bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visual and Vestibular Contributions to Head-Eye Coordination during Head-Free Pursuit
Authors: Barnes Graham R. , Lawson Jane F. 
Published: April 2012

AbstractThis chapter presents the results of the experiments that indicate that there is little evidence to support the existence of a central cancellation mechanism of the VOR in normal human subjects, as proposed by Robinson. The changes in gaze velocity with the frequency composition of the stimulus are discussed in this chapter. The enhancement of the highest frequency component is presented. The role of the vestibulo-ocular reflex during head-free pursuit is analyzed and investigated here. It is concluded that although there is little evidence to support the central cancellation hypothesis, other nonvisual mechanisms may have a role in vestibulo-ocular reflex suppression.
Mathematical Modeling of Visual and Nonvisual Mechanisms of Head-Eye Coordination
Authors: Barnes Graham R. 
Published: April 2012

AbstractThe gain of eye velocity during head-fixed pursuit is significantly modified by the frequency composition of a mixed-frequency, pseudorandom stimulus. The model of the visual and nonvisual control of smooth eye movement that has been developed is discussed here, as well as the results of a series of experiments related to head-eye coordination. In order to simulate the changes in gain and phase of eye velocity that occur during a number of oculomotor tasks, a model of oculomotor control is presented here. The results of the experiment indicate that there are two separate mechanisms involved in the visual control of eye movement. Evidence suggests that optimal VOR suppression can be achieved only through visual feedback.
Timing of Coordinated Head and Eye Movements during Changes in the Direction of Gaze
Authors: Steen Johannes Van Der 
Published: April 2012

AbstractThe objective of this chapter is to present the effects of voluntary control and stimulus conditions on three types of oculomotor behavior that were previously regarded as different subsystems. Examples are given in this chapter to illustrate that performance is determined by stimulus conditions and voluntary processes. The primary contribution of head movements to saccadic gaze shifts is a reduction of the duration of the gaze shift that results in different characteristics of the velocity profile. These experiments aim to study interactions between saccades and vergence or pursuit and vergence, and to give more insight into the degree to which the performance of the head motor systems and oculomotor behavior is determined by processing in modular subsystems.
Decoding of Optic Flow by the Primate Optokinetic System
Authors: Miles Frederick A. , Schwarz Urs , Busettini Claudio 
Published: April 2012

AbstractThe major concern in this chapter is the review of the recent argument of Miles which explains that the visual backup to the two labyrinth reflexes (rotational vestibulo-ocular reflex (RVOR) and translational vestibulo-ocular reflex (TVOR)) is provided by two individual tracking systems. One tracking system is the classical optokinetic system (OKR), which provides backup to canal-ocular reflexes and mainly deals with rotational disturbances of gaze. The other one provides the backup to otolith-ocular reflexes and mainly deals with translational disturbances of gaze. This chapter also offers some cautionary words concerning the decomposition of optic flow into rotational and translational components. It is suggested that the pursuit system be deployed by some attentional focusing mechanism.
Perception of Liminal and Supraliminal Whole-Body Angular Motion
Authors: Benson Alain J. , Brown Sally F. 
Published: April 2012

AbstractUnderstanding the head-neck system involves knowledge about the sensitivity and dynamics of the ampullary receptors of the semicircular canals, the macular receptors of the otolith organs, and the cervical mechanoreceptors. This chapter deals with the perception of sensory information from the semicircular canals engendered by whole-body angular motion stimuli. Thresholds for the detection of discrete angular movements in x, y, and z axes are presented in this chapter. Moreover, the effects of head-fixed visual display and stimulus duration on thresholds are discussed. It is concluded that although there is a complex interrelationship between velocity, acceleration, and frequency in determining the subjective intensity of whole-body angular acceleration, the experiments using supraliminal stimuli are in agreement with the studies about thresholds.
Cortical Representation of Head-in-Space Movement and Same Psychophysical Experiments on Head Movement
Authors: Grüsser Otto-Joachim , Guldin Wolfgang , Harris Lawrence , Lefèbre Johann-Christoph , Pause Max 
Published: April 2012

AbstractThe contribution of multimodal signals to the perception of head movements is discussed in this chapter. The experimental methods and the anatomic connections of the parieto-insular vestibular cortex (PVIC) in primates are presented here, as well as the description of the responses of single nerve cells in the PIVC to visual, vestibular, and somatosensory stimulation. The second part of this chapter contains a discussion of the latest psychophysical experiments performed in the laboratory with results that indicate the functional involvement of the PVIC beyond vection by optokinetic stimulation. It is concluded that the neurophysiological experiments performed provided strong evidence for the existence of a complex cortical neuronal network in the primate monitoring of the rotary movements of the head in space.
Eye-Head Coordination in Oblique Gaze Shifts in Cats
Authors: Roucoux André , Crommelinck Marc , Borel and Liliane 
Published: April 2012

AbstractThis chapter focuses on the discussion of the characteristics of neck muscle command signals and the descriptions of the aspects of head movement trajectories, eye saccades, and the coordination in visually triggered oblique gaze shifts by trained cats. The methods in the eye and head movement recording and the training procedure and experimental paradigm are presented. The results of the activity are explained in detail in this chapter, including (1) the timing of the neck muscle discharge as a function of the orientation of the head movement and (2) the temporal aspects of eye-head component coordination.
Vestibulo-Ocular Reflex Inhibition Mechanism during Goal-Directed Saccades in Man
Authors: Pélisson Denis , Prablanc Claude 
Published: April 2012

AbstractIt has been shown from recent studies that concurrent head velocity affects gaze shift kinematics due to an inhibition of the VOR during the saccade in man. The goal of this study is to quantify the VOR-saccade interactions during small gaze shifts. A procedure of passive head rotation is thus designed to be able to quantify VOR gain associate with gaze shifts of even smaller amplitude. The main findings are summarized in the gaze velocity profiles. It was found that when saccadic response is executed when the head is moving in the same direction, gaze velocity is faster than when the head is fixed. Another finding is that the gaze shift duration is inversely related to gaze shift velocity.
Do Head Position and Active Head Movements Influence Postural Stability?
Authors: Straube Andreas , Paulus Walter , Brandt Thomas 
Published: April 2012

AbstractThe differential effects of voluntary head movements (horizontal oscillations about the z axis) and varying head positions on postural sway are investigated in this chapter. The methods of the experiments are presented here. Ten subjects took part in the experiments, where their head movements were recorded using a head-fixed angular accelerometer. The main finding of the experiment is that the differential effects of varying head positions were surprisingly small. Moreover, the body sway does not significantly increase with head rotation and that indicated the precise reevaluation of head sway with respect to the head position relative to the trunk.
Influence of Tactile Cues on Visually Induced Postural Reactions
Authors: Young Lawrence R. , Standish Gail 
Published: April 2012

AbstractThe primary focus of this study is multi-sensory integration and its motor control and behavioral consequences. The series of experiments involve moving a spatial visual stimulus provided by a roughly hemispherical “rotating dome” filling the subject's field of view. It is discussed in this chapter how elementary reflexes that act to maintain an animal's head in the upright position depend upon numerous sensory inputs acting independently or in a group. This study demonstrates that the presence of lateral forces on the shoulders is enough to inhibit visually induced motion and the associated postural reactions of the neck and trunk.
Differential Influence of Vertical Head Posture during Walking
Authors: Zangemeister Wolfgang H. , Bulgheroni Maria V. , Pedotti Antonio 
Published: April 2012

AbstractThis study involves a kinematic analysis based on the examination of trajectories, velocities, and accelerations of all markers. The two questions pursued in this study are: (1) would it be possible to distinguish responses from subjects when normal humans walked under three different conditions of vertical head posture? (2) how could results fit into recent observations on the linkage between gaze position, otolith influences, and neck muscles as the uppermost part of the truncal/skeletal muscles? The results showed that the otolith input appears to dominate particularly neck prioceptive and gaze motor influences during normal gait. Thus, postural control depends on the integration of vestibular, somatosensory, and visual orientation signals.
Head-Shaking Nystagmus—A Tool to Detect Vestibular Asymmetries in Patients
Authors: Koenig Eberhard , Fetter Michael , Takahashi Sachiko , Dichgans Johannes 
Published: April 2012

AbstractHead-shaking nystagmus (HSN) is a transient nystagmus which is a result of a unilateral peripheral hypofunction based on Ewald's second law. This law states that there will be a stronger response of a labyrinth to excitatory than to inhibitory inputs with high-velocity stimuli. This chapter aims to understand the degree to which the HSN may be explained by the two hypotheses — unilateral peripheral hypofunction or asymmetry of central velocity storage — and to evaluate the correlation between HSN and SPN. It is concluded that the horizontal head-shaking maneuver is a highly sensitive method for detecting vestibular asymmetries resulting from the unilateral vestibular hypofunction or imbalance in the central velocity storage.
Effect of Peripheral Vestibular Disorders on Head-Trunk Coordination during Postural Sway in Humans
Authors: Shupert Charlotte L. , Horak Fay Bahling , Black F. Owen 
Published: April 2012

AbstractThe experiments in this study were performed to analyze how head motion is controlled during postural sway in two groups of patients with vestibular disorders and in normal subjects. The subjects were tested in conditions that resulted in postural sway primarily about the ankles, with little motion of the trunk, and in conditions that led to large motions of the body about the hips, with substantial motion of the trunk. The results have shown that the head and trunk movements are uncoordinated in normal subjects and patients with severe bilateral deficits. The results also indicated that when postural sway results in large movements of the trunk, the head movements of the normal subjects are controlled in a way that provides a stable platform for the vestibular and visual systems.
Eye-Head Coordination in Normal and Hemilabyrinthectomized Cats
Authors: Borel Liliane , Lacour Michel 
Published: April 2012

AbstractThis chapter studies the properties and the functional coupling of four sensory-motor subsystems that contribute to the head and eye stabilization during linear motion in the vertical plane. The problems investigated in this chapter include the way the reflexes interact and are functionally coupled and the solutions relating to the central nervous system (CNS) when the there is an impaired eye-head coordination. The dynamics of the vestibulocollic reflex, oculocollic coupling, and the compensatory eye movements are discussed here. It is concluded that tight coupling between the visual and vestibular systems in head postural control and gaze stabilization also operates during linear motion in the vertical plane.
Vestibular Compensation: Sensitive Period and Role of Sensory-Motor Activity in Substitution Processes
Authors: Zennou-Azogui Yohʼi , Xerri Christian 
Published: April 2012

AbstractThis chapter discusses vestibular compensation as a multisensory substitution process. The contribution of somatosensory afferents, the remaining labyrinthine afferents, and the visual afferents are also explained in this chapter. The authors also studied the effect of sensory motor restriction (SMR) on the recovery of locomotor equilibrium after unilateral vestibular neurectomy. The behavioral and neurophysiologic studies show the critical part that a substitution process can play in vestibular compensation. It is concluded that the sensory data transmitted to the central nervous system (CNS) could play a substitutive role in the recovery of dynamic function if they are available at an early and delimited period of compensation.
Response Characteristics of Central Vestibular Neurons and Compensatory Mechanisms following Hemilabyrinthectomy
Authors: Chan Ying-Sing , Hwang Joseph C. 
Published: April 2012

AbstractThe changes in vestibular neuronal activities that accompany hemilabyrinthectomy (HL) are the main focus of this study. The emphasis is on the acute and chronic changes in relation to the otolith system in response to HL. The compensatory process after HL is also discussed in relation to the involvement of neural structures and changes in synaptic mechanisms. The semicircular canal system and the otolith system are discussed in this chapter. The acute hemilabyrinthectomy, otolith function with bilateral labyrinths intact, and the response sensitivity and spatial coding properties of central vestibular units in the lesioned side are also described. The findings imply that inputs from the intact otoliths and/or semicircular canals in the lesioned animals are operative at the level of the vestibular nuclei bilaterally during natural head movements.
Vestibular N-Methyl-d-Aspartate Receptors in Normal and Compensated Guinea Pigs
Authors: Waele Catherine De , Vibert Nicholas , Berthoz Alain , Vidal Pierre Paul 
Published: April 2012

AbstractThe postural syndromes observed after unilateral global and selective lesions of the vestibular apparatus are discussed in the first part of this chapter. The second part includes the results that suggest that N-methyl-D-aspartate (NMDA) receptors contribute to the resting discharge of the vestibular neurons in normal guinea pigs in vivo. The third part contains the recommendation to increase the number and/or sensitivity of NMDA receptors on deafferented neurons in order to create denervation hypersensitivity. This could contribute to the functional recovery of the static reflexes in hemilabyrinthectomized guinea pigs.
Effects ofN-Methyl-d-Aspartate Receptor Antagonists on Vestibular Compensation in the Guinea Pig: In Vivo and In Vitro Studies
Authors: Smith Paul F. , Darlington Cynthia L. 
Published: April 2012

AbstractThis study investigates the contribution of NMDA receptors to vestibular compensation for UL in the guinea pig using the NMDA receptor/channel antagonists. Three experimental approaches were taken to examine the effect of NMDA antagonists on vestibular compensation. The results imply that NMDA receptor antagonists interfere with vestibular compensation during a limited period following UL. It is found that noncompetitive NMDA antagonists MK801 have a binding site similar to dissociative anesthetics such as ketamine.
Subjective Visual Vertical and Eye-Head Coordination (Roll) with Brain Stem Lesions
Authors: Marianne Dieterich , Brandt Thomas 
Published: April 2012

AbstractThe ocular tilt reaction (OTR) models a fundamental pattern of coordinated eye-head roll motion based on utricular/saccular as well as vertical canal input, made by the gaviceptive pathways from the labyrinths via pontomedullary vestibular nuclei to the rostral midbrain tegmentum. The direction of eye-head tilt in roll with brain stem lesions and the skew deviation and cyclorotation is discussed in this chapter. It is concluded that all patients with the OTR showed significant deviations of the subjective visual vertical (SVV) in the direction of the head tilt. The single features of the OTR, perceptual and oculomotor, can be induced separately depending on the site of the lesion.
Cervical Contribution to Balance: Cervical Vertigo
Authors: Brown Jeffrey J. 
Published: April 2012

AbstractDizziness is described as any alteration or perversion of the sense of balance. In this chapter, the evidence to support the diagnosis of the syndrome of imbalance that resulted from disturbance of cervical joint receptors is presented and tackled. Various experimental supports are presented in this chapter. Also, cervical vertigo syndrome is discussed in detail, including its definition and symptoms. The diagnostic dilemmas are also briefly discussed, such as the complaints that complicate the diagnosis of cervical vertigo due to the subjective signs of the disease. It is recommended from experimental evidence that there should be a validity of the diagnosis of cervical vertigo because of the increasing number of patients with characteristic syndrome.
Experimental Torticollis in Cats and Monkeys: Effect of Lesions and Drugs
Authors: Maulin Francine , Bédard Paul J. 
Published: April 2012

AbstractThis chapter provides supporting evidence that torticollis has a frontal and a horizontal component, related to dysfunction involving different systems. The posture and movements of the head are disturbed in a different manner according to the lesion inducing the torticollis. Moreover, the frequent occurrence of mixed forms of torticollies in humans may imply that a unifocal lesion can be responsible for head disturbances that involve interrelated systems. A parallel can be drawn between the variability of responses induced by the drugs in the experimental models of torticollis and the drug responses variability reported in patients with spasmodic torticollis.
Functional Outcome after Segmental Arthrodesis of the Cervical Spine
Authors: Mestdagh Henri , Leclet Hervé 
Published: April 2012

AbstractThe objective of this study is to evaluate the remaining range of head movement after surgery and to account for the behavior of the intervertebral levels beyond the site of arthrodesis. There is an accurate reduction of the fracture and/or dislocation. Moreover, compensatory motion can take place on either side of the site of operation. It is concluded that any surgical intervertebral fusion jeopardizes the range of motion of the cervical spine.
Fixed Gaze and Eye-Head Coordination in Basal Ganglia Diseases (Parkinson's Disease, Huntington's Chorea, and Pallidum Necrosis)
Authors: Bazalgette Didier , Zattara Maurice , Bathien Nguyen , Rondot Pierre 
Published: April 2012

AbstractThe role of the basal ganglia in eye-head coordination has been studied using neurophysiologic and mathematical tools. The authors tried to answer the questions: (1) How do normal subjects organize and stabilize a new eye-head coordination situation? (2) What changes occur in patients with basal ganglia disorders? (3) Do eye-head coordination disorders and posturokinetic coordination share common characteristics? In the experimental paradigm, the subjects maintained the gaze on a central target during active and passive isolated head rotations. It is suggested this paradigm is used in studying eye-head motor coordination in central nervous system disorders.
Abnormal Timing of Antagonist Splenius Burst in Head Movements of Patients with Cerebellar Disorders: Clinical and Modeling Results
Authors: Zangemeister Wolfgang H. , Dee Jürgen , Arlt Andreas C. 
Published: April 2012

AbstractThe objective of this study is to understand the role of the cerebellum with respect to the generating process and timing of the motor control signals. The model for simulation of head movements involves the approximation of a rigid sphere, rotating about its center of mass. The experimental setup involves the test subject sitting in front of a screen that is horizontally concave. The patient is asked to make time-optimal head movements of 80° amplitude. Experimental results for normal subjects and patients with cerebellar disorders are presented. The chapter discusses how increased fluctuations of premotor and reciprocal motor activation is responsible for cerebellar dysmetria.
Thirty Years Among Cortical Neurons
Authors: Prince David A. 
Published: April 2012

AbstractThis chapter begins a discussion of the concept of diversity as a key attribute of cortical neurons, and the importance of understanding interactions that occur among molecular-, cellular-, and circuit-level functions in predicting the effects of naturally occurring or experimentally induced alterations. The functional implications of intrinsic burst generation in subsets of neurons are used to illustrate the potentially unexpected results that may ensue when translating molecular (membrane) properties into the language of the cortex. The chapter then uses the results of experiments on epileptogenesis to emphasize the important contributions that work on abnormal cortical function has made to understanding the normal operation of the cortex. Diversity and the plastic changes in the cortex produced by activity and injury are discussed as they relate to the pathophysiology of epilepsy. The study of epileptogenesis is a pseudonym for the study of brain function. The core issues are the same as those that form some of today's challenges in neuroscience.
Cortical Synaptic Transmission: An Overview
Authors: Stevens Charles F. 
Published: April 2012

AbstractA microliter of brain contains approximately a billion synapses, about two-thirds of which are excitatory. Clearly synapses are vital because the brain uses so many of them, but their close packing makes the investigation of individual synapses for a complete elucidation of their function, very difficult. This chapter briefly summarizes the picture of transmission at the neuromuscular junction, defines some of the unresolved issues relating to the function of this model synapse, compares transmission at central synapses, and explores similarities and differences between the neuromuscular junction and central synapses.
The Cortical Neuron as an Electrophysiological Unit
Authors: Gutnick Michael J. , Crill Wayne E. 
Published: April 2012

AbstractCellular physiological studies from all areas of the brain have revealed that a rich assortment of ionic channels combine variously in the soma-dendritic membranes of different neurons to produce a diversity of firing types; the cortex is no exception. To add a dynamic dimension to our concept of the neocortical circuit, we must consider the distinctive input–output characteristics of different circuit elements and the diverse ionic channel types that determine them. This chapter briefly reviews the different firing types of neocortical neurons and summarizes the properties of the ionic currents that have been identified in cortex. It also considers mounting evidence that the elaborate dendrites of neocortical neurons are not merely passive accumulators of synaptic input but rather that they also possess functionally significant active properties.