Neural Correlates of Forward and Inverse Models for Eye Movements: Evidence from Three-Dimensional Kinematics

Ghasia, Fatema F.; Hui, Meng; Angelaki, Dora E.

doi:10.1523/jneurosci.0513-08.2008

Cited by 48 publications

(57 citation statements)

References 42 publications

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“…Such an inverse model can also be used as a first approximation for a neuronal inverse model (Kawato et al, 1987;Wolpert and Kawato, 1998) used by the rat vibrissal system for whisking control. A spike-based inverse model derived from the model presented here can complement existing rate-based descriptions of inverse models (e.g., Ghasia et al, 2008;Lisberger, 2009). …”

Section: Inverse Model Of Whiskingmentioning

confidence: 99%

Temporal and Spatial Characteristics of Vibrissa Responses to Motor Commands

Simony¹,

Bagdasarian²,

Herfst³

et al. 2010

Journal of Neuroscience

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A mechanistic description of the generation of whisker movements is essential for understanding the control of whisking and vibrissal active touch. We explore how facial-motoneuron spikes are translated, via an intrinsic muscle, to whisker movements. This is achieved by constructing, simulating, and analyzing a computational, biomechanical model of the motor plant, and by measuring spiking to movement transformations at small and large angles using high-precision whisker tracking in vivo. Our measurements revealed a supralinear summation of whisker protraction angles in response to consecutive motoneuron spikes with moderate interspike intervals (5 ms Ͻ ⌬t Ͻ 30 ms). This behavior is explained by a nonlinear transformation from intracellular changes in Ca 2ϩ concentration to muscle force. Our model predicts the following spatial constraints: (1) Contraction of a single intrinsic muscle results in movement of its two attached whiskers with different amplitudes; the relative amplitudes depend on the resting angles and on the attachment location of the intrinsic muscle on the anterior whisker. Counterintuitively, for a certain range of resting angles, activation of a single intrinsic muscle can lead to a retraction of one of its two attached whiskers. (2) When a whisker is pulled by its two adjacent muscles with similar forces, the protraction amplitude depends only weakly on the resting angle. (3) Contractions of two adjacent muscles sums up linearly for small amplitudes and supralinearly for larger amplitudes. The model provides a direct translation from motoneuron spikes to whisker movements and can serve as a building block in closed-loop motor-sensory models of active touch.

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Section: Inverse Model Of Whiskingmentioning

confidence: 99%

Temporal and Spatial Characteristics of Vibrissa Responses to Motor Commands

Simony¹,

Bagdasarian²,

Herfst³

et al. 2010

Journal of Neuroscience

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show abstract

“…Once smooth pursuit has been initiated, afferent visual feedback as well as efference copies of the motor commands are used for pursuit maintenance (Lisberger et al 1987). The traditional view of how smooth pursuit eye movements are initiated involves computing a two-dimensional (2D) velocitybased motor plan from the retinal slip information, which is then used to drive the 3D ocular plant (Angelaki and Hess 2004;Dicke and Thier 1999;Ghasia et al 2008;Klier et al 2006;Tweed et al 1992). This view proposes that 3D behavioral constraints such as Listing's law, which allows for 2D control of a 3D plant, are implemented through the extraocular muscle-pulley system (Demer 2004(Demer , 2006(Demer , 2007Quaia and Optican 1998).…”

Section: Introductionmentioning

confidence: 99%

Visuomotor Velocity Transformations for Smooth Pursuit Eye Movements

Blohm

Lefèvre

2010

Journal of Neurophysiology

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Blohm G, Lefèvre P. Visuomotor velocity transformations for smooth pursuit eye movements. J Neurophysiol 104: 2103-2115, 2010. First published August 18, 2010 doi:10.1152/jn.00728.2009. Smooth pursuit eye movements are driven by retinal motion signals. These retinal motion signals are converted into motor commands that obey Listing's law (i.e., no accumulation of ocular torsion). The fact that smooth pursuit follows Listing's law is often taken as evidence that no explicit reference frame transformation between the retinal velocity input and the head-centered motor command is required. Such eye-position-dependent reference frame transformations between eye-and head-centered coordinates have been well-described for saccades to static targets. Here we suggest that such an eye (and head)-position-dependent reference frame transformation is also required for target motion (i.e., velocity) driving smooth pursuit eye movements. Therefore we tested smooth pursuit initiation under different three-dimensional eye positions and compared human performance to model simulations. We specifically tested if the ocular rotation axis changed with vertical eye position, if the misalignment of the spatial and retinal axes during oblique fixations was taken into account, and if ocular torsion (due to head roll) was compensated for. If no eye-position-dependent velocity transformation was used, the pursuit initiation should follow the retinal direction, independently of eye position; in contrast, a correct visuomotor velocity transformation would result in spatially correct pursuit initiation. Overall subjects accounted for all three components of the visuomotor velocity transformation, but we did observe differences in the compensatory gains between individual subjects. We concluded that the brain does perform a visuomotor velocity transformation but that this transformation was prone to noise and inaccuracies of the internal model.

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“…The EH cells are thought to play a critical role in smooth pursuit eye movements (Cullen et al 1993;Ghasia et al 2008;Lisberger et al 1994;McFarland and Fuchs 1992;Scudder and Fuchs 1992). Their role in mediating the VOR may be secondary to that of PVPs (Cullen and Roy 2004).…”

Section: Neural Mechanisms For Attenuation In Eye Velocitymentioning

confidence: 99%

Matching the Oculomotor Drive During Head-Restrained and Head-Unrestrained Gaze Shifts in Monkey

Bechara

Gandhi

2010

Journal of Neurophysiology

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Bechara BP, Gandhi NJ. Matching the oculomotor drive during head-restrained and head-unrestrained gaze shifts in monkey. J Neurophysiol 104: 811-828, 2010. First published May 26, 2010 doi:10.1152/jn.01114.2009. High-frequency burst neurons in the pons provide the eye velocity command (equivalently, the primary oculomotor drive) to the abducens nucleus for generation of the horizontal component of both head-restrained (HR) and head-unrestrained (HU) gaze shifts. We sought to characterize how gaze and its eye-in-head component differ when an "identical" oculomotor drive is used to produce HR and HU movements. To address this objective, the activities of pontine burst neurons were recorded during horizontal HR and HU gaze shifts. The burst profile recorded on each HU trial was compared with the burst waveform of every HR trial obtained for the same neuron. The oculomotor drive was assumed to be comparable for the pair yielding the lowest root-mean-squared error. For matched pairs of HR and HU trials, the peak eye-in-head velocity was substantially smaller in the HU condition, and the reduction was usually greater than the peak head velocity of the HU trial. A time-varying attenuation index, defined as the difference in HR and HU eye velocity waveforms divided by head velocity [␣ ϭ (Ḣ hr Ϫ Ė hu )/Ḣ ] was computed. The index was variable at the onset of the gaze shift, but it settled at values several times greater than 1. The index then decreased gradually during the movement and stabilized at 1 around the end of gaze shift. These results imply that substantial attenuation in eye velocity occurs, at least partially, downstream of the burst neurons. We speculate on the potential roles of burst-tonic neurons in the neural integrator and various cell types in the vestibular nuclei in mediating the attenuation in eye velocity in the presence of head movements. I N T R O D U C T I O NTo align the visual axis on an object of interest, one must shift the line of sight (gaze) by rapidly moving the eyes in their orbits. For large changes in gaze, a head movement typically accompanies the eye-in-head rotation. Such rapid, coordinated movements of the eyes in the orbits and the head in space are termed head-unrestrained (HU) gaze shifts. For smaller changes in gaze or when the head is immobilized, redirections of the visual axis are executed by eye movements within the orbits. We refer to such high-velocity movements as head-restrained (HR) gaze shifts or saccades.The primary oculomotor drive that produces a saccadic rotation of the eyes in orbits is an eye velocity command from neurons in the saccadic burst generator (Robinson 1975). For horizontal eye movements, the eye velocity command is encoded as a high-frequency volley of action potentials by putative short-lead burst neurons (Van Gisbergen et al. 1981) that reside in the paramedian pontine reticular formation (PPRF) and project directly to the abducens motoneurons (Langer et al. 1986;Strassman et al. 1986a). When the head is restrained, properties of the burst specif...

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Neural Correlates of Forward and Inverse Models for Eye Movements: Evidence from Three-Dimensional Kinematics

Cited by 48 publications

References 42 publications

Temporal and Spatial Characteristics of Vibrissa Responses to Motor Commands

Temporal and Spatial Characteristics of Vibrissa Responses to Motor Commands

Visuomotor Velocity Transformations for Smooth Pursuit Eye Movements

Matching the Oculomotor Drive During Head-Restrained and Head-Unrestrained Gaze Shifts in Monkey

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