摘要:

AbstractThalamic projections from trigeminal and certain other nuclei of the brainstem of the rat have been investigated using the technique of retrograde transport of horseradish peroxidase (HRP).The pattern of trigeminothalamic projections is very specifically related to the individual subnuclei of the complex. The Main Sensory Nucleus (MSN) provides profuse crossed connections to the ventrobasal thalamus (VB); these arise exclusively from medium and small‐sized neurons, but never from the large cells. In addition to these crossed connections, a small ipsilateral dorsal trigeminothalamic tract arises from the dorsal third of the most rostral part of the MSN; this is the only ipsilateral connection to VB found in the trigeminal complex.Subnucleus Oralis has no projections to the thalamus; it is suggested that it may be concerned primarily with reflex activation of the facial nucleus, with which it is co‐extensive in the rostro‐caudal axis.Subnucleus Interpolaris has a well‐defined crossed projection of moderate size which arises from the large, medium and some of the small neurons.Subnucleus Caudalis has a sparse output to the thalamus and differs in its projections from rostral to caudal. At the most rostral level, all layers (marginal, transitional gelatinosa and magnocellularis) contain neurons which project to the thalamus; particularly conspicuous in this respect are the marginal neurons, most of which are strongly labelled. The presence of gelatinosa neurons projecting to the thalamus emphasizes a point made in earlier reports, that these neurons do not form an homogeneous population. At caudal levels, the marginal neurons are the major source of thalamic projections, while connections to the thalamus form deeper lying neurons are infrequent.With a single exception, the medullary reticular nuclei contained no neurons with thalamic connections; a small number of reticulo‐thalamic neurons were found in the ventral pontine area.Marked labelling of the medial cuneate nucleus and moderate labelling of the gracilis and lateral cuneate nuclei occurred contralaterally to the injection site. A small number of medial cuneate and gracile neurons project to the ipsilateral thalamus. Projections from the solitary nucleus were always ipsilateral.The boundaries of individual subnuclei of the lateral sensory trigeminal complex in the rat have been redefined on the basis of cytological criteria; these are in good accord with the corresponding thalamic projection

ISSN:0092-7317    

DOI:10.1002/cne.901830112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractRetrograde transport of horseradish peroxidase (HRP) was used to determine the origins of afferent connexions to the visual cortex (areas 17, 18a and 18b) in the hamster. The distribution of neurons projecting to the visual cortex from other cortical areas, from the thalamus and from the brainstem was studied using a computer technique for three‐dimensional reconstruction.There is a topographically organized projection from the dorsal lateral geniculate nucleus to area 17, but probably to no other of the areas studied. The lateral posterior nucleus of the thalamus (LP) projects to area 18a and weakly to area 17. The lateral nucleus (L) projects to area 18b and also, probably, weakly to area 17. The cortical projections from LP and L are also organized topographically but relatively grossly compared with the geniculo‐cortical pathway.There are reciprocal association projections between area 17 and areas 18a and 18b. Area 18a projects weakly to 18b. The main commissural connexions of the posterior neocortex are between the area 17/18a boundary zones in the two hemispheres, with little between the bodies of area 17.Labelled neurons were found bilaterally in the locus coeruleus, more ipsilaterally than contralaterally, after multiple injections into the visual cortex: single, small injections sometimes resulted in the labelling of a single cell body in the locus coerul

ISSN:0092-7317    

DOI:10.1002/cne.901830113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

摘要:

AbstractThe fiber composition of the human and cat trigeminal “motor roots” were studied utilizing the electron microscope. Twelve to twenty percent of fibers in the human trigeminal motor root are unmyelinated whereas 9–15% are unmyelinated in the cat. The only previous examination of the fiber composition of the peripheral trigeminal motor nerve utilized the light microscope and indicated that less than 5% of fibers were unmyelinated in cat. No study of the fiber composition of the motor nerve root is available. The present results are similar to those recently obtained by others for spinal ventral roots. The function of unmyelinated fibers in the trigeminal “motor root” is unknown, however indirect evidence, both laboratory and clinical, suggests a potential sensory function for them. The findings question seriously the concept that the functional separation of the nervous system into motor and sensory systems has anatomical correlates in the spinal and cranial nerve roots. The results relate directly to our conceptualization of the nervous system and also to the design of methods for the treatment of intract

ISSN:0092-7317    

DOI:10.1002/cne.901830114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901830101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1979

数据来源: WILEY