bims-climfi Biomed News
on Cerebellar cortical circuitry
Issue of 2020‒09‒20
three papers selected by
Jun Maruta
Mount Sinai Health System

  1. Neuroscience. 2020 Sep 15. pii: S0306-4522(20)30580-7. [Epub ahead of print]
      Biological motions commonly contain multiple frequency components in which each fundamental has to be adjusted by motor learning to acquire a new motor skill or maintain acquired skills. At times during this motor performance one frequency component needs to be enhanced (gain-up) while another is suppressed (gain-down). This pattern of simultaneous gain-up and -down adjustments at different frequencies is called frequency competitive motor learning. Currently we investigated cerebellar roles in this behavior utilizing the goldfish vestibulo-ocular reflex (VOR). Previously, VOR motor learning was shown in primates to be frequency selective and exhibit frequency competitive motor learning. Here we demonstrate that the goldfish VOR performs frequency competitive motor learning when high and low frequency components are trained to gain-up and gain-down, respectively. However, when the two frequency components were trained in the opposite directions only gain-up component was observed. We also found that cerebellectomy precluded any frequency competitive VOR motor learning. Complementary single unit recordings from vestibulo-cerebellar Purkinje cells revealed changes in firing modulation along with gain-down learning, but not with gain-up learning irrespective of frequency. These results demonstrate that the cerebellum is required for all frequency competitive VOR motor learning and Purkinje cell activity therein is well correlated with all gain-down behaviors independent of frequency. However, frequency competitive gain-up learning requires intact, recursive brainstem/cerebellar pathways. Collectively these findings support the idea that VOR gain-up and gain-down learning utilize separate brainstem/cerebellar circuitry that, in turn, clearly underlies the unique ability of the oculomotor system to deal with multiple frequency components.
    Keywords:  Cerebellum; Eye movement; OKR; Oculomotor; Purkinje cell; VOR
  2. Cerebellum. 2020 Sep 19.
      The paper is an English translation of Heinrich Obersteiner's lecture on the significance of the granular layer of the cerebellum, rendered from the original German text that was published under the title Über die Bedeutung der Körnerschichte des Kleinhirns in the Jahrbücher für Psychiatrie und Neurologie (the official organ of the Society for Psychiatry and Neurology in Vienna), volume 30, pages 192-200, 1909, communicated on 21 September 1909 before the Session on Neurology and Psychiatry at the 81st meeting of the Society of German Natural Scientists and Physicians held in Salzburg, Austria.
    Keywords:  Cerebellar histophysiology; Granule cell; Heinrich Obersteiner (1847–1922); History of neuroscience; Purkinje cell
  3. Cerebellum. 2020 Sep 19.
      This commentary highlights a "cerebellar classic" by Heinrich Obersteiner (1847-1922), the founder of Vienna's Neurological Institute. Obersteiner had a long-standing interest in the cerebellar cortex, its development, and pathology, having provided one of the early accurate descriptions of the external germinal layer (sometimes called the "marginal zone of Obersteiner" or "Obersteiner layer"). In his communication before the 81st meeting of the Society of German Natural Scientists and Physicians in Salzburg in September 1909, Obersteiner placed special emphasis on the histophysiology of the granule cell layer of the cerebellum and covered most of the fundamental elements of the cerebellar circuitry, on the basis of Ramón y Cajal's neuronism. Those elements are discussed in a historic and a modern perspective, including some recent ideas about the role of granule cells, beyond the mere relay of sensorimotor information from mossy fibers to the Purkinje cells, in learning and cognition.
    Keywords:  Cerebellar histophysiology; External germinal layer; Granule cell; History of neuroscience; Purkinje cell