摘要:

AbstractPigeons were trained to discriminate between pairs of visual stimuli that differed in intensity or pattern. After completion of traianing, bilateral, stereotaxic lesions were made in various cell groups in the mesencephalon and diencephalon that receive terminals of the optic tract. The target regions were nucleus ectomamillaris (accessory optic nucleus), nucleus lentiformis mesencephali and area pretectalis (pretectal complex) and the nucleus geniculatus lateralis, pars ventralis (ventral geniculate). In some cases, combined lesions of nucleus lentiformis mesencephali and area pretectalis were made. Lesions of nucleus ectomamillaris, nucleus lentiformis mesencephali, area pretectalis, or ventral geniculate did not produce major impairments of discrimination performance nor did combined lesions of nucleus lentiformis mesencephali and area pretectalis.A number of cases of intended destruction of the ventral geniculate also had extensive damage to the overlying nucleus rotundus. In several of these cases of combined destruction of nucleus rotundus and ventral geniculate, the previously reported discrimination deficits following nucleus rotundus lesions did not appear. In those cases in which the nucleus rotundus deficit was observed, the lesions were found to include the nucleus subpretectalis, which, like nucleus rotundus, receives tectofugal fibers via the brachium of the superior colliculus. The data of the ventral geniculate + rotundus cases and ventral geniculate + rotundus + subpretectalis cases suggest that sensory deficits following a lesion in a particular cell group may not necessarily indicate that the sensory information is processed in that cell group, but rather that the lesion had deprived other cell groups of the appropriate input necessary for their proper functioning.

ISSN:0092-7317    

DOI:10.1002/cne.901610103

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.901610102

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe locus ceruleus (LC) of the rhesus monkey (Macaca mulatta) was investigated using the histochemical fluorescence method and Nissl and ammoniacal silver stains. Caudally, a few fluorescent cells were observed in the lateral wall of the ventriculus quartus near the velum medullaris superior. Rostrally, the fluorescent cells were compactly clustered and reached their greatest density medial and, to a lesser extent, lateral to the tractus mesencephalicus n. trigemini at the level of the decussation of the nervus trochlearis. In the most rostral plane, fluorescent cells were more diffusely scattered ventral and medial to the pedunculus cerebellaris superior with a few cells situated near the nervus trochlearis. Nissl staining of tissue previously used for histochemical fluorescence showed that fluorescent cells were largely found in a region labelled LC in two rhesus monkey brain atlases and erroneously labelled nucleus tractus mesencephalicus n. trigemini in one brain atlas. Ammoniacal silver staining resulted in a dense accumulation of silver granules in the cells found to display a positive reaction for monoamines. The silver stains therefore offer an alternative to the histochemical fluorescence method for identifying the monoamine‐containing LC neuron

ISSN:0092-7317    

DOI:10.1002/cne.901610104

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

年代:1975

数据来源: WILEY

摘要:

AbstractThree species were studied, the rabbit, opossum and rat. Lesions of the main olfactory bulb caused terminal degeneration, assayed by the Fink‐Heimer method, to occur in the ipsilateral olfactory tubercle, prepyriform cortex (including its periamygdaloid part), ventrolateral entorhinal area, and in anterior and posterolateral divisions of the cortical amygdaloid nucleus. The various parts of the ipsilateral anterior olfactory nucleus and the rostroventral end of the anterior continuation of the hippocampus (hippocampal rudiment) also received this projection. Lesions of the accessory olfactory bulb, which receives its sensory input from the vomeronasal (Jacobson's) organ, caused terminal degeneration to occur in the medial amygdaloid nucleus and in a posteromedial part of the cortical amygdaloid nucleus. This projection was conveyed by an accessory olfactory tract, which is accompanied in part of its course by a small nucleus, the bed nucleus of the accessory olfactory tract. The accessory olfactory tract is initially a part of the lateral olfactory tract but becomes increasingly individuated at more posterior levels. It parts company with the lateral olfactory tract at the rostral end of the amygdaloid region, and, in addition to distributing to the medio‐cortical amygdaloid region, it enters the stria terminalis to terminate in the bed nucleus of the stria terminalis in a small region bearing cytoarchitectonic resemblance to the medial amygdaloid nucleus. The topographic segregation of the areas of termination of the olfactory and accessory olfactory (vomeronasal) projections is suggestive of a functional dichotomy in the organization of the olfactory system.A new interpretation of the fundamental subdivisions of the classically described cortico‐medial group of amygdaloid nuclei is evident from these results and was supported by concurrent cytoarchitectonic analysis. It was observed that the medial amygdaloid nucleus (vomeronasal) and the anterior cortical nucleus (olfactory) together form an almost uniform field of small cells. The posteromedial cortical nucleus (vomeronasal) and the posterolateral cortical nucleus (olfactory) form a larger‐celled region. Thus, a quadrantic subdivision of the cortico‐medial area allows two meaningful modes of subdivision, a mediolateral division along a vomeronasal‐olfactory boundary and an antero‐posterior division according to cellular composition. In the context of this analysis, the frequently described posterior extension of the medial amygdaloid nucleus is denied.The origins of the components of the stria terminalis are reviewed in relation to the hypothesis that the segregation of vomeronasal and olfactory pathways is maintained in further projections into the diencephalon. The quadrantic composition of the cortico‐medial area of the amygdala has not been considered in the experimental studies on the origins of the stria terminalis, but resolution of the diencephalic projections of the vomeronasal‐olfactory complex depends upon analytic inspection of the projections from t

ISSN:0092-7317    

DOI:10.1002/cne.901610105

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe entorhinal area projects to the Ammon's horn and the fascia dentata by way of the medial and lateral perforant paths that originate in the medial and lateral part of that area, respectively. The two tracts terminate at different laminar levels in the molecular layers of the ipsilateral hippocampal regio inferior and fascia dentata.Using the Fink‐Heimer technique, each of the perforant paths in the normal rabbit is now shown to innervate the antero‐dorsal extremes of the Ammon's horn and fascia dentata in both hemispheres. The crossed and uncrossed components of each path innervate homotopic zones on each side. This bilateral innervation contrasts with the situation in the rat where only very weak crossed components exist. Degeneration particles in the fascia dentata contralateral to a lesion of the perforant paths diminish in number along the course of the fibers as they proceed away from the midline, but are traceable for several millimeters. Crossed fibers are shown to pass from one hemisphere into the other directly through the fused molecular layers of the fasciae dentatae.The bilateral innervation in the rabbit indicates that even though the axons of the perforant paths are highly specific with respect to the class of neuron and the dendritic segments upon which they form synapses, they apparently do not possess a mechanism by which they can distinguish between the receptive fields in the two hemispheres. It is concluded that during ontogeny the perforant path fibers from both sides most likely compete for available synaptic sites in the rostral part of their terminal fields and that their relative amounts in the two hemispheres is governed by spatial and temporal fact

ISSN:0092-7317    

DOI:10.1002/cne.901610106

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

年代:1975

数据来源: WILEY

摘要:

AbstractIn the rat the perforant pathways from the entorhinal area normally innervate the fascia dentata only ipsilaterally. However, unilateral ablation of the entorhinal area (deentorhination) induces the formation of an anomalous crossed projection from the intact contralateral entorhinal area to the septal portion of the deafferented fascia dentata. After deentorhination of rats aged from 1–30 days the organization of this projection was analyzed (a) by producing secondary lesions in the intact entorhinal area or perforant paths and observing the resulting anterograde degeneration with Fink‐Heimer silver impregnation techniques, and (b) by staining with Timm's sulfide silver method which makes the terminal fields of afferent systems stand out in different tones or colors. Both methods showed the crossed entorhino‐dentate projection to consist of two separable components. They were named the crossed medial perforant path and the crossed lateral perforant path, corresponding to their similarity in origin, dendritic localization of termination and Timm stainability to the ordinary, uncrossed medial and lateral perforant pathways (MPP and LPP) which arise in the medial and the lateral parts of the entorhinal cortex, respectively. Similarly induced crossed projections were demonstrated to the subcallosal continuation of fascia dentata, the fasciola cinerea.The heaviest terminal field of the crossed entorhino‐dentate projection which was found in the most rostral and medial parts of the deafferented fascia dentata correlated with a lack of expected aberrant extension into the MPP and LPP terminal zones of commissural and ipsilateral hippocampodentate fibers.In Fink‐Heimer preparations there was little variation in the distribution of the aberrant crossed systems over the range of ages studied although the chronic operations performed earliest postnatally (5 days) tended to produce the heaviest representation. This latter observation appeared consistent with changes in the Timm staining pattern of the deafferented fascia dentata, since with an increase in age at the primary lesion from 5 to 14 days there was an increase in the spread into the fascia dentata of Timm stainable axon terminals from CA3, interpreted as a sign of fewer crossed entorhinal afferents succeeding in a presumable competition with the CA3‐derived system for available terminal space. The CA3‐derived terminals distributed in an intermediate band in the dentate molecular layer beneath the zones occupied by the crossed entorhinal projections.The appearance of a similarly placed, but less intense intermediate band of Timm staining on the side contralateral to the chronic lesion was observed. This is tentatively interpreted as an indication that anormalcrossed entorhinodentate projection does exist, its removal having caused a spread of Timm stainable terminals from the adjacent CA3. Both careful light microscopic analysis of the degeneration picture which followed acute entorhinal lesions of control animals as well as preliminary electron microscopic studies further indicated the existence of a sparse crossed entorhino‐dentate projection in normal rats.In the rabbit the existence of a normal crossed entorhino‐dentate projection has been demonstrated by the authors in an accompanying study. The differences in the morphology of the most septal parts of the fascia dentata and fasciola cinerea of the rat and the rabbit provided an excellent opportunity for evaluation of the role of spatial and temporal factors involved in the regulation of the growth of axons of

ISSN:0092-7317    

DOI:10.1002/cne.901610107

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

年代:1975

数据来源: WILEY

摘要:

AbstractAn exogeneous marker protein, horseradish peroxidase (HRP) was used to trace peripheral autonomic pathways in adult guinea pigs and cats. Small doses of HRP were injected into various organs and after a brief survival period, HRP activity appeared in the perikarya of autonomic neurons that supplied each injection site. After injection of HRP into the anterior chamber of the eye, reaction product was detected in the postganglionic sympathetic neurons of the superior cervical sympathetic ganglion. In another experiment, HRP reaction product was found in the cell bodies of the preganglionic sympathetic neurons that supply the adrenal medulla. These were located in the lateral gray column of the spinal cord at T6 and T7 segmental levels. Reaction product appeared in intramural postganglionic parasympathetic neurons close to an injection site in the wall of the urinary bladder and in a similar situation in Meissner's ganglia of the ileum. Following injection into the walls of the stomach and ileum, HRP labelled cells were detected in the nodose ganglion of the vagus and in preganglionic parasympathetic neurons in the dorsal motor nucleus of this nerve. After injection into the subepicardial tissue of the heart, reaction product appeared in the stellate ganglion and also in an upper thoracic dorsal root ganglion. These data suggest that HRP is taken up by peripheral autonomic nerves of all types, and then undergoes rapid retrograde axonal transport to the perikaryon. It appears, therefore, that HRP may be useful in tracing both motor and sensory peripheral autonomic pathways.

ISSN:0092-7317    

DOI:10.1002/cne.901610108

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

年代:1975

数据来源: WILEY

摘要:

AbstractA study has been made of the macroscopic, microscopic and electron‐microscopical appearance of intersegmental neural connections in the rat. Macroscopically, spinal roots and ganglia of adjacent segments were frequently observed to be linked by discrete, slender strands, mainly in the lumbosacral region where the roots are long. When examined under the light microscope, even the smallest was found to contain as many as 72 myelinated fibres with a range of diameters between 1.5–14 μm. They were commonly accompanied by blood vessels. Connections, when present, contributed to as much as 6–28% of the total number of myelinated axons in dorsal roots.Under the electron microscope, links between dorsal roots, or between dorsal roots and adjacent ganglia, contained unmyelinated fibres comparable in numbers to those found in the dorsal roots themselves. In links between ventral roots and ganglia the numbers of unmyelinated fibres proportionally exceeded those found in ventral roots.The presence of these connections may account for the reported finding of undamaged nerve fibres in the dorsal roots after dorsal root sectioning or ganglionectomy and in the ventral roots after ventral root sect

ISSN:0092-7317    

DOI:10.1002/cne.901610109

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

年代:1975

数据来源: WILEY

摘要:

AbstractUsing degeneration staining methods, central projections of the olfactory tracts in the bullhead catfish,Ictalurus nebulosuswere studied. Separate lesions were made of the lateral and medial olfactory tracts in an attempt to separate their zones of projection. Three major terminal fields were found: lateral, medial and central‐posterior complex. Two additional minor projections were seen: interbulbar and hypothalamic.The lateral division of the olfactory tract terminates in lateral, central and hypothalamic terminal fields. The medial tract projects to lateral, medial, posterior and hypothalamic fields. All terminal fields were found bilaterally; the lateral tract partly crossing in both the anterior and habenular commissures and the medial tract in only the anterior commissure. A small interbulbar commissure was also found to contain medial tract fibers.Evidence is given to show that the anterior olfactory nucleus, if present in catfish, may be located within the olfactory bulb itself. Similarities between mammalian and teleost olfactory systems are also discusse

ISSN:0092-7317    

DOI:10.1002/cne.901610110

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.901610101

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

年代:1975

数据来源: WILEY