Cerebellum and Sequences: BBS Call for Commentators

[Stevan Harnad]

    Below is the abstract of a forthcoming target article on:

        THE DETECTION AND GENERATION OF SEQUENCES AS A KEY TO
        CEREBELLAR FUNCTION.  EXPERIMENTS AND THEORY
        by V. Braitenberg, D. Heck and F. Sultan

This article has been accepted for publication in Behavioral and Brain
Sciences (BBS), an international, interdisciplinary journal providing
Open Peer Commentary on important and controversial current research in
the biobehavioral and cognitive sciences.

Commentators must be current BBS Associates or nominated by a current
BBS Associate. To be considered as a commentator for this article, to
suggest other appropriate commentators, or for information about how to
become a BBS Associate, please send email to:

bbs at ecs.soton.ac.uk or write to:

    Behavioral and Brain Sciences
    Department of Psychology
    University of Southampton
    Highfield, Southampton
    SO17 1BJ UNITED KINGDOM
    http://cogsci.ecs.soton.ac.uk/~harnad/bbs.html
    gopher://gopher.princeton.edu:70/11/.libraries/.pujournals
    ftp://ftp.princeton.edu/pub/harnad/BBS
    
To help us put together a balanced list of commentators, please give
some indication of the aspects of the topic on which you would bring
your areas of expertise to bear if you were selected as a commentator.
An electronic draft of the full text is available for inspection by
anonymous ftp (or gopher or world-wide-web) according to the
instructions that follow after the abstract.
____________________________________________________________________

        THE DETECTION AND GENERATION OF SEQUENCES AS A KEY TO
        CEREBELLAR FUNCTION.  EXPERIMENTS AND THEORY

                    Valentino Braitenberg, Detlef Heck and
                    Fahad Sultan
                    Max-Planck-Institute for biological cybernetics
                    Spemannstr. 38
                    72076 Tuebingen
                    Germany

    KEYWORDS: Cerebellum; motor control; allometric relation;
    parallel fibers; synchronicity; spatio-temporal activity;
    sequence addressable memory; cerebro-cerebellar interaction.

    ABSTRACT:Starting from macroscopic and microscopic facts of
    cerebellar histology, we propose a new functional interpretation
    which may elucidate the role of the cerebellum in movement control.
    Briefly, the idea is that the cerebellum is a large collection of
    individual lines (Eccles' "beams") which respond specifically to
    certain sequences of events in the input and in turn produce
    sequences of signals in the output. We believe that the sequence in
    - sequence out mode operation is as typical for the cerebellar
    cortex as the transformation of sets into sets of active neurons is
    typical for the cerebral cortex, and that both the histological
    differences between the two and their reciprocal functional
    interactions become understandable in the light of this dichotomy.
    The response of Purkinje cells to sequences of stimuli in the mossy
    fiber system was shown experimentally by Heck on surviving slices
    of rat and guinea pig cerebellum. Sequential activation of a row of
    eleven stimulating electrodes in the granular layer, imitating a
    "movement" of the stimuli along the folium, produces a powerful
    volley in the parallel fibers which strongly excites Purkinje
    cells, as evidenced by intracellular recording.  The volley, or
    "tidal wave" has maximal amplitude when the stimulus moves towards
    the recording site at the speed of conduction in parallel fibers,
    and much smaller amplitudes for lower or higher "velocities". The
    succession of stimuli has no effect when they "move" in the
    opposite direction.  Synchronous activation of the stimulus
    electrodes also had hardly any effect.  We believe that the
    sequences of mossy fiber activation which normally produce this
    effect in the intact cerebellum are a combination of motor
    planning, relayed to the cerebellum by the cerebral cortex, and
    information about ongoing movement, reaching the cerebellum from
    the spinal cord. The output elicited by the specific sequence to
    which a "beam" is tuned may well be a succession of well timed
    inhibitory volleys "sculpting" the motor sequences so as to adapt
    them to the complicated requirements of the physics of a
    multi-jointed system.

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To help you decide whether you would be an appropriate commentator for
this article, an electronic draft is retrievable by anonymous ftp from
ftp.princeton.edu according to the instructions below (the filename is
bbs.braitenberg). Please do not prepare a commentary on this draft.
Just let us know, after having inspected it, what relevant expertise
you feel you would bring to bear on what aspect of the article.
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    ftp://ftp.princeton.edu/pub/harnad/BBS/bbs.braitenberg
    ftp://cogsci.ecs.soton.ac.uk/pub/harnad/BBS/bbs.braitenberg

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