Lecture Notes: Vestibular System and Slow Head Movements
I. Acceleration Threshold and Vestibular Input
- The vestibular system only responds to accelerations above a certain threshold.
- Slow head movements don’t stimulate the cupula or otoconial mass enough to trigger a signal.
II. Integrating Vestibular and Visual Information
- Slow head movements are detected by combining vestibular information with visual input about optic flow.
- Optic flow is the unconscious processing of visual information about how the world is moving relative to the observer.
- This information comes from the midbrain and is integrated with vestibular signals in the vestibular nucleus.
III. The Limitation of Vestibular and Optic Flow Integration
- Vestibular nucleus neurons cannot distinguish between vestibular and optic flow signals.
- This can lead to illusions of motion, such as being unable to tell if you or another train is moving when both are moving slowly.
