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Newlands SD, Wei M. Tests of linearity in the responses of eye-movement-sensitive vestibular neurons to sinusoidal yaw rotation. J Neurophysiol 2013; 109:2571-84. [PMID: 23446694 PMCID: PMC3653051 DOI: 10.1152/jn.00930.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 02/26/2013] [Indexed: 11/22/2022] Open
Abstract
The rotational vestibulo-ocular reflex in primates is linear and stabilizes gaze in space over a large range of head movements. Best evidence suggests that position-vestibular-pause (PVP) and eye-head velocity (EHV) neurons in the vestibular nuclei are the primary mediators of vestibulo-ocular reflexes for rotational head movements, yet the linearity of these neurons has not been extensively tested. The current study was undertaken to understand how varying magnitudes of yaw rotation are coded in these neurons. Sixty-six PVP and 41 EHV neurons in the rostral vestibular nuclei of 7 awake rhesus macaques were recorded over a range of frequencies (0.1 to 2 Hz) and peak velocities (7.5 to 210°/s at 0.5 Hz). The sensitivity (gain) of the neurons decreased with increasing peak velocity of rotation for all PVP neurons and EHV neurons sensitive to ipsilateral rotation (type I). The sensitivity of contralateral rotation-sensitive (type II) EHV neurons did not significantly decrease with increasing peak velocity. These data show that, like non-eye-movement-related vestibular nuclear neurons that are believed to mediate nonlinear vestibular functions, PVP neurons involved in the linear vestibulo-ocular reflex also behave in a nonlinear fashion. Similar to other sensory nuclei, the magnitude of the vestibular stimulus is not linearly coded by the responses of vestibular neurons; rather, amplitude compression extends the dynamic range of PVP and type I EHV vestibular neurons.
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Affiliation(s)
- Shawn D Newlands
- Department of Otolaryngology, University of Rochester Medical Center, Rochester, New York 14642, USA.
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2
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The vestibular system implements a linear-nonlinear transformation in order to encode self-motion. PLoS Biol 2012; 10:e1001365. [PMID: 22911113 PMCID: PMC3404115 DOI: 10.1371/journal.pbio.1001365] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 06/13/2012] [Indexed: 11/19/2022] Open
Abstract
Early vestibular processing in macaque monkeys is inherently nonlinear and is optimized to detect specific features of self-motion. Although it is well established that the neural code representing the world changes at each stage of a sensory pathway, the transformations that mediate these changes are not well understood. Here we show that self-motion (i.e. vestibular) sensory information encoded by VIIIth nerve afferents is integrated nonlinearly by post-synaptic central vestibular neurons. This response nonlinearity was characterized by a strong (∼50%) attenuation in neuronal sensitivity to low frequency stimuli when presented concurrently with high frequency stimuli. Using computational methods, we further demonstrate that a static boosting nonlinearity in the input-output relationship of central vestibular neurons accounts for this unexpected result. Specifically, when low and high frequency stimuli are presented concurrently, this boosting nonlinearity causes an intensity-dependent bias in the output firing rate, thereby attenuating neuronal sensitivities. We suggest that nonlinear integration of afferent input extends the coding range of central vestibular neurons and enables them to better extract the high frequency features of self-motion when embedded with low frequency motion during natural movements. These findings challenge the traditional notion that the vestibular system uses a linear rate code to transmit information and have important consequences for understanding how the representation of sensory information changes across sensory pathways. Understanding how the coding of sensory information changes at different stages of sensory processing remains a fundamental challenge in systems neuroscience. Here we address this question by studying early sensory processing in vestibular pathways of monkeys, a system for which sensory stimuli are relatively easy to describe. Peripheral vestibular afferents detect and encode head motion in space to ensure posture and gaze is accurate and stable during everyday life. In this study, we show that central vestibular neurons nonlinearly integrate their afferent inputs, which helps explain the mechanisms that generate enhanced feature detection in sensory pathways. In addition, our results overturn conventional wisdom that early vestibular processing is linear, revealing a striking boosting nonlinearity that is a hallmark of the first central stage of vestibular processing. Studies from other sensory systems have shown that higher-order neurons can more efficiently detect specific features of sensory input, and that nonlinear transformations can increase this efficiency. We suggest that nonlinear integration of afferent input by central vestibular neurons extends their coding range and facilitates the detection of natural vestibular stimuli.
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Walker MF, Tian J, Shan X, Tamargo RJ, Ying H, Zee DS. The cerebellar nodulus/uvula integrates otolith signals for the translational vestibulo-ocular reflex. PLoS One 2010; 5:e13981. [PMID: 21085587 PMCID: PMC2981566 DOI: 10.1371/journal.pone.0013981] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 10/09/2010] [Indexed: 11/19/2022] Open
Abstract
Background The otolith-driven translational vestibulo-ocular reflex (tVOR) generates compensatory eye movements to linear head accelerations. Studies in humans indicate that the cerebellum plays a critical role in the neural control of the tVOR, but little is known about mechanisms of this control or the functions of specific cerebellar structures. Here, we chose to investigate the contribution of the nodulus and uvula, which have been shown by prior studies to be involved in the processing of otolith signals in other contexts. Methodology/Principal Findings We recorded eye movements in two rhesus monkeys during steps of linear motion along the interaural axis before and after surgical lesions of the cerebellar uvula and nodulus. The lesions strikingly reduced eye velocity during constant-velocity motion but had only a small effect on the response to initial head acceleration. We fit eye velocity to a linear combination of head acceleration and velocity and to a dynamic mathematical model of the tVOR that incorporated a specific integrator of head acceleration. Based on parameter optimization, the lesion decreased the gain of the pathway containing this new integrator by 62%. The component of eye velocity that depended directly on head acceleration changed little (gain decrease of 13%). In a final set of simulations, we compared our data to the predictions of previous models of the tVOR, none of which could account for our experimental findings. Conclusions/ Significance Our results provide new and important information regarding the neural control of the tVOR. Specifically, they point to a key role for the cerebellar nodulus and uvula in the mathematical integration of afferent linear head acceleration signals. This function is likely to be critical not only for the tVOR but also for the otolith-mediated reflexes that control posture and balance.
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Affiliation(s)
- Mark F Walker
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
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4
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Fetsch CR, Rajguru SM, Karunaratne A, Gu Y, Angelaki DE, Deangelis GC. Spatiotemporal properties of vestibular responses in area MSTd. J Neurophysiol 2010; 104:1506-22. [PMID: 20631212 PMCID: PMC2944682 DOI: 10.1152/jn.91247.2008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 07/10/2010] [Indexed: 11/22/2022] Open
Abstract
Recent studies have shown that many neurons in the primate dorsal medial superior temporal area (MSTd) show spatial tuning during inertial motion and that these responses are vestibular in origin. Given their well-studied role in processing visual self-motion cues (i.e., optic flow), these neurons may be involved in the integration of visual and vestibular signals to facilitate robust perception of self-motion. However, the temporal structure of vestibular responses in MSTd has not been characterized in detail. Specifically, it is not known whether MSTd neurons encode velocity, acceleration, or some combination of motion parameters not explicitly encoded by vestibular afferents. In this study, we have applied a frequency-domain analysis to single-unit responses during translation in three dimensions (3D). The analysis quantifies the stimulus-driven temporal modulation of each response as well as the degree to which this modulation reflects the velocity and/or acceleration profile of the stimulus. We show that MSTd neurons signal a combination of velocity and acceleration components with the velocity component being stronger for most neurons. These two components can exist both within and across motion directions, although their spatial tuning did not show a systematic relationship across the population. From these results, vestibular responses in MSTd appear to show characteristic features of spatiotemporal convergence, similar to previous findings in the brain stem and thalamus. The predominance of velocity encoding in this region may reflect the suitability of these signals to be integrated with visual signals regarding self-motion perception.
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Affiliation(s)
- Christopher R Fetsch
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, USA
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5
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Kang EE, Zalay OC, Cotic M, Carlen PL, Bardakjian BL. Transformation of neuronal modes associated with low-Mg2+/high-K+ conditions in an in vitro model of epilepsy. J Biol Phys 2010; 36:95-107. [PMID: 19669427 DOI: 10.1007/s10867-009-9144-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Accepted: 02/18/2009] [Indexed: 10/21/2022] Open
Abstract
Nonparametric system modeling constitutes a robust method for the analysis of physiological systems as it can be used to identify nonlinear dynamic input-output relationships and facilitate their description. First- and second-order kernels of hippocampal CA3 pyramidal neurons in an in vitro slice preparation were computed using the Volterra-Wiener approach to investigate system changes associated with epileptogenic low-magnesium/high-potassium (low-Mg(2+)/high-K(+)) conditions. The principal dynamic modes (PDMs) of neurons were calculated from the first- and second-order kernel estimates in order to characterize changes in neural coding functionality. From our analysis, an increase in nonlinear properties was observed in kernels under low-Mg(2+)/high-K(+). Furthermore, the PDMs revealed that the sampled hippocampal CA3 neurons were primarily of integrating character and that the contribution of a differentiating mode component was enhanced under low-Mg(2+)/high-K(+).
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Affiliation(s)
- Eunji E Kang
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, M5S 3G9, Canada
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6
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Chen-Huang C, Peterson BW. Frequency-dependent spatiotemporal tuning properties of non-eye movement related vestibular neurons to three-dimensional translations in squirrel monkeys. J Neurophysiol 2010; 103:3219-37. [PMID: 20375245 DOI: 10.1152/jn.00904.2009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Responses of vestibular-only translation sensitive (VOTS) neurons in vestibular nuclei of two squirrel monkeys were studied at multiple frequencies to three-dimensional translations and rotations. A novel frequency-dependent spatiotemporal analysis examined in each neuron whether complex models, with unrestricted response dynamics in three-dimensional (3D) space, provided significantly better fits than restricted models following simple, cosine rule. Subsequently, the statistically selected optimal model was used to predict the maximum translation direction, expressed as a unitary vector, Vt(max), and its associated sensitivity and phase across frequencies. Simple models were sufficient to quantify the 3D translational responses of 66% of neurons. Most VOTS neurons, complex or simple, exhibited flat-gain or low-pass response dynamics. The Vt(max) of simple neurons was fixed, whereas that of complex neurons changed with frequency. The spatial distribution of Vt(max) in simple neurons, which fell within 30 degrees of either the horizontal plane or/and the sagittal plane, was closely aligned with Vt(max) of vestibular afferents. In contrast, the frequency-dependent Vt(max) of most complex neurons migrated from the dorsoventral axis at higher frequency toward the horizontal plane, especially the interaural axis, at lower frequency. When the maximum rotation direction was estimated from responses of the same VOTS neurons to 1.2 Hz yaw, pitch, and roll rotations, complex neurons were more likely to respond to rotations activating vertical canals. Responses to 0.15-0.3 Hz linear accelerations produced by inertial or gravitational forces were indistinguishable in most complex neurons but significantly different in most simple neurons. These observations suggest that simple and complex VOTS neurons constitute distinctive vestibular pathways where complex neurons, exhibiting a novel spatiotemporal filtering mechanism in processing otolith-related signals, are well suited to drive tilt-related responses, whereas simple neurons probably mediate pure translation related responses.
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Affiliation(s)
- Chiju Chen-Huang
- Department of Physiology, Northwestern University, Chicago, IL 60611, USA.
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7
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Parabrachial nucleus neuronal responses to off-vertical axis rotation in macaques. Exp Brain Res 2009; 202:271-90. [PMID: 20039027 DOI: 10.1007/s00221-009-2130-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 12/07/2009] [Indexed: 10/20/2022]
Abstract
The caudal aspect of the parabrachial nucleus (PBN) contains neurons responsive to whole body, periodic rotational stimulation in alert monkeys (Balaban et al. in J Neurophysiol 88:3175-3193, 2002). This study characterizes the angular and linear motion-sensitive response properties of PBN unit responses during off-vertical axis rotation (OVAR) and position trapezoid stimulation. The OVAR responses displayed a constant firing component which varied from the firing rate at rest. Nearly two-thirds of the units also modulated their discharges with respect to head orientation (re: gravity) during constant velocity OVAR stimulation. The modulated response magnitudes were equal during ipsilateral and contralateral OVARs, indicative of a one-dimensional accelerometer. These response orientations during OVAR divided the units into three spatially tuned populations, with peak modulation responses centered in the ipsilateral ear down, contralateral anterior semicircular canal down, and occiput down orientations. Because the orientation of the OVAR modulation response was opposite in polarity to the orientation of the static tilt component of responses to position trapezoids for the majority of units, the linear acceleration responses were divided into colinear dynamic linear and static tilt components. The orientations of these unit responses formed two distinct population response axes: (1) units with an interaural linear response axis and (2) units with an ipsilateral anterior semicircular canal-contralateral posterior semicircular canal plane linear response axis. The angular rotation sensitivity of these units is in a head-vertical plane that either contains the linear acceleration response axis or is perpendicular to the linear acceleration axis. Hence, these units behave like head-based ('strapdown') inertial guidance sensors. Because the PBN contributes to sensory and interoceptive processing, it is suggested that vestibulo-recipient caudal PBN units may detect potentially dangerous anomalies in control of postural stability during locomotion. In particular, these signals may contribute to the range of affective and emotional responses that include panic associated with falling, malaise associated with motion sickness and mal-de-debarquement, and comorbid balance and anxiety disorders.
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8
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Liu S, Angelaki DE. Vestibular signals in macaque extrastriate visual cortex are functionally appropriate for heading perception. J Neurosci 2009; 29:8936-45. [PMID: 19605631 PMCID: PMC2728346 DOI: 10.1523/jneurosci.1607-09.2009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 05/23/2009] [Accepted: 06/03/2009] [Indexed: 11/21/2022] Open
Abstract
Visual and vestibular signals converge onto the dorsal medial superior temporal area (MSTd) of the macaque extrastriate visual cortex, which is thought to be involved in multisensory heading perception for spatial navigation. Peripheral otolith information, however, is ambiguous and cannot distinguish linear accelerations experienced during self-motion from those resulting from changes in spatial orientation relative to gravity. Here we show that, unlike peripheral vestibular sensors but similar to lobules 9 and 10 of the cerebellar vermis (nodulus and uvula), MSTd neurons respond selectively to heading and not to changes in orientation relative to gravity. In support of a role in heading perception, MSTd vestibular responses are also dominated by velocity-like temporal dynamics, which might optimize sensory integration with visual motion information. Unlike the cerebellar vermis, however, MSTd neurons also carry a spatial orientation-independent rotation signal from the semicircular canals, which could be useful in compensating for the effects of head rotation on the processing of optic flow. These findings show that vestibular signals in MSTd are appropriately processed to support a functional role in multisensory heading perception.
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Affiliation(s)
- Sheng Liu
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Dora E. Angelaki
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110
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9
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Newlands SD, Lin N, Wei M. Response linearity of alert monkey non-eye movement vestibular nucleus neurons during sinusoidal yaw rotation. J Neurophysiol 2009; 102:1388-97. [PMID: 19553479 DOI: 10.1152/jn.90914.2008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vestibular afferents display linear responses over a range of amplitudes and frequencies, but comparable data for central vestibular neurons are lacking. To examine the effect of stimulus frequency and magnitude on the response sensitivity and linearity of non-eye movement central vestibular neurons, we recorded from the vestibular nuclei in awake rhesus macaques during sinusoidal yaw rotation at frequencies between 0.1 and 2 Hz and between 7.5 and 210 degrees/s peak velocity. The dynamics of the neurons' responses across frequencies, while holding peak velocity constant, was consistent with previous studies. However, as the peak velocity was varied, while holding the frequency constant, neurons demonstrated lower sensitivities with increasing peak velocity, even at the lowest peak velocities tested. With increasing peak velocity, the proportion of neurons that silenced during a portion of the response increased. However, the decrease in sensitivity of these neurons with higher peak velocities of rotation was not due to increased silencing during the inhibitory portion of the cycle. Rather the neurons displayed peak firing rates that did not increase in proportion to head velocity as the peak velocity of rotation increased. These data suggest that, unlike vestibular afferents, the central vestibular neurons without eye movement sensitivity examined in this study do not follow linear systems principles even at low velocities.
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Affiliation(s)
- Shawn D Newlands
- University of Texas Medical Branch, Department of Otolaryngology, Galveston, TX, USA.
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10
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Angelaki DE, Yakusheva TA. How vestibular neurons solve the tilt/translation ambiguity. Comparison of brainstem, cerebellum, and thalamus. Ann N Y Acad Sci 2009; 1164:19-28. [PMID: 19645876 PMCID: PMC2860452 DOI: 10.1111/j.1749-6632.2009.03939.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The peripheral vestibular system is faced by a sensory ambiguity, where primary otolith afferents respond identically to translational (inertial) accelerations and changes in head orientation relative to gravity. Under certain conditions, this sensory ambiguity can be resolved using extra-otolith cues, including semicircular canal signals. Here we review and summarize how neurons in the vestibular nuclei, rostral fastigial nuclei, cerebellar nodulus/uvula, and thalamus respond during combinations of tilt and translation. We focus primarily on cerebellar cortex responses, as nodulus/uvula Purkinje cells reliably encode translation rather than net gravito-inertial acceleration. In contrast, neurons in the vestibular and rostral fastigial nuclei, as well as the ventral lateral and ventral posterior nuclei of the thalamus represent a continuum, with some encoding translation and some net gravito-inertial acceleration. This review also outlines how Purkinje cells use semicircular canal signals to solve the ambiguity problem and how this solution fails at low frequencies. We conclude by attempting to bridge the gap between the proposed roles of nodulus/uvula in tilt/translation discrimination and velocity storage.
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Affiliation(s)
- Dora E Angelaki
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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11
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Hasegawa T, Yamashita M, Suzuki T, Hisa Y, Wada Y. Active linear head motion improves dynamic visual acuity in pursuing a high-speed moving object. Exp Brain Res 2009; 194:505-16. [DOI: 10.1007/s00221-009-1716-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Accepted: 01/13/2009] [Indexed: 10/21/2022]
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12
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Bryan AS, Angelaki DE. Optokinetic and vestibular responsiveness in the macaque rostral vestibular and fastigial nuclei. J Neurophysiol 2008; 101:714-20. [PMID: 19073813 DOI: 10.1152/jn.90612.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recorded from rostral vestibular (VN) and rostral fastigial nuclei (FN) neurons that did not respond to eye movements during three-dimensional (3D) vestibular and optokinetic stimulation (OKS). The majority of neurons in both areas (76 and 69% in VN and FN, respectively) responded during both rotational and translational motion. Preferred directions scattered throughout 3D space for translation but showed some preference for pitch/roll over yaw for rotation. VN/FN neurons were also tested during OKS while monkeys suppressed their optokinetic nystagmus by fixating a head-fixed target. Only a handful of cells (VN: 17%, FN: 6%) modulated during 0.5-Hz OKS suppression, but the number of responsive cells increased (VN: 40%, FN: 48%) during 0.02-Hz OKS. Preferred directions for rotation and OKS were not matched on individual neurons, and OKS gains were smaller than the respective gains during rotation. These results were generally similar for VN and FN neurons. We conclude that optokinetic-vestibular convergence might not be as prevalent as earlier studies have suggested.
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Affiliation(s)
- Ayanna S Bryan
- Department of Neurobiology, Box 8108, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
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13
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Green AM, Angelaki DE. Coordinate transformations and sensory integration in the detection of spatial orientation and self-motion: from models to experiments. PROGRESS IN BRAIN RESEARCH 2008; 165:155-80. [PMID: 17925245 DOI: 10.1016/s0079-6123(06)65010-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
An accurate internal representation of our current motion and orientation in space is critical to navigate in the world and execute appropriate action. The force of gravity provides an allocentric frame of reference that defines one's motion relative to inertial (i.e., world-centered) space. However, movement in this environment also introduces particular motion detection problems as our internal linear accelerometers, the otolith organs, respond identically to either translational motion or changes in head orientation relative to gravity. According to physical principles, there exists an ideal solution to the problem of distinguishing between the two as long as the brain also has access to accurate internal estimates of angular velocity. Here, we illustrate how a nonlinear integrative neural network that receives sensory signals from the vestibular organs could be used to implement the required computations for inertial motion detection. The model predicts several distinct cell populations that are comparable with experimentally identified cell types and accounts for a number of previously unexplained characteristics of their responses. A key model prediction is the existence of cell populations that transform head-referenced rotational signals from the semicircular canals into spatially referenced estimates of head reorientation relative to gravity. This chapter provides an overview of how addressing the problem of inertial motion estimation from a computational standpoint has contributed to identifying the actual neuronal populations responsible for solving the tilt-translation ambiguity and has facilitated the interpretation of neural response properties.
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Affiliation(s)
- Andrea M Green
- Départment de Physiologie, Université de Montréal, 2960 Chemin de la Tour, Rm. 2140, Montréal, QC, Canada H3T 1J4.
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14
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Yakusheva TA, Shaikh AG, Green AM, Blazquez PM, Dickman JD, Angelaki DE. Purkinje cells in posterior cerebellar vermis encode motion in an inertial reference frame. Neuron 2007; 54:973-85. [PMID: 17582336 DOI: 10.1016/j.neuron.2007.06.003] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 05/02/2007] [Accepted: 06/05/2007] [Indexed: 11/17/2022]
Abstract
The ability to orient and navigate through the terrestrial environment represents a computational challenge common to all vertebrates. It arises because motion sensors in the inner ear, the otolith organs, and the semicircular canals transduce self-motion in an egocentric reference frame. As a result, vestibular afferent information reaching the brain is inappropriate for coding our own motion and orientation relative to the outside world. Here we show that cerebellar cortical neuron activity in vermal lobules 9 and 10 reflects the critical computations of transforming head-centered vestibular afferent information into earth-referenced self-motion and spatial orientation signals. Unlike vestibular and deep cerebellar nuclei neurons, where a mixture of responses was observed, Purkinje cells represent a homogeneous population that encodes inertial motion. They carry the earth-horizontal component of a spatially transformed and temporally integrated rotation signal from the semicircular canals, which is critical for computing head attitude, thus isolating inertial linear accelerations during navigation.
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Affiliation(s)
- Tatyana A Yakusheva
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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15
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Green AM, Shaikh AG, Angelaki DE. Sensory vestibular contributions to constructing internal models of self-motion. J Neural Eng 2005; 2:S164-79. [PMID: 16135882 DOI: 10.1088/1741-2560/2/3/s02] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ability to navigate in the world and execute appropriate behavioral and motor responses depends critically on our capacity to construct an accurate internal representation of our current motion and orientation in space. Vestibular sensory signals are among those that may make an essential contribution to the construction of such 'internal models'. Movement in a gravitational environment represents a situation where the construction of internal models becomes particularly important because the otolith organs, like any linear accelerometer, sense inertial and gravitational accelerations equivalently. Otolith afferents thus provide inherently ambiguous motion information, as they respond identically to translation and head reorientation relative to gravity. Resolution of this ambiguity requires the nonlinear integration of linear acceleration and angular velocity cues, as predicted by the physical equations of motion. Here, we summarize evidence that during translations and tilts from upright the firing rates of brainstem and cerebellar neurons encode a combination of dynamically processed semicircular canal and otolith signals appropriate to construct an internal model representation of the computations required for inertial motion detection.
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Affiliation(s)
- Andrea M Green
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8108, St Louis, MO 63110, USA
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16
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Dharani NE. The role of vestibular system and the cerebellum in adapting to gravitoinertial, spatial orientation and postural challenges of REM sleep. Med Hypotheses 2005; 65:83-9. [PMID: 15893123 DOI: 10.1016/j.mehy.2005.01.033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
The underlying reasons for, and mechanisms of rapid eye movement (REM) sleep events remain a mystery. The mystery has arisen from interpreting REM sleep events as occurring in 'isolation' from the world at large, and phylogenetically ancient brain areas using 'primal' gravity-dependent coordinates, reflexes and stimuli parameters to relay and process information about self and environment. This paper views REM sleep as a phylogenetically older form of wakefulness, wherein the brain uses a gravitoinertial-centred reference frame and an internal self-object model to evaluate and integrate inputs from several sensory systems and to adapt to spatial-temporal disintegration and malignant cholinergic-induced vasodepressor/ventilatory threat. The integration of vestibular and non-vestibular sensory graviceptor signals enables estimation and control of centre of the body mass, position and spatial relationship of body parts, gaze, head and whole-body tilt, spatial orientation and autonomic functions relative to gravity. The vestibulocerebellum and vermis, via vestibular and fastigial nucleus, coordinate inputs and outputs from several sensory systems and modulate the amplitude and duration of 'fight-or-flight' vestibulo-orienting and autonomic 'burst' responses to overcome the ongoing challenges. Resolving multisystem conflicts during the unique stresses (gravitoinertial, hypoxic, thermal, immobilisation, etc.) of REM sleep enables learning, cross-modal plasticity, higher-order integration and multidimensional spatial updating of sensory-motor-cognitive components. This paper aims to generate discussion, reinterpretation and creative testing of this novel hypothesis, which, if experimentally confirmed, has major implications across medicine, bioscience and space physiology, from developmental, clinical, research and theoretical perspectives.
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Affiliation(s)
- Nataraj E Dharani
- Royal Australian and New Zealand College of Psychiatrists, 309 La Trobe Street, Melbourne, Victoria 3000, Australia.
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17
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Green AM, Angelaki DE. An Integrative Neural Network for Detecting Inertial Motion and Head Orientation. J Neurophysiol 2004; 92:905-25. [PMID: 15056677 DOI: 10.1152/jn.01234.2003] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability to navigate in the world and execute appropriate behavioral responses depends critically on the contribution of the vestibular system to the detection of motion and spatial orientation. A complicating factor is that otolith afferents equivalently encode inertial and gravitational accelerations. Recent studies have demonstrated that the brain can resolve this sensory ambiguity by combining signals from both the otoliths and semicircular canal sensors, although it remains unknown how the brain integrates these sensory contributions to perform the nonlinear vector computations required to accurately detect head movement in space. Here, we illustrate how a physiologically relevant, nonlinear integrative neural network could be used to perform the required computations for inertial motion detection along the interaural head axis. The proposed model not only can simulate recent behavioral observations, including a translational vestibuloocular reflex driven by the semicircular canals, but also accounts for several previously unexplained characteristics of central neural responses such as complex otolith–canal convergence patterns and the prevalence of dynamically processed otolith signals. A key model prediction, implied by the required computations for tilt–translation discrimination, is a coordinate transformation of canal signals from a head-fixed to a spatial reference frame. As a result, cell responses may reflect canal signal contributions that cannot be easily detected or distinguished from otolith signals. New experimental protocols are proposed to characterize these cells and identify their contributions to spatial motion estimation. The proposed theoretical framework makes an essential first link between the computations for inertial acceleration detection derived from the physical laws of motion and the neural response properties predicted in a physiologically realistic network implementation.
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Affiliation(s)
- Andrea M Green
- Dept. of Anatomy and Neurobiology, Box 8108, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Hess BJM, Angelaki DE. Vestibular contributions to gaze stability during transient forward and backward motion. J Neurophysiol 2003; 90:1996-2004. [PMID: 12773497 DOI: 10.1152/jn.00302.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The accuracy with which the vestibular system anticipates and compensates for the visual consequences of translation during forward and backward movements was investigated with transient motion profiles in rhesus monkeys trained to fixate targets on an isovergence screen. Early during motion when visuomotor reflexes remain relatively ineffective and vestibular-driven mechanisms have an important role for controlling the movement of the eyes, a large asymmetry was observed for forward and backward heading directions. During forward motion, ocular velocity gains increased steeply and reached near unity gains as early as 40-50 ms after motion onset. In addition, instantaneous directional errors also remained <10 degrees for forward headings. In contrast, backward motion was characterized by smaller vestibular gains and larger directional errors during the first 70 ms of the movement. To evaluate the accumulated retinal slip and vergence errors during the early epochs of motion when vestibular-driven mechanisms dominate gaze stability, the movement of a virtual fixation point defined by the intersection of the two gaze lines was quantitatively compared with the respective movement of the extinguished target in head coordinates. Both conjugate retinal slip and vergence errors were <0.2 degrees during the first 70 ms of the movement, with forward motion conjugate errors typically being smaller as compared with backward motion directions. Thus vestibularly driven gaze stabilization mechanisms can effectively minimize conjugate retinal slip errors as well as keep binocular disparity errors low during the open loop interval of head movement.
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Affiliation(s)
- Bernhard J M Hess
- Department of Neurology, University Hospital Zurich, CH-8091 Zurich, Switzerland.
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