This document summarizes the proprioceptive and vestibular systems. It discusses how proprioceptive receptors provide information about muscle movement and position. The muscle spindle and Golgi tendon organ register muscle stretch and contraction. Proprioception allows for reflexes, muscle coordination, kinesthesia, and motor control. The vestibular system registers head motion using hair cells in the semicircular canals and otolith organs. It controls postural reflexes, gaze adjustment, and sense of self-motion. Both systems transmit signals to the brain for sensory integration.

1. Cogs 107b – Systems Neuroscience www.dnitz.com lec01072010 – proprioception and the vestibular system the weekly principle(s): ‘the neuron doctrine’ and ‘law of dynamic polarization’ 1

2. sensory organ receptors: across different sensory modalities, anatomical features of sensory organ receptors determine the dynamics of their electrical activity and, within a modality, the type of sensory information they convey

3. proprioception and touch sense: the ‘all-axon’ ganglion cell

4. a simple proprioceptive circuit / system – the knee-jerk reflex

5. the muscle spindle: activation by muscle elongation / stretch is modulated by contraction state of the muscle

6. the Golgi tendon organ: registering tendon stretch (= muscle contraction)

7. functions of proprioception: - joint-protecting reflexes (e.g., knee-jerk) - adjustment of muscle contraction / recruitment - kinesthesia: detection of body position and movement - coordination of motor commands - sense of self?

8. dorsal root ganglion pathways to the brain

9. somatosensory cortex: integration of proprioceptive and tactile information

10. the Pinnochio effect the Pinocchio effect

11. functions of the vestibular system: - postural reflexes - gaze adjustment - assessment of self motion - a reason not to drink too heavily?

12. the ‘hair cell’ receptor – transduction of both head motion (vestibular system) and sound waves (auditory system) into neural signals

13. the ‘hair cell’ receptor – transduction of both head motion and sound

14. the inner ear

15. orthogonal orientation of the semicircular canals and otolith organs

16. semicircular canals: hair cell registration of rotational velocity, orthogonality, and the L/R push-pull system

17. registration of linear translation and static head position via the otolith organs, the utricle and saccule registration of rotational velocity of the head (about the trunk) via the semicircular canals

18. utricle and saccule: registration of static head position (relative to ground / gravity), orthogonality, and the hair cell population code

20. vestibular afferents: pathway to the brain and spinal cord

21. integrating vestibular signals I – the vestibulo-ocular reflex – adjusting and maintaining gaze during head movements

22. integrating vestibular signals II – the ubiquitous ‘head-direction’ neuron