NeuroKit2 is an open-source, community-driven, and user-centered Python package for neurophysiological signal processing. It provides a comprehensive suite of processing routines for a variety of ...bodily signals (e.g., ECG, PPG, EDA, EMG, RSP). These processing routines include high-level functions that enable data processing in a few lines of code using validated pipelines, which we illustrate in two examples covering the most typical scenarios, such as an event-related paradigm and an interval-related analysis. The package also includes tools for specific processing steps such as rate extraction and filtering methods, offering a trade-off between high-level convenience and fine-tuned control. Its goal is to improve transparency and reproducibility in neurophysiological research, as well as foster exploration and innovation. Its design philosophy is centred on user-experience and accessibility to both novice and advanced users.
Turmoil has engulfed psychological science. Causes and consequences of the reproducibility crisis are in dispute. With the hope of addressing some of its aspects, Bayesian methods are gaining ...increasing attention in psychological science. Some of their advantages, as opposed to the frequentist framework, are the ability to describe parameters in probabilistic terms and explicitly incorporate prior knowledge about them into the model. These issues are crucial in particular regarding the current debate about statistical significance. Bayesian methods are not necessarily the only remedy against incorrect interpretations or wrong conclusions, but there is an increasing agreement that they are one of the keys to avoid such fallacies. Nevertheless, its flexible nature is its power and weakness, for there is no agreement about what indices of "significance" should be computed or reported. This lack of a consensual index or guidelines, such as the frequentist
-value, further contributes to the unnecessary opacity that many non-familiar readers perceive in Bayesian statistics. Thus, this study describes and compares several Bayesian indices, provide intuitive visual representation of their "behavior" in relationship with common sources of variance such as sample size, magnitude of effects and also frequentist significance. The results contribute to the development of an intuitive understanding of the values that researchers report, allowing to draw sensible recommendations for Bayesian statistics description, critical for the standardization of scientific reporting.
The use of heart rate variability (HRV) in research has been greatly popularized over the past decades due to the ease and affordability of HRV collection, coupled with its clinical relevance and ...significant relationships with psychophysiological constructs and psychopathological disorders. Despite the wide use of electrocardiograms (ECG) in research and advancements in sensor technology, the analytical approach and steps applied to obtain HRV measures can be seen as complex. Thus, this poses a challenge to users who may not have the adequate background knowledge to obtain the HRV indices reliably. To maximize the impact of HRV-related research and its reproducibility, parallel advances in users' understanding of the indices and the standardization of analysis pipelines in its utility will be crucial. This paper addresses this gap and aims to provide an overview of the most up-to-date and commonly used HRV indices, as well as common research areas in which these indices have proven to be very useful, particularly in psychology. In addition, we also provide a step-by-step guide on how to perform HRV analysis using an integrative neurophysiological toolkit, NeuroKit2.
Ageing is associated with grey matter atrophy and changes in task-related neural activations. This study investigated the effects of age and education on neural activation during a spatial working ...memory task in 189 participants aged between 20-80 years old, whilst controlling for grey matter density. Age was related to linear decreases in neural activation in task activated areas, and this effect was no longer significant when adjusting for education or accuracy. Age was also related to cubic increases in neural activation in non-task related areas, such as the temporal gyrus, cuneus and cerebellum when adjusting for accuracy and education. These findings support previous lifespan datasets indicating linear age-related decreases in task activation, but non-linear increases in non-task related areas during episodic memory tasks. The findings also support past studies indicating education offers a form of cognitive reserve through providing a form of neural compensation and highlights the need to consider education in ageing studies.
There has been an increasing trend towards the use of complexity analysis in quantifying neural activity measured by electroencephalography (EEG) signals. On top of revealing complex neuronal ...processes of the brain that may not be possible with linear approaches, EEG complexity measures have also demonstrated their potential as biomarkers of psychopathology such as depression and schizophrenia. Unfortunately, the opacity of algorithms and descriptions originating from mathematical concepts have made it difficult to understand what complexity is and how to draw consistent conclusions when applied within psychology and neuropsychiatry research. In this review, we provide an overview and entry‐level explanation of existing EEG complexity measures, which can be broadly categorized as measures of predictability and regularity. We then synthesize complexity findings across different areas of psychological science, namely, in consciousness research, mood and anxiety disorders, schizophrenia, neurodevelopmental and neurodegenerative disorders, as well as changes across the lifespan, while addressing some theoretical and methodological issues underlying the discrepancies in the data. Finally, we present important considerations when choosing and interpreting these metrics.
In light of the increasing popularity of complexity analysis in quantifying neural activity measured by electroencephalography (EEG) signals, we provide an overview of existing EEG complexity measures, broadly categorized as measures of predictability and regularity. We also synthesize complexity findings across different areas of psychological science (e.g., neuropsychiatric disorders and consciousness research), addressing theoretical and methodological issues underlying discrepancies in data.
There continues to be growing interest in the Science of Learning including identifying applications for findings from this work outside the laboratory to support learning. Presently, there exists a ...gap in our understanding of learning during healthy adulthood as well as effective ways in which that learning can be improved. Developing a more comprehensive understanding of learning during adulthood, and effective ways of improving that learning, are crucial goals given the impact of a rapidly aging global population. The main objective of the proposed systematic review is to identify and synthesize all recent cognitive and brain research investigating learning across the adult lifespan.
Searches will be performed across Scopus, Web of Science, and ProQuest databases. Both published and unpublished literature will be screened for inclusion. Included articles will be limited to research in healthy adult samples reporting measures of learning-related cognition, brain structure or function and their relationship with age, or the impact of interventions to improve learning. All steps of the review will be performed by three trained reviewers. Tabular, narrative, and quantitative syntheses will be provided based on the characteristics of included studies.
Findings from the proposed review will contribute to our understanding of learning in adulthood. Additionally, this review will identify research gaps in need of further investigation and relevant findings for translation, informing the scope of future funding priorities in the Science of Learning.
The observed variability in the effects of transcranial direct current stimulation (tDCS) is influenced by the amount of current reaching the targeted region-of-interest (ROI). Age and sex might ...affect current density at target ROI due to their impact on cortical anatomy. The present tDCS simulation study investigates the effects of cortical anatomical parameters (volumes, dimension, and torque) on simulated tDCS current density in healthy young, middle-aged, and older males and females.
Individualized head models from 240 subjects (120 males, 18–87 years of age) were used to identify the estimated current density (2 mA current intensity, 25 cm2 electrode) from two simulated tDCS montages (CP5_CZ and F3_FP2) targeting the inferior parietal lobule (IPL) and middle frontal gyrus (MFG), respectively. Cortical parameters including segmented brain volumes (cerebrospinal fluid CSF, grey and white matter), cerebral-dimensions (length/width &length/height) and brain-torque (front and back shift, petalia, and bending) were measured using the magnetic resonance images (MRIs) from each subject. The present study estimated sex differences in current density at these target ROIs mediated by these cortical parameters within each age group.
For both tDCS montages, females in the older age group received higher current density than their male counterparts at the target ROIs. No sex differences were observed in the middle-aged group. Males in the younger age group had a higher current density than females, only for the parietal montage. Across all age groups, CSF, and grey matter volumes significantly predicted the current intensity estimated at the target sites. In the older age group only, brain-torque was a significant mediator of the sex difference.
Our findings demonstrate the presence of sex differences in the simulated tDCS current density, however this pattern differed across age groups and stimulation locations. Future studies should consider influence of age and sex on individual cortical anatomy and tailor tDCS stimulation parameters accordingly.
•Older females (≥64 & <87 years) receive a higher simulated tDCS current at the target region (with 2 mA) compared to the males.•Similarly young males (≥18 & <41 years) receive higher current at target ROI compared to females only for a parietal montage.•The degree of cerebral atrophy determines the age-dependent sex difference in tDCS current intensity.•The higher current intensity is associated with larger grey matter and smaller cerebrospinal fluid volume at a young age.•This pattern reverses at old age, with brain torque emerging as a significant contributor.
There is significant interest in understanding the pathophysiology of Obsessive-Compulsive Disorder (OCD) using resting-state fMRI (rsfMRI). Previous studies acknowledge abnormalities within and ...beyond the fronto-striato-limbic circuit in OCD that require further clarifications. However, limited information could be inferred from the conventional way of investigating the functional connectivity differences between OCD and healthy controls. Here, we identified altered brain organization in patients with OCD by applying individual-based approaches to maximize the identification of underlying network-based features specific to the OCD group. rsfMRI of 20 patients with OCD and 22 controls were preprocessed, and individual-fMRI-subspace was derived for each subject within each group. We evaluated group differences in functional connectivity using individual-fMRI-subspace and established its advantage over conventional-fMRI methodology. We applied prediction-based approaches to highlight the group differences by evaluating the differences in functional connections that predicted the clinical scores (namely, the Obsessive-Compulsive Inventory-Revised (OCI-R) and Hamilton Anxiety Rating Scale). Then, we explored the brain network organization of both groups by estimating the subject-specific communities within each group. Lastly, we evaluated associations between the inter-individual variation of nodes in the communities to clinical measures using linear regression. Functional connectivity analysis using individual-fMRI-subspace detected 83 connections that were different between OCD and control groups, compared to none found using conventional-fMRI methodology. Connectome-based prediction analysis did not show significant overlap between the two groups in the functional connections that predicted the clinical scores. This suggests that the functional architecture in patients with OCD may be different compared to controls. Seven communities were found in both groups. Interestingly, within the OCD group but not controls, we observed functional connectivity between cerebellar and visual regions, and lack of connectivity between striato-limbic and frontal areas. Inter-individual variations in the community-size of these two communities were also associated with the OCI-R score (p < .005). Due to our small sample size, we further validated our results by (i) accounting for head motion, (ii) applying global signal regression (GSR) in data processing, and (iii) using an alternate atlas for parcellation. While the main results were consistently observed with accounting for head motion and using another atlas, the key findings were not reproduced with GSR application. The study demonstrated the existence of disconnectedness in fronto-striato-limbic community and connectedness between cerebellar and visual areas in OCD patients, which was also related to the clinical symptomatology of OCD.
•Selective stimulation of dorsal and ventral pathways of reading by tDCS.•Investigation of the effect of orthographic depth and language proficiency on Chinese-English bilinguals.•Script specific ...sub-lexical proficiency influences the stimulation of dorsal pathway.•Lower levels of sub-lexical proficiency are associated with greater effects of tDCS stimulation.
tDCS can modulate reading which is processed by lexical (ventral) and sub-lexical (dorsal) pathways. Previous research indicates that pathway recruitment in bilinguals depends on a script's orthographic depth and a reader's proficiency with it. The effect of tDCS on each reading pathway has not been investigated in bilinguals. We stimulated the left dorsal and ventral pathways separately in Chinese-English (C-E) bilinguals to understand whether pathway-specific modulation by tDCS is possible and, if so, how it is influenced by orthographic depth and script proficiency.
A double-blind, sham-controlled, within-subject experiment was designed wherein 16 balanced bilinguals received anodal tDCS in dorsal, ventral and sham sessions. Two tDCS montages of electrode sizes 5 × 5 cm2 with 1) anode at CP5 and cathode at CZ, and 2) anode at TP7 and cathode at nape of the neck, were applied for stimulating the dorsal and ventral pathways respectively. Bilinguals were asked to read word lists for each language before and after stimulation. RTs for accurate trials were analysed using linear mixed-effect modelling that included proficiency scores for reading English pseudo-words (PW) and Chinese pinyin.
For both languages, word reading RTs were faster following dorsal pathway stimulation. The dorsal stimulation effect (change in RT) was negatively correlated with pseudoword reading and pinyin proficiency. Stimulation of the ventral pathway decreased RTs only for Chinese reading.
Dorsal and ventral reading pathways can be selectively modulated by tDCS in bilingual readers with dorsal (sub-lexical) pathway stimulation affecting reading in both scripts and ventral (lexical) pathway stimulation selectively affecting Chinese reading. Dorsal pathway tDCS effects are modulated by sub-lexical reading proficiency.
Visual illusions are a gateway to understand how we construct our experience of reality. Unfortunately, important questions remain open, such as the hypothesis of a common factor underlying the ...sensitivity to different types of illusions, as well as of personality correlates of illusion sensitivity. In this study, we used a novel parametric framework for visual illusions to generate 10 different classic illusions (Delboeuf, Ebbinghaus, Rod and Frame, Vertical-Horizontal, Zöllner, White, Müller-Lyer, Ponzo, Poggendorff, Contrast) varying in strength, embedded in a perceptual discrimination task. We tested the objective effect of the illusions on errors and response times, and extracted participant-level performance scores (n=250) for each illusion. Our results provide evidence in favour of a general factor underlying the sensitivity to different illusions (labelled Factor i). Moreover, we report a positive link between illusion sensitivity and personality traits such as Agreeableness, Honesty-Humility, and negative relationships with Psychoticism, Antagonism, Disinhibition, and Negative Affect.
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