Read by QxMD icon Read

vor cancellation

Genjiro Hirose
Over the last decade, substantial information on cerebellar oculomotor control has been provided by the use of sophisticated neuroanatomical, neurophysiological, and imaging techniques. We now know that an intact cerebellum is a prerequisite for normal oculomotor performance. This review clarifies the current knowledge on structure-function correlations of the cerebellum in relation to ocular movements and allows them to be applied to topographical diagnosis of cerebellar lesions. The cerebellar regions most closely related to oculomotor function are: (1) the flocculus/paraflocculus for VOR suppression, cancellation, smooth pursuit eye movement and gaze-holding, (2) the nodulus/ventral uvula for velocity storage and low frequency prolonged vestibular response, and (3) the dorsal oculomotor vermis (declive VI, folium VII) and the posterior portion of the fastigial nucleus (fastigial oculomotor region) for saccades and smooth pursuit initiation...
March 2016: Brain and Nerve, Shinkei Kenkyū No Shinpo
Norie Ito, Hidetoshi Takei, Susumu Chiba, Kiyoharu Inoue, Kikuro Fukushima
Although impaired smooth-pursuit in Parkinson's disease (PD) is well known, reports are conflicting on the ability to cancel vestibulo-ocular reflex (VOR) when the target moves with head, requiring gaze-pursuit. To compare visual tracking performance with or without passive whole-body rotation, we examined eye movements of 10 PD patients and 6 age-matched controls during sinusoidal horizontal smooth-pursuit and passive whole-body rotation (0.3 Hz, ± 10°). Three tasks were tested: smooth-pursuit, VOR cancellation, and VORx1 while subjects fixated an earth-stationary spot during whole-body rotation...
2016: Rinshō Shinkeigaku, Clinical Neurology
Julian A Gingold, Joseph A Lee, Michael C Whitehouse, Jorge Rodriguez-Purata, Benjamin Sandler, Lawrence Grunfeld, Tanmoy Mukherjee, Alan B Copperman
BACKGROUND: Elevated follicle stimulating hormone (FSH) is associated with poor vaginal oocyte retrieval (VOR) outcomes and cycle cancellations but intercycle variability in basal FSH reportedly does not predict ovarian response. METHODS: We conducted a retrospective cohort study of basal FSH (n = 15573 cycles) in couples (n = 9132) who initiated IVF cycle(s) with basal estradiol (E2) <100 pg/mL between 2002 and 2014 to reevaluate this hypothesis. The most recent (current) FSH, maximum FSH (Max FSH) and prior cycle maximum basal FSH (PMax FSH) were computed for each cycle...
2015: Reproductive Biology and Endocrinology: RB&E
Emma D Wilson, Tareq Assaf, Martin J Pearson, Jonathan M Rossiter, Paul Dean, Sean R Anderson, John Porrill
The adaptive filter model of the cerebellar microcircuit has been successfully applied to biological motor control problems, such as the vestibulo-ocular reflex (VOR), and to sensory processing problems, such as the adaptive cancelation of reafferent noise. It has also been successfully applied to problems in robotics, such as adaptive camera stabilization and sensor noise cancelation. In previous applications to inverse control problems, the algorithm was applied to the velocity control of a plant dominated by viscous and elastic elements...
2015: Frontiers in Neurorobotics
Pablo M Blazquez, Tatyana A Yakusheva
Data from in vitro and anesthetized preparations indicate that inhibition plays a major role in cerebellar cortex function. We investigated the role of GABA-A inhibition in the macaque cerebellar ventral-paraflocculus while animals performed oculomotor behaviors that are known to engage the circuit. We recorded Purkinje cell responses to these behaviors with and without application of gabazine, a GABA-A receptor antagonist, near the recorded neuron. Gabazine increased the neuronal responsiveness to saccades in all directions and the neuronal gain to VOR cancellation and pursuit, most significantly the eye and head velocity sensitivity...
May 19, 2015: Cell Reports
Michael J Mustari, Seiji Ono
The visual and oculomotor systems of primates are immature at birth and sensitive to injury. If synergistic interactions between visual and oculomotor systems are compromised during the first months of life, disorders in eye alignment, gaze holding, and smooth pursuit (SP) follow. Here we consider some potential neural mechanisms supporting SP and associated vestibular ocular reflex (VOR) behavior in normal and strabismic monkeys. Experimental strabismus was created by prism goggle wearing or eye muscle surgery in rhesus monkeys (Macaca mulatta)...
September 2011: Annals of the New York Academy of Sciences
Kiyoshi Hiruma, Tsutomu Numata, Toshio Mitsuhashi, Takuya Tomemori, Ryoko Watanabe, Yoshitaka Okamoto
OBJECTIVES: We encountered patients who had static direction-changing positional nystagmus (DCPN) canceled at about 20-30° yaw head rotation from the supine position. This nystagmus was also canceled when the head was rotated 180° from this position. We termed these head positions neutral points. The positional nystagmus observed (except at the neutral points) was thought to occur due to a "heavy cupula" or "light cupula". The purpose of this study was to examine DCPN with neutral points as well as the pathomechanism of this condition...
February 2011: Auris, Nasus, Larynx
V Sturm, H Leiba, M N Menke, E M Valente, A Poretti, K Landau, E Boltshauser
PURPOSE: Joubert syndrome (JS) is an autosomal-recessive inherited complex malformation of the midbrain-hindbrain. It has been associated with ocular and oculomotor abnormalities. The aim of our study was to extend the ophthalmic knowledge in JS and to add new findings. METHODS: In a retrospective study, 10 consecutive patients, who met the revised diagnostic criteria of JS were included. Mutation analysis was carried out in all the cases. Each patient underwent a comprehensive neuro-ophthalmological examination...
February 2010: Eye
Teppei Akao, Sergei Kurkin, Junko Fukushima, Kikuro Fukushima
The smooth-pursuit system must interact with the vestibular system to maintain the accuracy of eye movements in space during head movement. Maintenance of a target image on the foveae is required not only during head rotation which activates primarily semi-circular canals but also during head translation which activates otolith organs. The caudal part of the frontal eye fields (FEF) contains pursuit neurons. The majority of them receive vestibular inputs induced by whole body rotation. However, it has not been tested whether FEF pursuit neurons receive otolith inputs...
March 2009: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Carlos R Gordon, Avi Caspi, Ronen Levite, Ari Z Zivotofsky
The vestibulo-ocular reflex (VOR) mechanism triggers eye movements as a result of head motion in order to keep gaze stationary relative to the world. However, in order to shift the direction of the gaze along with head motion, the VOR mechanism must be overridden ("cancelled"). Two mechanisms have been proposed to explain this cancellation: a reduction of the VOR gain or activation of smooth pursuit (SP) eye movements in the opposite direction. We studied VOR cancellation using the magnetic search coil in six spinocerebellar ataxia type 3 (SCA-3) and four episodic ataxia type 2 (EA-2) patients, conditions that are known to have degraded SP but different degrees of VOR impairment...
2008: Progress in Brain Research
Teppei Akao, Yousuke Kumakura, Sergei Kurkin, Junko Fukushima, Kikuro Fukushima
Young primates exhibit asymmetric eye movements during vertical smooth-pursuit across a textured background such that upward pursuit has low velocity and requires many catch-up saccades. The asymmetric eye movements cannot be explained by the un-suppressed optokinetic reflex resulting from background visual motion across the retina during pursuit, suggesting that the asymmetry reflects most probably, a low gain in upward eye commands (Kasahara et al. in Exp Brain Res 171:306-321, 2006). In this study, we examined (1) whether there are intrinsic differences in the upward and downward pursuit capabilities and (2) how the difficulty in upward pursuit is correlated with the ability of vertical VOR cancellation...
October 2007: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Teppei Akao, Hiroshi Saito, Junko Fukushima, Sergei Kurkin, Kikuro Fukushima
The smooth pursuit system and the vestibular system interact to keep the retinal target image on the fovea by matching the eye velocity in space to target velocity during head and/or whole body movement. The caudal part of the frontal eye fields (FEF) in the fundus of the arcuate sulcus contains pursuit-related neurons and the majority of them respond to vestibular stimulation induced by whole body movement. To understand the role of FEF pursuit neurons in the interaction of vestibular and pursuit signals, we examined the latency and time course of discharge modulation to horizontal whole body rotation during different vestibular task conditions in head-stabilized monkeys...
March 2007: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Seiji Ono, Michael J Mustari
Smooth pursuit (SP)-related neurons in the dorsal-medial part of medial superior temporal cortex (MSTd) carry extraretinal signals that may play a role in maintenance of SP once eye velocity matches target velocity. For example, it has not been determined whether the extraretinal signals reflect volitional SP commands or proprioception. The aim of this study was to test some potential sources of extraretinal signals in MSTd pursuit neurons. We tested 40 MSTd neurons during step-ramp SP with target blink conditions to show that they carried an extraretinal signal...
November 2006: Journal of Neurophysiology
Sarah Marti, Christopher J Bockisch, Dominik Straumann
Anatomical and electrophysiological studies have demonstrated up-down asymmetries in vertical ocular motor pathways. We investigated whether these asymmetries extend to the capacity for short-term adaptation of the vertical vestibulo-ocular reflex (VVOR) in humans. Specifically, we asked whether smooth pursuit signals are sufficient to asymmetrically adapt the VVOR. Healthy human subjects (N=8), positioned 90 degrees left-ear-down and fixating with their eyes upon a small laser dot (diameter: 0.1 degrees) projected on a sphere (distance: 1...
July 2006: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Hui Meng, Andrea M Green, J David Dickman, Dora E Angelaki
Under natural conditions, the vestibular and pursuit systems work synergistically to stabilize the visual scene during movement. How translational vestibular signals [translational vestibuloocular reflex (TVOR)] are processed in the premotor pathways for slow eye movements continues to remain a challenging question. To further our understanding of how premotor neurons contribute to this processing, we recorded neural activities from the prepositus and rostral medial vestibular nuclei in macaque monkeys. Vestibular neurons were tested during 0...
June 2005: Journal of Neurophysiology
Michael J Mustari, Seiji Ono, Vallabh E Das, Ronald J Tusa
Visual-vestibular behavior depends on signals traveling in climbing and mossy fiber pathways. Our study examined the role of the dorsolateral pontine nucleus (DLPN), a major component of the cortico-ponto-cerebellar mossy fiber pathway. DLPN neurons discharge in relation to smooth pursuit and during visual stimulation, indicating a potential role in visually guided motor learning in the vestibulo-ocular reflex (VOR). We used unilateral muscimol injections to determine the potential role of the DLPN in short-term VOR gain adaptation...
October 2003: Annals of the New York Academy of Sciences
Joseph M Furman, Martijn L T M Müller, Mark S Redfern, J Richard Jennings
Attention has been implicated in postural control and other tasks requiring sensory integration. The purpose of this study was to investigate the role of attention in sensory-motor processing of vestibular and combined visual-vestibular information during seated rotations using a dual-task interference approach. We hypothesized that auditory information processing would be influenced by concurrent visual-ocular, vestibulo-ocular, or combined visual-vestibulo-ocular processing. We further hypothesized that the effect would be greater in older subjects...
October 2003: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
N Takeichi, J Fukushima, S Kurkin, T Yamanobe, Y Shinmei, K Fukushima
The smooth pursuit system moves the eyes in space accurately while compensating for visual inputs from the moving background and/or vestibular inputs during head movements. To understand the mechanisms underlying such interactions, we examined the influence of a stationary textured visual background on smooth pursuit tracking and compared the results in young and adult humans and monkeys. Six humans (three children, three adults) and six macaque monkeys (five young, one adult) were used. Human eye movements were recorded using infrared oculography and evoked by a sinusoidally moving target presented on a computer monitor...
April 2003: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Benjamin T Crane, Junru Tian, Gerald Wiest, Joseph L Demer
The linear vestibulo-ocular reflex (LVOR) was studied in eight normal human subjects of average age 24+/-5 years. Subjects underwent a sudden heave (mediolateral) translation delivered by a pneumatic servo-driven chair with a peak acceleration of 0.5 g while viewing earth-fixed targets at 15, 25, 50, and 200 cm. Stimuli were provided both with targets continuously visible or extinguished just prior to motion. Cancellation was tested using chair-fixed targets at each viewing distance. Eye movements were recorded using binocular magnetic search coils...
January 2003: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
M Hashiba
It has been well known that the canal driven vestibulo-ocular reflex (VOR) is controlled and modulated through the central nervous system by external sensory information (e.g. visual, otolithic and somatosensory inputs) and by mental conditions. Because the origin of retinal image motion exists both in the subjects (eye, head and body motions) and in the external world (object motion), the head motion should be canceled and/or the object should be followed by smooth eye movements. Human has developed a lot of central nervous mechanisms for smooth eye movements (e...
December 2001: Uchū Seibutsu Kagaku
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"