision-making. We investigated these topics using a novel experimental paradigm, including carefully matched social and nonsocial rewards, and by focusing on facial responses. Facial expressions are indeed an often-cited implicit measure of rewards' hedonic impact. For example, food rewards elicit powerful facial responses - characterized by lip smacking, tongue protrusion, and relaxation of the middle face - in human newborns, juvenile monkeys, and adult rats. The same stimuli elicit more nuanced facial reactions in adult humans, which can be best captured with facial electromyography (fEMG). However, little is known about facial expressions preceding reward consumption, reflecting the motivation to obtain and possibly the expected pleasantness of a reward, and whether similar facial expressions are elicited by different types of rewards. To investigate these questions, a novel within-subject experimental paradigm was developed. During the anticipation and consumption of social (affective touch) and nonsocial (food) rewards, explicit (ratings of wanting and liking, physical effort) and implicit (fEMG) measures of wanting and liking were taken in 43 healthy adult participants. Reduced activation of the Corrugator Supercilii (CS) muscle (reflecting less frowning and indicating greater positive response) was found in trials with higher wanting and effort during the anticipation of food rewards, as well as in trials with higher liking and effort during the consumption of food rewards. The CS muscle is thus a sensitive measure of wanting and liking of food rewards both during their anticipation and consumption. Crucially, thanks to careful reward matching, these results cannot be explained by differences in subjective wanting, liking, or effort produced to obtain the two types of rewards. No significant modulation of the Zygomaticus Major (ZM) muscle was found for social or food rewards. Explorative analyses however indicated that the ZM may activate during the delivery of the most wanted touch, but not for the most wanted food. The absence of significant effects of social rewards on the activation of CS and ZM muscles are discussed in relation to the specifics of this innovative task comparing two types of matched rewards in the same participants. The present findings contribute to the understanding of the processes underlying motivational and hedonic aspects of rewards, and may therefore inform models of social and non-social decision-making.

Indirect (implicit) and direct (explicit) self-esteem measures are virtually unrelated: A meta-analysis of the initial preference task.

BACKGROUND: The initial preference task (IPT) is an implicit measure that has featured prominently in the literature and enjoys high popularity because it offers to provide an unobtrusive and objective assessment of self-esteem that is easy to administer. However, its use for self-esteem assessment may be limited because of weak associations with direct personality measures. Moreover, moderator effects of sample- and study-related variables need investigation to determine the value of IPT-based assessments of self-esteem. METHODS: Conventional and grey-literature database searches, as well as screening of reference lists of obtained articles, yielded a total of 105 independent healthy adult samples (N = 17,777) originating from 60 studies. Summary effect estimates and subgroup analyses for potential effect moderators (e.g., administration order, algorithm, rating type) were calculated by means of meta-analytic random- and mixed-effects models. Moreover, we accounted for potential influences of publication year, publication status (published vs. not), and participant sex in a weighted stepwise hierarchical multiple meta-regression. We tested for dissemination bias through six methods. RESULTS: There was no noteworthy correlation between IPT-based implicit and explicit self-esteem (r = .102), indicating conceptual independence of these two constructs. Effects were stronger when the B-algorithm was used for calculation of IPT-scores and the IPT was administered only once, whilst all other moderators did not show significant influences. Regression analyses revealed a somewhat stronger (albeit non-significant) effect for men. Moreover, there was no evidence for dissemination bias or a decline effect, although effects from published studies were numerically somewhat stronger than unpublished effects. DISCUSSION: We show that there is no noteworthy association between IPT-based implicit and explicit self-esteem, which is broadly consistent with dual-process models of implicit and explicit evaluations on the one hand, but also casts doubt on the suitability of the IPT for the assessment of implicit self-esteem on the other hand.

Characterizing the emotional response to art beyond pleasure: Correspondence between the emotional characteristics of artworks and viewers' emotional responses.

Although emotions are some of the most discussed aspects of the experience of art, we know very little about what emotions people experience during aesthetic encounters. In this chapter, we used emotional heat maps-a novel approach to characterizing art viewers' aesthetic responses to art-to examine the following research questions in two museum studies: (1) What emotions do people experience after encounters with art, and how intense are these emotions? (2) To what extent do museum visitors experience the same emotions to a particular exhibition or artwork? and (3) To what extent is there a correspondence between the emotional characteristics of an art exhibition or artwork and the emotions that viewers experienced? Results showed that there was fairly good agreement among viewers regarding the emotions that they experienced in response to a particular artwork or exhibition and that there were correspondences between art viewers' emotional responses and the emotional characteristics of the exhibition or artwork that they viewed. The use of emotional heat maps was effective in going beyond traditional aesthetics measures of liking and pleasure and allowing a nuanced characterization of the aesthetic experience of art.

Predicting perceived visual complexity of abstract patterns using computational measures: The influence of mirror symmetry on complexity perception.

Visual complexity is relevant for many areas ranging from improving usability of technical displays or websites up to understanding aesthetic experiences. Therefore, many attempts have been made to relate objective properties of images to perceived complexity in artworks and other images. It has been argued that visual complexity is a multidimensional construct mainly consisting of two dimensions: A quantitative dimension that increases complexity through number of elements, and a structural dimension representing order negatively related to complexity. The objective of this work is to study human perception of visual complexity utilizing two large independent sets of abstract patterns. A wide range of computational measures of complexity was calculated, further combined using linear models as well as machine learning (random forests), and compared with data from human evaluations. Our results confirm the adequacy of existing two-factor models of perceived visual complexity consisting of a quantitative and a structural factor (in our case mirror symmetry) for both of our stimulus sets. In addition, a non-linear transformation of mirror symmetry giving more influence to small deviations from symmetry greatly increased explained variance. Thus, we again demonstrate the multidimensional nature of human complexity perception and present comprehensive quantitative models of the visual complexity of abstract patterns, which might be useful for future experiments and applications.

The effects of visual context and individual differences on perception and evaluation of modern art and graffiti art.

Traditionally, artworks are seen as autonomous objects that stand (or should stand) on their own. However, at least since the emergence of Conceptual Art in the 1920s and Pop Art in the 1960s, art lacks any distinctive perceptual features that define it as such. Art, therefore, cannot be defined without reference to its context. Some studies have shown that context affects the evaluation of artworks, and that specific contexts (street for graffiti art, museum for modern art) elicit specific effects (Gartus & Leder, 2014). However, it is yet unclear how context changes perception and appreciation processes. In our study we measured eye-movements while participants (64 psychology undergraduates, 48% women) perceived and evaluated beauty, interest, emotional valence, as well as perceived style for modern art and graffiti art embedded into either museum or street contexts. For modern art, beauty and interest ratings were higher in a museum than in a street context, but context made no difference for the ratings of graffiti art. Importantly, we also found an interaction of context and individual interest in graffiti for beauty and interest ratings, as well as for number of fixations. Analyses of eye-movements also revealed that viewing times were in general significantly longer in museum than in street contexts. We conclude that context can have an important influence on aesthetic appreciation. However, some effects depend also on the style of the artworks and the individual art interests of the viewers.

The small step toward asymmetry: Aesthetic judgment of broken symmetries.

Symmetry and complexity both affect the aesthetic judgment of abstract patterns. However, although beauty tends to be associated with symmetry, there are indications that small asymmetries can also be beautiful. We investigated the influence of small deviations from symmetry on people's aesthetic liking for abstract patterns. Breaking symmetry not only decreased patterns' symmetry but also increased their complexity. While an increase of complexity normally results in a higher liking, we found that even a small decrease of symmetry has a strong effect, such that patterns with slightly broken symmetries were significantly less liked than fully symmetric ones.

Does clinical memory fMRI provide a comprehensive map of medial temporal lobe structures?

Successful clinical application of fMRI tasks requires reliable knowledge about the brain structures mapped by the task. With memory fMRI, diverging evidence exists concerning the location of major signal sources as well as hippocampal contributions. To clarify these issues, we investigated a frequently applied memory test (home town walking) in 33 patients with unilateral medial temporal lobe pathology, comparing healthy and diseased hemispheres. We focused on a detailed investigation of individual fMRI maps on non-transformed high-resolution functional images. Results show a clear dominance of activations around the collateral sulcus, corresponding to parahippocampal and entorhinal cortex activities. Hippocampus activity was absent in the vast majority of patients. The diseased hemispheres showed lower activation than the healthy hemispheres. We conclude that (1) the investigated memory test may be successfully applied for evaluation of the parahippocampal cortex, (2) the hippocampus is not reliably mapped by the task, and (3) the methods described for investigation of individual high-resolution functional images allow generation of application profiles for clinical fMRI tasks.

Probing overtly spoken language at sentential level: a comprehensive high-field BOLD-fMRI protocol reflecting everyday language demands.

Regarding the application of functional magnetic resonance imaging (fMRI) to preoperative mapping of language, the majority of previous studies applied silent vocalization at word level. Since mapping of language targets the protection of overt communication, the selection of the stimulation paradigm is a crucial issue. Typically, everyday language demands overt speech with construction of syntactically and semantically complete sentences. Here, 23 healthy right-handed subjects performed overt vocalization of complete german sentences. Subjects produced these sentences based on visually presented semantic choices. Special efforts were undertaken to minimize motion artifacts and maximize signal gain on a 3-T MR unit. Compared to previous studies, results showed a larger amount of highly reliable fMRI activations over the whole brain. Particularly, high sensitivity was found for Broca's and Wernicke's regions, as well as anterior and inferior temporal areas. Regarding the left hemisphere, simultaneous "Broca" and "Wernicke" activities were found in 95% of all subjects. When including atypical lateralizations, "Broca" and "Wernicke" activations were found in every subject. Overt vocalization at sentential level represents a new comprehensive language task with the potential to generate reliable activation maps that reflect brain activity associated with everyday language demands.

Cortical lateralization of bilateral symmetric chin movements and clinical relevance in tumor patients--a high field BOLD-FMRI study.

Although unilateral lesion studies concerning the opercular part of primary motor cortex report clinically severe motor deficits (e.g. anarthria, masticatory paralysis), functional lateralization of this area has not yet been addressed in neuroimaging studies. Using BOLD-FMRI, this study provides the first quantitative evaluation of a possible cortical lateralization of symmetric chin movements (rhythmic contraction of masticatory muscles) in right-handed healthy subjects and presurgical patients suffering tumorous lesions in the opercular primary motor cortex. Data were analyzed according to "activation volume" and "activation intensity". At group level, results showed a strong left-hemispheric dominance for chin movements in the group of healthy subjects. In contrast, patients indicated dominance of the healthy hemisphere. Here, a clinically relevant dissociation was found between "activation volume" and "activation intensity": Although "activation volume" may be clearly lateralized to the healthy hemisphere, "activation intensity" may indicate residual functionally important tissue close to the pathological tissue. In these cases, consideration of BOLD-FMRI maps with the exclusive focus on "activation volume" may lead to erroneous presurgical conclusions. We conclude that comprehensive analyses of presurgical fMRI data may help to avoid sustained postoperative motor deficits and dysarthria in patients with lesions in the opercular part of primary motor cortex.

Contrast-to-noise ratio (CNR) as a quality parameter in fMRI.

PURPOSE: To evaluate the impact of data quality on the localization of brain activation in functional magnetic resonance imaging (fMRI) and to explore whether the temporal contrast-to-noise-ratio (CNR) provides a quantitative parameter to estimate fMRI quality. MATERIALS AND METHODS: We investigated two methods for defining the CNR by comparing them on a single-run, single session, as well as on a group-wise basis. The CNRs of healthy subjects and a group of patients with brain lesions were calculated using two different strategies: one based on a general linear model (GLM) analysis (CNR_SPM), and one that acts as an adaptive low-pass filter and assumes that the high-frequency components contain the temporal noise (CNR_SG). Runs with low CNR were identified as outliers using a common exclusion criterion (2 x standard deviation (SD)). RESULTS: The results of the two CNR methods are highly correlated. Both between and within subjects and patients the CNR showed quite large variations, but the average CNR did not differ between a group of healthy subjects and a patient group. In total, seven of 213 runs (3.3% of all runs) had to be excluded when CNR_SG was used, and 14 of 213 (6.6%) runs had to be excluded when CNR_SPM was used. CONCLUSION: Calculating the CNR using an adaptive low-pass filter gives similar results to a GLM-based approach and could be advantageous for cases in which the hemodynamic response function (HRF) differs significantly from common assumptions. The CNR can be used to identify and exclude runs with suboptimal CNR, and to identify sessions with insufficient data quality. The CNR may serve as a quantitative and intuitive parameter to assess the performance and quality of clinical fMRI investigations, including information on both functional performance (contrast) and data quality (noise caused by the system and physiology).

Comparison of fMRI coregistration results between human experts and software solutions in patients and healthy subjects.

Functional magnetic resonance imaging (fMRI) performed by echo-planar imaging (EPI) is often highly distorted, and it is therefore necessary to coregister the functional to undistorted anatomical images, especially for clinical applications. This pilot study provides an evaluation of human and automatic coregistration results in the human motor cortex of normal and pathological brains. Ten healthy right-handed subjects and ten right-handed patients performed simple right hand movements during fMRI. A reference point chosen at a characteristic anatomical location within the fMRI sensorimotor activations was transferred to the high resolution anatomical MRI images by three human fMRI experts and by three automatic coregistration programs. The 3D distance between the median localizations of experts and programs was calculated and compared between patients and healthy subjects. Results show that fMRI localization on anatomical images was better with the experts than software in 70% of the cases and that software performance was worse for patients than healthy subjects (unpaired t-test: P = 0.040). With 45.6 mm the maximum disagreement between experts and software was quite large. The inter-rater consistency was better for the fMRI experts compared to the coregistration programs (ANOVA: P = 0.003). We conclude that results of automatic coregistration should be evaluated carefully, especially in case of clinical application.

FMRI reveals functional cortex in a case of inconclusive Wada testing.

OBJECTIVES: The intracarotid amobarbital test (Wada test) currently represents the gold standard for preoperative lateralization of hemispheric dominance. Here, we report an epileptic patient with a longstanding extended lesion of the left hemisphere showing absence of motor and speech dysfunction with left carotid amobarbital injection, but tetraplegia and speech arrest with right carotid injection interpreted as a neuroplastic shift of motor and language functions to the right hemisphere. In contrast to the Wada results, motor functional magnetic resonance imaging (fMRI) showed a strong left hemispheric activation with right hand movements. METHODS: Right and left hand motor fMRI was performed. FMRI results and neurophysiological information obtained by motor and sensory evoked potential measurements were compared with the Wada test results. RESULTS: Initial interpretation of neuroplastic shifts of intrinsic left hemisphere functions to the right brain was revised after fMRI results which were confirmed by motor and sensory evoked potentials. CONCLUSION: As motor inactivation usually is thought to be the most robust feature of the Wada test, this case demonstrates that fMRI may reveal residual functional cortex in cases of inconclusive Wada results.

Influence of fMRI smoothing procedures on replicability of fine scale motor localization.

Recent publications analyzing the influence of spatial smoothing on fMRI brain activation results demonstrated that smoothing may artificially combine activations from adjacent though functionally and anatomically distinct brain regions and that activation from large draining vessels may be smoothed into neighboring neuronal tissue. To investigate whether functional localizations may be artificially shifted by the smoothing procedure we performed replicability measurements. Localization centers of motor hand activations achieved during different conditions (isolated hand movements and simultaneous hand and chin movements) were compared with respect to smoothing effects. The voxel with the highest probability to represent a true positive activation was localized with a non-smoothed and a standard 4 x 4 x 6 mm smoothed correlational data analysis technique. Results show an increase of motor center aberrations between measurements by about 100% due to data smoothing indicating a statistically significant decrease in localization replicability.

Magnetoencephalography indicates finger motor somatotopy.

The existence or non-existence of fine-scale motor somatotopy of the hand is a fundamental problem with regard to the functioning of the human brain. In contrast to seldom contradicted early twentieth century descriptions of activation overlap, descriptions of finger motor somatotopy faced disagreement. Recent blood-flow-related brain mapping data achieved with functional magnetic resonance imaging (fMRI) argue in favour of fine-scale somatotopy. However, considerable discrepancies between blood oxygen-level-dependent fMRI activations and intracortically recorded neuronal activity have been reported and it is unclear whether the blood flow results truly reflect the neuronal situation. We have used recent advances in magnetoencephalography to detect signals deriving directly from neuronal tissue. Besides replication of the overlap aspect, we found statistically significant evidence for the existence of a somatotopic aspect of human hand motor representation when comparing the fifth and first finger motor dipoles along the superior-inferior axis. The average location of the fifth finger was found to be 2.31 mm superior to the first finger.