In the companion article, a variety of head movements were elicited by stimulation in, and adjacent to, the gigantocellular reticular nucleus (Cowie and Robinson 1994). We refer to this area, caudal to the abducens nucleus, as the gigantocellular head movement region. In the present paper, the anatomical connections of this region, as determined by injections of wheat-germ agglutinin conjugated horseradish peroxidase (WGA-HRP), are reported. The majority of efferent and afferent connections were with areas related to head movements. 2. Efferent fibers from the region projected via two paths to the caudal medulla and upper cervical spinal cord. Labeled fibers descended in the anterolateral funiculus of the ipsilateral spinal cord to terminate in lateral parts of the ventral horn. A second pathway descended bilaterally in the medial longitudinal fasciculus to the anterior funiculi and medial portions of the ventral gray. These efferents paralleled the head-movement topography demonstrated physiologically. Other projections included efferents to the interstitial nucleus of Cajal, caudal field H of Forel, paramedian pontine reticular formation, and caudal vestibular nuclei. Other efferent fibers projected to the trigeminal, facial, and hypoglossal nuclei, as well as to the parvocellular reticular field, which contains interneurons for these motor groups. However, no efferent or afferent labeling involved the ocular motor nuclei. 3. Afferents to the gigantocellular head movement region arose mainly from head-movement areas. In all animals, labeled cells were found in the intermediate and deep layers of the caudal superior colliculus. Labeled neurons also were found in the caudal field H of Forel, interstitial nucleus of Cajal, pontine medial tegmentum including the pontine paramedian reticular formation, nucleus subcoeruleus, and vestibular nuclear complex. Caudally, filled cells were located in the parvocellular, magnocellular, dorsal, and ventral reticular nuclei, the supraspinal nucleus, and the upper cervical ventral horn. 4. In one animal, the ipsilateral frontal cortex contained retrogradely labeled neurons. These cells were found in layer V of cortical areas 4 and 6. Other afferent cells were found consistently in the periventricular and periaqueductal gray matter. 5. A control injection into the caudal vestibular nuclear complex showed projections to the gigantocellular reticular formation and labeled cells in the vestibular and parvocellular reticular nuclei. These observations show that the connections of the gigantocellular region are not typical of all head movement sites. 6. These data indicate that the gigantocellular head-movement region has the requisite efferent and afferent connections to function in the subcortical control of head, but not eye, movements.(ABSTRACT TRUNCATED AT 400 WORDS)
摘要
在配套文章中，通过刺激巨细胞网状核及其附近区域引发了多种头部运动（考伊和罗宾逊，1994年）。我们将展神经核尾侧的这一区域称为巨细胞性头部运动区。在本文中，报告了通过注射小麦胚芽凝集素结合辣根过氧化物酶（WGA-HRP）确定的该区域的解剖学连接。大多数传出和传入连接都与头部运动相关区域有关。2. 该区域的传出纤维通过两条路径投射到延髓尾侧和颈髓上部。标记纤维在同侧脊髓前外侧索下行，终止于腹角外侧部分。第二条路径在双侧内侧纵束下行至前索和腹侧灰质内侧部分。这些传出纤维与生理学上显示的头部运动地形图平行。其他投射包括到 Cajal 间质核、Forel 尾侧 H 区、脑桥旁正中网状结构和尾侧前庭核的传出纤维。其他传出纤维投射到三叉神经核、面神经核和舌下神经核，以及小细胞网状区，该区域包含这些运动组的中间神经元。然而，没有传出或传入标记涉及动眼神经核。3. 巨细胞性头部运动区的传入纤维主要来自头部运动区域。在所有动物中，在尾侧上丘的中间层和深层发现了标记细胞。在 Forel 尾侧 H 区、Cajal 间质核、包括脑桥旁正中网状结构的脑桥内侧被盖、蓝斑下核和前庭核复合体中也发现了标记神经元。在尾侧，填充细胞位于小细胞、大细胞、背侧和腹侧网状核、脊髓上核和颈髓上部腹角。4. 在一只动物中，同侧额叶皮质含有逆行标记的神经元。这些细胞位于皮质4区和6区的V层。在脑室周围和导水管周围灰质中也始终发现其他传入细胞。5. 向尾侧前庭核复合体的对照注射显示了到巨细胞网状结构的投射以及前庭核和小细胞网状核中的标记细胞。这些观察结果表明，巨细胞区域的连接并非所有头部运动部位的典型连接。6. 这些数据表明，巨细胞性头部运动区具有必要的传出和传入连接，以在皮质下控制头部而非眼部运动中发挥作用。（摘要截短至400字）
