Connections of the lateral cortex in the lizard Podarcis hispanica (original) (raw)
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Experimental Neurology, 1977
The afferents to the parahippocampal area of the rat were studied with retrograde transport of horseradish peroxidase injected into the medial entorhinal cortex, lateral entorhinal cortex, parasubiculum, presubiculum, or a large injection which stained all these structures as well as the ventral hippocampus. Control rats were injected with horseradish peroxidase into the overlying visual cortex. Labeled neurcns in brains with injections into the medial entorhinal cortex and the adjacent parasubicular region were found in the ipsilateral and contralateral presubicular region, the medial septal nucleus, the thalamic nucleus reuniens, the dorsal part of the lateral nucleus of thalamus, the anterior periventricular nucleus of the thalamus, and the dorsal raphe nucleus. Brains with injections into the lateral entorhinal cortex yielded labeled neurons in the medial septal nucleus, nucleus reuniens, dorsal raphe nucleus, and nucleus locus ceruleus. Injections into the presubiculum resulted, in addition, in labeling of neurons in the lateral nucleus of the thalamus. Control injections aimed at the sensory cortex overlying the parahippocampal area yielded labeled neurons in the medial septal nucleus, the dorsal lateral geniculate nucleus, and the nucleus locus ceruleus.
Experimental Brain Research, 1985
The distribution of anterogradely-transported horseradish peroxidase (HRP) was examined in the rostral mesencephalon and thalamus of cats and raccoons that had received injections of HRP in the cervical and/or lumbosacral enlargements of the spinal cord. Labeling was consistently observed in a large number of loci. All regions previously identified as targets of spinomesencephalic or spinothalamic fibers were included. Evidence of topographical organization was obtained in several regions. Adjacent fields of labeling were often separable on the basis of the distribution, appearance and topographical organization of the labeling. Subject to the methodological constraints imposed by the possibilities of transneuronal and/or collateral labeling, we conclude that a wide variety of loci in the thalamus receive direct spinal input. The organization of these projections suggests that each terminal region may be associated with different aspects of spinal cord function.
Brain Research, 1974
Tile potential for using the physiologically occurring retrograde axonal transport of protein as a neuroanatomical tool for identifying the origin of neuronal connections within the adult central nervous system has been evaluated for the case of the rat caudoputamen. Following injections of a marker protein, in this case horseradish peroxidase (H RP), centering on but not limited solely to the caudoputamen, peroxidase labeled cell bodies could be identified in several cell territories known or thought to contain afferents to this structure. These included the pars compacta of the substantia nigra, the intralaminar and parafascicular nuclei of the thalamus, and tile dorsal nucleus of the midbrain raphe. In cases where only the caudoputamen and external segment of the globus pallidus were labeled directly at the injection site, no peroxidasecontaining ceils could be identified in the neocortex or in the thalamus outside the intralaminar and parafascicular nuclei. The evidence presented suggests first, that tile degree of localization at the injection site is compatible with approaching some problems in neuroanatomy; second, that anterograde transport of the marker protein, if Jt occurs, does not appear to confound tile interpretation of retrogradely labeled cell bodies: third, that many, though ,lot all. afferent cell populations can be identified: and fourth, that labeling by axons in passage does not appear to be a problem. A detailed description of the method, abilities and limitations of the technique, and sources of misinterpretation are also provided.
Journal of Comparative Neurology, 1977
Although retrograde and anterograde degeneration studies have provided important information concerning brain stem afferents to the fastigial nuclues (FN), these data may be incomplete and should be confirmed by axonal transport methods. Attempts were made to inject horseradish peroxidase (HRP) unilaterally into the FN in a series of adult cats. Animals were perfused with dextran and a fixative solution of paraformaldehyde and glutaraldehyde in 0.1 M phospate buffer. Representataive sections were treated by the Graham and Karnovsky (1966) method.Selective HRp injections in one FN resulted in retrograde transport of the marker of Purkinje cells of the ipsilateral vermis and distinctive appendages of the contralateral medial accessory olivary (MAO) nucleus (nucleus β and the dorso-medial cell column). Retrograde transport of the label was found bilaterally in cells of the medial (MVN) and inferior (IVN) vestibular nuclei, in cell group x and in the nucleus prepositus (PP). Labeled vestibular neurons, most numerous in MVN, were identified in dorsal, caudal and lateral regions, with a slight ipsilateral preponderance. Only a few neurons in caudal, dorsal and lateral regions of th IVN were labeled and none of these included cells of group f. Labeled cells in the caudal third of PP were greatest ipsilaterally. Rostral and caudal injections of FN labeled smaller numbers of cells in MVN, IVN, cell group x and PP.HRP injections of FN and portions of lobules VIII and IX resulted in bilateral retrograde lableing of larger numbers of cells in MVN, IVN and cell group x, and ipsilateral labeling of cells in group y and the interstitial nucleus of the vestibular nerve. Injections of HRP into basal folia of lobules V and VI resulted in retrograde transport of the marker to cells of the medial and dorsal accessory olivary nuclei contralaterally, and to cells of the ipsilateral accessory cuneate nucleus. Transport of label injected into portions of the pyramis was detected in parts of the contralateral MAO and bilaterally in parts of the pontine and reticulotegmental nucleiThis study suggests that the principal afferents of the fastigial nucleus arise from: (1) Purkinje cells of the ipsilateral vermis, (2) restricted portions of the contralateral MAO (nucleus ß and dorsomedial cell column), (3) portions of the MVN and IVN (bilaterally) and (4) caudala parts of the PP. Secondary vestibular inputs to the fastigial nucleus probably are relayed mainly by cells in the cerebellar cortex.
Brain Research, 1975
Biochemical and histofluorescent studies have shown that the putative synaptic transmitter serotonin (5-HT) is present in relatively high concentration in the corpus striatum z-4,6. The nerve terminals of the forebrain regions which contain 5-HT are derived exclusively from cell bodies located in the mesencephalic raphe nuclei z,21. Lesions of these nuclei, particularly the dorsal and median, or interruption of the projection fibres of the system at the level of the ventromedial tegmentum or medial forebrain bundle result in an extensive reduction of striatal 5-HT and of tryptophan hydroxylase13-l,5,19, 2°. On the other hand, an increased release of 5-HT from the striatum has been reported to follow stimulation of the raphe nuclei 11. These data suggest that a major anatomical pathway arises from neurones in the raphe nuclei and projects to the caudate-putamen (CP). The present investigation was designed to examine this hypothesis by using (1) retrograde and orthograde axonal transport techniques to identify the cells of origin and the terminal projections of the pathway and (2) electrophysiological recording to determine the effect of raphe stimulation on neuronal activity in the CP.
The Journal of Comparative Neurology, 1995
The lateral cortex of the lizard Gekko gecko is composed of three parts: a dorsal and ventral part located rostrally and a posterior part located caudally. In order to obtain detailed information about the efferent connections of these lateral cortex subdivisions, iontophoretic injections of the anterograde tracers Phaseolus vulgaris leucoagglutinin and biotinylated dextran were made in the various parts. The main projection from the dorsal part terminates in the caudal part of the medial cortex. Other cortical projections were noted to the ipsi-and contralateral lateral cortex, the large-celled part of the medial cortex, and the dorsal cortex. Additional fibers were found bilaterally in the anterior olfactory nucleus and the external amygdaloid nucleus. The ventral part of the lateral cortex projects mainly to the ipsilateral, posterior part of the dorsal ventricular ridge and the external amygdaloid nucleus. Minor contralateral projections to these nuclei were also found. Other projections were observed to travel to the caudal part of the medial cortex, to the nucleus sphericus, and bilaterally to the lateral cortex and the anterior olfactory nucleus. The posterior part of the lateral cortex has similar efferent connections as the dorsal part and should be regarded as the caudal continuation of the dorsal part. Because previous studies have shown that the medial cortex and the amygdaloid complex project to different hypothalamic areas, we conclude that the dorsal and ventral parts of the lateral cortex transmit olfactory information to separate hypothalamic areas that are probably involved with different types of behavior. e, 1995 Wiley-Liss, Inc. Indexing terms: reptiles, olfaction, hippocampus, area dentata, amygdala In the lizard Gekko gecko, as in other reptiles, three cortical areas have been identified: medial cortex, dorsal cortex, and lateral cortex (Fig. 1). A cytoarchitectonic map of the cortex has been published by Smeets et al. (1986a). The medial cortex is characterized by a mediodorsal smallcelled part and a dorsolateral large-celled region. On the basis of its relative position and its connections, this cortical area is considered to be the reptilian equivalent of the mammalian hippocampus (Bruce and Butler, 1984; Hoogland and Vermeulen-VanderZee, 1993). The dorsal cortex resembles the mammalian ventral subiculum as it is connected to comparable brain structures in both species (Hoogland and Vermeulen-VanderZee, 1989). The lateral cortex is the only cortical target for projections from the main olfactory bulb. The secondary olfactory projections terminate in the superficial half of the outer plexiform layer of the lateral cortex. In all reptiles studied these projections are bilateral, and in the majority of these reptiles they cover the whole lateral cortex on both hemispheres. The projections reach the contralateral side through the habenular commissure (for a review, see Lohman and Smeets, 1993). Apart from these projections from the main olfactory bulb, the lateral cortex of lizards has extensive intrinsic projections as well as projections from the anterior olfactory nucleus (Martinez-Garcia et al., 1986; Hoogland and Ver
Journal of Comparative Neurology, 1989
The efferent connections from the dorsal cortex of the lizard Gekko gecko have been studied with the anterograde tracer Phaseolus vulgaris-leucoagglutinin. I t appeared that the dorsal cortex is not a homogeneous structure as far as the efferent connections are concerned. All parts of the dorsal cortex project to the septum. All parts except the most medial project to the dorsal ventricular ridge, amygdala, nucleus periventricularis hypothalami, area lateralis hypothalami, and the anterior olfactory nucleus. The most medial part, in addition to the septa1 projections, is connected with the medial cortex and the contralateral medial and dorsal cortices. From the rostral part additional projections could be traced to the nucleus dorsolateralis hypothalami, nucleus ventromedialis thalami, nucleus dorsolateralis thalami, striatum, pallial thickening, medial cortex, nucleus olfactorius anterior, and the main and accessory olfactory bulbs. From the caudal part additional projections exist to the nucleus dorsomedialis thalami, nucleus accumbens, and the contralateral dorsal cortex. A system of intrinsic connections exists that can be subdivided into four subsystems, each of which subserves the interconnections within four subdivisions of the cortex: 1) the superficial medial part, 2) the deep medial part, 3) the caudal lateral and caudal intermediate parts, and 4) the rostral lateral and rostral intermediate parts. Connections between these four areas are scarce. From the present results the conclusion is drawn that the dorsal cortex of the lizard Gekko gecko has many hodological aspects in common with the ventral subiculum of mammals. The present results do not support the hypothesis that the dorsal cortex is the reptilian equivalent of the mammalian neocortex.