摘要:

AbstractThe efferent connections of the anterior olfactory nucleus in the female albino rabbit have been studied using the autoradiographic and horseradish peroxidase methods for tracing axonal pathways. Following a unilateral injection of3H‐leucine into the olfactory peduncle, radioactively labeled efferent projections from the anterior olfactory nucleus were traced into all layers of the ipsilateral main olfactory bulb beneath the olfactory nerve layer and through the ipsilateral anterior limb of the anterior commissure and plexiform layer of the medial side of the cerebral hemisphere to the deep half of the plexiform (IB) and pyramidal cell (II) layers of the prepyriform cortex, the tenia tecta, and the entire surface of the olfactory tubercle. Labeled projections crossing the midline within the anterior commissure were followed to layers IB and II of the contralateral anterior prepyriform cortex and pars externa, pars lateralis, and pars dorsalis of the anterior olfactory nucleus, and through the periventricular layer of the olfactory peduncle to all layers of the main olfactory bulb beneath the olfactory nerve layer. No well‐defined labeled projection was traced to the contralateral accessory olfactory bulb. Evidence for possible anterior olfactory nucleus and/or prepyriform cortical projections to the ipsilateral paleocortical half of the claustrum, horizontal limb of the nucleus of the diagonal band, the posterior lateral hypothalamus at the level of the mammillary complex, and to the bed nucleus of the stria terminalis is discussed. Intra‐axonal retrograde transport of horseradish peroxidase from axon terminals to parent cell bodies after unilateral injection of the protein into the main olfactory bulb or anterior olfactory nucleus revealed that anterior olfactory nucleus projections to the olfactory bulbs and the contralateral anterior olfactory nucleus arise predominately from the pars externa.The autoradiographic data indicate that the anterior olfactory nucleus projects to olfactory cortical structures which also receive afferent input from the olfactory bulb and that the termination of these projections is complementary to those from the olfactory

ISSN:0092-7317    

DOI:10.1002/cne.901640402

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

年代:1975

数据来源: WILEY

摘要:

AbstractExtracellular recordings of responses to tone‐burst stimulation were used to determine the tonotopic organization of n. magnocellularis (NM) and n. laminaris (NL) in hatchling chickens. NM cells show “primary‐like” response patterns to ipsilateral stimulation, and are arranged in dorso‐ventral isofrequency columns. Units responding to the highest frequency tones (about 4,100 Hz) are situated at the rostromedial pole of the medial division. Units with lower characteristic frequencies (CF's) are found at successively caudal and lateral sites, until extremely low CF's (<500 Hz) are represented dorsoventrally in the caudolateral tail of the lateral division. No evidence was found of auditory input to the region which receives projections from the macula lagena. NL receives polarized, binaural, excitatory input. Units have similar CF's and thresholds to tones presented to either ear. The tonotopic organization in NL matches that found in NM — high CF's rostromedially and low CF's caudal and lateral. Quantitative procedures were developed for relating CF to the position of a unit within either nucleus. These analyses account for 79% and 89% of the frequency variance found within NM and NL, respectively, and predict the CF of a neuron by its position within e

ISSN:0092-7317    

DOI:10.1002/cne.901640403

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe tonotopic and topographic organization of the bilateral projection from second‐order auditory neurons of nucleus magnocellularis (NM) to nucleus laminaris (NL) was examined in young chickens. In one group of birds, the NM axons which innervate the contralateral NL were severed by cutting the crossed dorsal cochlear tract at the midline. Heavy terminal degeineration in NL was confined to the neuropil area immediately ventral to the perikaryl lamina. Very little degeneration was seen in the dorsal neuropil region. In a second series of animals, the characteristic frequency (CF) of cells in an area of NM was first determined by microelectrode recording techniques and then a small electrolytic lesion was made through the recording electrode. Following survival periods of 24–48 hours, the distribution of projections from the lesioned area to the ipsilateral and contralateral NL was examined usinig the Fink‐Heimer method.As previously described in the pigeon, projections from NM terminate densely in the neuropil region immediately dorsal to the ipsilateral NL cell bodies and ventral to the perikaryl layer on the contralateral side, providing each NL neuron with segregated binaural innervation. Lesions in any area of NM produced degeneration confined to a limited caudo‐rostral and medio‐lateral portion of both laminar nuclei. To investigate this topographic relationship, the caudorostral extents of the lesion in NM and of the resulting degeneration in both NL were determined. Linear regression and correlation analyses then related these positional values to each other and to the CF found at the center of each lesion. All correlations were highly significant and ranged from 0.78 between the position of the lesion in NM and CF to 0.91 between the caudo‐rostral position of degeneration in the NL ipsilateral and contralateral to the lesion.It is concluded that neurons in NM project in a very discrete topographic, tonotopic and symmetrical fashion to NL on both sides of the brain, contributing to the binaural response properties and tonotopic organization of neurons in NL. The results also suggest that the organization of projections from NM to NL could provide a mechanism for the differential transmission delay required by a “place” model of low‐frequency s

ISSN:0092-7317    

DOI:10.1002/cne.901640404

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe distribution of labeled cells in the inferior olive of the cat has been mapped following injections of small amounts of horseradish peroxidase in the paramedian lobule of the cerebellum.The distribution of labeled cells was plotted in drawings of approximately serial transverse sections. The findings in each case were transferred to a standard diagram of the olive to facilitate comparison of cases.Previous studies of the distribution of retrograde cell loss in the inferior olive following cerebellar lesions (Brodal, '40b) showed that fibers ending in the paramedian lobule come from the caudal part of the ventral lamella of the principal olive. This was confirmed with the peroxidase method, but in addition three other separate and well circumscribed areas of the olive showed labeling: one in the dorsal accessory olive, another in the rostral part of the medial accessory olive, a third in the caudal part of the dorsal lamella of the principal olive (fig. 7). There is some degree of topical arrangement within the projection of each of these olivary areas to the paramedian lobule. It is particularly striking that the projection areas of the caudal one‐third of the lobule are different from and overlap only little with those of the rostral two‐thirds. On account of diffusion of the injected peroxidase solution in the folia it could not be decided whether the different olivary areas project to particular longitudinal zones in the paramedian lobule.The main findings can be correlated with the physiological observations of Armstrong et al. ('74). Some of the “paramedian” olivary areas are labeled also following peroxidase injections in other cerebellar parts, among them the nuclei interpositus anterior and posterior. The findings are compatible with the notion that olivocerebellar fibers branch to supply more than one cerebellar region.It is confirmed that the olivocerebellar projection, including that of the nuclei, is almost completely crossed. In the DISCUSSION it is emphasized that afferents from several sources converge on all four olivary regions projecting onto the paramedian lobule. The olivocerebellar projection obviously allows for divergence as well as convergence of impulses from the olive to the cerebellum.For further insight into the anatomical organization of the inferior olive, the entire olivocerebellar projection has to be mapped with the peroxidase method, and further studies of the afferents to the olive are needed. In such studies, as well as in physiological ones, it is essential that findings are described with meticulous reference to the topography of the olivary subdi

ISSN:0092-7317    

DOI:10.1002/cne.901640405

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe relative positions of pyramidal and polymorphic cell classes are inverted in the central olfactory cortical structures of the reeler mutant mouse. Each cell class is generated at the normal embryonic time. The polymorphic cells of the mutant, like those of the normal, are generated between E11–E13. The pyramidal cells are formed between E11–E16 in both. Despite the anomalous positions of their somata deep in the cortex the apical dendrites of many pyramidal cells reach and ramify at a superficial cortical level subjacent to the lateral olfactory tract. The main and accessory olfactory bulbs are cytoarchitectonically normal in the mutant and project normally upon the anterior olfactory nucleus, the olfactory tubercle, the hippocampal rudiment, the piriform cortex, the amygdaloid region and the entorhinal cortex. As in the normal animal the axons traverse layer Iα, and their terminals are concentrated in the immediately subjacent laminar zone. The rostrally directed cortico‐cortical association system of the piriform cortex projects upon the anterior olfactory nucleus in the mutant just as in the normal with a relative concentration of terminals in a lamina subjacent and complementary to the zone of termination of the lateral olfactory tract. The normal pattern of lamination of these two afferent systems in the abnormally laminated olfactory cortex of the mutant suggests that, in this system at least, the developmental mechanisms which determine relative position of neuron somata and those which govern axon trajectories and the distribution of axon terminals are largely indep

ISSN:0092-7317    

DOI:10.1002/cne.901640406

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

年代:1975

数据来源: WILEY

摘要:

AbstractAn atlas of the cerebral ganglion ofMoniliformis dubiushas been constructed and the cells identified by number. There is a total of 88 cells, two of which are binucleate. These cells (20 and 90) are located in the frontal plane. The cell population is equally distributed between each half of the ganglion, there being 41 cells on each side with six cells centrally located between the two halves. Most cells give rise to bilateral processes and are organized in such a way that there is an outer coat of somata or cell bodies. Cell bodies predominate on the ventral surface, but the dorsal surface is more of a mixture of cell bodies and nerve processes. The core or neuropile occupies the central part of the ganglion and is the site for cross over for many cell processes which then exist from the side opposite the cell body. The cytoarchitecture of these cells varies considerably. Most have a large round nucleus with well defined nucleoli.

ISSN:0092-7317    

DOI:10.1002/cne.901640407

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

年代:1975

数据来源: WILEY

摘要:

AbstractA functional map of the armadillo neocortex was produced by cortical stimulation and recording evoked potentials following somatic, auditory and visual stimuli. The results obtained were then correlated with the cortical architecture as revealed by Nissl, Golgi and myelin‐stained sections. Cortex rostral to the supraorbital sulcus has a wide layer IV and is mostly silent, except for a motor eye field and a part of the tongue sensory region in its caudal part. Two types of motor‐sensory cortex are present caudal to the supraorbital sulcus. Postsupraorbital I is mostly motor and has prominent pyramidal layers. Layer V is particuarly well developed and in rostral sections its superficial zone is broken up into clusters similar to the solid “barrels” seen in layer IV of other species. Postsupraorbital II has less prominent pyramidal layers and layers II and III are organized into clusters. This region corresponds to the sensory area for the limbs and trunk and the partially overlapping (surface recordings) sensory and motor areas for head, snout and tongue. Digits and limbs are rostral to the trunk representation in both the sensory and motor “homunculi.” Even though surface recording was employed, potentials evoked by visual stimuli could only be recorded from a small caudal area with a very thin layer IV. Although striate and peristriate areas appear similar in Nissl stained preparations, they can be readily differentiated in Weil stained sections. The stellate character of neurons in layer IV of the visual cortex is particularly apparent in Golgi material. Auditory evoked surface potentials were recorded from a broad oval region in the caudal lateral cortex which has a wide layer IV and aggregates of neurons in layers II and III. A Weil stain demonstrates inner and outer bands of Baillarger in this same region. The presumptive insular cortex is electrically silent to sensory stimulation and presents as a narrow band just dorsal to the rhinal fissure with indefinite cell lamination and li

ISSN:0092-7317    

DOI:10.1002/cne.901640408

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

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901640401

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

年代:1975

数据来源: WILEY