Computational
models for the representation of time and sequence in the brain
Shigeru Tanaka and Tadashi Yamazaki
Laboratory for Visual Neurocomputing, RIKEN Brain Science Institute
Wako, Saitama, Japan
Abstract; It is thought that enormous neurons in the brain mutually
communicate using their spike activities through complicated neural
networks so that the brain works as a parallel information processor.
From this point of view, the information processing principle of the
brain is completely different from that of conventional Von Neuman-type
computers. In spite of such a difference, actions in our behavior such
as body movement, speech and thinking are basically conducted sequentially
one by one. This raises a question of how sequential actions are generated
from parallel computation of the brain. One of examples of the information
processing of temporal sequences by the brain is the generation of voluntary
movement. When we try to drink water in a glass on the table, we will
extend our hand toward the glass, grasp it, bring it to our mouth and
decline the glass to drink water. Unless we conduct all the component
actions in this order, we cannot achieve the purpose of drinking water.
As can be seen in this example, it is necessary for the brain to elicit
motor commands for component actions in an adequate order when we wish
to achieve a particular purpose. The underlying mechanism for such information
processing by the brain is a long-standing target of research, known
as gthe serial order of motor behavior problemh. In addition, for smooth
and efficient behavior, timing and magnitude of neural activity representing
each component action is required. To approach these problems from the
computational viewpoint, I propose a network model of basal ganglia-thalamo-cortical
loops and cerebro-cerebellar loops for sequence generation and precise
control of motor actions.
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