Horizontal-Plane Arm Movements With Direction Reversals Performed by Normal Individuals and Individuals With Down Syndrome

2000 ◽  
Vol 84 (4) ◽  
pp. 1949-1960 ◽  
Author(s):  
Gil Lúcio Almeida ◽  
Daniel M. Corcos ◽  
Ziaul Hasan
Keyword(s):  
Down Syndrome ◽  
Horizontal Plane ◽  
Target Location ◽  
Arm Movements ◽  
Normal Subjects ◽  
Interaction Torque ◽  
Joint Torques ◽  
Normal Individuals ◽  
Neurologically Normal ◽  
Target Locations

We examined the systematic variation in shoulder and elbow torque, as well as movement kinematics, for horizontal-plane arm movements with direction reversals performed by normal individuals and individuals with Down syndrome. Eight neurologically normal individuals and eight individuals with Down syndrome performed horizontal, planar reversal movements to four different target locations. The four locations of the targets were chosen such that there is a systematic increase in elbow interaction torque for each of the four different target locations. This systematic increase in interaction torque has previously been shown to lead to progressively larger movement reversal errors, and trajectories that do not show a sharp reversal of direction, for movements to and from the target in patients who have proprioceptive abnormalities. We computed joint torques at the elbow and shoulder and found a high correlation between elbow and shoulder torque for the neurologically normal subjects. The ratio of joint torques varied systematically with target location. These findings extend previously reported findings of a linear synergy between shoulder and elbow joints for a variety of point-to-point movements. There was also a correlation between elbow and shoulder torque in individuals with Down syndrome, but the magnitude of the correlation was less. The ratio of joint torques changed systematically with target direction in individuals with Down syndrome but was slightly different from the ratio observed for neurologically normal individuals. The difference in the ratio was caused by the generation of proportionately more elbow torque than shoulder torque. The fingertip path of individuals with Down syndrome showed a sharp reversal in moving toward and then away from the target. In this respect, they were similar to neurologically normal individuals but dissimilar to individuals with proprioceptive deficits. Finally, we observed that individuals with Down syndrome spend proportionately more time in the vicinity of the target than normal individuals. Collectively these results show that there is a systematic relationship between joint torques at the elbow and shoulder. This relationship is present for reversal movements and is also present in individuals with Down syndrome.

Probability Cuing of Target Location Facilitates Visual Search Implicitly in Normal Participants and Patients with Hemispatial Neglect

2002 ◽  
Vol 13 (6) ◽  
pp. 520-525 ◽  
Author(s):  
Joy J. Geng ◽  
Marlene Behrmann
Keyword(s):  
Visual Search ◽  
Target Location ◽  
Hemispatial Neglect ◽  
Probability Matching ◽  
Response Facilitation ◽  
Normal Individuals ◽  
Probability Cuing ◽  
Target Locations ◽  
Contralesional Side ◽  
Do So

We explored how variability in the probability of target locations affects visual search in normal individuals and in patients with hemispatial neglect, a deficit in attending to the contralesional side of space. Young and elderly normal participants responded faster when targets appeared in the more probable region than when targets appeared in the less probable region. Similarly, patients were sensitive to the distribution of targets, even in the neglected field. Although the attentional gradient that characterizes neglect was not eliminated, the response facilitation due to the probability distribution was proportionate to that of control participants and equal in magnitude across the neglected field. All participants exploited the uneven distribution of targets to enhance task performance without explicit instructions to do so or awareness of biases in their behavior. These results suggest that attentional orientation and sensitivity to external probabilities are possibly dissociable. An early sensory and a late motor mechanism are postulated as possibly being involved in the observed probability-matching behavior of participants.

scholarly journals The Role of Age on Beta-Amyloid1–42 Plasma Levels in Healthy Subjects

2021 ◽  
Vol 13 ◽  
Author(s):  
Chiara Zecca ◽  
Giuseppe Pasculli ◽  
Rosanna Tortelli ◽  
Maria Teresa Dell’Abate ◽  
Rosa Capozzo ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Hematological Parameters ◽  
Multivariable Analysis ◽  
Age Groups ◽  
Normal Subjects ◽  
Normal Individuals ◽  
Amyloid Aβ ◽  
Neurologically Normal ◽  
Post Hoc

Beta-amyloid (Aβ) plaques have been observed in the brain of healthy elderlies with frequencies strongly influenced by age. The aim of the study is to evaluate the role of age and other biochemical and hematological parameters on Aβ1–42 plasma levels in cognitively and neurologically normal individuals. Two-hundred and seventy-five normal subjects stratified by age groups (<35 years, 35–65 years, and >65 years) were included in the study. Aβ1–42 plasma levels significantly correlated with age (rs = 0.27; p < 0.0001) in the whole sample, inversely correlated with age in the first age group (rs = −0.25, p = 0.01), positively correlated in the second group (rs = 0.22, p = 0.03), while there was no significant correlation in the older group (rs = 0.02, p = 0.86). Both age (β-estimate = 0.08; p < 0.001) and cholesterol (β-estimate = 0.03; p = 0.009) were significantly associated with Aβ1–42 plasma level in multivariable analysis. However, only the association with age survived post hoc adjustment for multiple comparisons. The different effects of age on the Aβ level across age groups should be explored in further studies to better understand the age-dependent variability. This could better define the value of plasma Aβ as a biomarker of the Alzheimer neuropathology.

Auditory Selective Attention in Cerebral-Palsied Individuals

1985 ◽  
Vol 16 (4) ◽  
pp. 260-266 ◽  
Author(s):  
Lee Ann Laraway
Keyword(s):  
Selective Attention ◽  
White Noise ◽  
Normal Subjects ◽  
Auditory Selective Attention ◽  
Normal Individuals ◽  
Significant Difference

The purpose of this study was to determine whether there is a statistically significant difference between the auditory selective attention abilities of normal and cerebral-palsied individuals. Twenty-three cerebral-palsied and 23 normal subjects between the ages of 5 and 21 were asked to repeat a series of 30 items consisting of from 2 to 4 digits in the presence of intermittent white noise. Results of the study indicate that cerebral-palsied individuals perform significantly poorer than normal individuals when the stimulus is accompanied by noise. Noise was not a significant factor in the performance of the normal subjects regardless of age.

scholarly journals Aging Is Positively Associated with Peri-Sinus Lymphatic Space Volume: Assessment Using 3T Black-Blood MRI

2020 ◽  
Vol 9 (10) ◽  
pp. 3353
Author(s):  
Mina Park ◽  
Jin Woo Kim ◽  
Sung Jun Ahn ◽  
Yoon Jin Cha ◽  
Sang Hyun Suh
Keyword(s):  
Normal Subjects ◽  
The Elderly ◽  
Cancer Staging ◽  
Elderly Group ◽  
Black Blood ◽  
Intracranial Volume ◽  
Contrast Enhanced ◽  
Neurologically Normal ◽  
N 93 ◽  
Space Volume

Objectives: Aging is a major risk factor for many neurological disorders and is associated with dural lymphatic dysfunction. We sought to evaluate the association of aging with the volume of the peri-sinus lymphatic space using contrast-enhanced 3T T1-weighted black-blood magnetic resonance imaging (MRI). Methods: In this retrospective study, 165 presumed neurologically normal subjects underwent brain MRIs for cancer staging between April and November 2018. The parasagittal peri-sinus lymphatic space was evaluated using contrast-enhanced 3D T1-weighted black-blood MRIs, and volumes were measured with semiautomatic method. We compared the volumes of normalized peri-sinus lymphatic spaces between the elderly (≥65 years, n = 72) and non-elderly (n = 93) groups and performed multivariate logistic regression analyses to assess if aging is independently associated with the volume of normalized peri-sinus lymphatic spaces. Results: The normalized peri-sinus lymphatic space volume was significantly higher in the elderly than in the non-elderly (mean, 3323 ± 758.7 mL vs. 2968.7 ± 764.3 mL, p = 0.047). After adjusting the intracranial volume, age age was the strongest factor independently associated with peri-sinus lymphatic space volume (β coefficient, 28.4 (5.7–51.2), p = 0.015) followed by male sex (β coefficient, 672.4 (113.5–1230.8), p = 0.019). Conclusions: We found that the peri-sinus dural lymphatic space volume was higher in the elderly group than in the non-elderly group, and the increased peri-sinus lymphatic space was independently associated with aging. These findings indicate that the peri-sinus lymphatic space may be related with the aging process and lymphatic system dysfunction as well.

Distribution of substance P in the spinal cord of patients with syringomyelia

1996 ◽  
Vol 84 (6) ◽  
pp. 992-998 ◽  
Author(s):  
Thomas H. Milhorat ◽  
Harrison T. M. Mu ◽  
Carole C. LaMotte ◽  
Ade T. Milhorat
Keyword(s):  
Spinal Cord ◽  
Substance P ◽  
Dorsal Horn ◽  
Ventral Horn ◽  
Immunohistochemical Method ◽  
Positive Staining ◽  
Content Type ◽  
Normal Individuals ◽  
Neurologically Normal ◽  
Intermediolateral Nucleus

✓ The distribution of substance P, a putative neurotransmitter and pain-related peptide, was studied using the peroxidase—antiperoxidase immunohistochemical method in the spinal cords obtained from autopsy of 10 patients with syringomyelia and 10 age- and sex-matched, neurologically normal individuals. Substance P immunoreactivity was present in axons and in terminal-like processes in close apposition to neurons in the first, second, and third laminae of the dorsal horn. Smaller amounts of peroxidase-positive staining were found in the fifth lamina of the dorsal horn, the intermediolateral nucleus, the intermediomedial nucleus, and the ventral horn. In nine of 10 patients with syringomyelia, there was a substantial increase in substance P immunoreactivity in the first, second, third, and fifth laminae below the level of the lesion. A marked reduction or absence of staining was present in segments of the spinal cord occupied by the syrinx. Central cavities produced bilateral abnormalities, whereas eccentric cavities produced changes that were ipsilateral to the lesion. No alterations in staining were found in the spinal cord of an asymptomatic patient with a small central syrinx. The authors conclude that syringomyelia can be associated with abnormalities in spinal cord levels of substance P, which may affect the modulation and perception of pain.

Total CO2, Pco2, and pH in human spinal fluid

1961 ◽  
Vol 16 (3) ◽  
pp. 485-487 ◽  
Author(s):  
Carl R. Merril ◽  
Harry W. Seipp ◽  
Peter C. Luchsinger
Keyword(s):  
Confidence Interval ◽  
Normal Subjects ◽  
Spinal Fluid ◽  
Marked Individual ◽  
Arterial Blood ◽  
Normal Individuals ◽  
Individual Variations ◽  
Hasselbalch Equation

The relationships between pH, CO, tension and total CO2 in spinal fluid and arterial blood were explored in 12 normal individuals and 15 patients with various diseases. It was found that, in the normal subjects, the pH in the spinal fluid was constant, with a mean of 7.31 and 99 % confidence interval of 7.29–7.33. The pH in the spinal fluid was lower than that of the arterial blood in all patients studied, whereas the CO2 tension was found to average 4 mm Hg higher in the spinal fluid than in the arterial blood in most of the normal subjects studied. The pK1' was calculated for each patient's spinal fluid and arterial blood by the Henderson-Hasselbalch equation. In contrast to tonometry experiments, pK1' showed marked individual variations. The factors responsible for these variations are delineated. Submitted on November 7, 1960

scholarly journals Delineation of homogenous regions using hydrological variables predicted by projection pursuit regression

2016 ◽  
Vol 20 (12) ◽  
pp. 4717-4729 ◽  
Author(s):  
Martin Durocher ◽  
Fateh Chebana ◽  
Taha B. M. J. Ouarda
Keyword(s):  
Target Location ◽  
Projection Pursuit ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Projection Pursuit Regression ◽  
Index Flood ◽  
Regional Flood Frequency Analysis ◽  
Quantile Estimates ◽  
Target Locations ◽  
Hydrological Variables

Abstract. This study investigates the utilization of hydrological information in regional flood frequency analysis (RFFA) to enforce desired properties for a group of gauged stations. Neighbourhoods are particular types of regions that are centred on target locations. A challenge for using neighbourhoods in RFFA is that hydrological information is not available at target locations and cannot be completely replaced by the available physiographical information. Instead of using the available physiographic characteristics to define the centre of a target location, this study proposes to introduce estimates of reference hydrological variables to ensure a better homogeneity. These reference variables represent nonlinear relations with the site characteristics obtained by projection pursuit regression, a nonparametric regression method. The resulting neighbourhoods are investigated in combination with commonly used regional models: the index-flood model and regression-based models. The complete approach is illustrated in a real-world case study with gauged sites from the southern part of the province of Québec, Canada, and is compared with the traditional approaches such as region of influence and canonical correlation analysis. The evaluation focuses on the neighbourhood properties as well as prediction performances, with special attention devoted to problematic stations. Results show clear improvements in neighbourhood definitions and quantile estimates.

scholarly journals Comparison of the Effects of Intravenous Papaverine Hydrochloride and Oral Pavabid HP Capsulets on Regional Cerebral Blood Flow in Normal Individuals

1983 ◽  
Vol 3 (4) ◽  
pp. 442-447 ◽  
Author(s):  
Lawrence C. McHenry ◽  
David A. Stump ◽  
George Howard ◽  
Thomas T. Novack ◽  
Don H. Bivins ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Regional Cerebral Blood Flow ◽  
Normal Subjects ◽  
Normal Male ◽  
Regional Cerebral Blood ◽  
Normal Individuals ◽  
Left And Right ◽  
Male Subjects ◽  
Papaverine Hydrochloride

A single-blind study was conducted in 13 right-handed normal male subjects to compare the effects of oral and i.v. papaverine on regional cerebral blood flow (rCBF). Six xenon-133 inhalation rCBF measurements were performed on each subject; three tests—baseline, placebo, and drug evaluations—were carried out on each of two separate days. The oral and i.v. drugs were randomized for first-day administration. rCBF, measured as flow gray (FG), increased significantly (p ≤ 0.001) from baseline with both drug forms. Increases of 10.53% and 13.94% (left and right hemispheres, respectively) were demonstrated 90 min after a single 600-mg dose of oral papaverine. Increases of 5.09% and 8.69%, respectively, were recorded immediately after a single 100-mg dose of i. v. papaverine. FG also increased significantly (p ≤ 0.001) for both drug forms when compared to that of placebo. Placebo produced only a slight increase (not significant) with both the oral and i.v. groups. The data show that both oral and i.v. papaverine are equally effective in increasing rCBF in normal subjects.

scholarly journals Age-dependent formation of TMEM106B amyloid filaments in human brain

2021 ◽  
Author(s):  
Manuel Schweighauser ◽  
Diana Arseni ◽  
Melissa Huang ◽  
Sofia Lövestam ◽  
Yang Shi ◽  
...  
Keyword(s):  
Human Brain ◽  
Transmembrane Protein ◽  
Amyloid Β ◽  
Dependent Manner ◽  
Type Ii ◽  
Western Blots ◽  
Normal Individuals ◽  
Age Dependent ◽  
Neurologically Normal ◽  
Filamentous Inclusions

Many age-dependent neurodegenerative diseases, like Alzheimer's and Parkinson's, are characterised by abundant inclusions of amyloid filaments. Filamentous inclusions of the proteins tau, amyloid-β (Aβ), α-synuclein and TDP-43 are the most common. Here, we used electron cryo-microscopy (cryo-EM) structure determination to show that residues 120-254 of the lysosomal type II transmembrane protein 106B (TMEM106B) also form amyloid filaments in the human brain. We solved cryo-EM structures of TMEM106B filaments from the brains of 22 individuals with neurodegenerative conditions, including sporadic and inherited tauopathies, Aβ-amyloidoses, synucleinopathies and TDP-43opathies, as well as from the brains of two neurologically normal individuals. We observed three different TMEM106B folds, with no clear relationship between folds and diseases. The presence of TMEM106B filaments correlated with that of a 29 kDa sarkosyl-insoluble fragment of the protein on Western blots. The presence of TMEM106B filaments in the brains of older, but not younger, neurologically normal individuals indicates that they form in an age-dependent manner.

scholarly journals Spatial updating of targets in front and behind

2004 ◽  
Vol 14 (27) ◽  
pp. 75-81 ◽  
Author(s):  
David Horn ◽  
Jack Loomis
Keyword(s):  
Target Location ◽  
Spatial Updating ◽  
Eyes Closed ◽  
Target Locations

This research compared the accuracy of spatial updating of targets in front with that of targets behind. The participant viewed a target on the ground several meters away and then, without vision, sidestepped along a guide rope while trying to mentally update the location of the target. On some trials, the target location was in front as the person sidestepped and, on other trials, the target location was behind. Participants responded by facing the updated target location with eyes closed. The results indicate that people are able to update target locations behind them very nearly as well as target locations in front.

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