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Oculomotor circuit

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https://www.readbyqxmd.com/read/28904108/comparison-of-three-models-of-saccade-disconjugacy-in-strabismus
#1
Mark M G Walton, Michael J Mustari
In pattern strabismus the horizontal and vertical misalignments vary with eye position along the orthogonal axis. The disorder is typically described in terms of overaction or underaction of oblique muscles. Recent behavioral studies in humans and monkeys, however, have reported that such actions are insufficient to fully explain the patterns of directional and amplitude disconjugacy of saccades. There is mounting evidence that the oculomotor abnormalities associated with strabismus are at least partially attributable to neurophysiological abnormalities...
September 13, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28842421/effects-of-selective-deafferentation-on-the-discharge-characteristics-of-medial-rectus-motoneurons
#2
Rosendo G Hernández, Beatriz Benítez-Temiño, Camilo J Morado-Díaz, María América Davis-López de Carrizosa, Rosa R de la Cruz, Angel M Pastor
Medial rectus motoneurons receive two main pontine inputs: abducens internuclear neurons, whose axons course through the medial longitudinal fasciculus (MLF), and neurons in the lateral vestibular nucleus, whose axons project through the ascending tract of Deiters (ATD). Abducens internuclear neurons are responsible for conjugate gaze in the horizontal plane, whereas ATD neurons provide medial rectus motoneurons with a vestibular input comprising mainly head velocity. To reveal the relative contribution of each input to the oculomotor physiology, single-unit recordings from medial rectus motoneurons were obtained in the control situation and after selective deafferentation from cats with unilateral transection of either the MLF or the ATD...
September 20, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28808217/electromyography-and-fos-immunostaining-study-establish-a-possible-functional-link-between-trigeminal-proprioception-and-the-oculomotor-system-in-rats
#3
Houcheng Liang, Jingdong Zhang, Pifu Luo, Hongna Zhu, Ying Qiao, Anle Su, Ting Zhang
The objective of this study was to explore whether there was a functional link between trigeminal proprioception and the oculomotor system mediated through jaw muscle afferents. Electromyography (EMG) was undertaken of the levator palpebrae (LP) and superior rectus (SR), and Fos expression was detected in the brainstem following consecutive down-stretching of the lower jaw at 2-4 Hz in rats. Retrograde tracing was undertaken of the interstitial nucleus of Cajal and Darkschewitsch nucleus (INC/DN) pre-oculomotor neurons...
January 19, 2017: Journal of Biomedical Research
https://www.readbyqxmd.com/read/28712570/electron-microscopic-reconstruction-of-functionally-identified-cells-in-a-neural-integrator
#4
Ashwin Vishwanathan, Kayvon Daie, Alexandro D Ramirez, Jeff W Lichtman, Emre R F Aksay, H Sebastian Seung
Neural integrators are involved in a variety of sensorimotor and cognitive behaviors. The oculomotor system contains a simple example, a hindbrain neural circuit that takes velocity signals as inputs and temporally integrates them to control eye position. Here we investigated the structural underpinnings of temporal integration in the larval zebrafish by first identifying integrator neurons using two-photon calcium imaging and then reconstructing the same neurons through serial electron microscopic analysis...
July 24, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28648497/selective-optogenetic-control-of-purkinje-cells-in-monkey-cerebellum
#5
Yasmine El-Shamayleh, Yoshiko Kojima, Robijanto Soetedjo, Gregory D Horwitz
Purkinje cells of the primate cerebellum play critical but poorly understood roles in the execution of coordinated, accurate movements. Elucidating these roles has been hampered by a lack of techniques for manipulating spiking activity in these cells selectively-a problem common to most cell types in non-transgenic animals. To overcome this obstacle, we constructed AAV vectors carrying the channelrhodopsin-2 (ChR2) gene under the control of a 1 kb L7/Pcp2 promoter. We injected these vectors into the cerebellar cortex of rhesus macaques and tested vector efficacy in three ways...
July 5, 2017: Neuron
https://www.readbyqxmd.com/read/28601961/basal-ganglia-movement-disorders-and-deep-brain-stimulation-advances-made-through-non-human-primate-research
#6
REVIEW
Thomas Wichmann, Hagai Bergman, Mahlon R DeLong
Studies in non-human primates (NHPs) have led to major advances in our understanding of the function of the basal ganglia and of the pathophysiologic mechanisms of hypokinetic movement disorders such as Parkinson's disease and hyperkinetic disorders such as chorea and dystonia. Since the brains of NHPs are anatomically very close to those of humans, disease states and the effects of medical and surgical approaches, such as deep brain stimulation (DBS), can be more faithfully modeled in NHPs than in other species...
June 10, 2017: Journal of Neural Transmission
https://www.readbyqxmd.com/read/28515286/responses-of-purkinje-cells-in-the-oculomotor-vermis-of-monkeys-during-smooth-pursuit-eye-movements-and-saccades-comparison-with-floccular-complex
#7
Ramanujan T Raghavan, Stephen G Lisberger
We recorded the responses of Purkinje cells in the oculomotor vermis during smooth pursuit and saccadic eye movements. Our goal was to characterize the responses in the vermis using approaches that would allow direct comparisons with responses of Purkinje cells in another cerebellar area for pursuit, the floccular complex. Simple-spike firing of vermis Purkinje cells is direction selective during both pursuit and saccades, but the preferred directions are sufficiently independent so that downstream circuits could decode signals to drive pursuit and saccades separately...
August 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28452866/effects-of-dopamine-and-norepinephrine-on-exercise-induced-oculomotor-fatigue
#8
Charlotte J W Connell, Benjamin Thompson, Jason Turuwhenua, Alexa Srzich, Nicholas Gant
INTRODUCTION: Fatigue-induced impairments in the control of eye movements are detectable via reduced eye movement velocity after a bout of prolonged, strenuous exercise. Slower eye movements caused by neural fatigue within the oculomotor system can be prevented by caffeine, and the upregulation of central catecholamines may be responsible for this effect. This study explored the individual contribution of dopamine and norepinephrine to fatigue-related impairments in oculomotor control...
September 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28443002/to-wait-or-not-to-wait-separate-mechanisms-in-the-oculomotor-circuit-of-basal-ganglia
#9
Masaharu Yasuda, Okihide Hikosaka
We reach a goal immediately after detecting the target, or later by withholding the immediate action. Each time, we choose one of these actions by suppressing the other. How does the brain control these antagonistic actions? We hypothesized that the output of basal ganglia (BG), substantia nigra pars reticulata (SNr), suppresses antagonistic oculomotor signals by sending strong inhibitory output to superior colliculus (SC). To test this hypothesis, we trained monkeys to perform two kinds of saccade task: Immediate (visually guided) and delayed (visually-withheld but memory-guided) saccade tasks...
2017: Frontiers in Neuroanatomy
https://www.readbyqxmd.com/read/28258438/clinical-application-of-eye-movement-tasks-as-an-aid-to-understanding-parkinson-s-disease-pathophysiology
#10
REVIEW
Kikuro Fukushima, Junko Fukushima, Graham R Barnes
Parkinson's disease (PD) is a progressive neurodegenerative disorder of the basal ganglia. Most PD patients suffer from somatomotor and oculomotor disorders. The oculomotor system facilitates obtaining accurate information from the visual world. If a target moves slowly in the fronto-parallel plane, tracking eye movements occur that consist primarily of smooth-pursuit interspersed with corrective saccades. Efficient smooth-pursuit requires appropriate target selection and predictive compensation for inherent processing delays...
May 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28226411/the-control-of-eye-movements-by-the-cerebellar-nuclei-polysynaptic-projections-from-the-fastigial-interpositus-posterior-and-dentate-nuclei-to-lateral-rectus-motoneurons-in-primates
#11
Vincent Prevosto, Werner Graf, Gabriella Ugolini
Premotor circuits driving extraocular motoneurons and downstream motor outputs of cerebellar nuclei are well known. However, there is, as yet, no unequivocal account of cerebellar output pathways controlling eye movements in primates. Using retrograde transneuronal transfer of rabies virus from the lateral rectus (LR) eye muscle, we studied polysynaptic pathways to LR motoneurons in primates. Injections were placed either into the central or distal muscle portion, to identify innervation differences of LR motoneurons supplying singly innervated (SIFs) or multiply innervated muscle fibers (MIFs)...
February 22, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28177526/segregated-fronto-cortical-and-midbrain-connections-in-the-mouse-and-their-relation-to-approach-and-avoidance-orienting-behaviors
#12
Michael Anthony Savage, Richard McQuade, Alexander Thiele
The orchestration of orienting behaviors requires the interaction of many cortical and subcortical areas, for example the superior colliculus (SC), as well as prefrontal areas responsible for top-down control. Orienting involves different behaviors, such as approach and avoidance. In the rat, these behaviors are at least partially mapped onto different SC subdomains, the lateral (SCl) and medial (SCm), respectively. To delineate the circuitry involved in the two types of orienting behavior in mice, we injected retrograde tracer into the intermediate and deep layers of the SCm and SCl, and thereby determined the main input structures to these subdomains...
June 1, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28053244/distinct-neural-circuits-for-control-of-movement-vs-holding-still
#13
REVIEW
Reza Shadmehr
In generating a point-to-point movement, the brain does more than produce the transient commands needed to move the body part; it also produces the sustained commands that are needed to hold the body part at its destination. In the oculomotor system, these functions are mapped onto two distinct circuits: a premotor circuit that specializes in generating the transient activity that displaces the eyes and a "neural integrator" that transforms that transient input into sustained activity that holds the eyes. Different parts of the cerebellum adaptively control the motor commands during these two phases: the oculomotor vermis participates in fine tuning the transient neural signals that move the eyes, monitoring the activity of the premotor circuit via efference copy, whereas the flocculus participates in controlling the sustained neural signals that hold the eyes, monitoring the activity of the neural integrator...
April 1, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28028221/stable-population-coding-for-working-memory-coexists-with-heterogeneous-neural-dynamics-in-prefrontal-cortex
#14
John D Murray, Alberto Bernacchia, Nicholas A Roy, Christos Constantinidis, Ranulfo Romo, Xiao-Jing Wang
Working memory (WM) is a cognitive function for temporary maintenance and manipulation of information, which requires conversion of stimulus-driven signals into internal representations that are maintained across seconds-long mnemonic delays. Within primate prefrontal cortex (PFC), a critical node of the brain's WM network, neurons show stimulus-selective persistent activity during WM, but many of them exhibit strong temporal dynamics and heterogeneity, raising the questions of whether, and how, neuronal populations in PFC maintain stable mnemonic representations of stimuli during WM...
January 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27989457/bk-channels-are-required-for-multisensory-plasticity-in-the-oculomotor-system
#15
Alexandra B Nelson, Michael Faulstich, Setareh Moghadam, Kimberly Onori, Andrea Meredith, Sascha du Lac
Neural circuits are endowed with several forms of intrinsic and synaptic plasticity that could contribute to adaptive changes in behavior, but circuit complexities have hindered linking specific cellular mechanisms with their behavioral consequences. Eye movements generated by simple brainstem circuits provide a means for relating cellular plasticity to behavioral gain control. Here we show that firing rate potentiation, a form of intrinsic plasticity mediated by reductions in BK-type calcium-activated potassium currents in spontaneously firing neurons, is engaged during optokinetic reflex compensation for inner ear dysfunction...
January 4, 2017: Neuron
https://www.readbyqxmd.com/read/27916956/functional-diversity-of-neurotrophin-actions-on-the-oculomotor-system
#16
REVIEW
Beatriz Benítez-Temiño, María A Davis-López de Carrizosa, Sara Morcuende, Esperanza R Matarredona, Rosa R de la Cruz, Angel M Pastor
Neurotrophins play a principal role in neuronal survival and differentiation during development, but also in the maintenance of appropriate adult neuronal circuits and phenotypes. In the oculomotor system, we have demonstrated that neurotrophins are key regulators of developing and adult neuronal properties, but with peculiarities depending on each neurotrophin. For instance, the administration of NGF (nerve growth factor), BDNF (brain-derived neurotrophic factor) or NT-3 (neurotrophin-3) protects neonatal extraocular motoneurons from cell death after axotomy, but only NGF and BDNF prevent the downregulation in ChAT (choline acetyltransferase)...
December 1, 2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27844097/the-effects-of-unilateral-versus-bilateral-subthalamic-nucleus-deep-brain-stimulation-on-prosaccades-and-antisaccades-in-parkinson-s-disease
#17
Lisa C Goelz, Fabian J David, John A Sweeney, David E Vaillancourt, Howard Poizner, Leonard Verhagen Metman, Daniel M Corcos
Unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson's disease improves skeletomotor function assessed clinically, and bilateral STN DBS improves motor function to a significantly greater extent. It is unknown whether unilateral STN DBS improves oculomotor function and whether bilateral STN DBS improves it to a greater extent. Further, it has also been shown that bilateral, but not unilateral, STN DBS is associated with some impaired cognitive-motor functions. The current study compared the effect of unilateral and bilateral STN DBS on sensorimotor and cognitive aspects of oculomotor control...
February 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/27833536/patterns-of-activity-in-the-human-frontal-and-parietal-cortex-differentiate-large-and-small-saccades
#18
Marie-Hélène Grosbras
A vast literature indicates that small and large saccades, respectively, subserve different perceptual and cognitive strategies and may rely on different programming modes. While it is well-established that in monkeys' main oculomotor brain regions small and large eye movements are controlled by segregated neuronal populations, the representation of saccade amplitude in the human brain remains unclear. To address this question we used functional magnetic resonance imaging to scan participants while they performed saccades toward targets at either short (4°) or large (30°) eccentricity...
2016: Frontiers in Integrative Neuroscience
https://www.readbyqxmd.com/read/27793591/association-between-comt-genotype-and-the-control-of-memory-guided-saccades-individual-differences-in-healthy-adults-reveal-a-detrimental-role-of-dopamine
#19
Jutta Billino, Jürgen Hennig, Karl R Gegenfurtner
The neural circuits involved in oculomotor control are well described; however, neuromodulation of eye movements is still hardly understood. Memory guided saccades have been extensively studied and in particular neurophysiological evidence from monkey studies points to a crucial functional role of prefrontal dopamine activity. We exploited individual differences in dopamine regulation due to the well established COMT (catechol-O-methyltransferase) Val(158)Met polymorphism to explore the link between prefrontal dopamine activity and memory guided saccades in healthy subjects...
December 15, 2016: Vision Research
https://www.readbyqxmd.com/read/27781300/functional-synergy-between-postural-and-visual-behaviors-when-performing-a-difficult-precise-visual-task-in-upright-stance
#20
Cédrick T Bonnet, Sébastien Szaffarczyk, Stéphane Baudry
Previous works usually report greater postural stability in precise visual tasks (e.g., gaze-shift tasks) than in stationary-gaze tasks. However, existing cognitive models do not fully support these results as they assume that performing an attention-demanding task while standing would alter postural stability because of the competition of attention between the tasks. Contrary to these cognitive models, attentional resources may increase to create a synergy between visual and postural brain processes to perform precise oculomotor behaviors...
August 2017: Cognitive Science
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