Article

Purkinje cells in posterior cerebellar vermis encode motion in an inertial reference frame.

Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Neuron (Impact Factor: 15.98). 07/2007; 54(6):973-85. DOI: 10.1016/j.neuron.2007.06.003
Source: PubMed

ABSTRACT The ability to orient and navigate through the terrestrial environment represents a computational challenge common to all vertebrates. It arises because motion sensors in the inner ear, the otolith organs, and the semicircular canals transduce self-motion in an egocentric reference frame. As a result, vestibular afferent information reaching the brain is inappropriate for coding our own motion and orientation relative to the outside world. Here we show that cerebellar cortical neuron activity in vermal lobules 9 and 10 reflects the critical computations of transforming head-centered vestibular afferent information into earth-referenced self-motion and spatial orientation signals. Unlike vestibular and deep cerebellar nuclei neurons, where a mixture of responses was observed, Purkinje cells represent a homogeneous population that encodes inertial motion. They carry the earth-horizontal component of a spatially transformed and temporally integrated rotation signal from the semicircular canals, which is critical for computing head attitude, thus isolating inertial linear accelerations during navigation.

1 Follower
 · 
116 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Current concepts postulate a decisive role of the cerebellar nodulus in the processing of otolith input. We hypothesized that nodular lesions abolish otolith-perceptual integration, predicting alignment of perceived direction of earth-vertical with the z-axis of the head and not with gravity. In an 80-year-old patient with acute heminodular infarction, the subjective visual vertical (SVV) deviated contralesional by -21.1° when upright. After subtracting this offset, perceived vertical closely matched the patient's head orientation when roll-tilted. Otolith-ocular reflexes remained normal. This is the first report on abolished earth-verticality perception in heminodular stroke and underlines the importance of the nodulus in spatial orientation. This article is protected by copyright. All rights reserved.
    Annals of Neurology 12/2014; 77(2). DOI:10.1002/ana.24329 · 11.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The cerebellar cortex is among the brain's most well studied circuits and includes distinct classes of excitatory and inhibitory interneurons. Several studies have attempted to characterize the in-vivo properties of cerebellar interneurons, yet little is currently known about their stimulus-driven properties. Here we quantify both spontaneous and stimulus-driven responses of interneurons in lobules X (nodulus) and IXc,d (ventral uvula) of the macaque caudal vermis during vestibular stimulation. Interneurons were identified as cells located >100 microns away from the Purkinje cell layer that did not exhibit complex spikes. Based on baseline firing, three types of interneurons could be distinguished. First, there was a group of very regular firing interneurons with high mean discharge rates, which consistently encoded tilt, rather than translational head movements. Second, there was a group of low firing interneurons with a range of discharge regularity. This group had more diverse vestibular properties, where most were translation-selective and a few tilt- or gravitoinertial acceleration-selective. Third, we also encountered interneurons that were similar to Purkinje cells in terms of discharge regularity and mean firing rate. This group also encoded mixtures of tilt and translation signals. A small number of mossy fibers showed unprocessed, otolith-afferent-like properties, encoding the gravitoinertial acceleration. We conclude that tilt- and translation-selective signals, which reflect neural computations transforming vestibular afferent information, are not only encountered in Purkinje cell responses. Instead, upstream interneurons within the cerebellar cortex are also characterized by similar properties, thus implying a widespread network computation.This article is protected by copyright. All rights reserved
    The Journal of Physiology 10/2014; 593(1). DOI:10.1113/jphysiol.2014.278523 · 4.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    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.
    Frontiers in Systems Neuroscience 11/2014; 8:205. DOI:10.3389/fnsys.2014.00205

Full-text (2 Sources)

Download
55 Downloads
Available from
May 20, 2014