The internal-model hypothesis for mental activities
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The internal-model hypothesis for mental activities

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The internal-model hypothesis for mental activities The internal-model hypothesis for mental activities Presentation Transcript

  • 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 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
  • 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
  • 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
  • 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
  • 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
  • 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/
  • 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/
  • 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
  • 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
  • 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