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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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
  • 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)
  • 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