scholarly journals Generating surrogates from recurrences

2007 ◽  
Vol 366 (1865) ◽  
pp. 545-557 ◽  
Author(s):  
M Thiel ◽  
M.C Romano ◽  
J Kurths ◽  
M Rolfs ◽  
R Kliegl
Keyword(s):  
Independent Copy ◽  
Close Link ◽  
Left And Right ◽  
The Brain

In this paper, we present an approach to recover the dynamics from recurrences of a system and then generate (multivariate) twin surrogate (TS) trajectories. In contrast to other approaches, such as the linear-like surrogates, this technique produces surrogates which correspond to an independent copy of the underlying system, i.e. they induce a trajectory of the underlying system visiting the attractor in a different way. We show that these surrogates are well suited to test for complex synchronization, which makes it possible to systematically assess the reliability of synchronization analyses. We then apply the TS to study binocular fixational movements and find strong indications that the fixational movements of the left and right eye are phase synchronized. This result indicates that there might be only one centre in the brain that produces the fixational movements in both eyes or a close link between the two centres.

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

scholarly journals The Hammer and the Nail: Biomechanics of Striking and Struck Canadian University Football Players

2021 ◽  
Author(s):  
Jeffrey S. Brooks ◽  
Adam Redgrift ◽  
Allen A. Champagne ◽  
James P. Dickey
Keyword(s):  
College Football ◽  
Head Impact ◽  
Football Players ◽  
Video Footage ◽  
Impact Location ◽  
Rule Changes ◽  
Left And Right ◽  
The Brain

AbstractThis study sought to evaluate head accelerations in both players involved in a football collision. Players on two opposing Canadian university teams were equipped with helmet mounted sensors during one game per season, for two consecutive seasons. A total of 276 collisions between 58 instrumented players were identified via video and cross-referenced with sensor timestamps. Player involvement (striking and struck), impact type (block or tackle), head impact location (front, back, left and right), and play type were recorded from video footage. While struck players did not experience significantly different linear or rotational accelerations between any play types, striking players had the highest linear and rotational head accelerations during kickoff plays (p ≤ .03). Striking players also experienced greater linear and rotational head accelerations than struck players during kickoff plays (p = .001). However, struck players experienced greater linear and rotational accelerations than striking players during kick return plays (p ≤ .008). Other studies have established that the more severe the head impact, the greater risk for injury to the brain. This paper’s results highlight that kickoff play rule changes, as implemented in American college football, would decrease head impact exposure of Canadian university football athletes and make the game safer.

Age and sex specific brain biometrical study in Vanaraja chickens

2017 ◽  
Author(s):  
Kuldeep Kumar Panigrahy ◽  
Kumaresh Behera ◽  
Lal Mohan Mohapatra ◽  
Arun Kumar Mandal ◽  
Kamdev Sethy ◽  
...  
Keyword(s):  
Brain Volume ◽  
Cerebral Hemispheres ◽  
Male And Female ◽  
Cervical Dislocation ◽  
Left And Right ◽  
The Mean ◽  
The Brain ◽  
Biometrical Study ◽  
Age And Sex

The objective of this study was to evaluate the brain biometrical dynamics with advancement of age between sexes. One hundred fifty day-old sexed Vanaraja chicks (75 male + 75 female) were selected and distributed equally in two groups. Birds were slaughtered by cervical dislocation method at 21, 42, 63 and 84 days of age and biometrical measurements were taken. From our present study we observed brain volume had shown significant (P>0.05) changes with respect to age and sex of birds. The mean length of both left and right cerebral hemispheres between male and female birds had varied significantly (P>0.05). With advancement of age, hemispheric length varied significantly (P>0.05). The major finding was that cerebral width significantly (P>0.05) increased from 42-63 days of age and in male birds cerebellar length increased from 63 days onwards. There were age-specific changes in all the morphometrical parameters where as between sexes there were some minor variations.

scholarly journals Influence of Gender and Age on Average Dimensions of Arteries Forming the Circle of Willis Study by Magnetic Resonance Angiography on Kosovo’s Population

2017 ◽  
Vol 5 (6) ◽  
pp. 714-719 ◽  
Author(s):  
Jeton Shatri ◽  
Dorentina Bexheti ◽  
Sadi Bexheti ◽  
Serbeze Kabashi ◽  
Shaip Krasniqi ◽  
...  
Keyword(s):  
Interventional Radiology ◽  
Collateral Circulation ◽  
Descriptive Study ◽  
Circle Of Willis ◽  
Clinical Center ◽  
Gender And Age ◽  
Left And Right ◽  
Cadaver Studies ◽  
The University ◽  
The Brain

BACKGROUND: Circulus arteriosus cerebri is the main source of blood supply to the brain; it connects the left and right hemispheres with anterior and posterior parts. Located at the interpenducular fossa at the base of the brain the circle of Willis is the most important source of collateral circulation in the presence of the disease in the carotid or vertebral artery.AIM: The purpose of the research is to study the diameter and length of arteries and provide an important source of reference on Kosovo’s population.METHODS: This is an observative descriptive study performed at the University Clinical Center of Kosovo. A randomised sample of 133 angiographic examinations in adult patients of both sexes who were instructed to exploration is included.RESULTS: The diameters and lengths measured in our study were comparable with other brain-cadaver studies especially those performed by MRA. All dimensions of the arteries are larger in male than female, except the diameter of PCoA that is larger in female (p < 0.05) and length of the ACoA (p < 0.05). Significant differences were found in diameters of arteries between the younger and the older age groups.CONCLUSION: Knowing the dimensions of the arteries of the circle of Willis has a great importance in interventional radiology as well as during anatomy lessons.

Asymmetry of pressure autoregulation after traumatic brain injury

2003 ◽  
Vol 99 (6) ◽  
pp. 991-998 ◽  
Author(s):  
Eric A. Schmidt ◽  
Marek Czosnyka ◽  
Luzius A. Steiner ◽  
Marcella Balestreri ◽  
Piotr Smielewski ◽  
...  
Keyword(s):  
Head Injuries ◽  
Cerebral Arteries ◽  
Brain Lesion ◽  
Fatal Outcome ◽  
Midline Shift ◽  
Content Type ◽  
Arterial Blood ◽  
Left And Right ◽  
The Brain ◽  
Fine Print

Object. The aim of this study was to assess the asymmetry of autoregulation between the left and right sides of the brain by using bilateral transcranial Doppler ultrasonography in a cohort of patients with head injuries. Methods. Ninety-six patients with head injuries comprised the study population. All significant intracranial mass lesions were promptly removed. The patients were given medications to induce sedation and paralysis, and artificial ventilation. Arterial blood pressure (ABP) and intracranial pressure (ICP) were monitored in an invasive manner. A strategy based on the patient's cerebral perfusion pressure (CPP = ABP − ICP) was applied: CPP was maintained at a level higher than 70 mm Hg and ICP at a level lower than 25 mm Hg. The left and right middle cerebral arteries were insonated daily, and bilateral flow velocities (FVs) were recorded. The correlation coefficient between the CPP and FV, termed Mx, was calculated and time-averaged over each recording period on both sides. An Mx close to 1 signified that slow fluctuations in CPP produced synchronized slow changes in FV, indicating a defective autoregulation. An Mx close to 0 indicated preserved autoregulation. Computerized tomography scans in all patients were reviewed; the side on which the major brain lesion was located was noted and the extent of the midline shift was determined. Outcome was measured 6 months after discharge. The left—right difference in the Mx between the hemispheres was significantly higher in patients who died than in those who survived (0.16 ± 0.04 compared with 0.08 ± 0.01; p = 0.04). The left—right difference in the Mx was correlated with a midline shift (r = −0.42; p = 0.03). Autoregulation was worse on the side of the brain where the lesion was located (p < 0.035). Conclusions. The left—right difference in autoregulation is significantly associated with a fatal outcome. Autoregulation in the brain is worse on the side ipsilateral to the lesion and on the side of expansion in cases in which there is a midline shift.

scholarly journals Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow

2007 ◽  
Vol 292 (4) ◽  
pp. R1532-R1541 ◽  
Author(s):  
T.-K. Lee ◽  
J. H. Lois ◽  
J. H. Troupe ◽  
T. D. Wilson ◽  
B. J. Yates
Keyword(s):  
Blood Flow ◽  
Brain Stem ◽  
Pseudorabies Virus ◽  
Muscle Blood Flow ◽  
Ventrolateral Medulla ◽  
Cell Group ◽  
Sympathetic Outflow ◽  
Survival Times ◽  
Left And Right ◽  
The Brain

Despite considerable interest in the neural mechanisms that regulate muscle blood flow, the descending pathways that control sympathetic outflow to skeletal muscles are not adequately understood. The present study mapped these pathways through the transneuronal transport of two recombinant strains of pseudorabies virus (PRV) injected into the gastrocnemius muscles in the left and right hindlimbs of rats: PRV-152 and PRV-BaBlu. To prevent PRV from being transmitted to the brain stem via motor circuitry, a spinal transection was performed just below the L2 level. Infected neurons were observed bilaterally in all of the areas of the brain that have previously been shown to contribute to regulating sympathetic outflow: the medullary raphe nuclei, rostral ventrolateral medulla (RVLM), rostral ventromedial medulla, A5 adrenergic cell group region, locus coeruleus, nucleus subcoeruleus, and the paraventricular nucleus of the hypothalamus. The RVLM, the brain stem region typically considered to play the largest role in regulating muscle blood flow, contained neurons infected following the shortest postinoculation survival times. Approximately half of the infected RVLM neurons were immunopositive for tyrosine hydroxylase, indicating that they were catecholaminergic. Many (47%) of the RVLM neurons were dually infected by the recombinants of PRV injected into the left and right hindlimb, suggesting that the central nervous system has a limited capacity to independently regulate blood flow to left and right hindlimb muscles.

scholarly journals Neuronal pathway and signal modulation for motor communication

2019 ◽  
pp. 106-113 ◽  
Author(s):  
Parth Chholak ◽  
Alexander N. Pisarchik ◽  
Semen A. Kurkin ◽  
Vladimir A. Maksimenko ◽  
Alexander E. Hramov
Keyword(s):  
Brain Activity ◽  
Dominant Role ◽  
Motor Command ◽  
Gamma Activity ◽  
Frequency Range ◽  
Inferior Parietal Cortex ◽  
Left And Right ◽  
Gamma Frequencies ◽  
Phase Amplitude ◽  
The Brain

The knowledge of the mechanisms of motor imagery (MI) is very important for the development of braincomputer interfaces. Depending on neurophysiological cortical activity, MI can be divided into two categories: visual imagery (VI) and kinesthetic imagery (KI). Our magnetoencephalography (MEG) experiments with ten untrained subjects provided evidences that inhibitory control plays a dominant role in KI. We found that communication between inferior parietal cortex and frontal cortex is realised in the mu-frequency range. We also pinpointed three gamma frequencies to be used for motor command communication. The use of artificial intelligence allowed us to classify MI of left and right hands with maximal classification accuracy using the brain activity encoded in the identified gamma frequencies which were then proposed to be used for communication of specifics. Mu-activity was identified as the carrier of gamma-activity between these areas by means of phase-amplitude coupling similar to the modern day radio wave transmission.

scholarly journals CHANGES OF THE LOCAL FUNCTIONAL BRAIN ACTIVITY ASSOCIATED WITH SPEECH DISORDERS IN CHILDREN WITH EPILEPSY AND DEVELOPMENTAL DELAY (PET STUDY)

2019 ◽  
pp. 39-43
Author(s):  
Yu. G. Khomenko ◽  
G. V. Kataeva ◽  
V. I. Kolomiec
Keyword(s):  
Cerebral Metabolism ◽  
Brain Activity ◽  
Brain Structures ◽  
Speech Disorders ◽  
Speech Development ◽  
Metabolism Rate ◽  
Local Functional ◽  
Left And Right ◽  
Functional Brain Activity ◽  
The Brain

PET study of cerebral glucose metabolism was performed in 73 children with epilepsy and mental retardation. Expressive speech disorders were associated with decrease of cerebral metabolism rate of glucose (CMRglu) in the upper frontal gyrus, caudate nucleus and thalamus of the left and right hemispheres. In the group with combined expressive and impressive speech disorders the significant CMRglu reduction in the middle temporal and supramarginal gyrus of the left hemisphere was observed. The obtained results confirm that the brain structures associated with the executive functions and complex association processes have a great significance in the speech development.

scholarly journals Resting state functional connectivity in the human spinal cord

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Robert L Barry ◽  
Seth A Smith ◽  
Adrienne N Dula ◽  
John C Gore
Keyword(s):  
Spinal Cord ◽  
Functional Connectivity ◽  
Resting State ◽  
Low Frequency ◽  
Blood Oxygenation ◽  
Resting State Functional Connectivity ◽  
Human Spinal Cord ◽  
Oxygenation Level ◽  
Left And Right ◽  
The Brain

Functional magnetic resonance imaging using blood oxygenation level dependent (BOLD) contrast is well established as one of the most powerful methods for mapping human brain function. Numerous studies have measured how low-frequency BOLD signal fluctuations from the brain are correlated between voxels in a resting state, and have exploited these signals to infer functional connectivity within specific neural circuits. However, to date there have been no previous substantiated reports of resting state correlations in the spinal cord. In a cohort of healthy volunteers, we observed robust functional connectivity between left and right ventral (motor) horns, and between left and right dorsal (sensory) horns. Our results demonstrate that low-frequency BOLD fluctuations are inherent in the spinal cord as well as the brain, and by analogy to cortical circuits, we hypothesize that these correlations may offer insight into the execution and maintenance of sensory and motor functions both locally and within the cerebrum.

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