Dorsal Y group in the squirrel monkey. II. Contribution of the cerebellar flocculus to neuronal responses in normal and adapted animals

Partsalis, A. M.; Zhang, Y.; Highstein, Stephen M.

doi:10.1152/jn.1995.73.2.632

Cited by 138 publications

(68 citation statements)

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“…Thus it seems unlikely that projections from EH neurons to the abducens nucleus (Scudder and Fuchs 1992) impact VOR function in this condition. This proposal is consistent with prior studies that have shown that inactivation of the flocculus has little effect on the behavioral VOR gain (Partsalis et al 1995;Zhang et al 1995a,b). We suggest that the contribution of EH neurons becomes significant in situations where the VOR gain must be modified such as during adaptation following spectacle-induced motor learning (Lisberger 1994;Lisberger et al 1994a), and vestibular injury.…”

Section: Floccular Inputs To Eh Neuronssupporting

confidence: 92%

Brain Stem Pursuit Pathways: Dissociating Visual, Vestibular, and Proprioceptive Inputs During Combined Eye-Head Gaze Tracking

Roy

Cullen

2003

Journal of Neurophysiology

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. Brain stem pursuit pathways: dissociating visual, vestibular, and proprioceptive inputs during combined eye-head gaze tracking. J Neurophysiol 90: 271-290, 2003; 10.1152/jn.01074.2002 neurons within the medial vestibular nuclei are thought to be the primary input to the extraocular motoneurons during smooth pursuit: they receive direct projections from the cerebellar flocculus/ventral paraflocculus, and in turn, project to the abducens motor nucleus. Here, we recorded from EH neurons during head-restrained smooth pursuit and headunrestrained combined eye-head pursuit (gaze pursuit). During headrestrained smooth pursuit of sinusoidal and step-ramp target motion, each neuron's response was well described by a simple model that included resting discharge (bias), eye position, and velocity terms. Moreover, eye acceleration, as well as eye position, velocity, and acceleration error (error ϭ target movement Ϫ eye movement) signals played no role in shaping neuronal discharges. During head-unrestrained gaze pursuit, EH neuron responses reflected the summation of their head-movement sensitivity during passive whole-body rotation in the dark and gaze-movement sensitivity during smooth pursuit. Indeed, EH neuron responses were well predicted by their head-and gaze-movement sensitivity during these two paradigms across conditions (e.g., combined eye-head gaze pursuit, smooth pursuit, wholebody rotation in the dark, whole-body rotation while viewing a target moving with the head (i.e., cancellation), and passive rotation of the head-on-body). Thus our results imply that vestibular inputs, but not the activation of neck proprioceptors, influence EH neuron responses during head-on-body movements. This latter proposal was confirmed by demonstrating a complete absence of modulation in the same neurons during passive rotation of the monkey's body beneath its neck. Taken together our results show that during gaze pursuit EH neurons carry vestibular-as well as gaze-related information to extraocular motoneurons. We propose that this vestibular-related modulation is offset by inputs from other premotor inputs, and that the responses of vestibuloocular reflex interneurons (i.e., position-vestibular-pause neurons) are consistent with such a proposal. I N T R O D U C T I O NIn the head-restrained condition, primates generate smooth eye movements, termed smooth pursuit, to follow a slowly moving target. A number of parallel and interconnected pathways are involved in initiating and maintaining smooth-pursuit eye movements (for review, see Keller and Heinen 1991); however, particular importance has been assigned to the cortico-ponto-cerebellar pathway arising from the medial superior temporal sulcus (MST) of the extrastriate cortex. This pathway accesses the brain stem circuitry via inhibitory projections from the ipsilateral cerebellar flocculus and ventral paraflocculus, herein referred to as the floccular lobe (Balaban et al. 1981;Dow 1937;Gerrits and Voogd 1989;Langer et al. 1985). Under more natural conditions (i.e., when the hea...

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Section: Floccular Inputs To Eh Neuronssupporting

confidence: 92%

Brain Stem Pursuit Pathways: Dissociating Visual, Vestibular, and Proprioceptive Inputs During Combined Eye-Head Gaze Tracking

Roy

Cullen

2003

Journal of Neurophysiology

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“…Repetitive climbing fiber stimulation, which causes floccular shutdown, had no effect on changes in VOR gain that were learned over several days (Luebke and Robinson 1994), suggesting that the cerebellar cortex does not participate in the longterm storage of motor memory. Unilateral inactivation of the lateral vestibulocerebellum in monkeys also did not abolish longterm memory in the vertical VOR (Partsalis et al 1995). However, in the goldfish, McElligott and coworkers (McElligott et al 1998) were able to completely abolish changes in gain that had been learned within the previous few hours, by infusing lidocaine into the flocculus.…”

Section: Consolidation Of Vor Motor Memorymentioning

confidence: 96%

Learning in a Simple Motor System

Broussard¹,

Kassardjian²

2004

Learn. Mem.

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Motor learning is a very basic, essential form of learning that appears to share common mechanisms across different motor systems. We evaluate and compare a few conceptual models for learning in a relatively simple neural system, the vestibulo-ocular reflex (VOR) of vertebrates. We also compare the different animal models that have been used to study the VOR. In the VOR, a sensory signal from the semicircular canals is transformed into a motor signal that moves the eyes. The VOR can modify the transformation under the guidance of vision. The changes are persistent and share some characteristics with other types of associative learning. The cerebellar cortex is directly linked to the VOR reflex circuitry in a partnership that is present in all vertebrates, and which is necessary for motor learning. Early theories of Marr, Albus, and Ito, in which motor memories are stored solely in the cerebellar cortex, have not explained the bulk of the experimental data. Many studies appear to indicate a site of learning in the vestibular nuclei, and the most successful models have incorporated long-term memory storage in both the cerebellar cortex and the brainstem. Plausible cellular mechanisms for learning have been identified in both structures. We propose that short-term motor memory is initially stored in the cerebellar cortex, and that during consolidation of the motor memory the locus of storage shifts to include a brainstem site. We present experimental results that support our hypothesis.In many situations, inaccurate movements are worse than useless. If the movement is slow, errors can be corrected online by visual or other sensory feedback. However, rapid movements must be intrinsically accurate. This could be accomplished by hard-wiring an accurate movement, which has the obvious disadvantage that the movement cannot be readjusted for changes in downstream motor centers or (in the case of a reflex) for changes in sensory sensitivity. A better solution is to calibrate the movement by trial and error, that is, by motor learning. For our purposes, motor learning is defined as the process by which we acquire precise, coordinated movements, like those that are required in order to run, serve a tennis ball, and type accurately. Because accurate movements are necessary whenever predators must be avoided or prey captured, we can speculate that motor learning may have been one of the earliest types of associative learning to evolve. It has been demonstrated in the ventral nerve cord of insects (Horridge 1962) and is probably universal in freely-moving animals. Furthermore, because its substrate can be relatively simple and well understood, there is a real possibility of understanding motor learning both on the molecular level and on the level of brain circuitry.Motor learning is classified as procedural learning. Errors are monitored and used to guide adaptive changes without conscious awareness. Instead of learning a concept, the subject learns an accurate and appropriate motor response. Distinctions have also been made b...

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“…More specifically, during visual/vestibular stimuli that increase VOR gain and during head movements in the dark in animals with a learned high VOR gain, Purkinje cells increase their firing during contraversive head movements. During visual/vestibular stimuli that drive decreases in VOR gain and during head movements in the dark in animals with a learned low VOR gain, the Purkinje cells increase their firing during ipsiversive head movements (Dufosse et al 1978;Lisberger and Fuchs 1978;Miles et al 1980a,b;Watanabe 1984;Lisberger et al 1994;Partsalis et al 1995).…”

Section: Candidate Neural Mechanisms For the Extinction-like Process mentioning

confidence: 99%

Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

Cohen¹,

Meissner²,

Schafer³

et al. 2004

Learn. Mem.

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Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the possibility that a process similar to extinction may reverse learned changes in the VOR. We induced a learned alteration of the VOR response in rhesus monkeys using magnifying or miniaturizing goggles, which caused head movements to be accompanied by visual image motion. After learning, head movements in the absence of visual stimulation caused a loss of the learned eye movement response. When the learned gain was low, this reversal of learning occurred only when head movements were delivered, and not when the head was held stationary in the absence of visual input, suggesting that this reversal is mediated by an active, extinction-like process.

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Dorsal Y group in the squirrel monkey. II. Contribution of the cerebellar flocculus to neuronal responses in normal and adapted animals

Cited by 138 publications

References 0 publications

Brain Stem Pursuit Pathways: Dissociating Visual, Vestibular, and Proprioceptive Inputs During Combined Eye-Head Gaze Tracking

Brain Stem Pursuit Pathways: Dissociating Visual, Vestibular, and Proprioceptive Inputs During Combined Eye-Head Gaze Tracking

Learning in a Simple Motor System

Reversal of Motor Learning in the Vestibulo-Ocular Reflex in the Absence of Visual Input

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