摘要:

AbstractThe effects of discrete lesions in the pretectal region of the monkey upon the pupillary light reflex were studied, using infrared pupillography. Resulting degeneration was studied by silver impregnation methods.The nucleus of the optic tract (NOT) and the sublentiform nucleus (SL) project fibers to the nuclei of the posterior commissure (NPC) and to portions of the ipsilateral inferior pulvinar, pregeniculate nucleus and dorsal lateral geniculate body. NPC gives rise to the bulk of the fibers in the posterior commissure (PC) which largely terminate upon contralateral cells of NPC. Some fibers arising from NPC enter the ipsilateral central gray and terminate bilaterally primarily upon cells of the medial visceral columns of the oculomotor complex (OMC). These fibers partially decussate ventral to the aqueduct.Fibers from the olivary nucleus (ON) cross in the PC and project to terminations upon: (1) large cells of the opposite ON and (2) the anterior median nuclei and the contralateral lateral visceral cell column of OMC. NOT, and possibly ON, give rise to fibers crossing in PC that project to the contralateral accessory optic tract nucleus (AOTN).Unilateral lesions that fairly selectively destroy parts of NOT, ON, SL, NPC, central fibers of PC or the nucleus of the pretectal area (NPA), produce neither miosis, mydriasis, anisocoria, nor do they impair direct or consensual pupillary light reflexes. Unilateral lesions, which impair pupillary light reflexes, involve multiple structures, such as NPC, PC and lateral regions of the central gray.

ISSN:0092-7317    

DOI:10.1002/cne.901490302

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe intrinsic organization and the connections of the pericentral nucleus of the inferior colliculus have been studied with the Golgi and Nauta techniques. The pericentral nucleus is a thin sheet of densely packed cells extending over the dorsal and posterior surfaces of the inferior colliculus.The pericentral nucleus is composed of spiny and non‐spiny cells. There are large and small spiny neurons, all of which have numerous dendritic spines. The large cells are the most spiny and frequently have spines on their somata. The small spiny cells in most cases have spines on the initial segments of their axons as well as on their somata. The small cell type has a locally ramifying axon and should probably be regarded as an interneuron. The non‐spiny cell‐types are large, and multipolar or fusiform. The dendrites of the multipolar cells extend through the thickness of the pericentral nucleus and the parent cell probably gives rise to the efferents of the nucleus.Although the pericentral nucleus has previously been described as having a layered “cortical” structure, there is little evidence to justify this, since no clearly defined axonal or cellular layers are present. The pericentral nucleus receives a heavy descending projection of fibers from the auditory cortex, and an ascending projection from the upper brainstem (probably only from the dorsal nucleus of the lateral lemniscus). The ascending system of fibers may also contribute branches to the central nucleus of the inferior colliculus. The ascending and descending afferents run parallel to the surface of the pericentral nucleus but at right‐angles to each other, thus forming a rectangular grid. The possible functional significance of this grid‐like arrangement is discussed.No evidence was found for a projection from the central nucleus to the pericentral nucleus, but axons were seen to pass in the opposite direction, from the pericentral nucleus to the central nucleus, running parallel to the cellular laminae in the l

ISSN:0092-7317    

DOI:10.1002/cne.901490303

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

年代:1973

数据来源: WILEY

摘要:

AbstractAntennal growth in the cockroach,Periplaneta americana, takes place by division of the meriston (third antennal segment) and the meristal segments at the base of the antennal flagellum. Olfactory and contact chemoreceptive sense organs are the most numerous receptor organs on the antenna at all stages of postembryonic development. The sensory complement of male and female antennae is identical during the nymphal period, but a large difference between sexes appears at the adult stage. The adult male has nearly twice as many olfactory sensilla as the female, and more than half of these sensilla appear at the adult stage. These morphological data are consistent with the hypothesis that sensory receptors specific to the female sex attractant appear in the male only at the adult stage.

ISSN:0092-7317    

DOI:10.1002/cne.901490304

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

年代:1973

数据来源: WILEY

摘要:

AbstractSerial thin sections have been used to reconstruct neuronal processes in the outer portions of layer I of adult rat somatosensory cortex. The reconstructions show that two distinct forms of dendrites exist in this area: one that is smooth and varicose and another that bears spines along a shaft of relatively constant diameter. These two dendritic types, which originate from nonpyramidal and pyramidal neurons respectively, have differences in the distribution of organelles. Cortical dendrites terminate with no apparent morphological modification which would permit their identification in isolated thin sections. A pyramidal dendritic ending is blunt, about 0.5 μ in diameter, with microtubules and smooth endoplasmic reticulum in the terminal cytoplasm. Very long mitochondria which are invariably present within pyramidal dendrites, penetrate into an ending. A smooth dendrite terminates in an expansion containing microtubules and smooth endoplasmic reticulum, but no long mitochondrion. One or two asymmetrical synapses occur at the end of each terminating dendrite but do not encompass the tip. The principal axonal elements in layer I are small unmyelinated axons with en passant boutons. Serial examination reveals that various combinations of synaptic contacts are possible between axons and dendrites of both types

ISSN:0092-7317    

DOI:10.1002/cne.901490305

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

年代:1973

数据来源: WILEY

摘要:

AbstractFollowing lesions of different sizes and locations of the superior colliculus the distribution of degenerating fibers in the pontine nuclei was determined in the cat in Nauta and Fink and Heimer impregnated sections. The superior colliculus projects exclusively to most of the dorsolateral nucleus in the ipsilateral pontine nuclei. There appears to be some degree of topical arrangement in the projection.Three cases with lesions of the superior colliculus on one side and of the inferior colliculus, the cerebral auditory or cerebral visual areas, respectively, on the other side, permit comparisons between the projections of the superior colliculus with those from the other structures mentioned. The inferior colliculus projects onto the dorsolateral nucleus of the pons in an area which overlaps to some extent with that of the superior colliculus. Confirming more systematic studies of P. Brodal it is found that the pontine projection area of the auditory cortex to a large extent coincides with that of the superior colliculus, while the pontine projection area of the visual cortex is entirely different.These findings, together with other data from the literature, strongly suggest that the pathway for optic impulses to the vermal visual area of the cerebellum passes via the superior colliculus and the dorsolateral pontine nucleus. Direct tectocerebellar fibers or pathways via the reticular formation are scarcely involved in this process. Anatomically there is evidence for another route for visual impulses to the cerebellum: via the visual cerebral cortex and the pons to regions in the cerebellar hemisphere. This is in agreement with physiological findings and suggests that there may be at least two visual areas in the cerebellum.The anatomical data show that there are ample possibilities for an integration of optic, acoustic and other impulses in the superior colliculus as well as in its projection area in the pons.

ISSN:0092-7317    

DOI:10.1002/cne.901490306

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901490307

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

年代:1973

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901490301

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

年代:1973

数据来源: WILEY