The Simpson's paradox and fMRI: Similarities and differences between functional connectivity measures derived from within-subject and across-subject correlations.

Task-related functional connectivity (fc-MRI) indexes the interaction of brain regions during cognitive tasks. Two general classes of methods exist to investigate fc-MRI: the most widely-used method calculates temporal correlations between voxels/regions within subjects, and then determines if within-subject correlations are reliable across subjects (ws-fcMRI); the other calculates the average (BOLD) signal within voxels/regions and then performs correlations across subjects (as-fcMRI). That is, while both methods rely on correlational techniques, the level at which correlations are calculated is fundamentally different. While conceptually distinct, it is not known how well these two methods of fc-MRI analyses converge on the same findings. The current study addresses this question across a number of analyses. First, using default-mode network regions as seeds, we show that as-fcMRI does not strongly predict ws-fcMRI during episodic simulation tasks. Next, we show that the relationship between as-fcMRI and ws-fcMRI is contingent on whether correlations are calculated between regions from the same functional network (default mode or dorsal attention networks) or between regions from different functional networks. Lastly, we compare seed partial least squares (PLS) - a well-established as-fcMRI method - with a novel version of seed PLS that combines the multivariate approach of PLS analyses and within-subject correlations. The results showed that while many regions exhibited congruent as-fcMRI and ws-fcMRI effects, in some regions the two analyses produced effects in opposite directions. Results are discussed in relation to the Simpson's Paradox, a phenomenon in which across-subject correlations are reversed within individuals present in a sample. Overall, our results suggest that the findings of as-fcMRI do not always map onto those from ws-fcMRI. We end by discussing the advantages associated with using ws-fcMRI to assess the task-related interactions between brain regions.

Do strategic processes contribute to the specificity of future simulation in depression?

OBJECTIVES: The tendency to generate overgeneral past or future events is characteristic of individuals with a history of depression. Although much research has investigated the contribution of rumination and avoidance to the reduced specificity of past events, comparatively little research has examined (1) whether the specificity of future events is differentially reduced in depression and (2) the role of executive functions in this phenomenon. Our study aimed to redress this imbalance. METHODS: Participants with either current or past experience of depressive symptoms ('depressive group'; N = 24) and matched controls ('control group'; N = 24) completed tests of avoidance, rumination, and executive functions. A modified Autobiographical Memory Test was administered to assess the specificity of past and future events. RESULTS: The depressive group were more ruminative and avoidant than controls, but did not exhibit deficits in executive function. Although overall the depressive group generated significantly fewer specific events than controls, this reduction was driven by a significant group difference in future event specificity. Strategic retrieval processes were correlated with both past and future specificity, and predictive of the future specificity, whereas avoidance and rumination were not. CONCLUSIONS: Our findings demonstrate that future simulation appears to be particularly vulnerable to disruption in individuals with current or past experience of depressive symptoms, consistent with the notion that future simulation is more cognitively demanding than autobiographical memory retrieval. Moreover, our findings suggest that even subtle changes in executive functions such as strategic processes may impact the ability to imagine specific future events. PRACTITIONER POINTS: Future simulation may be particularly vulnerable to executive dysfunction in individuals with current/previous depressive symptoms, with evidence of a differential reduction in the specificity of future events. Strategic retrieval abilities were associated with the degree of future event specificity whereas levels of rumination and avoidance were not. Given that the ability to generate specific simulations of the future is associated with enhanced psychological wellbeing, problem solving and coping behaviours, understanding how to increase the specificity of future simulations in depression is an important direction for future research and clinical practice. Interventions focusing on improving the ability to engage strategic processes may be a fruitful avenue for increasing the ability to imagine specific future events in depression. The autobiographical event tasks have somewhat limited ecological validity as they do not account for the many social and environmental cues present in everyday life; the development of more clinically-relevant tasks may be of benefit to this area of study.

Examining the Peer-Reviewed Published Literature Regarding Low Back Pain in Rowing: A Scoping Review.

Background: Low back pain (LBP) is highly prevalent in the rowing population. The body of existing research variously investigates risk factors, prevention, and treatment methods. Purpose: The purpose of this scoping review was to explore the breadth and depth of the LBP literature in rowing and to identify areas for future research. Study Design: Scoping review. Methods: PubMed, Ebsco and ScienceDirect were searched from inception to November 1, 2020. Only published, peer-reviewed, primary, and secondary data pertaining to LBP in rowing were included for this study. Arksey and O'Malley's framework for guided data synthesis was used. Reporting quality of a subsection of the data was assessed using the STROBE tool. Results: Following the removal of duplicates and abstract screening, a set of 78 studies were included and divided into the following categories: epidemiology, biomechanics, biopsychosocial, and miscellaneous. The incidence and prevalence of LBP in rowers were well mapped. The biomechanical literature covered a wide range of investigations with limited cohesion. Significant risk factors for LBP in rowers included back pain history and prolonged ergometer use. Conclusion: A lack of consistent definitions within the studies caused fragmentation of the literature. There was good evidence for prolonged ergometer use and history of LBP to constitute risk factors and this may assist future LBP preventative action. Methodological issues such as small sample size and barriers to injury reporting increased heterogeneity and decreased data quality. Further exploration is required to determine the mechanism of LBP in rowers through research with larger samples.

Defining and measuring objective and subjective spinal stiffness: a scoping review.

PURPOSE: Examine and identify the breadth of definitions and measures of objective and subjective spinal stiffness in the literature, with a focus on clinical implications. METHODS: A scoping review was conducted to determine what is known about definitions and measures of the specific term of spinal stiffness. Following the framework by Arksey and O'Malley, eligible peer-reviewed studies identified using PubMed, Ebsco health, and Scopus were included if they reported definitions or measures of spinal stiffness. Using a data abstraction form, the studies were classified into four themes: biomechanical, surgical, pathophysiological, and segmental spinal assessment. To identify similarities and differences between studies, sixteen categories were generated. RESULTS: In total, 2426 records were identified, and 410 met the eligibility criteria. There were 350 measures (132 subjective; 218 objective measures) and 93 indicators of spinal stiffness. The majority of studies (n = 69%) did not define stiffness. CONCLUSION: This review highlights the breadth of objective and subjective measures that are both clinically and methodologically diverse. There is no consensus regarding a standardised definition of stiffness in the reviewed literature.

There is a need for a consensus definition of stiffness, as we did not find a consensus definition of stiffness in the reviewed literature.Definitions of stiffness should be included alongside self-reported or patient-reported outcome measures.There is a need to establish the relationship between subjective and objective measures in future studies.Clinicians should be aware that stiffness is a symptom that may indicate the presence of underlying pathophysiology.

Individualized Virtual Reality for Increasing Self-Compassion: Evaluation Study.

BACKGROUND: Depression and anxiety are common and debilitating mental disorders with severe negative repercussions at both individual and societal levels. Although virtual reality (VR) has emerged as a safe and effective tool for the treatment of anxiety disorders, studies of the therapeutic application of VR to treat depression are more limited. OBJECTIVE: The purpose of this study was to test whether a novel type of individualized VR (iVR) can be used to improve self-compassion and decrease depressive symptoms and to evaluate the usability and acceptability of this approach, as rated by participants. The iVR system was designed and developed based on the feedback obtained from a previous study, with improved appearance and feel of the avatar and enhanced graphical quality. METHODS: A total of 36 young adult participants were recruited from a university community social media site. Participants were aware that the study was investigating a treatment for depression but were not recruited based on depression diagnosis. Participants were asked to complete 2 iVR sessions, spaced 2 weeks apart. At baseline and upon completion of each iVR session, participants were asked to complete validated measures of self-compassion and depression. Upon completion of both iVR sessions, additional measures were administered to assess participants' perceptions about the perceived usability and system acceptability of the iVR approach. RESULTS: Self-compassion was assessed at the beginning of session 1 (preintervention baseline) and at the end of session 1 (postintervention assessment). Owing to COVID-19 constraints, 36% (13/36) of the participants were unable to complete the follow-up iVR session. Self-compassion was assessed again for the remaining 64% (23/36) of the participants at the end of session 2 (postintervention assessment). Within-group analyses revealed that self-compassion was significantly increased at the end of both session 1 (P=.01) and session 2 (P=.03) relative to baseline. There was also a nonsignificant trend for depressive symptoms to be low at the end of session 2 relative to baseline. Both quantitative and qualitative participant data supported the iVR approach as being acceptable and usable. CONCLUSIONS: Although these data must be treated as preliminary owing to the small sample size and potential selection bias, the data provide encouraging initial evidence that iVR might be a useful tool to enhance self-compassion and reduce depressive symptoms, highlighting the need for randomized controlled trials in the future.

Touching base: The effect of participant and stimulus modulation factors on a haptic line bisection task.

Acquiring information about our environment through touch is vital in everyday life. Yet very little literature exists about factors that may influence haptic or tactile processing. Recent neuroimaging studies have reported haptic laterality effects that parallel those reported in the visual literature. With the use of a haptic variant of the classical line bisection task, the present study aimed to determine the presence of laterality effects on a behavioural level. Specifically, three handedness groups including strong dextrals, strong sinistrals, and-the to-date largely neglected group of-mixed-handers were examined in their ability to accurately bisect stimuli constructed from corrugated board strips of various lengths. Stimulus factors known to play a role in visuospatial perception including stimulus location, the hand used for bisection, and direction of exploration were systematically varied through pseudo-randomisation. Similar to the visual domain, stimulus location and length as well as participants' handedness and the hand used for bisection exerted a significant influence on participants' estimate of the centre of haptically explored stimuli. However, these effects differed qualitatively from those described for the visual domain, and the factor direction of exploration did not exert any significant effect. This indicates that laterality effects reported on a neural level are sufficiently pronounced to result in measurable behavioural effects. The results, first, add to laterality effects reported for the visual and auditory domain, second, are in line with supramodal spatial processing and third, provide additional evidence to a conceptualisation of pseudoneglect and neglect as signs of hemispheric attentional asymmetries.

Hard and fast rules about the body: contributions of the action stream to judging body space.

Analogously to the visual system, somatosensory processing may be segregated into two streams, with the body constituting either part of the action system or a perceptual object. Experimental studies with participants free from neurological disease which test this hypothesis are rare, however. The present study explored the contributions of the two putative streams to a task that requires participants to estimate the spatial properties of their own body. Two manipulations from the visuospatial literature were included. First, participants were required to point either backward towards pre-defined landmarks on their own body (egocentric reference frame) or to a forward projection of their own body (allocentric representation). Second, a manipulation of movement mode was included, requiring participants to perform pointing movements either immediately, or after a fixed delay, following instruction. Results show that accessing an allocentric representation of one's own body results in performance changes. Specifically, the spatial bias shown to exist for body space when pointing backward at one's own body disappears when participants are requested to mentally project their body to a pre-defined location in front space. Conversely, delayed execution of pointing movements does not result in performance changes. Altogether, these findings provide support for a constrained dual stream hypothesis of somatosensory processing and are the first to show similarities in the processing of body space and peripersonal space.

Sinistrals' upper hand: evidence for handedness differences in the representation of body space.

A difference in the perception of extrapersonal space has been shown to exist between dextrals and sinistrals. On the classical line bisection task, this difference is evident in a greater left bias for dextrals compared to sinistrals. Different modalities and regions of space can be affected. However, it has not yet been investigated whether a systematic bias also exists for the perception of personal or body space. We investigated this by using three tasks which assess different aspects of personal space in an implicit and explicit way. These tasks were performed by strongly right-handed (dextrals), strongly left-handed (sinistrals) and mixed-handed participants. First, a task of pointing to three areas of one's own body without the use of visual information showed dextrals to have an asymmetric estimation of their body. In right hemispace, dextrals' pointing was at a greater distance from the midsagittal plane compared to pointing in left hemispace. No such asymmetry was present for sinistrals, while mixed-handers' performance was intermediate to that of strong right- and strong left-handers. Second, a task of recovering circular patches from their body surface whilst blindfolded also showed superior performance of sinistrals compared to dextrals. On these two tasks, there was also a moderate relationship between handedness scores and performance measures. Third, a computer-based task of adjusting scaled body-outline-halves showed no handedness differences. Overall, these findings suggest handedness differences in the implicit but not explicit representation of one's own body space. Possible mechanisms underlying the handedness differences shown for the implicit tasks are a stronger lateralization or a greater activation imbalance for dextrals and/or greater access to right hemispheric functions, such as an "up-to-date body" representation, by sinistrals. In contrast, explicit measures of how body space is represented may not be affected due to their relying on a different processing pathway.

Effect of acute experimental hand pain on left-right discrimination response latency for hand recognition.

Background: Recent work has indicated that acute experimental pain affects left-right discrimination latency. This phenomenon highlights an effect of pain on the cortex that may have significant clinical importance in the form of pain state assessment. However, to date only limited study has further qualified this effect. A more thorough understanding of the magnitude and characteristics of this phenomenon is needed to determine its potential clinical utility. Objective: This study aimed to closely replicate previous studies investigating response latency changes for left-right discrimination judgements as a result of acute experimental pain. Methods: Twenty-two right-handed participants (n = 11 female, n = 11 male) free from pain, analgesia use, pain-related conditions, upper limb trauma/conditions, visual impairment, and dyslexia took part in this study. Participants completed a hand left-right discrimination judgement task before, during, and after an experimental pain stimulus was delivered to each hand separately. Experimental pain was achieved using an intramuscular injection of hypertonic (5%) saline into the thenar eminence of the left and right hands. Mean response times for the left-right discrimination task were determined and compared for pain location (right, left), pain condition (before, during, after), and image laterality (right, left). Pain intensity was rated at 20 s intervals during each left-right discrimination task. Results: A main effect of pain condition (p = 0.028) confirmed that pain intensity was significantly higher in the "during pain" condition compared to the "before pain" and "after pain" conditions. A main effect of image laterality (p = 0.002) further showed that response latency for right-hand pain was significantly shorter compared to left-hand pain. No significant interaction between the factors pain location and image laterality (p = 0.086) was found. For right-hand pain, response latencies for the unaffected hand were, however, descriptively greater compared to the affected hand, and this was not the case for left-hand pain. Furthermore, no main effect of pain stimulus or of pain location on response times was found (p = 1.00 and p = 0.202, respectively). Conclusion: Our results were not consistent with previous hand left-right discrimination response latency results and may cast doubt on the attentional bias hypothesis that is currently considered to underpin response latency changes during acute experimental hand pain. Individual responses to pain, subsets of participants, and differing mental rotation strategies during the left-right discrimination task may have influenced the results.

Behavioural activation and inhibition systems in relation to pain intensity and duration in a sample of people experiencing chronic musculoskeletal pain.

BACKGROUND: There is potential clinical utility in tailoring patients' pain management based on behavioural tendencies. Previous work demonstrates a link between behavioural approach/inhibition and pain experience. OBJECTIVES: To investigate the relationship of pain intensity and duration with behavioural activation and inhibition tendencies and fear-avoidance beliefs, kinesiophobia, and disability, in a sample group (n = 709) reporting chronic musculoskeletal pain. METHODS: Regression analyses assessed the predictive value of these variables on pain intensity and on pain duration. Differences in behavioural tendencies between groups reporting high and low pain intensities were examined. RESULTS: Neither pain intensity nor pain duration were correlated with behavioural activation (BAS) and inhibition (BIS). Both pain intensity and duration were correlated with fear-avoidance beliefs (intensity p < .001, duration p = .005), kinesiophobia (intensity and duration both p < .001, and disability (intensity and duration both p < .001). There were significant positive relationships between pain intensity and fear-avoidance beliefs (p < .001), kinesiophobia (p = .021), and disability (p < .001), as well as positive relationships between pain duration and fear-avoidance (p = .543), kinesiophobia (p = .084) and disability (p = .002). Fear-avoidance beliefs, kinesiophobia and disability accounted for 31% of the variance in pain intensity. CONCLUSIONS: Neither BIS nor BAS significantly related to, or predicted pain intensity or duration. No differences in activation and inhibition tendencies were evident between high and low pain intensity groups. This study provides further support for the inter-relationships between fear-avoidance beliefs, kinesiophobia, disability and pain duration and intensity. No explicit support for behavioural links to pain were shown, however, this may be due to the measurement instrument rather than an invalid theory.

MoodJumper: An Exploration of Game Interface Preferences in Users With/Out Mood Disorder.

Mental health conditions pose a major challenge to healthcare providers and society at large. The World Health Organization predicts that by 2030 mental illnesses will be the leading disease burden globally. Mental health services are struggling to meet the needs of users and arguably fail to reach large proportions of those in need. According to New Zealand Mental Health Foundation, one in five will experience a serious mood disorder, including depression, at some time in their life. Games for Health including those supporting mental health have recently gained a lot of attention. However, game interface preferences for users with a history of mental health conditions have not been systematically studied, making it difficult to determine what game features may attract and further engage users affected by mental health conditions. We present MoodJumper, a prototype Android mobile game, which enables players to jump to the top of the level by steering the avatar from platform to platform, gradually gaining height and collecting coins on the way up. We conducted a preliminary study (n = 25), in which participants were able to modify different settings of the game (background color, dark/light, character movement, gender, and music), while their gaming behavior was tracked. The results show that regardless of self-reported history of mood disorder, the majority of participants prefer the dark and colored layout setting and there were no differences in gaming variables including session duration and high scores. This represents a first indication that history of mood disorder does not affect user preferences for game interface settings. It will be important to follow up with data on users currently affected by low mood. Systematic study of game interface preferences in users with mood disorder constitutes a vital step in being able to harness the potential power of games for supporting mental health.

Cerebral ischemic lesions on diffusion-weighted imaging are associated with neurocognitive decline after cardiac surgery.

BACKGROUND AND PURPOSE: Improvements in cardiac surgery mortality and morbidity have focused interest on the neurological injury such as stroke and cognitive decline that may accompany an otherwise successful operation. We aimed to investigate (1) the rate of stroke, new ischemic change on MRI, and cognitive impairment after cardiac valve surgery; and (2) the controversial relationship between perioperative cerebral ischemia and cognitive decline. METHODS: Forty patients (26 men; mean [SD] age 62.1 [13.7] years) undergoing intracardiac surgery (7 also with coronary artery bypass grafting) were studied. Neurological, neuropsychological, and MRI examinations were performed 24 hours before surgery and 5 days (MRI and neurology) and 6 weeks (neuropsychology and neurology) after surgery. Cognitive decline from baseline was determined using the Reliable Change Index. RESULTS: Two of 40 (5%) patients had perioperative strokes and 22 of 35 (63%) tested had cognitive decline in at least one measure (range, 1 to 4). Sixteen of 37 participants (43%) with postoperative imaging had new ischemic lesions (range, 1 to 17 lesions) with appearances consistent with cerebral embolization. Cognitive decline was seen in all patients with, and 35% of those without, postoperative ischemic lesions (P<0.001), and there was an association between the number of abnormal cognitive tests and ischemic burden (P<0.001). CONCLUSIONS: We have provided a reliable estimate of the rate of stroke, postoperative ischemia, and cognitive impairment at 6 weeks after cardiac valve surgery. Cognitive impairment is associated with perioperative ischemia and is more severe with greater ischemic load.

Characterizing cerebellar activity during autobiographical memory retrieval: ALE and functional connectivity investigations.

Previous neuroimaging research has shown that the cerebellum is often activated during autobiographical memory (AM) retrieval. However, the reliability of that activation, its localization within the cerebellum, and its relationship to other areas of the AM network remains unknown. The current study used Activation Likelihood Estimation meta-analysis (ALE) as well as resting-state and task-related functional connectivity analyses to better characterize cerebellar activation in relation to AM. The ALE meta-analysis was run on 32 neuroimaging studies of AM retrieval. The results revealed a cluster of reliable AM-related activity within the Crus I lobule of the right posterior cerebellum. Using the peak ALE coordinate within Crus I as a seed region, both task-related and resting state functional connectivity analyses were run on fMRI data from 38 healthy participants. To determine the specificity of connectivity patterns to Crus I, we also included a cerebellar seed region in right Lobule VI previously identified in an ALE meta-analysis as associated with working memory. Resting-state functional connectivity analyses indicated that Crus I was intrinsically connected with other areas of the AM network as well as surrounding and contralateral cerebellar regions. In contrast, the Lobule VI seed was functionally connected with cerebral and cerebellar regions typically associated with working memory. The task-related connectivity analyses revealed a similar pattern, where the Crus I seed exhibited significant connectivity with key nodes of the AM network while the Lobule IV seed did not. During a semantic control task, both Crus I and Lobule VI showed significant correlations with a network of regions that was largely distinct from the AM network. Together these results indicate that right Crus I lobule is reliably engaged during AM retrieval and is functionally connected to the AM network both during rest, and more importantly, during AM retrieval.

In (or outside of) your neck of the woods: laterality in spatial body representation.

Beside language, space is to date the most widely recognized lateralized systems. For example, it has been shown that even mental representations of space and the spatial representation of abstract concepts display lateralized characteristics. For the most part, this body of literature describes space as distal or something outside of the observer or actor. What has been strangely absent in the literature on the whole and specifically in the spatial literature until recently is the most proximal space imaginable - the body. In this review, we will summarize three strands of literature showing laterality in body representations. First, evidence of hemispheric asymmetries in body space in health and, second in body space in disease will be examined. Third, studies pointing to differential contributions of the right and left hemisphere to illusory body (space) will be summarized. Together these studies show hemispheric asymmetries to be evident in body representations at the level of simple somatosensory and proprioceptive representations. We propose a novel working hypothesis, whereby neural systems dedicated to processing action-oriented information about one's own body space may ontogenetically serve as a template for the perception of the external world.

Neural changes associated with the generation of specific past and future events in depression.

It is well established that individuals affected by depression experience difficulty in remembering the past and imagining the future. This impairment is evident in increased rumination on non-specific, generic events and in the generation of fewer specific events during tasks tapping past and future thinking. The present fMRI study investigated whether neural changes during the construction of autobiographical events was evident in depression, even when key aspects of performance (event specificity, vividness) were matched. We employed a multivariate technique (Spatiotemporal Partial Least Squares) to examine whether task-related whole brain patterns of activation and functional connectivity of the hippocampus differed between depressed participants and non-depressed controls. Results indicate that although the depression group retained the ability to recruit the default network during the autobiographical tasks, there was reduced activity in regions associated with episodic richness and imagery (e.g., hippocampus, precuneus, cuneus). Moreover, patterns of hippocampal connectivity in the depression group were comparable to those of the control group, but the strength of this connectivity was reduced in depression. These depression-related reductions were accompanied by increased recruitment of lateral and medial frontal regions in the depression group, as well as distinct patterns of right hippocampal connectivity with regions in the default and dorsal attention networks. The recruitment of these additional neural resources may reflect compensatory increases in post-retrieval processing, greater effort and/or greater self-related referential processing in depression that support the generation of specific autobiographical events.