Responses of cerebellar fastigal neurons to afferent inputs from neck muscles and macular labyrinthine receptors
Erway, L.C.; Ghelarducci, B.; Pompeiano, O.; Stanojević, M.
Archives Italiennes de Biologie 116(2): 173-204
1978
ISSN/ISBN: 0003-9829 PMID: 686944 Document Number: 125353
Whether somatic afferent inputs, including those from the neck muscles and labyrinthine input from macular receptors converge within the cerebellar fastigial nucleus was determined in precollicular decerebrate cats. Among 96 fastigial units tested for nerve stimulation, 66 units responded to stimulation of neck (splenius), forelimb and hindlimb nerves of both sides; 2 units responded to stimulation of forelimb and hindlimb nerves of both sides but not of the splenius nerves, while 19 units did not respond to any of the peripheral nerves used for stimulation. Of 83 fastigial units tested, 36 units showed positional responses during 20.degree. tilt in 1 or in both directions of the median plane, due to natural stimulation of macular labyrinthine receptors. Most responses were characterized by a rate increase during tilt in the opposite direction. Of the units affected by tilt, 66.7% were also influenced by stimulation of the neck, of the forelimb and hindlimb nerve afferents of both sides; 22.2% of the units affected by tilt were influenced only by the somatic input from the 4 limbs but not by the neck input, while only 11.1% of the units affected by tilt were neither influenced by neck muscle afferents, nor affected by limb nerve stimulation. In addition to fastigial units responding selectively either to somatosensory inputs from the periphery, including the neck musculature, or the macular input, there appears to be a rostrofastigial region in which the 2 inputs converge. During the positional reflex, this rostrofastigial region integrates not only signals originating from macular receptors, which are responsible for the labyrinthine control of neck motoneurons, but also the somatosensory input which originates from neck muscle receptors as a result of the actual displacement in head position induced by the vestibulospinal reflex.