scholarly journals Change of cortical foot activation following 70 days of head-down bed rest

2018 ◽  
Vol 119 (6) ◽  
pp. 2145-2152 ◽  
Author(s):  
Peng Yuan ◽  
Vincent Koppelmans ◽  
Patricia Reuter-Lorenz ◽  
Yiri De Dios ◽  
Nichole Gadd ◽  
...  
Keyword(s):  
Neural Control ◽  
Balance Control ◽  
Brain Activity ◽  
Brain Activation ◽  
Bed Rest ◽  
Functional Mobility ◽  
Healthy Men ◽  
Control Subjects ◽  
Long Duration ◽  
Foot Tapping

Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to study some of the effects of microgravity on human physiology, cognition, and sensorimotor functions. Previous studies have reported declines in balance control and functional mobility after spaceflight and HDBR. In this study we investigated how the brain activation for foot movement changed with HDBR. Eighteen healthy men participated in the current HDBR study. They were in a 6° head-down tilt position continuously for 70 days. Functional MRI scans were acquired to estimate brain activation for foot movement before, during, and after HDBR. Another 11 healthy men who did not undergo HDBR participated as control subjects and were scanned at four time points. In the HDBR subjects, the cerebellum, fusiform gyrus, hippocampus, and middle occipital gyrus exhibited HDBR-related increases in activation for foot tapping, whereas no HDBR-associated activation decreases were found. For the control subjects, activation for foot tapping decreased across sessions in a couple of cerebellar regions, whereas no activation increase with session was found. Furthermore, we observed that less HDBR-related decline in functional mobility and balance control was associated with greater pre-to-post HDBR increases in brain activation for foot movement in several cerebral and cerebellar regions. Our results suggest that more neural control is needed for foot movement as a result of HDBR. NEW & NOTEWORTHY Long-duration head-down bed rest serves as a spaceflight analog research environment. We show that brain activity in the cerebellum and visual areas during foot movement increases from pre- to post-bed rest and then shows subsequent recovery. Greater increases were seen for individuals who exhibited less decline in functional mobility and balance control, suggestive of adaptive changes in neural control with long-duration bed rest.

Postural Reflexes, Balance Control, and Functional Mobility with Long-Duration Head-Down Bed Rest

2009 ◽  
Vol 80 (5) ◽  
pp. A45-A54 ◽  
Author(s):  
Millard F. Reschke ◽  
Jacob J. Bloomberg ◽  
William H. Paloski ◽  
Ajitkumar P. Mulavara ◽  
Alan H. Feiveson ◽  
...  
Keyword(s):  
Balance Control ◽  
Bed Rest ◽  
Functional Mobility ◽  
Postural Reflexes ◽  
Long Duration

Relation Between Level of Prefrontal Activity and Subject's Performance

1999 ◽  
Vol 13 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Laurence Casini ◽  
Françoise Macar ◽  
Marie-Hélène Giard
Keyword(s):  
Brain Activity ◽  
Sensory Information ◽  
Practice Phase ◽  
Trained Subjects ◽  
Anagram Task ◽  
Economic Information ◽  
Long Duration ◽  
Level Of Activity ◽  
The Brain ◽  
Processing Mechanism

Abstract The experiment reported here was aimed at determining whether the level of brain activity can be related to performance in trained subjects. Two tasks were compared: a temporal and a linguistic task. An array of four letters appeared on a screen. In the temporal task, subjects had to decide whether the letters remained on the screen for a short or a long duration as learned in a practice phase. In the linguistic task, they had to determine whether the four letters could form a word or not (anagram task). These tasks allowed us to compare the level of brain activity obtained in correct and incorrect responses. The current density measures recorded over prefrontal areas showed a relationship between the performance and the level of activity in the temporal task only. The level of activity obtained with correct responses was lower than that obtained with incorrect responses. This suggests that a good temporal performance could be the result of an efficacious, but economic, information-processing mechanism in the brain. In addition, the absence of this relation in the anagram task results in the question of whether this relation is specific to the processing of sensory information only.

CLINICAL EVALUATION OF THE THYROID STIMULATING HORMONE ACTIVITY IN EXOPHTHALMOS

1961 ◽  
Vol 38 (4) ◽  
pp. 577-584 ◽  
Author(s):  
Sven Erik Björkman ◽  
Torsten Denneberg ◽  
Inge Hedenskog
Keyword(s):  
Clinical Evaluation ◽  
Thyroid Stimulating Hormone ◽  
Significant Rise ◽  
Hormone Activity ◽  
Control Subjects ◽  
Long Duration ◽  
Stimulating Factor ◽  
Stimulating Hormone

ABSTRACT A method for demonstrating the presence of a thyroid stimulating factor in the blood of patients with progressive exophthalmos after thyroidectomy or after treatment with radioiodine is described. The method consists of transfusing freshly drawn blood from the patients to euthyroid recipients and subsequently following the PBI level of the recipients at regular intervals. Six exophthalmic patients tested in this manner were found to have such a factor in their circulating blood. After transfusion of their blood a significant rise in the PBI level of the recipients could be demonstrated. Two other patients, one with exophthalmos of long duration did not show this response nor did it occur after transfusion of blood from two control subjects. In one case the action of this factor was compared with that of animal thyrotrophin and found to be of the same magnitude.

scholarly journals Association Between Brain Activation and Functional Connectivity

2018 ◽  
Vol 29 (5) ◽  
pp. 1984-1996 ◽  
Author(s):  
Dardo Tomasi ◽  
Nora D Volkow
Keyword(s):  
Functional Connectivity ◽  
Brain Activity ◽  
Low Frequency ◽  
Brain Activation ◽  
Blood Oxygen Level Dependent ◽  
Common Source ◽  
Functional Connectivity Density ◽  
Density Mapping ◽  
Human Connectome Project ◽  
Bold Responses

Abstract The origin of the “resting-state” brain activity recorded with functional magnetic resonance imaging (fMRI) is still uncertain. Here we provide evidence for the neurovascular origins of the amplitude of the low-frequency fluctuations (ALFF) and the local functional connectivity density (lFCD) by comparing them with task-induced blood-oxygen level dependent (BOLD) responses, which are considered a proxy for neuronal activation. Using fMRI data for 2 different tasks (Relational and Social) collected by the Human Connectome Project in 426 healthy adults, we show that ALFF and lFCD have linear associations with the BOLD response. This association was significantly attenuated by a novel task signal regression (TSR) procedure, indicating that task performance enhances lFCD and ALFF in activated regions. We also show that lFCD predicts BOLD activation patterns, as was recently shown for other functional connectivity metrics, which corroborates that resting functional connectivity architecture impacts brain activation responses. Thus, our findings indicate a common source for BOLD responses, ALFF and lFCD, which is consistent with the neurovascular origin of local hemodynamic synchrony presumably reflecting coordinated fluctuations in neuronal activity. This study also supports the development of task-evoked functional connectivity density mapping.

Perilymph Fistulas

1978 ◽  
Vol 87 (6) ◽  
pp. 797-803 ◽  
Author(s):  
George T. Singleton ◽  
Kathryn Nolan Post ◽  
Marc Simeon Karlan ◽  
Douglas G. Bock
Keyword(s):  
Discriminant Analysis ◽  
Effective Means ◽  
Bed Rest ◽  
Sudden Onset ◽  
Effective Control ◽  
Speech Discrimination ◽  
Mean Values ◽  
Long Duration ◽  
History Of ◽  
Physical Findings

Fifty-one patients suspected of having a perilymph fistula were evaluated. We postulated that many patients with predominantly vestibular complaints had unrecognized perilymph fistulas. An analysis was made of symptoms, physical findings, vestibular and audiometric test results in order to determine appropriate diagnostic criteria for the presence of perilymph fistulas. The patient population was divided into two groups, those with and without fistulas. Data from both groups were compared by mean values of variables, step-wise discriminant analysis, and factor analysis. A history of trauma with sudden onset of dizziness and/or hearing loss should alert the physician to a fistula. Findings of significance were positional nystagmus of short latency and long duration without import of nystagmus direction, canal paresis and reduced speech reception threshold with poor speech discrimination scores. Discriminant analysis correctly classified 19 fistula and 10 nonfistula cases explored operatively and identified two error judgments in 22 nonoperated cases. Bed rest for the first five days proved to be the most effective means of therapy. Surgical intervention with repair of the fistula by perichondrial graft provided effective control of vertigo more frequently than restoration of hearing.

scholarly journals Interpersonal Synchrony Special Issue The role of anterior prefrontal cortex (area 10) in face-to-face deception measured with fNIRS

2020 ◽  
Author(s):  
Paola Pinti ◽  
Andrea Devoto ◽  
Isobel Greenhalgh ◽  
Ilias Tachtsidis ◽  
Paul W Burgess ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Near Infrared ◽  
Brain Activity ◽  
Lie Detection ◽  
Brain Activation ◽  
Functional Near Infrared Spectroscopy ◽  
Face To Face ◽  
Interpersonal Synchrony ◽  
Anterior Prefrontal Cortex

Abstract Anterior prefrontal cortex (PFC, Brodmann area 10) activations are often, but not always, found in neuroimaging studies investigating deception, and the precise role of this area remains unclear. To explore the role of the PFC in face-to-face deception, we invited pairs of participants to play a card game involving lying and lie detection while we used functional near infrared spectroscopy (fNIRS) to record brain activity in the PFC. Participants could win points for successfully lying about the value of their cards or for detecting lies. We contrasted patterns of brain activation when the participants either told the truth or lied, when they were either forced into this or did so voluntarily and when they either succeeded or failed to detect a lie. Activation in the anterior PFC was found in both lie production and detection, unrelated to reward. Analysis of cross-brain activation patterns between participants identified areas of the PFC where the lead player’s brain activity synchronized their partner’s later brain activity. These results suggest that during situations that involve close interpersonal interaction, the anterior PFC supports processing widely involved in deception, possibly relating to the demands of monitoring one’s own and other people’s behaviour.

scholarly journals Long-term bedrest study and astronaut training

2016 ◽  
Author(s):  
Edwin Mulder ◽  
Alexandra Noppe ◽  
Ulrich Limper
Keyword(s):  
Bed Rest ◽  
Dual Purpose ◽  
Planetary Environments ◽  
Exercise Regimen ◽  
Long Duration ◽  
Astronaut Training ◽  
Health Support ◽  
Art Research ◽  
Induced Changes

In the context of space physiology, research is being conducted to understand the physiological effects from radiation, hypogravity, spaceflight and planetary environments. The goal is to identify new methods to address the unique challenges in medical treatment, human factors, and behavioral health support on future exploration missions. As crew size is small and time is limited during actual missions, space agencies resort to addressing the effects of space travel in analog environments that have features similar to those of spaceflight. Head-down tilt bed rest (HDBR), for instance, is one of the established terrestrial models used to simulate some of the physiological changes experienced during spaceflight under weightless conditions and is therefore considered a valuable testbed to prepare for future long-duration exploration missions. HDBR studies are performed in extremely-well controlled laboratory settings, offering the possibility to test the effects of – what is in essence - physical inactivity and fluid shift. However, HDBR studies have a dual purpose, as they are also invaluable for the development, testing and validation of countermeasures aimed at mitigating microgravity-induced changes to the human body. With respect to the latter, the consensus is that short-term bed rest studies (< 14 days) serve foremost as a first screening of potential promising countermeasures, particularly for the cardiovascular system. Screening of preventative procedures and protocols for the muscular system requires at least mid-term (14 -28 days), whereas studies aiming to validate countermeasures for bone require long-term HDBR studies, in the order of 60-90 days. Hitherto the preferred countermeasure during spaceflight has been physical exercise. The presentation will therefore provide a short overview of the current onboard exercise regimen and will, in light of this, outline the scientific background and aims of the ongoing 60-day HDBR study at the :envihab (from the words ‘Environment’ and ‘Habitat’), the DLR Institute of Aerospace Medicine’s state-of-the-art research facility.

scholarly journals Decreased otolith-mediated vestibular response in 25 astronauts induced by long-duration spaceflight

2016 ◽  
Vol 115 (6) ◽  
pp. 3045-3051 ◽  
Author(s):  
Emma Hallgren ◽  
Ludmila Kornilova ◽  
Erik Fransen ◽  
Dmitrii Glukhikh ◽  
Steven T. Moore ◽  
...  
Keyword(s):  
Orthostatic Intolerance ◽  
Balance Control ◽  
Head Tilt ◽  
Otolith Organs ◽  
Negative Effects ◽  
Spatial Disorientation ◽  
Long Duration ◽  
Before And After ◽  
Ocular Counterrolling ◽  
Otolith System

The information coming from the vestibular otolith organs is important for the brain when reflexively making appropriate visual and spinal corrections to maintain balance. Symptoms related to failed balance control and navigation are commonly observed in astronauts returning from space. To investigate the effect of microgravity exposure on the otoliths, we studied the otolith-mediated responses elicited by centrifugation in a group of 25 astronauts before and after 6 mo of spaceflight. Ocular counterrolling (OCR) is an otolith-driven reflex that is sensitive to head tilt with regard to gravity and tilts of the gravito-inertial acceleration vector during centrifugation. When comparing pre- and postflight OCR, we found a statistically significant decrease of the OCR response upon return. Nine days after return, the OCR was back at preflight level, indicating a full recovery. Our large study sample allows for more general physiological conclusions about the effect of prolonged microgravity on the otolith system. A deconditioned otolith system is thought to be the cause of several of the negative effects seen in returning astronauts, such as spatial disorientation and orthostatic intolerance. This knowledge should be taken into account for future long-term space missions.

scholarly journals Towards Using the Instrumented Timed Up-and-Go Test for Screening of Sensory System Performance for Balance Control in Older Adults

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 622 ◽  
Author(s):  
Thomas Gerhardy ◽  
Katharina Gordt ◽  
Carl-Philipp Jansen ◽  
Michael Schwenk
Keyword(s):  
Older Adults ◽  
System Performance ◽  
Fall Risk ◽  
Balance Control ◽  
Sensory System ◽  
Sensory Systems ◽  
Community Dwelling ◽  
Functional Mobility ◽  
Timed Up And Go ◽  
Community Dwelling Older Adults

Background: Decreasing performance of the sensory systems’ for balance control, including the visual, somatosensory and vestibular system, is associated with increased fall risk in older adults. A smartphone-based version of the Timed Up-and-Go (mTUG) may allow screening sensory balance impairments through mTUG subphases. The association between mTUG subphases and sensory system performance is examined. Methods: Functional mobility of forty-one community-dwelling older adults (>55 years) was measured using a validated mTUG. Duration of mTUG and its subphases ‘sit-to-walk’, ‘walking’, ‘turning’, ‘turn-to-sit’ and ‘sit-down’ were extracted. Sensory systems’ performance was quantified by validated posturography during standing (30 s) under different conditions. Visual, somatosensory and vestibular control ratios (CR) were calculated from posturography and correlated with mTUG subphases. Results: Vestibular CR correlated with mTUG total time (r = 0.54; p < 0.01), subphases ‘walking’ (r = 0.56; p < 0.01), and ‘turning’ (r = 0.43; p = 0.01). Somatosensory CR correlated with mTUG total time (r = 0.52; p = 0.01), subphases ‘walking’ (r = 0.52; p < 0.01) and ‘turning’ (r = 0.44; p < 0.01). Conclusions: Supporting the proposed approach, results indicate an association between specific mTUG subphases and sensory system performance. mTUG subphases ‘walking’ and ‘turning’ may allow screening for sensory system deterioration. This is a first step towards an objective, detailed and expeditious balance control assessment, however needing validation in a larger study.

scholarly journals Head-down tilt bed rest with or without artificial gravity is not associated with motor unit remodeling

2020 ◽  
Vol 120 (11) ◽  
pp. 2407-2415 ◽  
Author(s):  
Julia Attias ◽  
Andrea Grassi ◽  
Alessandra Bosutti ◽  
Bergita Ganse ◽  
Hans Degens ◽  
...  
Keyword(s):  
Motor Unit ◽  
Compound Muscle Action Potential ◽  
Bed Rest ◽  
Artificial Gravity ◽  
Whole Body ◽  
Healthy Individuals ◽  
Long Duration ◽  
Muscle Action Potential ◽  
Abductor Digiti Minimi ◽  
Healthy Participants

Abstract Purpose The objective of this study was to assess whether artificial gravity attenuates any long-duration head-down 60 bed rest (HDBR)-induced alterations in motor unit (MU) properties. Methods Twenty-four healthy participants (16 men; 8 women; 26–54 years) underwent 60-day HDBR with (n = 16) or without (n = 8) 30 min artificial gravity daily induced by whole-body centrifugation. Compound muscle action potential (CMAP), MU number (MUNIX) and MU size (MUSIX) were estimated using the method of Motor Unit Number Index in the Abductor digiti minimi and tibialis anterior muscles 5 days before (BDC-5), and during day 4 (HDT4) and 59 (HDT59) of HDBR. Results The CMAP, MUNIX, and MUSIX at baseline did not change significantly in either muscle, irrespective of the intervention (p > 0.05). Across groups, there were no significant differences in any variable during HDBR, compared to BDC-5. Conclusion Sixty days of HDBR with or without artificial gravity does not induce alterations in motor unit number and size in the ADM or TA muscles in healthy individuals.

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