Head-Down Tilt Position, but Not the Duration of Bed Rest Affects Resting State Electrocortical Activity

Adverse cognitive and behavioral conditions and psychiatric disorders are considered a critical and unmitigated risk during future long-duration space missions (LDSM). Monitoring and mitigating crew health and performance risks during these missions will require tools and technologies that allow to reliably assess cognitive performance and mental well-being. Electroencephalography (EEG) has the potential to meet the technical requirements for the non-invasive and objective monitoring of neurobehavioral conditions during LDSM. Weightlessness is associated with fluid and brain shifts, and these effects could potentially challenge the interpretation of resting state EEG recordings. Head-down tilt bed rest (HDBR) provides a unique spaceflight analog to study these effects on Earth. Here, we present data from two long-duration HDBR experiments, which were used to systematically investigate the time course of resting state electrocortical activity during prolonged HDBR. EEG spectral power significantly reduced within the delta, theta, alpha, and beta frequency bands. Likewise, EEG source localization revealed significantly lower activity in a broad range of centroparietal and occipital areas within the alpha and beta frequency domains. These changes were observed shortly after the onset of HDBR, did not change throughout HDBR, and returned to baseline after the cessation of bed rest. EEG resting state functional connectivity was not affected by HDBR. The results provide evidence for a postural effect on resting state brain activity that persists throughout long-duration HDBR, indicating that immobilization and inactivity per se do not affect resting state electrocortical activity during HDBR. Our findings raise an important issue on the validity of EEG to identify the time course of changes in brain function during prolonged HBDR, and highlight the importance to maintain a consistent body posture during all testing sessions, including data collections at baseline and recovery.

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Brain Connectivity and Behavioral Changes in a Spaceflight Analog Environment with Elevated CO2

10.1101/2020.09.28.317404 ◽

2020 ◽

Author(s):

Heather R. McGregor ◽

Jessica K. Lee ◽

Edwin R. Mulder ◽

Yiri E. De Dios ◽

Nichole E. Beltran ◽

...

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Time Course ◽

Brain Connectivity ◽

Space Station ◽

Bed Rest ◽

Ambient Air ◽

Control Group ◽

Resting State Functional Connectivity ◽

Sensorimotor Performance

ABSTRACTAstronauts are exposed to microgravity and elevated CO2 levels onboard the International Space Station. Little is known about how microgravity and elevated CO2 combine to affect the brain and sensorimotor performance during and after spaceflight. Here we examined changes in resting-state functional connectivity (FC) and sensorimotor behavior associated with a spaceflight analog environment. Participants underwent 30 days of strict 6° head-down tilt bed rest with elevated ambient CO2 (HDBR+CO2). Resting-state functional magnetic resonance imaging and sensorimotor assessments were collected 13 and 7 days prior to bed rest, on days 7 and 29 of bed rest, and 0, 5, 12, and 13 days following bed rest. We assessed the time course of FC changes from before, during, to after HDBR+CO2. We then compared the observed connectivity changes with those of a HDBR control group, which underwent HDBR in standard ambient air. Moreover, we assessed associations between post-HDBR+CO2 FC changes and alterations in sensorimotor performance. HDBR+CO2 was associated with significant changes in functional connectivity between vestibular, visual, somatosensory and motor brain areas. Several of these sensory and motor regions showed post-HDBR+CO2 FC changes that were significantly associated with alterations in sensorimotor performance. We propose that these FC changes reflect multisensory reweighting associated with adaptation to the HDBR+CO2 microgravity analog environment. This knowledge will further improve HDBR as a model of microgravity exposure and contribute to our knowledge of brain and performance changes during and after spaceflight.

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Long-duration head down bed rest as an analog of microgravity: Effects on the static perception of upright

Journal of Vestibular Research ◽

10.3233/ves-210016 ◽

2021 ◽

pp. 1-16

Author(s):

Laurence R. Harris ◽

Michael Jenkin ◽

Rainer Herpers

Keyword(s):

Character Recognition ◽

Visual Cues ◽

Time Course ◽

Critical Time ◽

Bed Rest ◽

Long Duration ◽

Visual Vertical ◽

Microgravity Conditions ◽

Line Test

BACKGROUND: Humans demonstrate many physiological changes in microgravity for which long-duration head down bed rest (HDBR) is a reliable analog. However, information on how HDBR affects sensory processing is lacking. OBJECTIVE: We previously showed (25) that microgravity alters the weighting applied to visual cues in determining the perceptual upright (PU), an effect that lasts long after return. Does long-duration HDBR have comparable effects? METHODS: We assessed static spatial orientation using the luminous line test (subjective visual vertical, SVV) and the oriented character recognition test (PU) before, during and after 21 days of 6° HDBR in 10 participants. Methods were essentially identical as previously used in orbit (25). RESULTS: Overall, HDBR had no effect on the reliance on visual relative to body cues in determining the PU. However, when considering the three critical time points (pre-bed rest, end of bed rest, and 14 days post-bed rest) there was a significant decrease in reliance on visual relative to body cues, as found in microgravity. The ratio had an average time constant of 7.28 days and returned to pre-bed-rest levels within 14 days. The SVV was unaffected. CONCLUSIONS: We conclude that bed rest can be a useful analog for the study of the perception of static self-orientation during long-term exposure to microgravity. More detailed work on the precise time course of our effects is needed in both bed rest and microgravity conditions.

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Lasting effects of a single psilocybin dose on resting-state functional connectivity in healthy individuals

Journal of Psychopharmacology ◽

10.1177/02698811211026454 ◽

2021 ◽

pp. 026988112110264

Author(s):

Drummond E-Wen McCulloch ◽

Martin Korsbak Madsen ◽

Dea Siggaard Stenbæk ◽

Sara Kristiansen ◽

Brice Ozenne ◽

...

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Clinical Symptoms ◽

Brain Connectivity ◽

Well Being ◽

Long Term Effects ◽

Resting State Functional Connectivity ◽

Positive Effects ◽

Personality Changes ◽

Psychedelic Drug

Background: Psilocybin is a psychedelic drug that has shown lasting positive effects on clinical symptoms and self-reported well-being following a single dose. There has been little research into the long-term effects of psilocybin on brain connectivity in humans. Aim: Evaluate changes in resting-state functional connectivity (RSFC) at 1 week and 3 months after one psilocybin dose in 10 healthy psychedelic-naïve volunteers and explore associations between change in RSFC and related measures. Methods: Participants received 0.2–0.3 mg/kg psilocybin in a controlled setting. Participants completed resting-state functional magnetic resonance imaging (fMRI) scans at baseline, 1-week and 3-month post-administration and [11C]Cimbi-36 PET scans at baseline and 1 week. We examined changes in within-network, between-network and region-to-region RSFC. We explored associations between changes in RSFC and psilocybin-induced phenomenology as well as changes in psychological measures and neocortex serotonin 2A receptor binding. Results: Psilocybin was well tolerated and produced positive changes in well-being. At 1 week only, executive control network (ECN) RSFC was significantly decreased (Cohen’s d = −1.73, pFWE = 0.010). We observed no other significant changes in RSFC at 1 week or 3 months, nor changes in region-to-region RSFC. Exploratory analyses indicated that decreased ECN RSFC at 1 week predicted increased mindfulness at 3 months ( r = −0.65). Conclusions: These findings in a small cohort indicate that psilocybin affects ECN function within the psychedelic ‘afterglow’ period. Our findings implicate ECN modulation as mediating psilocybin-induced, long-lasting increases in mindfulness. Although our findings implicate a neural pathway mediating lasting psilocybin effects, it is notable that changes in neuroimaging measures at 3 months, when personality changes are observed, remain to be identified.

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Effects of zolpidem on the EEG spectral power and resting state functional connectivity in patients with UWS

International Journal of Psychophysiology ◽

10.1016/j.ijpsycho.2016.07.328 ◽

2016 ◽

Vol 108 ◽

pp. 109

Author(s):

Laura Pérez ◽

Calixto Machado ◽

Valia Rodríguez ◽

Mario Estévez ◽

Mauricio Chinchilla

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Spectral Power ◽

Resting State Functional Connectivity ◽

Eeg Spectral Power

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Lasting effects of a single psilocybin dose on resting-state functional connectivity in healthy individuals

10.1101/2021.01.28.428377 ◽

2021 ◽

Author(s):

Drummond E-Wen McCulloch ◽

Martin Korsbak Madsen ◽

Dea Siggard Stenbæk ◽

Sara Kristiansen ◽

Brice Ozenne ◽

...

Keyword(s):

Functional Connectivity ◽

Resting State ◽

Clinical Symptoms ◽

Brain Connectivity ◽

Well Being ◽

Resting State Fmri ◽

Long Term Effects ◽

Resting State Functional Connectivity ◽

Positive Effects ◽

Personality Changes

ABSTRACTBackgroundPsilocybin is a psychedelic drug that has shown lasting positive effects on clinical symptoms and self-reported well-being following a single dose. There has been little research into the long-term effects of psilocybin on brain connectivity in humans.AimsEvaluate changes in resting-state functional connectivity (RSFC) at one-week and three-months after one psilocybin dose in 10 healthy psychedelic-naïve volunteers and explore associations between change in RSFC and related measures.MethodsParticipants received 0.2-0.3 mg/kg psilocybin in a controlled setting. Participants completed resting-state fMRI scans at baseline, one-week and three-months post-administration and [11C]Cimbi-36 PET scans at baseline and one-week. We examined changes in within-network, between-network and region-to-region RSFC. We explored associations between changes in RSFC and psilocybin-induced phenomenology as well as changes in psychological measures and neocortex serotonin 2A receptor binding.ResultsPsilocybin was well tolerated and produced positive changes in well-being. At one-week only, executive control network (ECN) RSFC was significantly decreased (Cohen’s d=-1.73, pFWE=0.010). We observed no other significant changes in RSFC at one-week or three-months, nor changes in region-to-region RSFC. Exploratory analyses indicated that decreased ECN RSFC at one-week predicted increased mindfulness at three-months (r =-0.65).ConclusionsThese findings in a small cohort indicate that psilocybin affects ECN function within the psychedelic “afterglow” period. Our findings implicate ECN modulation as mediating psilocybin-induced, long-lasting increases in mindfulness. Although our findings implicate a neural pathway mediating lasting psilocybin effects, it is notable that changes in neuroimaging measures at three-months, when personality changes are observed, remain to be identified.

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Hierarchical Heterogeneity Across Human Cortex Shapes Large-Scale Neural Dynamics

10.1101/341966 ◽

2018 ◽

Cited By ~ 5

Author(s):

Murat Demirtaş ◽

Joshua B. Burt ◽

Markus Helmer ◽

Jie Lisa Ji ◽

Brendan D. Adkinson ◽

...

Keyword(s):

Resting State ◽

Large Scale ◽

Spectral Power ◽

Resting State Functional Connectivity ◽

Human Cortex ◽

Cortical Organization ◽

Long Range Interactions ◽

Neuroimaging Data ◽

Local Properties ◽

Local Circuits

SummaryThe large-scale organization of dynamical neural activity across cortex emerges through long-range interactions among local circuits. We hypothesized that large-scale dynamics are also shaped by heterogeneity of intrinsic local properties across cortical areas. One key axis along which microcircuit properties are specialized relates to hierarchical levels of cortical organization. We developed a large-scale dynamical circuit model of human cortex that incorporates heterogeneity of local synaptic strengths, following a hierarchical axis inferred from MRI-derived T1w/T2w mapping, and fit the model using multimodal neuroimaging data. We found that incorporating hierarchical heterogeneity substantially improves the model fit to fMRI-measured resting-state functional connectivity and captures sensory-association organization of multiple fMRI features. The model predicts hierarchically organized high-frequency spectral power, which we tested with resting-state magnetoencephalography. These findings suggest circuit-level mechanisms linking spatiotemporal levels of analysis and highlight the importance of local properties and their hierarchical specialization on the large-scale organization of human cortical dynamics.

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Resting-state connectivity and its association with cognitive performance, educational attainment, and household income in UK Biobank (N = 3,950)

10.1101/164053 ◽

2017 ◽

Author(s):

Xueyi Shen ◽

Simon R Cox ◽

Mark J Adams ◽

David M Howard ◽

Stephen M Lawrie ◽

...

Keyword(s):

Educational Attainment ◽

Cognitive Ability ◽

Cognitive Performance ◽

Resting State ◽

Household Income ◽

Well Being ◽

Uk Biobank ◽

Resting State Functional Connectivity ◽

Numerical Reasoning ◽

Neuroimaging Data

AbstractCognitive ability is an important predictor of lifelong physical and mental well-being and its impairments are associated with many psychiatric disorders. Higher cognitive ability is also associated with greater educational attainment and increased household income. Understanding neural mechanisms underlying cognitive ability is therefore of crucial importance for determining the nature of these associations. In the current study, we examined the spontaneous activity of the brain at rest to investigate its relationships with not only cognitive ability, but also educational attainment and household income. We used a large sample of resting-state neuroimaging data from UK Biobank (N=3,950). Firstly, analysis at the whole-brain level showed that connections involving the default mode network (DMN), fronto-parietal network (FPN) and cingulo-opercular network (CON) were significantly positively associated with levels of cognitive performance assessed by a verbal-numerical reasoning test (standardised β ranged from 0.054 to 0.097). Connections associated with higher levels of cognitive performance were also significantly positively associated with educational attainment (r=0.48, N=4,160) and household income (r=0.38, N=3,793). Further, analysis on the coupling of functional networks showed that better cognitive performance was associated with more positive DMN-CON connections, decreased cross-hemisphere connections between homotopic network in CON and FPN, and stronger CON-FPN connections (absolute β ranged from 0.034 to 0.063). The present study finds that variation in brain resting state functional connectivity associated with individual differences in cognitive ability, largely involving DMN and lateral prefrontal networks. Additionally, we provide further evidence of shared neural associations of cognitive ability, educational attainment, and household income.

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Ophthalmic Changes in a Spaceflight Analog Are Associated with Brain Functional Reorganization

10.1101/2020.09.09.289827 ◽

2020 ◽

Author(s):

Heather R. McGregor ◽

Jessica K. Lee ◽

Edwin R. Mulder ◽

Yiri E. De Dios ◽

Nichole E. Beltran ◽

...

Keyword(s):

Functional Connectivity ◽

Optic Disc ◽

Resting State ◽

Large Scale ◽

Space Station ◽

Bed Rest ◽

Ambient Air ◽

Resting State Functional Connectivity ◽

Optic Disc Edema ◽

Disc Edema

ABSTRACTImportanceFollowing long-duration missions onboard the International Space Station, some astronauts develop ophthalmic abnormalities collectively referred to as Spaceflight Associated Neuro-ocular Syndrome (SANS). Optic disc edema is a common sign of SANS. SANS presents significant potential risk to astronaut health and performance; however, the origin and effects of SANS are not understood as signs of SANS have not manifested in previous spaceflight analog studies.ObjectiveTo investigate whether development of optic disc edema during a spaceflight analog impacts resting-state functional connectivity.Design, Setting and ParticipantsEleven healthy volunteers participated in this 58-day longitudinal study conducted at the :envihab facility at the German Aerospace Center.Interventions or ExposuresBaseline data were collected during a 14-day ambulatory phase in standard ambient air. All participants then underwent a spaceflight analog intervention: 30 days of strict head-down tilt bed rest in elevated ambient carbon dioxide (HDBR+CO2). The elevated CO2 level (0.5%) was matched to the hypercapnic environment of the International Space Station. The intervention was followed by a 14-day ambulatory recovery phase in standard ambient air. During the HDBR+CO2 spaceflight analog, 5 participants developed optic disc edema (SANS subgroup) and 6 did not (NoSANS group).Main Outcomes and MeasuresUsing functional magnetic resonance imaging (fMRI), we acquired resting-state data at 6 time points throughout the study: before (2), during (2), and after (2) the HDBR+CO2 intervention. We assessed the time course of resting-state functional connectivity changes from before, during, to after the HDBR+CO2, and contrasted longitudinal changes between the SANS and NoSANS subgroups. We also assessed if the SANS and NoSANS subgroups exhibited differential patterns of resting-state functional connectivity prior to the HDBR+CO2 intervention.ResultsThe SANS and NoSANS subgroups exhibited differential patterns of resting-state connectivity changes during the HDBR+CO2 spaceflight analog within visual and vestibular-related brain networks. We further found that the SANS and NoSANS subgroups exhibited differential resting-state brain activity prior to the spaceflight analog within a visual cortical network and within a large-scale network of brain areas involved in multisensory integration.Conclusions and RelevanceSubgroup differences in resting-state functional connectivity changes may reflect differential patterns of visual and vestibular reweighting as optic disc edema develops during the HDBR+CO2 spaceflight analog. This finding suggests that SANS impacts not only neuro-ocular structures, but also brain function. Future prospective investigations incorporating sensory assessments are required to determine the functional significance of the observed connectivity differences.KEY POINTSQuestionDoes optic disc edema development during head-down tilt bed rest with elevated carbon dioxide impact brain resting-state functional connectivity?FindingsA subset of participants developed optic disc edema during the head-down tilt bed rest intervention with elevated ambient CO2. Participants who developed optic disc edema exhibited a distinct pattern of resting-state functional connectivity changes within visual and vestibular-related networks during the spaceflight analog compared to participants who did not. Participants who developed optic disc edema exhibited different resting-state brain activity prior to the spaceflight analog within a visual cortical network and within a large-scale network of brain areas involved in multisensory integration.MeaningDevelopment of optic disc edema was associated with distinct patterns of brain resting-state functional connectivity during and prior to the spaceflight analog.

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