title: Spatial anisotropy in the encoding of three-dimensional passive limb position by the spinocerebellum.
abstract: In an earlier study, we found that the encoding of limb position in the sagittal plane across the population of spinocerebellar Purkinje cells was anisotropic with a preferential gradient along horizontal direction. The aim of this study was to extend to a three-dimensional (3D) workspace the analysis of the relationships between Purkinje cells activity and rat's forelimb spatial position. In anesthetized animals, the extracellular activity of 121 neurons was recorded while a robot passively placed the limb in 18 positions within a cubic workspace (3x3x3 cm). In order to characterize the relationship between spatial locations and Purkinje cell activity we performed a backward stepwise regression starting from a model with three independent variables representing the antero-posterior, the medial-lateral and the vertical axes of workspace. Regression analysis showed that the firing of most cells was modulated exclusively along the antero-posterior (25%) or the medial-lateral (38%) axis, while a small portion was related only to the vertical axis (8%), indicating a generalized nonuniform sensitivity of Purkinje cells to limb displacement in 3D space.
authors.affiliation: Department of Physiological Sciences, University of Catania, viale A. Doria 6, 95125 Catania, Italy.
authors.forename: M S
authors.initials: MS
authors.lastname: Valle
authors.forename: A
authors.initials: A
authors.lastname: Casabona
authors.forename: G
authors.initials: G
authors.lastname: Bosco
authors.forename: V
authors.initials: V
authors.lastname: Perciavalle
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D016880:Anisotropy; D002525:Cerebellar Cortex / Q000033:anatomy & histology / Q000502:physiology*; D005121:Extremities / Q000294:innervation / Q000502:physiology*; D007699:Kinesthesis / Q000502:physiology*; D008297:Male; D009949:Orientation / Q000502:physiology; D011187:Posture / Q000502:physiology; D011434:Proprioception / Q000502:physiology*; D011689:Purkinje Cells / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013028:Space Perception / Q000502:physiology