Fig 6.

Mechanosensory model of IA proprioceptor adapted from Bewick & Banks (2014). Neural mechanisms in mechano-transduction and sensory encoding for IA afferent fitted to muscle spindle structure including intrafusal muscle fiber (pink) wrapped by annulospiral ending (green) that extends unmyelinated followed by myelinated axon. Mechano-transduction involves mechano-sensitive sodium channels (MSSC) and metabotropic glutamate receptors (M-GLUR) that act through a phospholipase D (PLD) mechanism to modulate glutamate release from synaptic like vesicles (SLV). Sensory-encoding mechanisms include BK and SK potassium channels activated by Ca²⁺; P/Q- and T-type Ca²⁺ channels; and voltage-gated Na⁺ channels (NaV) including Na⁺ persistent inward current (PIC), which we add to the model based on preliminary findings presented in this report.