Geographical and economic influences on neuroimaging modality choice

The current neuroimaging literature is unrepresentative of the world’s population due to bias towards particular types of people living in a subset of geographical locations. This is true of both the people running the research and those participating in it. These biases mean we may be missing insights into how the brain works. As neuroimaging research expands out to more of the world, the reality of global economic disparities become salient. With economic conditions having an effect on many background conditions for research, we can ask whether they also influence the neuroimaging research being done. To investigate this, the number of neuroimaging publications originating from a country was used as a proxy for the type of research being done there in terms of imaging modalities employed. This was then related to local economic conditions, as represented by national gross domestic product and research and development spending. National financial metrics were positively associated with neuroimaging output. The imaging modalities used were also found to be associated with local economic conditions, with MRI research positively and EEG negatively associated with national research spending. These results suggest that economic conditions may be relevant when planning how neuroimaging research can be expanded globally.</p

Dimensions of interoception predict premonitory urges and tic severity in Tourette syndrome

Interoceptive processes in Tourette syndrome may foster the premonitory urges that commonly precede tics. Twenty-one adults with TS and 22 controls completed heartbeat tracking and discrimination tasks. Three dimensions of interoception were examined: objective accuracy, metacognitive awareness, and subjective (self-report) sensibility. Trait interoceptive prediction error was calculated as the discrepancy between accuracy and sensibility. Participants with TS had numerically lower interoceptive accuracy on the heartbeat tracking task, and increased self-reported interoceptive sensibility. While these group differences were not significant, the discrepancy between lower interoceptive accuracy and heightened sensibility, i.e. the trait interoceptive prediction error, was significantly greater in TS compared to controls. This suggests a heightened higher-order sensitivity to bodily sensations in TS, relative to a noisier perceptual representation of afferent bodily signals. Moreover, interoceptive sensibility predicted the severity of premonitory sensations and tics. This suggests interventions that work to align dimensions of interoceptive experience in TS hold therapeutic potential

Interoceptive accuracy predicts nonplanning trait impulsivity

Influential theories concerning personality argue that many impulsive individuals show physiological underarousal at rest. This interoceptive state is proposed to be egodystonic, motivating impulsive maladaptive actions to enhance arousal. However, there is little empirical research on this matter. The current study tested the relationship between physiological markers of arousal, measures of interoceptive (in)sensitivity, and trait impulsivity in a nonclinical sample of young adults. Experiment 1 investigated whether individuals (N = 31) with high trait impulsivity show decreased resting measures of arousal (indexed from heart rate, heart rate variability, and sympathetic electrodermal activity). Experiment 2 assessed whether trait impulsivity is linked to interoceptive abilities (N = 60). Overall, our results do not provide any compelling support for the underarousal theory of impulsivity. However, impaired interoceptive (cardiac discrimination) accuracy predicted the degree of Barratt nonplanning impulsivity, such that individuals with a better ability to distinguish between internal (bodily) and external signals manifest lower levels of nonplanning trait impulsivity. These findings open an avenue for potential novel interventions aimed at improving planning abilities via better interoceptive discrimination

Affective neural correlates in joint hypermobility and anxiety

IntroductionJoint hypermobility represents underlying variant connective tissue. Hypermobile individuals in addition to experiencing musculoskeletal issues, such as joint pain and stiffness, appear to be overly represented among people experiencing anxiety. This is the first study to explore in brain the relationship between clinical anxiety and joint hypermobility building on earlier work on healthy participants that implicates the amygdala and insula.MethodSixty-three participants including 30 participants with generalized anxiety disorder (GAD) and age and gender matched controls underwent fMRI. Eighteen patients with GAD and seven controls were classified as having Joint Hypermobility Syndrome (JHS) resulting in four groups. Participants were presented with angry, afraid, disgusted, neutral and happy faces and were asked to make an incidental judgement of whether they could see teeth or not.ResultsAnxious participants showed greater activity in the left amygdala and insula when viewing emotional faces compared to the non-anxious, as expected. Non-JHS participants showed greater activity in the inferior frontal gyrus, precuneus, pre-supplementary motor area, posterior and anterior cingulate gyrus and supramarginal gyrus compared to the JHS participants. In the JHS group, there was greater activation in the left amygdala, posterior insula and paracingulate gyrus in the anxious participants related to the non-anxious. Furthermore, within insula there was a significant interaction of degree of hypermobility on anxiety in that the hypermobility score correlated with insula activation in the anxious group, but not in the non-anxious participants. Functional connectivity changes when viewing emotional faces were examined through a series of psychophysiological interactions. JHS participants showed a greater psychophysiological interaction between the left amygdala and precuneus compared to non-JHS.DiscussionThese findings suggest a particular pattern of affective reactivity implicating emotional-processing brain regions such as the left amygdala and posterior insula in anxiety patients who have hypermobility and could provide further insight into personalised cognitive treatment targets.</p

Ten recommendations for reducing the carbon footprint of research computing in human neuroimaging

Given that scientific practices contribute to the climate crisis, scientists should reflect on the planetary impact of their work. Research computing can have a substantial carbon footprint in cases where researchers employ computationally expensive processes with large amounts of data. Analysis of human neuroimaging data, such as Magnetic Resonance Imaging brain scans, is one such case. Here, we consider ten ways in which those who conduct human neuroimaging research can reduce the carbon footprint of their research computing, by making adjustments to the ways in which studies are planned, executed, and analysed; as well as where and how data is stored.</p

Measuring and reducing the carbon footprint of fMRI preprocessing in fMRIPrep

Computationally expensive data processing in neuroimaging research places demands on energy consumption – and the resulting carbon emissions contribute to the climate crisis. We measured the carbon footprint of the fMRI preprocessing tool fMRIPrep, testing the effect of varying parameters on estimated carbon emissions and preprocessing performance. Performance was quantified using (a) statistical individual-level task activation in regions of interest and (b) mean smoothness of preprocessed data. Eight variants of fMRIPrep were run with 257 participants who had completed an fMRI stop signal task (the same data also used in the original validation of fMRIPrep). Some variants led to substantial reductions in carbon emissions without sacrificing data quality: for instance, disabling FreeSurfer surface reconstruction reduced carbon emissions by 48%. We provide six recommendations for minimising emissions without compromising performance. By varying parameters and computational resources, neuroimagers can substantially reduce the carbon footprint of their preprocessing. This is one aspect of our research carbon footprint over which neuroimagers have control and agency to act upon.</p

Elevated representational similarity of voluntary action and inhibition in Tourette syndrome

Many people with Tourette syndrome are able to volitionally suppress tics, under certain circumstances. To understand better the neural mechanisms that underlie this ability, we used functional magnetic resonance neuroimaging to track regional brain activity during performance of an intentional inhibition task. On some trials, Tourette syndrome and comparison participants internally chose to make or withhold a motor action (a button press), while on other trials, they followed 'Go' and 'NoGo' instructions to make or withhold the same action. Using representational similarity analysis, a functional magnetic resonance neuroimaging multivariate pattern analysis technique, we assessed how Tourette syndrome and comparison participants differed in neural activity when choosing to make or to withhold an action, relative to externally cued responses on Go and NoGo trials. Analyses were pre-registered, and the data and code are publicly available. We considered similarity of action representations within regions implicated as critical to motor action release or inhibition and to symptom expression in Tourette syndrome, namely the pre-supplementary motor area, inferior frontal gyrus, insula, caudate nucleus and primary motor cortex. Strikingly, in the Tourette syndrome compared to the comparison group, neural activity within the pre-supplementary motor area displayed greater representational similarity across all action types. Within the pre-supplementary motor area, there was lower response-specific differentiation of activity relating to action and inhibition plans and to internally chosen and externally cued actions, implicating the region as a functional nexus in the symptomatology of Tourette syndrome. Correspondingly, patients with Tourette syndrome may experience volitional tic suppression as an effortful and tiring process because, at the top of the putative motor decision hierarchy, activity within the population of neurons facilitating action is overly similar to activity within the population of neurons promoting inhibition. However, not all pre-supplementary motor area group differences survived correction for multiple comparisons. Group differences in representational similarity were also present in the primary motor cortex. Here, representations of internally chosen and externally cued inhibition were more differentiated in the Tourette syndrome group than in the comparison group, potentially a consequence of a weaker voluntary capacity earlier in the motor hierarchy to suppress actions proactively. Tic severity and premonitory sensations correlated with primary motor cortex and caudate nucleus representational similarity, but these effects did not survive correction for multiple comparisons. In summary, more rigid pre-supplementary motor area neural coding across action categories may constitute a central feature of Tourette syndrome, which can account for patients' experience of 'unvoluntary' tics and effortful tic suppression.</p

Understanding the mechanisms of fatigue in multiple sclerosis: linking interoception, metacognition and white matter dysconnectivity

One of the most prominent symptoms in multiple sclerosis(MS) is pathological fatigue, often described by sufferers as one of the most debilitating symptoms, affecting quality of life and employment. However, the mechanisms of both, physical and cognitive fatigue in multiple sclerosis remain elusive. Here we use behavioural tasks and quantitative MRI to investigate the neural correlates of interoception (the ability to sense internal bodily signals) and metacognition (the ability of the brain to assess its own performance), in modulating cognitive fatigue. Assuming that structural damage caused by MS pathology might impair the neural pathways subtending interoception and/or metacognition, we considered three alternative hypotheses to explain fatigue as a consequence of, respectively: 1) reduced interoceptive accuracy, 2) reduced interoceptive insight, or 3) reduced global metacognition. We then explored associations between these behavioural measures and white matter microstructure, assessed by diffusion and magnetization transfer MRI. Seventy-one relapsing-remitting MS patients participated in this cross-sectional study (mean age 43), 62% female. Patient outcomes relevant for fatigue were measured, including disability, disease duration, depression, anxiety, sleepiness, cognitive function, MS disease modifying treatment and quality of life. Interoceptive and metacognitive parameters were measured using heartbeat tracking and discrimination tasks, and metacognitive visual and memory tasks. MRI was performed in 69 participants, including diffusion tensor MRI, neurite orientation dispersion and density imaging and quantitative magnetization transfer. Associations between interoception and metacognition and the odds of high cognitive fatigue were tested by unconditional binomial logistic regression. The odds of cognitive fatigue were higher in the people with low interoceptive insight (p=0.03), while no significant relationships were found between MS fatigue and other interoceptive or metacognitive parameters, suggesting a specific impairment in interoceptive metacognition, rather than interoception generally, or metacognition generally. Diffusion MRI-derived fractional anisotropy and neurite density index showed significant (p<0.05) negative associations with cognitive fatigue in a widespread bilateral white matter network. Moreover, there was a significant (p<0.05) interaction between cognitive fatigue and interoceptive insight, suggesting that the poorer the white matter structure, the lower the interoceptive insight, and the worse the fatigue. 3 The results point towards metacognitive impairment confined to the interoceptive domain, in relapsing-remitting patients with cognitive fatigue. The neural basis of this impairment is supported by a widespread white matter network in which loss of neurite density plays a role. Key words: Multiple Sclerosis, cognitive fatigue, white matter, interoceptive insight, diffusion MRI Abbreviations: ASE=Allostatic self-efficacy; BICAMS = The Brief International Cognitive Assessment for MS; DMT = disease-modifying treatment; DT = diffusion tensor; EDSS = Expanded Disability Status Scale; ESS = Epworth Sleepiness Scale; FA = fractional anisotropy; FAMS = Functional Assessment in Multiple Sclerosis; FSL = FMRIB Software Library; FSS = fatigue Severity Scale; HADS-A = Hospital Anxiety and Depression Scale – Anxiety sub-domain; HADS-D = Hospital Anxiety and Depression Scale – Depression subdomain; HDT = heartbeat discrimination task; HTT = Heartbeat Tracking Task; ISO = isotropic compartment volume fraction; MD = mean diffusivity; MFIS = Modified Fatigue Impact Scale; MFIS-Tot = total MFIS; MFIS-Cog = cognitive MFIS; MFIS-phys = physical MFIS; MFISSoc = psychosocial MFIS; MRI = magnetic resonance imaging; MS = multiple sclerosis; MT = magnetization transfer; NDI = neurite density; NODDI = neurite orientation dispersion and density imaging; ODI = orientation dispersion; Q-Q = quantile-quantile; RRMS= relapsingremitting multiple sclerosis; TBSS = Tract-Based Spatial Statistics; TFCE = threshold-free cluster enhancement; VAS = visual analogue scale</p

How can we reduce the climate costs of OHBM? A vision for a more sustainable meeting

Climate change threatens the future of humanity. It will also significantly impede our ability to conduct science, by destabilising societies globally. Aviation, including travel to scientific conferences, generates a huge carbon footprint. This must be addressed if we are to limit global warming to the 1.5-2C mandated by the Paris agreement of the 2015 UN Climate Change Conference, and time is running very short: we are already at 1.2C of warming. This also means we must urgently transform the way we attend conferences. Although OHBM is only one medium-sized society, it is crucial to recognise that collective action has the power to change social norms, in science, and society more broadly. This has far-reaching consequences beyond the direct carbon savings of updating the meeting format. In this report, authored by the Sustainability and Environment Action Special Interest Group (SEA-SIG), we analysed the carbon footprint of previous Organisation for Human Brain Mapping (OHBM) meetings. On average, attendees travelling to an in-person meeting generate over 10,000 tonnes of carbon – as much as 1250 average German residents would emit over the course of one year (mean of 8t in 2021). Virtually all these emissions are eliminated when we meet online instead. The location of in-person meetings also matters: setting the meeting in a place that requires more colleagues to fly long-haul very significantly increases climate costs by up to three times as much as the lowest-carbon locations. We can do things differently, however. Hybrid meetings - accessible both in-person and online - are set to become the norm for academic societies around the world. Although driven by the COVID-19 pandemic, hybrid meetings should be here to stay, because of the many other benefits they bring to both accessibility and sustainability. There are also several other alternative meeting formats being explored by academic societies, such as a biennial meeting (every other year), and multiple regional hubs, in which attendees travel to their nearest geographical meeting location. Using aviation carbon footprint modelling, we calculated the carbon savings that OHBM would make under these future meeting formats. We also determined the most climate-friendly locations for in-person aspects of future meetings and the least climate-friendly places. As a result, we recommend that all future OHBM meetings are fully hybrid. We furthermore recommend that OHBM transitions to a multiple regional hub model (with hybrid attendance also supported), in locations specifically chosen to minimise long-distance aviation. We do not advocate carbon offsetting as a suitable alternative to tackling real-time and long-term reductions in aviation emissions. We conclude that updating the way OHBM meetings are run for a post-pandemic, climate-crisis-era will save thousands of tonnes of carbon and send a crucial sign at a time of climate emergency. Furthermore, setting the meeting in locations that minimise the need for long-distance flying is critical. Finally, supporting colleagues to attend online and more locally will enhance accessibility, furthering the society’s mission to provide educational forums for the exchange of groundbreaking neuroimaging research. Importantly, as a scientific community we are in an ideal position to lead by example and experiment with new ways of sharing knowledge, including the way we attend conferences