A Reevaluation of the Inverse Dynamic Model for Eye Movements

Green, Andrea M.; Hui, Meng; Angelaki, Dora E.

doi:10.1523/jneurosci.3822-06.2007

Cited by 46 publications

(74 citation statements)

References 66 publications

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“…Schematic of inverse and forward models for eye movement generation. In addition to driving motoneurons (MN) and the eye plant, an efference copy of the motor command is also used by a forward model to compute an efference copy of the evoked eye movement, a signal needed to refine the motor command [adapted from the study by Green et al (2007)]. …”

Section: Resultsmentioning

confidence: 99%

“…3D eye movements (833.33 Hz) were calibrated daily while fixating vertically and horizontally eccentric targets (Klier et al, 2005). Electrode penetrations were made into the nucleus prepositus hypoglossi, the medial and superior vestibular nuclei [same neurons as in the studies by Green et al (2007), Meng et al (2005), and Meng and Angelaki (2006)], and the interstitial nucleus of Cajal, as well as cells scattered between the abducens and oculomotor nuclei [locations identified in the studies by Ghasia and Angelaki (2005) and Klier et al (2006)]. …”

Section: Methodsmentioning

confidence: 99%

“…Superb candidates for this role are burst-tonic (BT) neurons that are found throughout the brainstem, including the nucleus prepositus hypoglossi (McFarland and Fuchs, 1992), vestibular nuclei (Scudder and Fuchs, 1992), interstitial nucleus of Cajal (Fukushima, 1991), and paramedian tract (Buttner-Ennever and Horn, 1996;Nakamagoe et al, 2000). The notion that BT cells represent the output of the inverse model was first introduced by Belknap and McCrea (1988) and recently resurrected, because BT cell dynamics during pursuit and the vestibulo-ocular reflex (VOR) are identical to those of extraocular motoneurons (Green et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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

Ghasia¹,

Hui²,

Angelaki³

2008

J. Neurosci.

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Inverse and forward dynamic models have been conceptually important in computational motor control. In particular, inverse models are thought to convert desired action into appropriate motor commands. In parallel, forward models predict the consequences of the motor command on behavior by constructing an efference copy of the actual movement. Despite theoretical appeal, their neural representation has remained elusive. Here, we provide evidence supporting the notion that a group of premotor neurons called burst-tonic (BT) cells represent the output of the inverse model for eye movements. We show that BT neurons, like extraocular motoneurons but different from the evoked eye movement, do not carry signals appropriate for the half-angle rule of ocular kinematics during smoothpursuit eye movements from eccentric positions. Along with findings of identical response dynamics as motoneurons, these results strongly suggest that BT cells carry a replica of the motor command. In contrast, eye-head (EH) neurons, a premotor cell type that is the target of Purkinje cell inhibition from the cerebellar flocculus/ventral paraflocculus, exhibit properties that could be consistent with the half-angle rule. Therefore, EH cells may be functionally related to the output of a forward internal model thought to construct an efference copy of the actual eye movement.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Ghasia¹,

Hui²,

Angelaki³

2008

J. Neurosci.

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“…1) controls the effective time constant of the integrator. The cerebellum, receiving an efference copy of the outgoing motor command (see also Hirata and Highstein 2001; Green et al 2007) via the PMT and/or Y, estimates the current eye velocity on behalf of an internal forward model of the eye plant, similar to the proposal of Porrill and coauthors (Porrill et al 2004). By comparing this central estimate of current eye velocity with desired eye velocity, the latter being given by the SCCs for VOR and by middle superior temporal (MST) for pursuit, the cerebellum obtains an error signal that is amplified and then supplied back to the brainstem integrator via the VN.…”

Section: Gaze Holdingmentioning

confidence: 99%

A model-based theory on the origin of downbeat nystagmus

et al. 2008

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A model-based theory on the origin of downbeat nystagmus AbstractThe pathomechanism of downbeat nystagmus (DBN), an ocular motor sign typical for vestibulo-cerebellar lesions, remains unclear. Previous hypotheses conjectured various deficits such as an imbalance of central vertical vestibular or smooth pursuit pathways to be causative for the generation of spontaneous upward drift. However, none of the previous theories explains the full range of ocular motor deficits associated with DBN, i.e., impaired vertical smooth pursuit (SP), gaze evoked nystagmus, and gravity dependence of the upward drift. We propose a new hypothesis, which explains the ocular motor signs of DBN by damage of the inhibitory vertical gaze-velocity sensitive Purkinje cells (PCs) in the cerebellar flocculus (FL). These PCs show spontaneous activity and a physiological asymmetry in that most of them exhibit downward on-directions. Accordingly, a loss of vertical floccular PCs will lead to disinhibition of their brainstem target neurons and, consequently, to spontaneous upward drift, i.e., DBN. Since the FL is involved in generation and control of SP and gaze holding, a single lesion, e.g., damage to vertical floccular PCs, may also explain the associated ocular motor deficits. To test our hypothesis, we developed a computational model of vertical eye movements based on known ocular motor anatomy and physiology, which illustrates how cortical, cerebellar, and brainstem regions interact to generate the range of vertical eye movements seen in healthy subjects. Model simulation of the effect of extensive loss of floccular PCs resulted in ocular motor features typically associated with cerebellar DBN: (1) spontaneous upward drift due to decreased spontaneous PC activity, (2) gaze evoked nystagmus corresponding to failure of the cerebellar loop supporting neural integrator function, (3) asymmetric vertical SP deficit due to low gain and asymmetric attenuation of PC firing, and (4) gravity-dependence of DBN caused by an interaction of otolith-ocular pathways with impaired neural integrator function.

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“…For high-frequency oscillatory VOR movements, the command will be primarily a velocity signal. Furthermore, the appropriate motor command needs to compensate for the ocular plant dynamics, which will be frequency dependent (6,20). Because the mechanical impedance of the eye-plant increases with increasing frequency, the motor command signal would need to increase accordingly so that even under constant velocity conditions we should expect that the EMG signal should show a "highpass" response.…”

Section: Discussionmentioning

confidence: 99%

Contributions of ocular vestibular evoked myogenic potentials and the electrooculogram to periocular potentials produced by whole-body vibration

Todd

Bell

Paillard

et al. 2012

Journal of Applied Physiology

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Todd NPM, Bell SL, Paillard AC, Griffin MJ. Contributions of ocular vestibular evoked myogenic potentials and the electrooculogram to periocular potentials produced by whole-body vibration. J Appl Physiol 113: 1613-1623. First published September 13, 2012 doi:10.1152/japplphysiol.00375.2012In this paper we report the results of an experiment to investigate the emergence of ocular vestibular evoked myogenic potentials (OVEMPs) during the linear vestibular ocular reflex (LVOR) evoked by whole-body vibration (WBV). OVEMP and electrooculogram (EOG) montages were employed to record periocular potentials (POPs) from six subjects during WBV in the nasooccipital (NO) axis over a range of frequencies from 0.5 to 64 Hz with approximately constant peak head acceleration of 1.0 ms Ϫ2 (i.e., 0.1 g). Measurements were made in two context conditions: a fixation context to examine the effect of gaze eccentricity (0 vs. 20°), and a visual context, where a target was either head-fixed or earth-fixed. The principal results are that from 0.5 to 2 Hz POP magnitude in the earth-fixed condition is related to head displacement, so with constant acceleration at all frequencies it reduces with increasing frequency, but at frequencies greater than 2 Hz both POP magnitude and POP gain, defined as the ratio of POP magnitude at 20 and 0°, increase with increasing frequency. By exhibiting this high-pass characteristic, a property shared with the LVOR, the results are consistent with the hypothesis that the OVEMP, as commonly employed in the clinical setting, is a high-frequency manifestation of the LVOR. However, we also observed low-frequency acceleration following POPs in head-fixed conditions, consistent with a low-frequency OVEMP, and found evidence of a highfrequency visual context effect, which is also consistent with the OVEMP being a manifestation of the LVOR.

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A Reevaluation of the Inverse Dynamic Model for Eye Movements

Cited by 46 publications

References 66 publications

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

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

A model-based theory on the origin of downbeat nystagmus

Contributions of ocular vestibular evoked myogenic potentials and the electrooculogram to periocular potentials produced by whole-body vibration

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