51
|
Rondi-Reig L, Paradis AL, Lefort JM, Babayan BM, Tobin C. How the cerebellum may monitor sensory information for spatial representation. Front Syst Neurosci 2014; 8:205. [PMID: 25408638 PMCID: PMC4219422 DOI: 10.3389/fnsys.2014.00205] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 10/01/2014] [Indexed: 01/09/2023] Open
Abstract
The cerebellum has already been shown to participate in the navigation function. We propose here that this structure is involved in maintaining a sense of direction and location during self-motion by monitoring sensory information and interacting with navigation circuits to update the mental representation of space. To better understand the processing performed by the cerebellum in the navigation function, we have reviewed: the anatomical pathways that convey self-motion information to the cerebellum; the computational algorithm(s) thought to be performed by the cerebellum from these multi-source inputs; the cerebellar outputs directed toward navigation circuits and the influence of self-motion information on space-modulated cells receiving cerebellar outputs. This review highlights that the cerebellum is adequately wired to combine the diversity of sensory signals to be monitored during self-motion and fuel the navigation circuits. The direct anatomical projections of the cerebellum toward the head-direction cell system and the parietal cortex make those structures possible relays of the cerebellum influence on the hippocampal spatial map. We describe computational models of the cerebellar function showing that the cerebellum can filter out the components of the sensory signals that are predictable, and provides a novelty output. We finally speculate that this novelty output is taken into account by the navigation structures, which implement an update over time of position and stabilize perception during navigation.
Collapse
Affiliation(s)
- Laure Rondi-Reig
- Sorbonne Universités, UPMC Univ Paris 06, UMR-S 8246/UM 119, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Institut National de la Santé et de la Recherche Médicale 1130, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Centre National de la Recherche Scientifique, UMR 8246, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France
| | - Anne-Lise Paradis
- Sorbonne Universités, UPMC Univ Paris 06, UMR-S 8246/UM 119, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Institut National de la Santé et de la Recherche Médicale 1130, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Centre National de la Recherche Scientifique, UMR 8246, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France
| | - Julie M Lefort
- Sorbonne Universités, UPMC Univ Paris 06, UMR-S 8246/UM 119, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Institut National de la Santé et de la Recherche Médicale 1130, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Centre National de la Recherche Scientifique, UMR 8246, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France
| | - Benedicte M Babayan
- Sorbonne Universités, UPMC Univ Paris 06, UMR-S 8246/UM 119, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Institut National de la Santé et de la Recherche Médicale 1130, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Centre National de la Recherche Scientifique, UMR 8246, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France
| | - Christine Tobin
- Sorbonne Universités, UPMC Univ Paris 06, UMR-S 8246/UM 119, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Institut National de la Santé et de la Recherche Médicale 1130, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France ; Centre National de la Recherche Scientifique, UMR 8246, Neuroscience Paris Seine, Cerebellum, Navigation and Memory Team Paris, France
| |
Collapse
|
52
|
Abstract
Motion sickness is a complex syndrome that includes many features besides nausea and vomiting. This review describes some of these factors and points out that under normal circumstances, many cases of motion sickness go unrecognized. Motion sickness can occur during exposure to physical motion, visual motion, and virtual motion, and only those without a functioning vestibular system are fully immune. The range of vulnerability in the normal population varies about 10,000 to 1. Sleep deprivation can also enhance susceptibility. Systematic studies conducted in parabolic flight have identified velocity storage of semicircular canal signals-velocity integration-as being a key factor in both space motion sickness and terrestrial motion sickness. Adaptation procedures that have been developed to increase resistance to motion sickness reduce this time constant. A fully adequate theory of motion sickness is not presently available. Limitations of two popular theories, the evolutionary and the ecological, are described. A sensory conflict theory can explain many but not all aspects of motion sickness elicitation. However, extending the theory to include conflicts related to visceral afferent feedback elicited by voluntary and passive body motion greatly expands its explanatory range. Future goals should include determining why some conflicts are provocative and others are not but instead lead to perceptual reinterpretations of ongoing body motion. The contribution of visceral afferents in relation to vestibular and cerebellar signals in evoking sickness also deserves further exploration. Substantial progress is being made in identifying the physiological mechanisms underlying the evocation of nausea, vomiting, and anxiety, and a comprehensive understanding of motion sickness may soon be attainable. Adequate anti-motion sickness drugs without adverse side effects are not yet available.
Collapse
Affiliation(s)
- James R Lackner
- Volen Center for Complex Systems, Brandeis University, Waltham, MA, 02454, USA,
| |
Collapse
|
53
|
Hitier M, Besnard S, Smith PF. Vestibular pathways involved in cognition. Front Integr Neurosci 2014; 8:59. [PMID: 25100954 PMCID: PMC4107830 DOI: 10.3389/fnint.2014.00059] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 06/30/2014] [Indexed: 01/30/2023] Open
Abstract
Recent discoveries have emphasized the role of the vestibular system in cognitive processes such as memory, spatial navigation and bodily self-consciousness. A precise understanding of the vestibular pathways involved is essential to understand the consequences of vestibular diseases for cognition, as well as develop therapeutic strategies to facilitate recovery. The knowledge of the “vestibular cortical projection areas”, defined as the cortical areas activated by vestibular stimulation, has dramatically increased over the last several years from both anatomical and functional points of view. Four major pathways have been hypothesized to transmit vestibular information to the vestibular cortex: (1) the vestibulo-thalamo-cortical pathway, which probably transmits spatial information about the environment via the parietal, entorhinal and perirhinal cortices to the hippocampus and is associated with spatial representation and self-versus object motion distinctions; (2) the pathway from the dorsal tegmental nucleus via the lateral mammillary nucleus, the anterodorsal nucleus of the thalamus to the entorhinal cortex, which transmits information for estimations of head direction; (3) the pathway via the nucleus reticularis pontis oralis, the supramammillary nucleus and the medial septum to the hippocampus, which transmits information supporting hippocampal theta rhythm and memory; and (4) a possible pathway via the cerebellum, and the ventral lateral nucleus of the thalamus (perhaps to the parietal cortex), which transmits information for spatial learning. Finally a new pathway is hypothesized via the basal ganglia, potentially involved in spatial learning and spatial memory. From these pathways, progressively emerges the anatomical network of vestibular cognition.
Collapse
Affiliation(s)
- Martin Hitier
- Inserm, U 1075 COMETE Caen, France ; Department of Pharmacology and Toxicology, Brain Health Research Center, University of Otago Dunedin, New Zealand ; Department of Anatomy, UNICAEN Caen, France ; Department of Otolaryngology Head and Neck Surgery, CHU de Caen Caen, France
| | | | - Paul F Smith
- Department of Pharmacology and Toxicology, Brain Health Research Center, University of Otago Dunedin, New Zealand
| |
Collapse
|
54
|
Oman CM, Cullen KE. Brainstem processing of vestibular sensory exafference: implications for motion sickness etiology. Exp Brain Res 2014; 232:2483-92. [PMID: 24838552 DOI: 10.1007/s00221-014-3973-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/20/2014] [Indexed: 11/29/2022]
Abstract
The origin of the internal "sensory conflict" stimulus causing motion sickness has been debated for more than four decades. Recent studies show a subclass of neurons in the vestibular nuclei and deep cerebellar nuclei that respond preferentially to passive head movements. During active movement, the semicircular canal and otolith input ("reafference") to these neurons are canceled by a mechanism comparing the expected consequences of self-generated movement (estimated with an internal model-presumably located in the cerebellum) with the actual sensory feedback. The un-canceled component ("exafference") resulting from passive movement normally helps compensate for unexpected postural disturbances. Notably, the existence of such vestibular "sensory conflict" neurons had been postulated as early as 1982, but their existence and putative role in posture control and motion sickness have been long debated. Here, we review the development of "sensory conflict" theories in relation to recent evidence for brainstem and cerebellar reafference cancelation, and identify some open research questions. We propose that conditions producing persistent activity of these neurons, or their targets, stimulate nearby brainstem emetic centers-via an as yet unidentified mechanism. We discuss how such a mechanism is consistent with the notable difference in motion sickness susceptibility of drivers as opposed to passengers, human immunity to normal self-generated movement and why head restraint or lying horizontal confers relative immunity. Finally, we propose that fuller characterization of these mechanisms and their potential role in motion sickness could lead to more effective, scientifically based prevention and treatment for motion sickness.
Collapse
Affiliation(s)
- Charles M Oman
- Man Vehicle Laboratory, Massachusetts Institute of Technology, Room 37-219, MIT 77 Massachusetts Avenue, Cambridge, MA, 02139, USA,
| | | |
Collapse
|
55
|
Moreau-Debord I, Martin CZ, Landry M, Green AM. Evidence for a reference frame transformation of vestibular signal contributions to voluntary reaching. J Neurophysiol 2014; 111:1903-19. [DOI: 10.1152/jn.00419.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To contribute appropriately to voluntary reaching during body motion, vestibular signals must be transformed from a head-centered to a body-centered reference frame. We quantitatively investigated the evidence for this transformation during online reach execution by using galvanic vestibular stimulation (GVS) to simulate rotation about a head-fixed, roughly naso-occipital axis as human subjects made planar reaching movements to a remembered location with their head in different orientations. If vestibular signals that contribute to reach execution have been transformed from a head-centered to a body-centered reference frame, the same stimulation should be interpreted as body tilt with the head upright but as vertical-axis rotation with the head inclined forward. Consequently, GVS should perturb reach trajectories in a head-orientation-dependent way. Consistent with this prediction, GVS applied during reach execution induced trajectory deviations that were significantly larger with the head forward compared with upright. Only with the head forward were trajectories consistently deviated in opposite directions for rightward versus leftward simulated rotation, as appropriate to compensate for body vertical-axis rotation. These results demonstrate that vestibular signals contributing to online reach execution have indeed been transformed from a head-centered to a body-centered reference frame. Reach deviation amplitudes were comparable to those predicted for ideal compensation for body rotation using a biomechanical limb model. Finally, by comparing the effects of application of GVS during reach execution versus prior to reach onset we also provide evidence that spatially transformed vestibular signals contribute to at least partially distinct compensation mechanisms for body motion during reach planning versus execution.
Collapse
Affiliation(s)
- Ian Moreau-Debord
- Département de Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| | | | - Marianne Landry
- Département de Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| | - Andrea M. Green
- Département de Neurosciences, Université de Montréal, Montreal, Quebec, Canada
| |
Collapse
|
56
|
Arshian MS, Hobson CE, Catanzaro MF, Miller DJ, Puterbaugh SR, Cotter LA, Yates BJ, McCall AA. Vestibular nucleus neurons respond to hindlimb movement in the decerebrate cat. J Neurophysiol 2014; 111:2423-32. [PMID: 24671527 DOI: 10.1152/jn.00855.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The vestibular nuclei integrate information from vestibular and proprioceptive afferents, which presumably facilitates the maintenance of stable balance and posture. However, little is currently known about the processing of sensory signals from the limbs by vestibular nucleus neurons. This study tested the hypothesis that limb movement is encoded by vestibular nucleus neurons and described the changes in activity of these neurons elicited by limb extension and flexion. In decerebrate cats, we recorded the activity of 70 vestibular nucleus neurons whose activity was modulated by limb movements. Most of these neurons (57/70, 81.4%) encoded information about the direction of hindlimb movement, while the remaining neurons (13/70, 18.6%) encoded the presence of hindlimb movement without signaling the direction of movement. The activity of many vestibular nucleus neurons that responded to limb movement was also modulated by rotating the animal's body in vertical planes, suggesting that the neurons integrated hindlimb and labyrinthine inputs. Neurons whose firing rate increased during ipsilateral ear-down roll rotations tended to be excited by hindlimb flexion, whereas neurons whose firing rate increased during contralateral ear-down tilts were excited by hindlimb extension. These observations suggest that there is a purposeful mapping of hindlimb inputs onto vestibular nucleus neurons, such that integration of hindlimb and labyrinthine inputs to the neurons is functionally relevant.
Collapse
Affiliation(s)
- Milad S Arshian
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania; Midwestern University College of Osteopathic Medicine, Chicago, Illinois
| | - Candace E Hobson
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Michael F Catanzaro
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Daniel J Miller
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sonya R Puterbaugh
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Lucy A Cotter
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Bill J Yates
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Andrew A McCall
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, Pennsylvania;
| |
Collapse
|
57
|
Shinder ME, Newlands SD. Sensory convergence in the parieto-insular vestibular cortex. J Neurophysiol 2014; 111:2445-64. [PMID: 24671533 DOI: 10.1152/jn.00731.2013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Vestibular signals are pervasive throughout the central nervous system, including the cortex, where they likely play different roles than they do in the better studied brainstem. Little is known about the parieto-insular vestibular cortex (PIVC), an area of the cortex with prominent vestibular inputs. Neural activity was recorded in the PIVC of rhesus macaques during combinations of head, body, and visual target rotations. Activity of many PIVC neurons was correlated with the motion of the head in space (vestibular), the twist of the neck (proprioceptive), and the motion of a visual target, but was not associated with eye movement. PIVC neurons responded most commonly to more than one stimulus, and responses to combined movements could often be approximated by a combination of the individual sensitivities to head, neck, and target motion. The pattern of visual, vestibular, and somatic sensitivities on PIVC neurons displayed a continuous range, with some cells strongly responding to one or two of the stimulus modalities while other cells responded to any type of motion equivalently. The PIVC contains multisensory convergence of self-motion cues with external visual object motion information, such that neurons do not represent a specific transformation of any one sensory input. Instead, the PIVC neuron population may define the movement of head, body, and external visual objects in space and relative to one another. This comparison of self and external movement is consistent with insular cortex functions related to monitoring and explains many disparate findings of previous studies.
Collapse
Affiliation(s)
- Michael E Shinder
- Department of Otolaryngology, University of Texas Medical Branch, Galveston, Texas
| | - Shawn D Newlands
- Department of Otolaryngology, University of Texas Medical Branch, Galveston, Texas
| |
Collapse
|
58
|
Beyond the basal ganglia: cFOS expression in the cerebellum in response to acute and chronic dopaminergic alterations. Neuroscience 2014; 267:219-31. [PMID: 24631673 DOI: 10.1016/j.neuroscience.2014.02.046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 02/15/2014] [Accepted: 02/28/2014] [Indexed: 11/21/2022]
Abstract
The suggestion of an anatomical and functional relationship between the basal ganglia and cerebellum is recent. Traditionally, these structures were considered as neuronal circuits working separately to organize and control goal-directed movements and cognitive functions. However, several studies in rodents and primates have described an anatomical interaction between cortico-basal and cortico-cerebellar networks. Most importantly, functional changes have been observed in one of these circuits when altering the other one. In this context, we aimed to accomplish an extensive description of cerebellar activation patterns using cFOS expression (cFOS-IR) after acute and chronic manipulation of dopaminergic activity. In the acute study, substantia nigra pars compacta (SNc) activity was stimulated or suppressed by intra cerebral administration of picrotoxin or lidocaine, respectively. In addition, we analyzed cerebellar activity after the induction of a parkinsonism model, the tremulous jaw movements. In this model, tremulous jaw movements were induced in male rats by IP chronic administration of the dopamine antagonist haloperidol (1.5mg/kg). Acute stimulation of SNc by picrotoxin increased cFOS-IR in the vermis and cerebellar hemispheres. However, lidocaine did not produce an effect. After 14days of haloperidol treatment, the vermis and cerebellar hemispheres showed an opposite regulation of cFOS expression. Chronic dopaminergic antagonism lessened cFOS expression in the vermis but up-regulated such expression in the cerebellar hemisphere. Overall, the present data indicate a very close functional relationship between the basal ganglia and the cerebellum and they may allow a better understanding of disorders in which there are dopamine alterations.
Collapse
|
59
|
Multimodal integration of self-motion cues in the vestibular system: active versus passive translations. J Neurosci 2014; 33:19555-66. [PMID: 24336720 DOI: 10.1523/jneurosci.3051-13.2013] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The ability to keep track of where we are going as we navigate through our environment requires knowledge of our ongoing location and orientation. In response to passively applied motion, the otolith organs of the vestibular system encode changes in the velocity and direction of linear self-motion (i.e., heading). When self-motion is voluntarily generated, proprioceptive and motor efference copy information is also available to contribute to the brain's internal representation of current heading direction and speed. However to date, how the brain integrates these extra-vestibular cues with otolith signals during active linear self-motion remains unknown. Here, to address this question, we compared the responses of macaque vestibular neurons during active and passive translations. Single-unit recordings were made from a subgroup of neurons at the first central stage of sensory processing in the vestibular pathways involved in postural control and the computation of self-motion perception. Neurons responded far less robustly to otolith stimulation during self-generated than passive head translations. Yet, the mechanism underlying the marked cancellation of otolith signals did not affect other characteristics of neuronal responses (i.e., baseline firing rate, tuning ratio, orientation of maximal sensitivity vector). Transiently applied perturbations during active motion further established that an otolith cancellation signal was only gated in conditions where proprioceptive sensory feedback matched the motor-based expectation. Together our results have important implications for understanding the brain's ability to ensure accurate postural and motor control, as well as perceptual stability, during active self-motion.
Collapse
|
60
|
Watson TC, Becker N, Apps R, Jones MW. Back to front: cerebellar connections and interactions with the prefrontal cortex. Front Syst Neurosci 2014; 8:4. [PMID: 24550789 PMCID: PMC3912388 DOI: 10.3389/fnsys.2014.00004] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/08/2014] [Indexed: 11/13/2022] Open
Abstract
Although recent neuroanatomical evidence has demonstrated closed-loop connectivity between prefrontal cortex and the cerebellum, the physiology of cerebello-cerebral circuits and the extent to which cerebellar output modulates neuronal activity in neocortex during behavior remain relatively unexplored. We show that electrical stimulation of the contralateral cerebellar fastigial nucleus (FN) in awake, behaving rats evokes distinct local field potential (LFP) responses (onset latency ~13 ms) in the prelimbic (PrL) subdivision of the medial prefrontal cortex. Trains of FN stimulation evoke heterogeneous patterns of response in putative pyramidal cells in frontal and prefrontal regions in both urethane-anesthetized and awake, behaving rats. However, the majority of cells showed decreased firing rates during stimulation and subsequent rebound increases; more than 90% of cells showed significant changes in response. Simultaneous recording of on-going LFP activity from FN and PrL while rats were at rest or actively exploring an open field arena revealed significant network coherence restricted to the theta frequency range (5–10 Hz). Granger causality analysis indicated that this coherence was significantly directed from cerebellum to PrL during active locomotion. Our results demonstrate the presence of a cerebello-prefrontal pathway in rat and reveal behaviorally dependent coordinated network activity between the two structures, which could facilitate transfer of sensorimotor information into ongoing neocortical processing during goal directed behaviors.
Collapse
Affiliation(s)
- Thomas C Watson
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| | - Nadine Becker
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| | - Richard Apps
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| | - Matthew W Jones
- School of Physiology and Pharmacology, University of Bristol Bristol, UK
| |
Collapse
|
61
|
Cullen KE. The neural encoding of self-generated and externally applied movement: implications for the perception of self-motion and spatial memory. Front Integr Neurosci 2014; 7:108. [PMID: 24454282 PMCID: PMC3888934 DOI: 10.3389/fnint.2013.00108] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/23/2013] [Indexed: 12/03/2022] Open
Abstract
The vestibular system is vital for maintaining an accurate representation of self-motion. As one moves (or is moved) toward a new place in the environment, signals from the vestibular sensors are relayed to higher-order centers. It is generally assumed the vestibular system provides a veridical representation of head motion to these centers for the perception of self-motion and spatial memory. In support of this idea, evidence from lesion studies suggests that vestibular inputs are required for the directional tuning of head direction cells in the limbic system as well as neurons in areas of multimodal association cortex. However, recent investigations in monkeys and mice challenge the notion that early vestibular pathways encode an absolute representation of head motion. Instead, processing at the first central stage is inherently multimodal. This minireview highlights recent progress that has been made towards understanding how the brain processes and interprets self-motion signals encoded by the vestibular otoliths and semicircular canals during everyday life. The following interrelated questions are considered. What information is available to the higher-order centers that contribute to self-motion perception? How do we distinguish between our own self-generated movements and those of the external world? And lastly, what are the implications of differences in the processing of these active vs. passive movements for spatial memory?
Collapse
Affiliation(s)
- Kathleen E Cullen
- Aerospace Medical Research Unit, Department of Physiology, McGill University Montreal, QC, Canada
| |
Collapse
|
62
|
Diaz MR, Vollmer CC, Zamudio-Bulcock PA, Vollmer W, Blomquist SL, Morton RA, Everett JC, Zurek AA, Yu J, Orser BA, Valenzuela CF. Repeated intermittent alcohol exposure during the third trimester-equivalent increases expression of the GABA(A) receptor δ subunit in cerebellar granule neurons and delays motor development in rats. Neuropharmacology 2013; 79:262-74. [PMID: 24316160 DOI: 10.1016/j.neuropharm.2013.11.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 10/17/2013] [Accepted: 11/25/2013] [Indexed: 02/01/2023]
Abstract
Exposure to ethanol (EtOH) during fetal development can lead to long-lasting alterations, including deficits in fine motor skills and motor learning. Studies suggest that these are, in part, a consequence of cerebellar damage. Cerebellar granule neurons (CGNs) are the gateway of information into the cerebellar cortex. Functionally, CGNs are heavily regulated by phasic and tonic GABAergic inhibition from Golgi cell interneurons; however, the effect of EtOH exposure on the development of GABAergic transmission in immature CGNs has not been investigated. To model EtOH exposure during the 3rd trimester-equivalent of human pregnancy, neonatal pups were exposed intermittently to high levels of vaporized EtOH from postnatal day (P) 2 to P12. This exposure gradually increased pup serum EtOH concentrations (SECs) to ∼60 mM (∼0.28 g/dl) during the 4 h of exposure. EtOH levels gradually decreased to baseline 8 h after the end of exposure. Surprisingly, basal tonic and phasic GABAergic currents in CGNs were not significantly affected by postnatal alcohol exposure (PAE). However, PAE increased δ subunit expression at P28 as detected by immunohistochemical and western blot analyses. Also, electrophysiological studies with an agonist that is highly selective for δ-containing GABA(A) receptors, 4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-ol (THIP), showed an increase in THIP-induced tonic current. Behavioral studies of PAE rats did not reveal any deficits in motor coordination, except for a delay in the acquisition of the mid-air righting reflex that was apparent at P15 to P18. These findings demonstrate that repeated intermittent exposure to high levels of EtOH during the equivalent of the last trimester of human pregnancy has significant but relatively subtle effects on motor coordination and GABAergic transmission in CGNs in rats.
Collapse
Affiliation(s)
- Marvin R Diaz
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Cyndel C Vollmer
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Paula A Zamudio-Bulcock
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - William Vollmer
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Samantha L Blomquist
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Russell A Morton
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Julie C Everett
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Agnieszka A Zurek
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jieying Yu
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Beverley A Orser
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Department of Anesthesia, University of Toronto, Toronto, Ontario, Canada; Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - C Fernando Valenzuela
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
| |
Collapse
|
63
|
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.
Collapse
Affiliation(s)
- Ioana Medrea
- Aerospace Medical Research Unit, Department of Physiology, McGill University, Montreal, Quebec, Canada
| | | |
Collapse
|
64
|
Brooks JX, Cullen KE. The primate cerebellum selectively encodes unexpected self-motion. Curr Biol 2013; 23:947-55. [PMID: 23684973 DOI: 10.1016/j.cub.2013.04.029] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/06/2013] [Accepted: 04/11/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND The ability to distinguish sensory signals that register unexpected events (exafference) from those generated by voluntary actions (reafference) during self-motion is essential for accurate perception and behavior. The cerebellum is most commonly considered in relation to its contributions to the fine tuning of motor commands and sensorimotor calibration required for motor learning. During unexpected motion, however, the sensory prediction errors that drive motor learning potentially provide a neural basis for the computation underlying the distinction between reafference and exafference. RESULTS Recording from monkeys during voluntary and applied self-motion, we demonstrate that individual cerebellar output neurons encode an explicit and selective representation of unexpected self-motion by means of an elegant computation that cancels the reafferent sensory effects of self-generated movements. During voluntary self-motion, the sensory responses of neurons that robustly encode unexpected movement are canceled. Neurons with vestibular and proprioceptive responses to applied head and body movements are unresponsive when the same motion is self-generated. When sensory reafference and exafference are experienced simultaneously, individual neurons provide a precise estimate of the detailed time course of exafference. CONCLUSIONS These results provide an explicit solution to the longstanding problem of understanding mechanisms by which the brain anticipates the sensory consequences of our voluntary actions. Specifically, by revealing a striking computation of a sensory prediction error signal that effectively distinguishes between the sensory consequences of self-generated and externally produced actions, our findings overturn the conventional thinking that the sensory errors coded by the cerebellum principally contribute to the fine tuning of motor activity required for motor learning.
Collapse
Affiliation(s)
- Jessica X Brooks
- Department of Physiology, Aerospace Medical Research Unit, McGill University, Montréal, QC H3G 1Y6, Canada
| | | |
Collapse
|
65
|
Rochefort C, Lefort JM, Rondi-Reig L. The cerebellum: a new key structure in the navigation system. Front Neural Circuits 2013; 7:35. [PMID: 23493515 PMCID: PMC3595517 DOI: 10.3389/fncir.2013.00035] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Accepted: 02/22/2013] [Indexed: 12/03/2022] Open
Abstract
Early investigations of cerebellar function focused on motor learning, in particular on eyeblink conditioning and adaptation of the vestibulo-ocular reflex, and led to the general view that cerebellar long-term depression (LTD) at parallel fiber (PF)–Purkinje cell (PC) synapses is the neural correlate of cerebellar motor learning. Thereafter, while the full complexity of cerebellar plasticities was being unraveled, cerebellar involvement in more cognitive tasks—including spatial navigation—was further investigated. However, cerebellar implication in spatial navigation remains a matter of debate because motor deficits frequently associated with cerebellar damage often prevent the dissociation between its role in spatial cognition from its implication in motor function. Here, we review recent findings from behavioral and electrophysiological analyses of cerebellar mutant mouse models, which show that the cerebellum might participate in the construction of hippocampal spatial representation map (i.e., place cells) and thereby in goal-directed navigation. These recent advances in cerebellar research point toward a model in which computation from the cerebellum could be required for spatial representation and would involve the integration of multi-source self-motion information to: (1) transform the reference frame of vestibular signals and (2) distinguish between self- and externally-generated vestibular signals. We eventually present herein anatomical and functional connectivity data supporting a cerebello-hippocampal interaction. Whilst a direct cerebello-hippocampal projection has been suggested, recent investigations rather favor a multi-synaptic pathway involving posterior parietal and retrosplenial cortices, two regions critically involved in spatial navigation.
Collapse
|
66
|
Luan H, Gdowski MJ, Newlands SD, Gdowski GT. Convergence of vestibular and neck proprioceptive sensory signals in the cerebellar interpositus. J Neurosci 2013; 33:1198-210a. [PMID: 23325256 PMCID: PMC3711745 DOI: 10.1523/jneurosci.3460-12.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 11/17/2012] [Accepted: 11/25/2012] [Indexed: 11/21/2022] Open
Abstract
The cerebellar interpositus nucleus (IN) contributes to controlling voluntary limb movements. We hypothesized that the vestibular signals within the IN might be transformed into coordinates describing the body's movement, appropriate for controlling limb movement. We tested this hypothesis by recording from IN neurons in alert squirrel monkeys during vestibular and proprioceptive stimulation produced during (1) yaw head-on-trunk rotation about the C1-C2 axis while in an orthograde posture and (2) lateral side-to-side flexion about the C6-T3 axis while in a pronograde posture. Neurons (44/67) were sensitive to vestibular stimulation (23/44 to rotation and translation, 14/44 to rotation only, 7/44 to translation only). Most neurons responded during contralateral movement. Neurons (29/44) had proprioceptive responses; the majority (21/29) were activated during neck rotation and lateral flexion. In all 29 neurons with convergent vestibular and neck proprioceptive input those inputs functionally canceled each other during all combined sensory stimulation, whether in the orthograde or pronograde posture. These results suggest that two distinct populations of IN neurons exist, each of which has vestibular sensitivity. One population carries vestibular signals that describe the head's movement in space as is traditional for vestibular signals without proprioceptive signals. A second population of neurons demonstrated precise matching of vestibular and proprioceptive signals, even for complicated stimuli, which activated the semicircular canals and otolith organs and involved both rotation and flexion in the spine. Such neurons code body (not head) motion in space, which may be the appropriate platform for controlling limb movements.
Collapse
Affiliation(s)
- Hongge Luan
- Departments of Neurobiology and Anatomy
- Otolaryngology, University of Rochester, Rochester, New York 14642
| | | | - Shawn D. Newlands
- Departments of Neurobiology and Anatomy
- Otolaryngology, University of Rochester, Rochester, New York 14642
| | - Greg T. Gdowski
- Departments of Neurobiology and Anatomy
- Biomedical Engineering, and
| |
Collapse
|
67
|
Barresi M, Bruschini L, Li Volsi G, Manzoni D. Effects of leg-to-body position on the responses of rat cerebellar and vestibular nuclear neurons to labyrinthine stimulation. THE CEREBELLUM 2012; 11:212-22. [PMID: 21739187 DOI: 10.1007/s12311-011-0298-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The spatial organization of vestibulospinal (VS) reflexes, elicited by labyrinthine signals and related to head motion, depends on the direction of body tilt, due to proprioceptive neck afferents acting through the cerebellar anterior vermis. The responses of Purkinje cells located within this region to labyrinthine stimulation are modulated by the head-to-body position. We investigated, in urethane-anesthetized rats, whether a 90° leg-to-trunk displacement modifies the responses of corticocerebellar and vestibular nuclear neurons to the labyrinthine input, which would indicate that VS reflexes are tuned by the leg-to-trunk position. With this aim, unit activity was recorded during "wobble" stimuli that allow evaluating the gain and spatiotemporal properties of neuronal responses. The response gain of corticocerebellar units showed a significant drop in the leg-rotated position with respect to the control one. Following a change in leg position, a proportion of the recorded neurons showed significant changes in the direction and phase of the response vector. In contrast, vestibular nuclear neurons did not show significant modifications in their response gain and direction. Thus, proprioceptive afferents signaling leg-to-trunk position seem to affect the processing of directional labyrinthine signals within the cerebellar cortex.
Collapse
Affiliation(s)
- Massimo Barresi
- Department of Physiological Sciences, Pisa University, Via S. Zeno 31, 56127 Pisa, Italy
| | | | | | | |
Collapse
|
68
|
Anatomical characterization of a rabbit cerebellar eyeblink premotor pathway using pseudorabies and identification of a local modulatory network in anterior interpositus. J Neurosci 2012; 32:12472-87. [PMID: 22956838 DOI: 10.1523/jneurosci.2088-12.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Rabbit eyeblink conditioning is a well characterized model of associative learning. To identify specific neurons that are part of the eyeblink premotor pathway, a retrograde transsynaptic tracer (pseudorabies virus) was injected into the orbicularis oculi muscle. Four time points (3, 4, 4.5, and 5 d) were selected to identify sequential segments of the pathway and a map of labeled structures was generated. At 3 d, labeled first-order motor neurons were found in dorsolateral facial nucleus ipsilaterally. At 4 d, second-order premotor neurons were found in reticular nuclei, and sensory trigeminal, auditory, vestibular, and motor structures, including contralateral red nucleus. At 4.5 d, labeled third-order premotor neurons were found in the pons, midbrain, and cerebellum, including dorsolateral anterior interpositus nucleus and rostral fastigial nucleus. At 5 d, labeling revealed higher-order premotor structures. Labeled fourth-order Purkinje cells were found in ipsilateral cerebellar cortex in cerebellar lobule HVI and in lobule I. The former has been implicated in eyeblink conditioning and the latter in vestibular control. Labeled neurons in anterior interpositus were studied, using neurotransmitter immunoreactivity to classify individual cell types and delineate their interconnectivity. Labeled third-order premotor neurons were immunoreactive for glutamate and corresponded to large excitatory projection neurons. Labeled fourth-order premotor interneurons were immunoreactive for GABA (30%), glycine (18%), or both GABA and glycine (52%) and form a functional network within anterior interpositus involved in modulation of motor commands. These results identify a complete eyeblink premotor pathway, deep cerebellar interconnectivity, and specific neurons responsible for the generation of eyeblink responses.
Collapse
|
69
|
Carmona S, Ferrero A, Pianetti G, Escolá N, Arteaga MV, Frankel L. Galvanic vestibular stimulation improves the results of vestibular rehabilitation. Ann N Y Acad Sci 2012; 1233:E1-7. [PMID: 22360772 DOI: 10.1111/j.1749-6632.2011.06269.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Here, we present findings from a three-step investigation of the effect of galvanic vestibular stimulation (GVS) in normal subjects and in subjects undergoing vestibular rehabilitation (VR). In an initial study, we examined the body sway of 10 normal subjects after one minute of 2 mA GVS. The effect of the stimulation lasted for at least 20 minutes in all subjects and up to two hours in 70% of the subjects. We then compared a group of patients who received conventional VR (40 patients) with a group that received a combination of VR and GVS. Results suggest a significant improvement in the second group. Finally, we attempted to establish the optimal number of GVS sessions and to rule out a placebo effect. Fifteen patients received "systematic" GVS: five sessions, once a week. Five patients received "nonsystematic" galvanic stimulation in a sham protocol, which included two stimulations of the clavicle. These data were analyzed with Fisher's exact test and indicated that the best results were obtained after three sessions of GVS and no placebo effect was observed.
Collapse
Affiliation(s)
- Sergio Carmona
- Neurotology Department, Instituto San Lucas Neurociencias, Rosario, Argentina.
| | | | | | | | | | | |
Collapse
|
70
|
Cullen KE. The neural encoding of self-motion. Curr Opin Neurobiol 2012; 21:587-95. [PMID: 21689924 DOI: 10.1016/j.conb.2011.05.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 05/03/2011] [Accepted: 05/24/2011] [Indexed: 11/25/2022]
Abstract
As we move through the world, information can be combined from multiple sources in order to allow us to perceive our self-motion. The vestibular system detects and encodes the motion of the head in space. In addition, extra-vestibular cues such as retinal-image motion (optic flow), proprioception, and motor efference signals, provide valuable motion cues. Here I focus on the coding strategies that are used by the brain to create neural representations of self-motion. I review recent studies comparing the thresholds of single versus populations of vestibular afferent and central neurons. I then consider recent advances in understanding the brain's strategy for combining information from the vestibular sensors with extra-vestibular cues to estimate self-motion. These studies emphasize the need to consider not only the rules by which multiple inputs are combined, but also how differences in the behavioral context govern the nature of what defines the optimal computation.
Collapse
Affiliation(s)
- Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, PQ, H3G 1Y6, Canada.
| |
Collapse
|
71
|
Cullen KE. The vestibular system: multimodal integration and encoding of self-motion for motor control. Trends Neurosci 2012; 35:185-96. [PMID: 22245372 DOI: 10.1016/j.tins.2011.12.001] [Citation(s) in RCA: 365] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/03/2011] [Accepted: 12/02/2011] [Indexed: 01/16/2023]
Abstract
Understanding how sensory pathways transmit information under natural conditions remains a major goal in neuroscience. The vestibular system plays a vital role in everyday life, contributing to a wide range of functions from reflexes to the highest levels of voluntary behavior. Recent experiments establishing that vestibular (self-motion) processing is inherently multimodal also provide insight into a set of interrelated questions. What neural code is used to represent sensory information in vestibular pathways? How do the interactions between the organism and the environment shape encoding? How is self-motion information processing adjusted to meet the needs of specific tasks? This review highlights progress that has recently been made towards understanding how the brain encodes and processes self-motion to ensure accurate motor control.
Collapse
Affiliation(s)
- Kathleen E Cullen
- Department of Physiology, McGill University, Montreal, Quebec H3G 1Y6, Canada.
| |
Collapse
|
72
|
Rochefort C, Arabo A, André M, Poucet B, Save E, Rondi-Reig L. Cerebellum shapes hippocampal spatial code. Science 2011; 334:385-9. [PMID: 22021859 DOI: 10.1126/science.1207403] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Spatial representation is an active process that requires complex multimodal integration from a large interacting network of cortical and subcortical structures. We sought to determine the role of cerebellar protein kinase C (PKC)-dependent plasticity in spatial navigation by recording the activity of hippocampal place cells in transgenic L7PKCI mice with selective disruption of PKC-dependent plasticity at parallel fiber-Purkinje cell synapses. Place cell properties were exclusively impaired when L7PKCI mice had to rely on self-motion cues. The behavioral consequence of such a deficit is evidenced here by selectively impaired navigation capabilities during a path integration task. Together, these results suggest that cerebellar PKC-dependent mechanisms are involved in processing self-motion signals essential to the shaping of hippocampal spatial representation.
Collapse
Affiliation(s)
- Christelle Rochefort
- Neurobiologie des Processus Adaptatifs (UMR 7102), Navigation, Memory, and Aging (ENMVI) Team, Université Pierre et Marie Curie-Centre National de la Recherche Scientifique (CNRS), F-75005 Paris, France
| | | | | | | | | | | |
Collapse
|
73
|
Schneider AD, Cullen KE, Chacron MJ. In vivo conditions induce faithful encoding of stimuli by reducing nonlinear synchronization in vestibular sensory neurons. PLoS Comput Biol 2011; 7:e1002120. [PMID: 21814508 PMCID: PMC3140969 DOI: 10.1371/journal.pcbi.1002120] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 05/26/2011] [Indexed: 12/04/2022] Open
Abstract
Previous studies have shown that neurons within the vestibular nuclei (VN) can faithfully encode the time course of sensory input through changes in firing rate in vivo. However, studies performed in vitro have shown that these same VN neurons often display nonlinear synchronization (i.e. phase locking) in their spiking activity to the local maxima of sensory input, thereby severely limiting their capacity for faithful encoding of said input through changes in firing rate. We investigated this apparent discrepancy by studying the effects of in vivo conditions on VN neuron activity in vitro using a simple, physiologically based, model of cellular dynamics. We found that membrane potential oscillations were evoked both in response to step and zap current injection for a wide range of channel conductance values. These oscillations gave rise to a resonance in the spiking activity that causes synchronization to sinusoidal current injection at frequencies below 25 Hz. We hypothesized that the apparent discrepancy between VN response dynamics measured in in vitro conditions (i.e., consistent with our modeling results) and the dynamics measured in vivo conditions could be explained by an increase in trial-to-trial variability under in vivo vs. in vitro conditions. Accordingly, we mimicked more physiologically realistic conditions in our model by introducing a noise current to match the levels of resting discharge variability seen in vivo as quantified by the coefficient of variation (CV). While low noise intensities corresponding to CV values in the range 0.04-0.24 only eliminated synchronization for low (<8 Hz) frequency stimulation but not high (>12 Hz) frequency stimulation, higher noise intensities corresponding to CV values in the range 0.5-0.7 almost completely eliminated synchronization for all frequencies. Our results thus predict that, under natural (i.e. in vivo) conditions, the vestibular system uses increased variability to promote fidelity of encoding by single neurons. This prediction can be tested experimentally in vitro.
Collapse
Affiliation(s)
| | | | - Maurice J. Chacron
- Department of Physics, McGill University, Montreal, Quebec, Canada
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| |
Collapse
|
74
|
Cullen KE, Brooks JX, Jamali M, Carriot J, Massot C. Internal models of self-motion: computations that suppress vestibular reafference in early vestibular processing. Exp Brain Res 2011; 210:377-88. [PMID: 21286693 DOI: 10.1007/s00221-011-2555-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Accepted: 12/29/2010] [Indexed: 01/11/2023]
Abstract
In everyday life, vestibular sensors are activated by both self-generated and externally applied head movements. The ability to distinguish inputs that are a consequence of our own actions (i.e., active motion) from those that result from changes in the external world (i.e., passive or unexpected motion) is essential for perceptual stability and accurate motor control. Recent work has made progress toward understanding how the brain distinguishes between these two kinds of sensory inputs. We have performed a series of experiments in which single-unit recordings were made from vestibular afferents and central neurons in alert macaque monkeys during rotation and translation. Vestibular afferents showed no differences in firing variability or sensitivity during active movements when compared to passive movements. In contrast, the analyses of neuronal firing rates revealed that neurons at the first central stage of vestibular processing (i.e., in the vestibular nuclei) were effectively less sensitive to active motion. Notably, however, this ability to distinguish between active and passive motion was not a general feature of early central processing, but rather was a characteristic of a distinct group of neurons known to contribute to postural control and spatial orientation. Our most recent studies have addressed how vestibular and proprioceptive inputs are integrated in the vestibular cerebellum, a region likely to be involved in generating an internal model of self-motion. We propose that this multimodal integration within the vestibular cerebellum is required for eliminating self-generated vestibular information from the subsequent computation of orientation and posture control at the first central stage of processing.
Collapse
Affiliation(s)
- Kathleen E Cullen
- Aerospace Medical Research Unit, Department of Physiology, McGill University, Montreal, PQ, H3G 1Y6, Canada.
| | | | | | | | | |
Collapse
|
75
|
Multisensory integration: resolving sensory ambiguities to build novel representations. Curr Opin Neurobiol 2010; 20:353-60. [PMID: 20471245 DOI: 10.1016/j.conb.2010.04.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 04/10/2010] [Accepted: 04/14/2010] [Indexed: 11/19/2022]
Abstract
Multisensory integration plays several important roles in the nervous system. One is to combine information from multiple complementary cues to improve stimulus detection and discrimination. Another is to resolve peripheral sensory ambiguities and create novel internal representations that do not exist at the level of individual sensors. Here we focus on how ambiguities inherent in vestibular, proprioceptive and visual signals are resolved to create behaviorally useful internal estimates of our self-motion. We review recent studies that have shed new light on the nature of these estimates and how multiple, but individually ambiguous, sensory signals are processed and combined to compute them. We emphasize the need to combine experiments with theoretical insights to understand the transformations that are being performed.
Collapse
|
76
|
Abstract
The parieto-insular vestibular cortex (PIVC) is thought to contain an important representation of vestibular information. Here we describe responses of macaque PIVC neurons to three-dimensional (3D) vestibular and optic flow stimulation. We found robust vestibular responses to both translational and rotational stimuli in the retroinsular (Ri) and adjacent secondary somatosensory (S2) cortices. PIVC neurons did not respond to optic flow stimulation, and vestibular responses were similar in darkness and during visual fixation. Cells in the upper bank and tip of the lateral sulcus (Ri and S2) responded to sinusoidal vestibular stimuli with modulation at the first harmonic frequency and were directionally tuned. Cells in the lower bank of the lateral sulcus (mostly Ri) often modulated at the second harmonic frequency and showed either bimodal spatial tuning or no tuning at all. All directions of 3D motion were represented in PIVC, with direction preferences distributed approximately uniformly for translation, but showing a preference for roll rotation. Spatiotemporal profiles of responses to translation revealed that half of PIVC cells followed the linear velocity profile of the stimulus, one-quarter carried signals related to linear acceleration (in the form of two peaks of direction selectivity separated in time), and a few neurons followed the derivative of linear acceleration (jerk). In contrast, mainly velocity-coding cells were found in response to rotation. Thus, PIVC comprises a large functional region in macaque areas Ri and S2, with robust responses to 3D rotation and translation, but is unlikely to play a significant role in visual/vestibular integration for self-motion perception.
Collapse
|
77
|
Dakin CJ, Luu BL, van den Doel K, Inglis JT, Blouin JS. Frequency-Specific Modulation of Vestibular-Evoked Sway Responses in Humans. J Neurophysiol 2010; 103:1048-56. [PMID: 20032237 DOI: 10.1152/jn.00881.2009] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Galvanic vestibular stimulation (GVS) results in characteristic muscle and whole-body responses in humans maintaining standing balance. However, the relationship between these two vestibular-evoked responses remains elusive. This study seeks to determine whether mechanical filtering from conversion of lower-limb muscle activity to body sway, during standing balance, can be used to attenuate sway while maintaining biphasic lower-limb muscle responses using frequency-limited stochastic vestibular stimulation (SVS). We hypothesized that SVS deprived of frequencies <2 Hz would evoke biphasic muscle responses with minimal whole-body sway due to mechanical filtering of the higher-frequency muscle responses. Subjects were exposed to five stimulus bandwidths: two meant to induce sway responses (0–1 and 0–2 Hz) and three to dissociate vestibular-evoked muscle responses from whole-body sway (0–25, 1–25, and 2–25 Hz). Two main results emerged: 1) SVS-related sway was attenuated when frequencies <2 Hz were excluded, whereas multiphasic muscle and force responses were retained; and 2) the gain of the estimated transfer functions exhibited successive low-pass filtering of vestibular stimuli during conversion to muscle activity, anteroposterior (AP) moment, and sway. This successive low-pass filtering limited the transfer of signal power to frequencies <20 Hz in muscle activity, <5 Hz in AP moment, and <2 Hz in AP trunk sway. Consequently, the present results show that SVS delivered at frequencies >2 Hz to standing humans do not cause a destabilizing whole-body sway response but are associated with the typical biphasic lower-limb muscle responses.
Collapse
Affiliation(s)
| | | | | | - John Timothy Inglis
- School of Human Kinetics,
- Brain Research Center, and
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | | |
Collapse
|
78
|
Liu S, Yakusheva T, DeAngelis GC, Angelaki DE. Direction discrimination thresholds of vestibular and cerebellar nuclei neurons. J Neurosci 2010; 30:439-48. [PMID: 20071508 PMCID: PMC2810396 DOI: 10.1523/jneurosci.3192-09.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 09/22/2009] [Accepted: 11/10/2009] [Indexed: 12/27/2022] Open
Abstract
To understand the roles of the vestibular system in perceptual detection and discrimination of self-motion, it is critical to account for response variability in computing the sensitivity of vestibular neurons. Here we study responses of neurons with no eye movement sensitivity in the vestibular (VN) and rostral fastigial nuclei (FN) using high-frequency (2 Hz) oscillatory translational motion stimuli. The axis of translation (i.e., heading) varied slowly (1 degrees /s) in the horizontal plane as the animal was translated back and forth. Signal detection theory was used to compute the threshold sensitivity of VN/FN neurons for discriminating small variations in heading around all possible directions of translation. Across the population, minimum heading discrimination thresholds averaged 16.6 degrees +/- 1 degrees SE for FN neurons and 15.3 degrees +/- 2.2 degrees SE for VN neurons, severalfold larger than perceptual thresholds for heading discrimination. In line with previous studies and theoretical predictions, maximum discriminability was observed for directions where firing rate changed steeply as a function of heading, which occurs at headings approximately perpendicular to the maximum response direction. Forward/backward heading thresholds tended to be lower than lateral motion thresholds, and the ratio of lateral over forward heading thresholds averaged 2.2 +/- 6.1 (geometric mean +/- SD) for FN neurons and 1.1 +/- 4.4 for VN neurons. Our findings suggest that substantial pooling and/or selective decoding of vestibular signals from the vestibular and deep cerebellar nuclei may be important components of further processing. Such a characterization of neural sensitivity is critical for understanding how early stages of vestibular processing limit behavioral performance.
Collapse
Affiliation(s)
- Sheng Liu
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, and
| | - Tatyana Yakusheva
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, and
| | - Gregory C. DeAngelis
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, New York 14603
| | - Dora E. Angelaki
- Department of Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, and
| |
Collapse
|
79
|
Green AM, Angelaki DE. Internal models and neural computation in the vestibular system. Exp Brain Res 2010; 200:197-222. [PMID: 19937232 PMCID: PMC2853943 DOI: 10.1007/s00221-009-2054-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 10/08/2009] [Indexed: 10/20/2022]
Abstract
The vestibular system is vital for motor control and spatial self-motion perception. Afferents from the otolith organs and the semicircular canals converge with optokinetic, somatosensory and motor-related signals in the vestibular nuclei, which are reciprocally interconnected with the vestibulocerebellar cortex and deep cerebellar nuclei. Here, we review the properties of the many cell types in the vestibular nuclei, as well as some fundamental computations implemented within this brainstem-cerebellar circuitry. These include the sensorimotor transformations for reflex generation, the neural computations for inertial motion estimation, the distinction between active and passive head movements, as well as the integration of vestibular and proprioceptive information for body motion estimation. A common theme in the solution to such computational problems is the concept of internal models and their neural implementation. Recent studies have shed new insights into important organizational principles that closely resemble those proposed for other sensorimotor systems, where their neural basis has often been more difficult to identify. As such, the vestibular system provides an excellent model to explore common neural processing strategies relevant both for reflexive and for goal-directed, voluntary movement as well as perception.
Collapse
Affiliation(s)
- Andrea M Green
- Dépt. de Physiologie, Université de Montréal, 2960 Chemin de la Tour, Rm. 4141, Montreal, QC H3T 1J4, Canada.
| | | |
Collapse
|