Input/output properties of the lateral vestibular nucleus

摘要

The lateral vestibular nucleus (LVN) is one of the four main cellular masses of the brainstem in the floor of the fourth ventricle collectively known as the vestibular nuclei complex. Gravito-inertial accelerations of the head are sensed by the otolith structures of the inner ear, transformed into a neural code and carried by vestibular nerve afferents to the LVN. The acceleration signals are used either alone, in combination with events from other sensors or derived internally into a signal to excite the extensor musculature and regulate body posture. Based on input and output properties the LVN can be portioned into a dorsal cell group, called dorsal Deiters', which contains the conspicuously giant cells of Deiters', and into a ventral area (vLV) comprised of small -to medium-sized neurons. Classic anatomical and physiological investigations (2, 23, 49, 71, 77, 91) clearly showed that the lateral vestibulospinal tract (LVST) originates from both the dorsal and ventral cell groups and that the pathway is somatotopically organized: neurons in the vLV innervate the upper and lower cervical spinal segments and those in dorsal Deiters' supply the lumbosacral cord. The LVST descends over slow to fast fibers ranging from 25 to 140 m/sec (2, 16, 49, 91, cf. 77) ipsilaterally to their target sites primarily in laminae VII, VIII and IX of the ventral horn (48, 72). Neurons participating in both the medial vestibulospinal tract (MVST), vestibulo-ocular-collic (VOC) and vestibuloocular reflex (VOR) pathways originate from the vLV as well as the medial nucleus (9, 16).