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You searched for subject:(Monkey brain imaging). Showing records 1 – 3 of 3 total matches.

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1. Yttri, Eric. Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches.

Degree: PhD, Biology and Biomedical Sciences: Neurosciences, 2011, Washington University in St. Louis

A principle task of our brain is to guide movements, includng saccade: fast eye movements) and reaches towards things that we see. Regions in the parietal cortex such as LIP and PRR are active during visually-guided movements. Neurons in these areas respond differentially for saccades versus reaches, but in most parietal areas there is some response: in single unit recording as well as in fMRI imaging) with either type of movement. This raises an important question. What is the functional significance of the neuronal activity in parietal areas? Recording and imaging studies can only show correlations; causal roles must be inferred. The activity in any particular area could reflect where the subject's spatial attention is directed, without regard for what behavior the subject will perform. Stronger activity in one task compared to another could reflect differential allocation of attention. For example, we might attend more strongly to a target for an eye movement than to a target for an arm movement, or vice versa. Alternatively, might play a causal role in driving only one type of movement. In this case, the weaker activity evoked during a different type of movement might serve no purpose at all; it might represent a contingency plan to perform the non-selected movement; or it might be serve some other function unrelated to the specific movement - for example, weak saccade-related activity in an area with strong arm movement related signals might support play no role in driving eye movements, but instead provide timing information to the reaching system to support eye-hand coordination. To help resolve this mystery, we used an interventional approach. We asked what happens to reaches and saccades when we reversibly lesioned specific areas in the monkey parietal cortex. In order to establish what brain regions were affected in each inactivation experiment, we developed a novel technique to image the location of the lesions in vivo. The results of this causal manipulation were clear: LIP lesions delay the initiation of saccades and have no effect on reaches, while PRR lesions delay the initiation of reaches and have no effect on saccades. We obtained further evidence for a more motoric role for parietal areas than previously suspected. PRR was active for reaches of only the contralateral arm, aimed at targets in either hemisphere - similar to the typical profiles of motor but not visual sensory areas. Interestingly, LIP lesions did influence reaches, but only when the animals were allowed to first look at the target before reaching for it. We believe that in this case, the reaching movement "waits" for the saccade system, and so the direct effect of the lesion on the saccades has an indirect effect on the reaches. These results are important for several reasons. First, they resolve a long-standing debate regarding the functional specificity of parietal areas with regard to particular movements and attention. They provide new information on the circuits guiding eye movements, arm movements and eye-hand coordination.… Advisors/Committee Members: Lawrence Snyder.

Subjects/Keywords: Neurosciences; Psychobiology; brain, imaging, lesion, monkey, reach, saccade

brain to organize a complex series of computations. As this example exhibits, we are… …between “monkey see” and “monkey do” sits the posterior parietal cortex (PPC), where… …visuomotor transformation, can provide insight to the organization of the brain. Early visual areas… …an important one, and its analysis is vital to comprehending how and where the brain… …of the lesioned area, but rather they reveal how the brain functions without the region of… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Yttri, E. (2011). Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches. (Doctoral Dissertation). Washington University in St. Louis. Retrieved from https://openscholarship.wustl.edu/etd/394

Chicago Manual of Style (16th Edition):

Yttri, Eric. “Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches.” 2011. Doctoral Dissertation, Washington University in St. Louis. Accessed September 23, 2020. https://openscholarship.wustl.edu/etd/394.

MLA Handbook (7th Edition):

Yttri, Eric. “Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches.” 2011. Web. 23 Sep 2020.

Vancouver:

Yttri E. Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches. [Internet] [Doctoral dissertation]. Washington University in St. Louis; 2011. [cited 2020 Sep 23]. Available from: https://openscholarship.wustl.edu/etd/394.

Council of Science Editors:

Yttri E. Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches. [Doctoral Dissertation]. Washington University in St. Louis; 2011. Available from: https://openscholarship.wustl.edu/etd/394

2. Tounekti, Slimane. Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI.

Degree: Docteur es, Imagerie médicale. Sciences et ingénierie pour la santé, 2019, Lyon

L’IRM de diffusion (IRMd) est l’unique technique non invasive qui permet l’exploration de la microstructure cérébrale. En plus d’une large utilisation pour les applications médicales, l’IRMd est aussi utilisée en neuroscience pour comprendre l’organisation et le fonctionnement du cerveau. Toutefois, sa faible résolution spatiale et sa sensibilité aux artéfacts limitent son utilisation chez le primate non humain.L’objectif de cette étude est de développer une nouvelle approche qui permette d’acquérir des données d’IRMd à très haute résolution spatiale sur des cerveaux de macaques anesthésiés. Cette méthode est basée sur un balayage 3D de l’espace de Fourier avec un module de lecture d’Echo Planar-segmenté.Cette méthode a été tout d’abord implémentée sur une machine IRM 3 Tesla (Prisma, Siemens), puis validée et optimisée in-vitro et in-vivo. Par rapport à la méthode d’acquisition classique, un gain de sensibilité de l’ordre de 3 pour la substance grise cérébrale et de 4.7 pour la substance blanche cérébrale a été obtenu grâce à la méthode développée.Cette méthode a permis de réaliser l’IRMd du cerveau de Macaque avec une résolution spatiale isotrope de 0.5 mm jamais atteinte auparavant. L’intérêt de réaliser des données d’IRMd à une telle résolution pour visualiser et analyser in-vivo des structures fines non détectables avec la méthode d’acquisition classique comme les sous-champs de l’hippocampe ou encore la substance blanche superficielle, a été démontré dans cette étude. Des résultats préliminaires très encourageants ont également été obtenus chez l’homme

Diffusion MRI (dMRI) is the unique non-invasive technique that allows exploring the cerebral microstructure. Besides a wide use for medical applications, dMRI is also employed in neuroscience to understand the brain organization and connectivity. However, the low spatial resolution and the sensitivity to artefacts limit its application to non-human primates.This work aims to develop a new approach that allows to acquire dMRI at very high spatial resolution on anesthetized macaque brains. This method is based on a 3D sampling of Fourier space with a segmented Echo Planar imaging readout module. This method has been firstly implemented on a 3 Tesla MR scanner (Prisma, Siemens), validated and optimized in-vitro and in-vivo. Compared to the conventional acquisition method, a gain of sensitivity of 3 for the cerebral grey matter and of 4.7 for the white matter was obtained with the proposed approach.This method allowed us to acquire dMRI data on the macaque brain with a spatial isotropic resolution of 0.5 mm ever reached before. The interest to acquire dMRI data with such a spatial resolution to visualize and analyze in-vivo fine structures not detectable with the classical acquisition method, like the sub-fields of hippocampus and the superficial white matter, has also illustrated in this study. Finally, very encouraging preliminary results were also obtained in humans

Advisors/Committee Members: Hiba, Bassem (thesis director), Ben Hamed, Suliann (thesis director).

Subjects/Keywords: Imagerie par résonance magnétique; Imagerie tenseur de diffusion; IRM de diffusion 3D; Imagerie cérébrale de singes macaques; L’imagerie cérébrale chez l’homme; Haute résolution; L’Hippocampe et la matière blanche superficielle; Magnetic resonance imaging; Diffusion tensor imaging; 3D diffusion MRI; Monkey brain imaging; Human brain imaging; High resolution; Hippocampus and superficial white matter; 530

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Tounekti, S. (2019). Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI. (Doctoral Dissertation). Lyon. Retrieved from http://www.theses.fr/2019LYSE1008

Chicago Manual of Style (16th Edition):

Tounekti, Slimane. “Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI.” 2019. Doctoral Dissertation, Lyon. Accessed September 23, 2020. http://www.theses.fr/2019LYSE1008.

MLA Handbook (7th Edition):

Tounekti, Slimane. “Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI.” 2019. Web. 23 Sep 2020.

Vancouver:

Tounekti S. Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI. [Internet] [Doctoral dissertation]. Lyon; 2019. [cited 2020 Sep 23]. Available from: http://www.theses.fr/2019LYSE1008.

Council of Science Editors:

Tounekti S. Développements des méthodes d'acquisition à haute résolution spatiale en IRM de diffusion : Development of high spatial resolution acquisition methods for diffusion MRI. [Doctoral Dissertation]. Lyon; 2019. Available from: http://www.theses.fr/2019LYSE1008

3. Ward, Matthew K. High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements.

Degree: PhD, 2008, University of Alabama – Birmingham

Animals with eyes positioned towards the front of the head are capable of making saccadic and smooth pursuit eye movements to fixate an object at a given distance. These eye movements are conjugate (i.e. both eyes move the same amount in the same direction). To fixate objects at different distances, such animals are also capable of making vergence eye movements in which both eyes move the same amount in opposite directions i.e. disconjugately. While purely conjugate or vergence eye movements rarely occur in daily life, it is useful to study these types of eye movements separately due to the relative simplicity of addressing a single system. Further, the neural networks responsible for these eye movements represent an ideal model for sensory processing, sensorimotor integration/transformation and motor output in that all of the components are contained within one localized area: the head. While much is known about the subcortical networks involved in both types of eye movements and about the cortical networks involved in conjugate eye movements, the cortical areas involved in vergence eye movements remain to be fully elucidated. To delineate the cortical areas involved in the initiation and execution of vergence eye movements, we trained a rhesus macaque monkey (Macaca mulatta) to perform visually-guided vergence eye movements during functional magnetic resonance imaging (fMRI). As the entire system responsible for these movements is contained within the head and the possible cortical candidates underlying these movements were many, fMRI provided an ideal tool by which to identify vergence-related areas. We found that there was a distributed cortical network involved in the stimulus processing and/or production of a motor signal for vergence movements including the superior temporal sulcus, the arcuate sulcus, the intraparietal sulcus and the principle sulcus. We also found a dissociation of function for these areas in that some were more strongly related to the processing of the vergence-eliciting stimuli whereas others were more strongly related to the motor component of the eye movement. The rapidity with which these data were acquired and the spatial/functional specificity of the resultant statistical maps illustrate the power and versatility of implementing fMRI to investigate brain function, especially when there is relatively little known about the behavior in question.

viii, 114 p. : col. ill., facsim., digital, PDF file.

Psychology

Social and Behavioral Sciences

fMRI Vergence BOLD Monkey Alert Eye movement

UNRESTRICTED

Advisors/Committee Members: Gamlin, Paul, Amthor, Frank <br>, Busettini, Claudio <br>, Cox, James <br>, Weller, Rosalyn.

Subjects/Keywords: Vergence (Binocular vision) <; br>; Eye  – Movements  – Regulation <; br>; Brain  – Localization of functions <; br>; Higher nervous activity <; br>; Brain  – Magnetic resonance imaging <; br>; Rhesus monkey  – Physiology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ward, M. K. (2008). High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements. (Doctoral Dissertation). University of Alabama – Birmingham. Retrieved from http://contentdm.mhsl.uab.edu/u?/etd,471

Chicago Manual of Style (16th Edition):

Ward, Matthew K. “High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements.” 2008. Doctoral Dissertation, University of Alabama – Birmingham. Accessed September 23, 2020. http://contentdm.mhsl.uab.edu/u?/etd,471.

MLA Handbook (7th Edition):

Ward, Matthew K. “High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements.” 2008. Web. 23 Sep 2020.

Vancouver:

Ward MK. High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements. [Internet] [Doctoral dissertation]. University of Alabama – Birmingham; 2008. [cited 2020 Sep 23]. Available from: http://contentdm.mhsl.uab.edu/u?/etd,471.

Council of Science Editors:

Ward MK. High field functional magnetic resonance imaging in the awake, behaving primate : cortical networks involved in vergence eye movements. [Doctoral Dissertation]. University of Alabama – Birmingham; 2008. Available from: http://contentdm.mhsl.uab.edu/u?/etd,471

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