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Grouvel G, Boutabla A, Corre J, Revol R, Franco Carvalho M, Cavuscens S, Ranieri M, Cugnot JF, McCrum C, van de Berg R, Guinand N, Pérez Fornos A, Armand S. Full-body kinematics and head stabilisation strategies during walking in patients with chronic unilateral and bilateral vestibulopathy. Sci Rep 2024; 14:11757. [PMID: 38783000 PMCID: PMC11116555 DOI: 10.1038/s41598-024-62335-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 05/15/2024] [Indexed: 05/25/2024] Open
Abstract
Chronic imbalance is a frequent and limiting symptom of patients with chronic unilateral and bilateral vestibulopathy. A full-body kinematic analysis of the movement of patients with vestibulopathy would provide a better understanding of the impact of the pathology on dynamic tasks such as walking. Therefore, this study aimed to investigate the global body movement during walking, its variability (assessed with the GaitSD), and the strategies to stabilise the head (assessed with the head Anchoring Index). The full-body motion capture data of 10 patients with bilateral vestibulopathy (BV), 10 patients with unilateral vestibulopathy (UV), and 10 healthy subjects (HS) walking at several speeds (slow, comfortable, and fast) were analysed in this prospective cohort study. We observed only a few significant differences between groups in parts of the gait cycle (shoulder abduction-adduction, pelvis rotation, and hip flexion-extension) during the analysis of kinematic curves. Only BV patients had significantly higher gait variability (GaitSD) for all three walking speeds. Head stabilisation strategies depended on the plan of motion and walking speed condition, but BV and UV patients tended to stabilise their head in relation to the trunk and HS tended to stabilise their head in space. These results suggest that GaitSD could be a relevant biomarker of chronic instability in BV and that the head Anchoring Index tends to confirm clinical observations of abnormal head-trunk dynamics in patients with vestibulopathy while walking.
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Affiliation(s)
- Gautier Grouvel
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
- Kinesiology Laboratory, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
| | - Anissa Boutabla
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Julie Corre
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Rebecca Revol
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Marys Franco Carvalho
- Kinesiology Laboratory, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Samuel Cavuscens
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Maurizio Ranieri
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Jean-François Cugnot
- Division of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Christopher McCrum
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Raymond van de Berg
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - Nils Guinand
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Angélica Pérez Fornos
- Division of Otorhinolaryngology Head and Neck Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Stéphane Armand
- Kinesiology Laboratory, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
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Zaraza D, Chernov MM, Yang Y, Rogers JA, Roe AW, Friedman RM. Head-mounted optical imaging and optogenetic stimulation system for use in behaving primates. CELL REPORTS METHODS 2022; 2:100351. [PMID: 36590689 PMCID: PMC9795332 DOI: 10.1016/j.crmeth.2022.100351] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 08/25/2022] [Accepted: 10/27/2022] [Indexed: 11/23/2022]
Abstract
Advances in optical technology have revolutionized studies of brain function in freely behaving mice. Here, we describe an optical imaging and stimulation device for use in primates that easily attaches to an intracranial chamber. It consists of affordable commercially available or 3D-printed components: a monochromatic camera, a small standard lens, a wireless μLED stimulator powered by an induction coil, and an LED array for illumination. We show that the intrinsic imaging performance of this device is comparable to a standard benchtop system in revealing the functional organization of the visual cortex for awake macaques in a primate chair or under anesthesia. Imaging revealed neural modulatory effects of wireless focal optogenetic stimulation aimed at identified functional domains. With a 1 to 2 cm field of view, 100× larger than previously used in primates without head restraint, our device permits widefield optical imaging and optogenetic stimulation for ethological studies in primates.
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Affiliation(s)
- Derek Zaraza
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Mykyta M. Chernov
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Yiyuan Yang
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - John A. Rogers
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Anna W. Roe
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Robert M. Friedman
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
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3
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Chaudhary S, Saywell N, Taylor D. The Differentiation of Self-Motion From External Motion Is a Prerequisite for Postural Control: A Narrative Review of Visual-Vestibular Interaction. Front Hum Neurosci 2022; 16:697739. [PMID: 35210998 PMCID: PMC8860980 DOI: 10.3389/fnhum.2022.697739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 01/18/2022] [Indexed: 11/13/2022] Open
Abstract
The visual system is a source of sensory information that perceives environmental stimuli and interacts with other sensory systems to generate visual and postural responses to maintain postural stability. Although the three sensory systems; the visual, vestibular, and somatosensory systems work concurrently to maintain postural control, the visual and vestibular system interaction is vital to differentiate self-motion from external motion to maintain postural stability. The visual system influences postural control playing a key role in perceiving information required for this differentiation. The visual system’s main afferent information consists of optic flow and retinal slip that lead to the generation of visual and postural responses. Visual fixations generated by the visual system interact with the afferent information and the vestibular system to maintain visual and postural stability. This review synthesizes the roles of the visual system and their interaction with the vestibular system, to maintain postural stability.
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Rubio Barañano A, Faisal M, Barrett BT, Buckley JG. Using a smartphone on the move: do visual constraints explain why we slow walking speed? Exp Brain Res 2021; 240:467-480. [PMID: 34792640 PMCID: PMC8858309 DOI: 10.1007/s00221-021-06267-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/29/2021] [Indexed: 11/24/2022]
Abstract
Viewing one’s smartphone whilst walking commonly leads to a slowing of walking. Slowing walking speed may occur because of the visual constraints related to reading the hand-held phone whilst in motion. We determine how walking-induced phone motion affects the ability to read on-screen information. Phone-reading performance (PRP) was assessed whilst participants walked on a treadmill at various speeds (Slow, Customary, Fast). The fastest speed was repeated, wearing an elbow brace (Braced) or with the phone mounted stationary (Fixed). An audible cue (‘text-alert’) indicated participants had 2 s to lift/view the phone and read aloud a series of digits. PRP was the number of digits read correctly. Each condition was repeated 5 times. 3D-motion analyses determined phone motion relative to the head, from which the variability in acceleration in viewing distance, and in the point of gaze in space in the up-down and right-left directions were assessed. A main effect of condition indicated PRP decreased with walking speed; particularly so for the Braced and Fixed conditions (p = 0.022). Walking condition also affected the phone’s relative motion (p < 0.001); post-hoc analysis indicated that acceleration variability for the Fast, Fixed and Braced conditions were increased compared to that for Slow and Customary speed walking (p ≤ 0.05). There was an inverse association between phone acceleration variability and PRP (p = 0.02). These findings may explain why walking speed slows when viewing a hand-held phone: at slower speeds, head motion is smoother/more regular, enabling the motion of the phone to be coupled with head motion, thus making fewer demands on the oculomotor system. Good coupling ensures that the retinal image is stable enough to allow legibility of the information presented on the screen.
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Affiliation(s)
| | - Muhammad Faisal
- Faculty of Health Studies, University of Bradford, Bradford, UK
| | - Brendan T Barrett
- School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - John G Buckley
- Department of Biomedical and Electronics Engineering, University of Bradford, Bradford, UK.
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5
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Schröder L, von Werder D, Ramaioli C, Wachtler T, Henningsen P, Glasauer S, Lehnen N. Unstable Gaze in Functional Dizziness: A Contribution to Understanding the Pathophysiology of Functional Disorders. Front Neurosci 2021; 15:685590. [PMID: 34354560 PMCID: PMC8330597 DOI: 10.3389/fnins.2021.685590] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 06/16/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: We are still lacking a pathophysiological mechanism for functional disorders explaining the emergence and manifestation of characteristic, severely impairing bodily symptoms like chest pain or dizziness. A recent hypothesis based on the predictive coding theory of brain function suggests that in functional disorders, internal expectations do not match the actual sensory body states, leading to perceptual dysregulation and symptom perception. To test this hypothesis, we investigated the account of internal expectations and sensory input on gaze stabilization, a physiologically relevant parameter of gaze shifts, in functional dizziness. Methods: We assessed gaze stabilization in eight functional dizziness patients and 11 healthy controls during two distinct epochs of large gaze shifts: during a counter-rotation epoch (CR epoch), where the brain can use internal models, motor planning, and resulting internal expectations to achieve internally driven gaze stabilization; and during an oscillation epoch (OSC epoch), where, due to terminated motor planning, no movement expectations are present, and gaze is stabilized by sensory input alone. Results: Gaze stabilization differed between functional patients and healthy controls only when internal movement expectations were involved [F(1,17) = 14.63, p = 0.001, and partial η2 = 0.463]: functional dizziness patients showed reduced gaze stabilization during the CR (p = 0.036) but not OSC epoch (p = 0.26). Conclusion: While sensory-driven gaze stabilization is intact, there are marked, well-measurable deficits in internally-driven gaze stabilization in functional dizziness pointing at internal expectations that do not match actual body states. This experimental evidence supports the perceptual dysregulation hypothesis of functional disorders and is an important step toward understanding the underlying pathophysiology.
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Affiliation(s)
- Lena Schröder
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Department of Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Dina von Werder
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
| | - Cecilia Ramaioli
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Thomas Wachtler
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Department of Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Peter Henningsen
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Stefan Glasauer
- Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
- Faculty of Health Sciences Brandenburg, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
| | - Nadine Lehnen
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
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6
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Genetically Defined Functional Modules for Spatial Orienting in the Mouse Superior Colliculus. Curr Biol 2019; 29:2892-2904.e8. [PMID: 31474533 PMCID: PMC6739420 DOI: 10.1016/j.cub.2019.07.083] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/26/2019] [Accepted: 07/30/2019] [Indexed: 01/27/2023]
Abstract
In order to explore and interact with their surroundings, animals need to orient toward specific positions in space. Throughout the animal kingdom, head movements represent a primary form of orienting behavior. The superior colliculus (SC) is a fundamental structure for the generation of orienting responses, but how genetically distinct groups of collicular neurons contribute to these spatially tuned behaviors remains largely to be defined. Here, through the genetic dissection of the murine SC, we identify a functionally and genetically homogeneous subclass of glutamatergic neurons defined by the expression of the paired-like homeodomain transcription factor Pitx2. We show that the optogenetic stimulation of Pitx2ON neurons drives three-dimensional head displacements characterized by stepwise, saccade-like kinematics. Furthermore, during naturalistic foraging behavior, the activity of Pitx2ON neurons precedes and predicts the onset of spatially tuned head movements. Intriguingly, we reveal that Pitx2ON neurons are clustered in an orderly array of anatomical modules that tile the entire intermediate layer of the SC. Such a modular organization gives origin to a discrete and discontinuous representation of the motor space, with each Pitx2ON module subtending a defined portion of the animal’s egocentric space. The modularity of Pitx2ON neurons provides an anatomical substrate for the convergence of spatially coherent sensory and motor signals of cortical and subcortical origins, thereby promoting the recruitment of appropriate movement vectors. Overall, these data support the view of the superior colliculus as a selectively addressable and modularly organized spatial-motor register. Pitx2 expression labels a functionally homogeneous class of projecting SC neurons Pitx2ON neurons drive three-dimensional head movements during foraging behavior Pitx2ON neurons are organized in an orderly array of anatomical modules Modularity of Pitx2ON neurons defines a discrete motor map for spatial orienting
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7
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Poletti M, Aytekin M, Rucci M. Head-Eye Coordination at a Microscopic Scale. Curr Biol 2015; 25:3253-9. [PMID: 26687623 DOI: 10.1016/j.cub.2015.11.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 10/28/2015] [Accepted: 11/03/2015] [Indexed: 10/22/2022]
Abstract
Humans explore static visual scenes by alternating rapid eye movements (saccades) with periods of slow and incessant eye drifts [1-3]. These drifts are commonly believed to be the consequence of physiological limits in maintaining steady gaze, resulting in Brownian-like trajectories [4-7], which are almost independent in the two eyes [8-10]. However, because of the technical difficulty of recording minute eye movements, most knowledge on ocular drift comes from artificial laboratory conditions, in which the head of the observer is strictly immobilized. Little is known about eye drift during natural head-free fixation, when microscopic head movements are also continually present [11-13]. We have recently observed that the power spectrum of the visual input to the retina during ocular drift is largely unaffected by fixational head movements [14]. Here we elucidate the mechanism responsible for this invariance. We show that, contrary to common assumption, ocular drift does not move the eyes randomly, but compensates for microscopic head movements, thereby yielding highly correlated movements in the two eyes. This compensatory behavior is extremely fast, persists with one eye patched, and results in image motion trajectories that are only partially correlated on the two retinas. These findings challenge established views of how humans acquire visual information. They show that ocular drift is precisely controlled, as long speculated [15], and imply the existence of neural mechanisms that integrate minute multimodal signals.
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Affiliation(s)
- Martina Poletti
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA
| | - Murat Aytekin
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA
| | - Michele Rucci
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, USA; Graduate Program in Neuroscience, Boston University, Boston, MA 02215, USA.
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8
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Medrea I, Cullen KE. Multisensory integration in early vestibular processing in mice: the encoding of passive vs. active motion. J Neurophysiol 2013; 110:2704-17. [PMID: 24089394 DOI: 10.1152/jn.01037.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The mouse has become an important model system for studying the cellular basis of learning and coding of heading by the vestibular system. Here we recorded from single neurons in the vestibular nuclei to understand how vestibular pathways encode self-motion under natural conditions, during which proprioceptive and motor-related signals as well as vestibular inputs provide feedback about an animal's movement through the world. We recorded neuronal responses in alert behaving mice focusing on a group of neurons, termed vestibular-only cells, that are known to control posture and project to higher-order centers. We found that the majority (70%, n = 21/30) of neurons were bimodal, in that they responded robustly to passive stimulation of proprioceptors as well as passive stimulation of the vestibular system. Additionally, the linear summation of a given neuron's vestibular and neck sensitivities predicted well its responses when both stimuli were applied simultaneously. In contrast, neuronal responses were suppressed when the same motion was actively generated, with the one striking exception that the activity of bimodal neurons similarly and robustly encoded head on body position in all conditions. Our results show that proprioceptive and motor-related signals are combined with vestibular information at the first central stage of vestibular processing in mice. We suggest that these results have important implications for understanding the multisensory integration underlying accurate postural control and the neural representation of directional heading in the head direction cell network of mice.
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Affiliation(s)
- Ioana Medrea
- Aerospace Medical Research Unit, Department of Physiology, McGill University, Montreal, Quebec, Canada
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9
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Zur O, Ronen A, Melzer I, Carmeli E. Vestibulo-ocular response and balance control in children and young adults with mild-to-moderate intellectual and developmental disability: a pilot study. RESEARCH IN DEVELOPMENTAL DISABILITIES 2013; 34:1951-1957. [PMID: 23584174 DOI: 10.1016/j.ridd.2013.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 03/07/2013] [Accepted: 03/07/2013] [Indexed: 06/02/2023]
Abstract
The vestibulo-ocular response (VOR) may not be fully developed in children with an intellectual and developmental disability (IDD). This study aimed to identify the presence of VOR deficit in children and young adults with unspecified mild-to-moderate intellectual and developmental disability and its effect on balance control. Twenty-one children and young adults with IDD ranging in age from 8 to 22 years (mean 17.5 ± 3.9 years) were included in the study. The VOR was evaluated with the Head Impulse Test and the Static and Dynamic Visual Acuity Test (S&D-VAT). Postural stability was measured in an upright standing position by the Clinical Test for Sensory Interaction in Balance (CTSIB), single leg stance (SLS) during eyes open and eyes closed, and Romberg stance under eyes open and eyes closed conditions using a force platform. Reduced vestibulo-ocular responses were found in 13 of 21 (62%) participants who were able to complete testing. In the fifth condition of the CTSIB (standing on foam with eyes closed), those without VOR deficit were able to maintain balance longer than those with VOR deficit (29 s [median 30] vs. 12s [median 7.3], respectively; p=0.03). The study demonstrates potential effects of VOR deficit in children and young adults with IDD and some significant differences in balance control between those with and without a VOR deficit. VOR function in children and young adults with IDD should be routinely tested to enable early detection of deficits.
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Affiliation(s)
- Oz Zur
- Israel Center for Treating Dizziness and Balance Disorders, Raanana, Israel.
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10
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King WM. Getting ahead of oneself: anticipation and the vestibulo-ocular reflex. Neuroscience 2013; 236:210-9. [PMID: 23370320 DOI: 10.1016/j.neuroscience.2012.12.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 10/27/2022]
Abstract
Compensatory counter-rotations of the eyes provoked by head turns are commonly attributed to the vestibulo-ocular reflex (VOR). A recent study in guinea pigs demonstrates, however, that this assumption is not always valid. During voluntary head turns, guinea pigs make highly accurate compensatory eye movements that occur with zero or even negative latencies with respect to the onset of the provoking head movements. Furthermore, the anticipatory eye movements occur in animals with bilateral peripheral vestibular lesions, thus confirming that they have an extra vestibular origin. This discovery suggests the possibility that anticipatory responses might also occur in other species including humans and non-human primates, but have been overlooked and mistakenly identified as being produced by the VOR. This review will compare primate and guinea pig vestibular physiology in light of these new findings. A unified model of vestibular and cerebellar pathways will be presented that is consistent with current data in primates and guinea pigs. The model is capable of accurately simulating compensatory eye movements to active head turns (anticipatory responses) and to passive head perturbations (VOR induced eye movements) in guinea pigs and in human subjects who use coordinated eye and head movements to shift gaze direction in space. Anticipatory responses provide new evidence and opportunities to study the role of extra vestibular signals in motor control and sensory-motor transformations. Exercises that employ voluntary head turns are frequently used to improve visual stability in patients with vestibular hypofunction. Thus, a deeper understanding of the origin and physiology of anticipatory responses could suggest new translational approaches to rehabilitative training of patients with bilateral vestibular loss.
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Affiliation(s)
- W M King
- Department of Otolaryngology and the Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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11
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Chen LL, Lee D, Fukushima K, Fukushima J. Submovement composition of head movement. PLoS One 2012; 7:e47565. [PMID: 23139749 PMCID: PMC3489904 DOI: 10.1371/journal.pone.0047565] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 09/18/2012] [Indexed: 11/19/2022] Open
Abstract
Limb movement is smooth and corrections of movement trajectory and amplitude are barely noticeable midflight. This suggests that skeletomuscular motor commands are smooth in transition, such that the rate of change of acceleration (or jerk) is minimized. Here we applied the methodology of minimum-jerk submovement decomposition to a member of the skeletomuscular family, the head movement. We examined the submovement composition of three types of horizontal head movements generated by nonhuman primates: head-alone tracking, head-gaze pursuit, and eye-head combined gaze shifts. The first two types of head movements tracked a moving target, whereas the last type oriented the head with rapid gaze shifts toward a target fixed in space. During head tracking, the head movement was composed of a series of episodes, each consisting of a distinct, bell-shaped velocity profile (submovement) that rarely overlapped with each other. There was no specific magnitude order in the peak velocities of these submovements. In contrast, during eye-head combined gaze shifts, the head movement was often comprised of overlapping submovements, in which the peak velocity of the primary submovement was always higher than that of the subsequent submovement, consistent with the two-component strategy observed in goal-directed limb movements. These results extend the previous submovement composition studies from limb to head movements, suggesting that submovement composition provides a biologically plausible approach to characterizing the head motor recruitment that can vary depending on task demand.
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Affiliation(s)
- Lewis L Chen
- Department of Otolaryngology, Neurobiology and Anatomical Sciences, Ophthalmology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
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12
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Shanidze N, Lim K, Dye J, King WM. Galvanic stimulation of the vestibular periphery in guinea pigs during passive whole body rotation and self-generated head movement. J Neurophysiol 2012; 107:2260-70. [PMID: 22262827 DOI: 10.1152/jn.00314.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Irregular vestibular afferents exhibit significant phase leads with respect to angular velocity of the head in space. This characteristic and their connectivity with vestibulospinal neurons suggest a functionally important role for these afferents in producing the vestibulo-collic reflex (VCR). A goal of these experiments was to test this hypothesis with the use of weak galvanic stimulation of the vestibular periphery (GVS) to selectively activate or suppress irregular afferents during passive whole body rotation of guinea pigs that could freely move their heads. Both inhibitory and excitatory GVS had significant effects on compensatory head movements during sinusoidal and transient whole body rotations. Unexpectedly, GVS also strongly affected the vestibulo-ocular reflex (VOR) during passive whole body rotation. The effect of GVS on the VOR was comparable in light and darkness and whether the head was restrained or unrestrained. Significantly, there was no effect of GVS on compensatory eye and head movements during volitional head motion, a confirmation of our previous study that demonstrated the extravestibular nature of anticipatory eye movements that compensate for voluntary head movements.
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Affiliation(s)
- N Shanidze
- Department of Otolaryngology, University of Michigan, Ann Arbor, MI, USA.
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