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The internal-model hypothesis
for mental activities
Advanced Concepts and Methods in Cognitive Systems
Masao Ito
Japanese neuroscientist born in 1928
Discovered the inhibitory action of cerebellar Purkinje cells
and the LTD i...
The internal-model hypothesis
○ Theories of motor control
postulate that the brain uses
internal models of the body to
con...
The internal-model hypothesis
○ The cerebellum forms an
internal model that reproduces
the dynamics (forward model)
or the...
The prefrontal cortex as a controller
○ Collection of interconnected
neocortical areas in the frontal
lobe
○ Performs exec...
The prefrontal cortex as a controller
○ Neurons on the PFC generate
command signals that control
many neural processes
○ W...
Mental models in the temporo-parietal cortex
○ Small-scale model used to
reason, explain current events or
anticipate futu...
Mental models in the temporo-parietal cortex
○ Sensory information in the
neocortex is analysed and then
integrated to for...
Internal models in the cerebellum
○ The cerebellum is composed of
numerous modules called micro-
complexes
○ Microcircuit ...
Neural mechanisms of thought
○ Ito assumes thoughts involve
both explicit (cerebral cortex)
and implicit (cerebellum) proc...
Conclusions
○ Consistent evidence that cerebellar internal models control mental
activities
○ Difficulties on analyse sign...
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The internal-model hypothesis for mental activities

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The internal-model hypothesis for mental activities

  1. 1. The internal-model hypothesis for mental activities Advanced Concepts and Methods in Cognitive Systems
  2. 2. Masao Ito Japanese neuroscientist born in 1928 Discovered the inhibitory action of cerebellar Purkinje cells and the LTD in these cells Has developed a theory of the cerebellum as a general learning machine for acquiring both motor skills and implicit memory in thought
  3. 3. The internal-model hypothesis ○ Theories of motor control postulate that the brain uses internal models of the body to control movements accurately ○ Previous studies have shown that the cerebellar cortex can acquire internal models through motor learning http://www.nature.com/nrn/journal/v9/n4/fig_tab/nrn2332_F3.html
  4. 4. The internal-model hypothesis ○ The cerebellum forms an internal model that reproduces the dynamics (forward model) or the inverse dynamics (inverse model) of a body part ○ Adjusted by a learning process controlled by error feedback signals ○ Internal-models for mental activities are also generated in the cerebellum http://www.nature.com/nrn/journal/v9/n4/fig_tab/nrn2332_F3.html
  5. 5. The prefrontal cortex as a controller ○ Collection of interconnected neocortical areas in the frontal lobe ○ Performs executive functions that are important for the conscious control of thought and action in accordance with internal goals ○ Dorsolateral PFC: abstract reasoning & problem solving ○ Orbitofrontal and medial cortex: affective & motivational functions http://pubs.niaaa.nih.gov/publications/arh313/215-230.htm
  6. 6. The prefrontal cortex as a controller ○ Neurons on the PFC generate command signals that control many neural processes ○ Working memory holds information for a brief period of time, it does mental manipulation and functions only driven by attention http://pubs.niaaa.nih.gov/publications/arh313/215-230.htm
  7. 7. Mental models in the temporo-parietal cortex ○ Small-scale model used to reason, explain current events or anticipate future ones ○ Constructed by perception, imagination or comprehension of discourse ○ Is the controlled object in the internal-model hypothesis http://www.quarkpop.com/2010/08/tbi/
  8. 8. Mental models in the temporo-parietal cortex ○ Sensory information in the neocortex is analysed and then integrated to form a perception in the temporo-parietal association areas ○ The perceptions are integrated to form mental representations, that aggregated form mental models ○ Episodic, semantic memories or visual imagery http://www.quarkpop.com/2010/08/tbi/
  9. 9. Internal models in the cerebellum ○ The cerebellum is composed of numerous modules called micro- complexes ○ Microcircuit or unit learning machine ○ Internal model for a specific function ○ I/O modified by CF (error or teaching signals) ○ Update internal model ○ IO may be responsible of signal comparison http://www.nature.com/nrn/journal/v9/n4/fig_tab/nrn2332_F3.html
  10. 10. Neural mechanisms of thought ○ Ito assumes thoughts involve both explicit (cerebral cortex) and implicit (cerebellum) process ○ An internal model that mimics a MM is formed in the cerebellum ○ A forward model would replace the MM as the controlled object (not aware of content of thought) ○ An inverse model would replace the PFC as the controller (implicit and unconscious thought) http://www.nature.com/nrn/journal/v9/n4/fig_tab/nrn2332_F4.html
  11. 11. Conclusions ○ Consistent evidence that cerebellar internal models control mental activities ○ Difficulties on analyse signals of individual neurons ○ Computational models to validate and understand the model ○ Understand implicit and explicit thoughts mechanisms ○ Unconscious processes

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