Wilson V J, Zarzecki P, Schor R H, Isu N, Rose P K, Sato H, Thomson D B, Umezaki T
The Rockefeller University, New York, NY 10021, USA.
Exp Brain Res. 1999 Mar;125(1):1-13. doi: 10.1007/s002210050651.
Our goal was to study potential substrates for cortical modulation of vestibular reflexes in the cat. In initial experiments, injections of wheat-germ-agglutinate-horseradish-peroxidase into Deiters' nucleus and the rostral descending nucleus revealed bilateral colonies of retrogradely filled neurons in cortical areas 6, 2, and 3a (about 60 cells per colony). In cats anesthetized with chloralose-urethane, we stimulated areas 2 and 3a with trains of pulses while recording from ipsilateral vestibular-nucleus neurons, which were characterized by their responses to sinusoidal tilts and tested for the presence of antidromic responses to stimulation of the upper cervical cord. A majority of the neurons was affected by cortical stimulation, showing either facilitation, inhibition, or a mixture of the two. Stimulation in area 2 was more effective than stimulation in area 3a. Despite the anatomic presence of direct cortico-vestibular projections, properties of facilitation and inhibition suggest that both were evoked by polysynaptic pathways. Cortical effects were broadly distributed to vestibular neurons without regard to responses of these neurons to sinusoidal tilts. There was no significant difference between effects on lateral and medial vestibulospinal tract neurons, but, as a group, vestibulospinal neurons were much more likely to be affected by cortical stimulation than neurons not antidromically activated from the C2 segment. We conclude that, by their influence on vestibulospinal neurons, neurons in cortical areas 2 and 3a should be able to modulate, in behaving animals, vestibular reflexes acting on the neck and limbs.
我们的目标是研究猫前庭反射的皮质调制的潜在底物。在最初的实验中，将小麦胚芽凝集素-辣根过氧化物酶注射到Deiters核和延髓降核中，结果显示在皮质6区、2区和3a区出现双侧逆行填充神经元群（每个神经元群约60个细胞）。在用氯醛糖-乌拉坦麻醉的猫中，我们在记录同侧前庭核神经元时，用脉冲串刺激2区和3a区，这些神经元通过对正弦倾斜的反应来表征，并测试对上颈髓刺激的逆向反应的存在。大多数神经元受到皮质刺激的影响，表现为易化、抑制或两者混合。2区的刺激比3a区的刺激更有效。尽管存在直接的皮质-前庭投射，但易化和抑制特性表明两者都是由多突触通路诱发的。皮质效应广泛分布于前庭神经元，而不考虑这些神经元对正弦倾斜的反应。对外侧和内侧前庭脊髓束神经元的影响没有显著差异，但作为一个群体，前庭脊髓神经元比未从C2节段逆向激活的神经元更容易受到皮质刺激的影响。我们得出结论，通过对前庭脊髓神经元的影响，皮质2区和3a区的神经元应该能够在行为动物中调节作用于颈部和四肢的前庭反射。
