bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for a functional and anatomical relationship between the lateral septum and the hypothalamus in the control of flank marking behavior in golden hamsters
Authors: Ferris Craig F. , Gold Larry , De Vries Geert J. , Potegal Michael
Published: January 2005

Golden hamsters with established dominant/subordinate relationships communicate their social status by rubbing pheromone‐producing flank glands against objects in the environment. This behavior, called flank marking, is controlled by vasopressin‐sensitive neurons localized to the anterior hypothalamus. Vasopressinergic magnocellular neurons in the nucleus circularis and medial aspect of the supraoptic nucleus are thought to be a source of neurotransmitter for the initiation of flank marking.

The present study was undertaken to examine the extrahypothalamic control of flank marking. The anatomical and functional connections between the lateral septum and the vasopressin‐containing nuclear groups in and around the anterior hypothalamus were examined by: (1) tracing afferent and efferent connections following microinjection of horseradish peroxidase and Phaseolus vulgaris‐leucoagglutinin into the lateral septum, and (2) recording odor‐induced flank marking prior to and following ibotenate lesions in the septum.

The greatest number of perikarya retrogradely labeled with horseradish peroxidase were found lateral to the anterior hypothalamus and ventral to the fornix in the area of the lateral hypothalamus. The vasopressin‐containing nuclear groups, e. g., paraventricular, supraoptic, suprachiasmatic nuclei, and the nucleus circularis, were devoid of labeled perikarya. Nerve terminals anterogradely labeled with Phaseolus vulgaris‐leucoagglutinin were primarily localized to the anterior hypothalamus, in and around the nucleus circularis, and the medial aspect of the supraoptic nucleus. The lateral aspect of the supraoptic nucleus was devoid of nerve terminals as were the paraventricular and suprachiasmatic nuclei. The anatomical connections between the lateral septum and the hypothalamus appear to be necessary for the control of flank marking, since the microinjection of ibotenate into this limbic site significantly reduced odor‐induced flank marking as compared to control microinjections of 0.9% NaCl.
Connections of the parabrachial nucleus with the nucleus of the solitary tract and the medullary reticular formation in the rat
Authors: Herbert Horst , Moga Margaret M. , Saper Clifford B.
Published: January 2005

We examined the subnuclear organization of projections to the parabrachial nucleus (PB) from the nucleus of the solitary tract (NTS), area postrema, and medullary reticular formation in the rat by using the anterograde and retrograde transport of wheat germ agglutinin‐horseradish peroxidase conjugate and anterograde tracing with Phaseolus vulgaris‐leucoagglutinin. Different functional regions of the NTS/area postrema complex and medullary reticular formation were found to innervate largely nonoverlapping zones in the PB.

The general visceral part of the NTS, including the medial, parvicellular, intermediate, and commissural NTS subnuclei and the core of the area postrema, projects to restricted terminal zones in the inner portion of the external lateral PB, the central and dorsal lateral PB subnuclei, and the “waist” area. The dorsomedial NTS subnucleus and the rim of the area postrema specifically innervate the outer portion of the external lateral PB subnucleus. In addition, the medial NTS innervates the caudal lateral part of the external medial PB subnucleus.

The respiratory part of the NTS, comprising the ventrolateral, intermediate, and caudal commissural subnuclei, is reciprocally connected with the Kölliker‐Fuse nucleus, and with the far lateral parts of the dorsal and central lateral PB subnuclei. There is also a patchy projection to the caudal lateral part of the external medial PB subnucleus from the ventrolateral NTS.

The rostral, gustatory part of the NTS projects mainly to the caudal medial parts of the PB complex, including the “waist” area, as well as more rostrally to parts of the medial, external medial, ventral, and central lateral PB subnuclei.

The connections of different portions of the medullary reticular formation with the PB complex reflect the same patterns of organization, but are reciprocal. The periambiguus region is reciprocally connected with the same PB subnuclei as the ventrolateral NTS; the rostral ventrolateral reticular nucleus with the same PB subnuclei as both the ventrolateral (respiratory) and medial (general visceral) NTS; and the parvicellular reticular area, adjcent to the rostral NTS, and with parts of the central and ventral lateral and the medial PB subnuclei that also receive rostral (gustatory) NTS input. In addition, the rostral ventrolateral reticular nucleus and the parvicellular reticular formation have more extensive connections with parts of the rostal PB and the subjacent reticular formation that recieve little if any NTS input.

The PB contains a series of topographically complex terminal domains reflecting the functional organization of its afferent sources in the NTS and medullary reticular formation.
Postnatal development of palatal and laryngeal taste buds in the hamster
Authors: Belecky Teri L. , Smith David V.
Published: January 2005

Mammalian taste buds are distributed within several distinct subpopulations, innervated by branches of three cranial nerves. These taste bud populations originate and mature at different times in various mammalian species and are thought to play differential roles in the control of taste‐mediated behaviors. The hamster is a common animal for the electrophysiological study of the gustatory system, and it has been shown that taste buds innervated by the IXth nerve develop postnatally in this species. To delineate further the development of the gustatory system of hamsters, we quantified the number of taste buds appearing on the palatal, nasopharyngeal, and laryngeal epithelium from birth through 120 days of age. Taste buds are present in almost adult numbers on the soft palate at birth, but only 39% of these are mature. Distinct taste pores, indicative of mature taste buds, increase in number until about 20‐30 days of life, at which time all of the taste buds on the soft palate and on the nasoincisive papillae are fully developed. Taste buds are concentrated primarily on the posterior and medial portions of the soft palate. Taste buds located on the laryngeal surface of the epiglottis and the aryepiglottal folds are absent at birth and originate and mature over the following 120 days. Laryngeal taste buds are more concentrated on the aryepiglottal folds than on the epiglottis. On the soft palate and in the epiglottal region, the maturation of taste buds is well characterized by a logarithmic function (Y=a log X + B) relating the number of mature taste buds to postnatal age. On the soft palate, the length of the taste buds from base to apex correlates with the thickness of the epithelium, which increases with development. The diameter of mature taste buds on the soft palate does not change with age. In contrast to many mammalian species, in rodents taste bud development occurs mostly after birth. Rapid postnatal development progresses at a time when ingestive behavior is undergoing a number of significant changes. Taste buds in the larynx have been implicated in a number of laryngeal reflexes (i.e., apnea, swallowing) in several nonrodent species. The electrophysiological properties of superior laryngeal nerve fibers would suggest a similar function for epiglottal taste buds in the hamster.
Migratory pathways and selective aggregation of the lateral reticular neurons in the rat embryo: A horseradish peroxidase in vitro study, with special reference to migration patterns of the precerebellar nuclei
Authors: Bourrat Franck , Sotelo Constantino
Published: January 2005

The migration and ultimate domain invasion of postmitotic lateral reticular nucleus (LRN) neurons were followed in embryonic day 15–20 (E15‐E20)rat embryos, by using a horseradish peroxidase (HRP) in vitro axonal tracing method. All of the LRN axons elongate and neuronal somata migrate via the subpial or marginal migratory stream (mms), circumnavigating the ventrolateral aspect of the medulla at the glial endfeet level. They reach the ventral midline at E16, bypass it, and begin to settle in their final territory at E17. At E18 the LRN anlage is fully formed, and at E19‐E20 its cells have finished their migration and are rapidly differentiating. Comparison of these sequential steps with their counterparts in the development of the inferior olive (ION) and external cuneatus (ECN) brings to light the essential role of the neuroepithelial cells of the interolivary commissure (the “floor plate”). This zone is likely to act as (1) a chemoattractant for the growth cones of the LRN, ION, and ECN, and (2) a decision‐making center, which instructs the somata of these neurons to cross the midline or not, ultimately governing the crossed or uncrossed pattern of their projection to their common target, the cerebellum. Finally, the ontogeny of the LRN and ECN provides a most surprising example, even unique in the central nervous system, of long‐distance, neurophilic migration that conveys neuronal cell bodies contralaterally to the side on which they proliferate.
Expression of compartmentation antigen zebrin I in cerebellar transplants
Authors: Wassef Marion , Sotelo Constantino , Thomasset Monique , Granholm Ann‐Charlotte , Leclerc Nicole , Rafrafi Jamel , Hawkes Richard
Published: January 2005

The mammalian cerebellum is divided into multiple parasagittal compartments as defined by the organization of afferent and efferent projections and by the pattern of expression of several biochemical markers. One such marker is the antigen zebrin I, a 120 kD polypeptide of unknown function that is expressed differentially by a subset of Purkinje cells. Zebrin I+ Purkinje cells are grouped into an array of 14 parasagittal bands interposed by zebrin I− compartments. This Purkinje cell compartmentation corresponds to compartments in the olivocerebellar projection. The afferent axon compartments are present prior to the expression of the mature zebrin I phenotype, thus raising the possibility that differential afferent input regulates the zebrin I phenotype of the target of that input. Lesion studies in the neonate preclude a role for afferent inputs in the regulation of zebrin I expression postnatally, but a prenatal role in commitment still remains open. To explore this possibility, cerebellar anlagen were dissected from embryos at embryonic days 12–15, that is, prior to any contact with afferents, and transplanted ectopically into adult hosts. In the first series of experiments, the grafts were placed into the anterior chamber of the eye, and in the second series, into cavities prepared in the neocortex. Grafts were allowed to mature and then were immunoperoxidase or immunofluorescence stained for zebrin I immunoreactivity. Zebrin I was expressed by grafted Purkinje cells in cortico and in oculo. Double‐labelling experiments confirmed that both the zebrin I+ and the zebrin I− phenotypes were present. The zebrin I immunoreactivity revealed that the zebrin I+ Purkinje cells resemble those in situ with an extensive dendritic arborization that extends through the molecular layer perpendicular to the long axes of the folia. In conclusion, the present data suggest that afferent input does not play a role in the determination of the zebrin I phenotype of Purkinje cells.
Ultrastructure of substance P‐ and CGRP‐immunoreactive nerve fibers in the nasal epithelium of rodents
Authors: Finger Thomas E. , Jeor Var L. St. , Kinnamon John C. , Silver Wayne L.
Published: January 2005

The respiratory and olfactory mucosae of rats and mice were examined at ultrastructural levels for the presence of intraepithelial nerve endings. Immunocytochemical studies utilizing antisera directed against substance P and calcitonin gene‐related peptide (CGRP) revealed numerous intraepithelial peptide‐immunoreactive fibers near the basal region of the epithelium. Occasional transepithelial fibers were observed to extend outward to nearly reach the epithelial surface. In no cases, however, did the transepithelial fibers reach the surface, but instead, stopped at the line of tight junctions approximately 1 μm from the surface. No specialized contacts between the nerve fibers and the epithelial cells were observed. The transepithelial fibers provide a possible anatomical substrate for the sensitivity of the trigeminal nerve to many air‐borne chemical stimuli. That potential chemical stimuli must traverse the tightjunctional barrier may explain why lipid solubility is related to effectiveness for trigeminal stimuli.
Involvement of specific placental antigen X‐P2 in rat olfaction: An immunohistochemical study in the olfactory bulb
Authors: Shinoda Koh , Yagi Hideo , Osawa Yoshio , Shiotani Yahe
Published: January 2005

Human placental antigen X‐P2 (hPAX‐P2), an antigen complex associated with cytochrome P‐450 of aromatase within estrogen synthesizing tissues, has been reported to be present in a distinct group of rat primary olfactory receptors involved in suckling behavior. In this study, most of the mitral and tufted cells in the rat olfactory bulb were found to possess hPAX‐P2 immunoreactivity. This suggests that the activity of these cells can be hormonally modulated and that hPAX‐P2 is involved in rat olfaction not only at the receptor level but also at integrative brain levels via the secondary projecting neurons of the olfactory pathway.
Neuropeptide diversity in Ascaris: An immunocytochemical study
Authors: Sithigorngul Paisarn , Stretton Antony O. W. , Cowden Cynthia
Published: January 2005

An immunocytochemical method was used for localization of various peptide‐like substances in the Ascaris nervous system. Out of 45 antipeptide antisera, 12 demonstrated immunoreactivity in different subsets of neurons; these 12 antisera were raised against luteinizing hormone‐releasing hormone (LHRH), Aplysia peptide L11 (L11), Aplysia peptide 12B (12B), small cardioactive peptide B (SCPB), neuropeptide Y (NPY), FMRFamide, gastrin‐17, cholecystokinin octapeptide (CCK‐8), α‐melanocyte stimulating hormone (α;MSH), calcitonin gene related peptide (CGRP), corticotropin releasing factor (CRF), and vasoactive intestinal peptide (VIP). Several peptide‐like substances were colocalized to the same neuron. Our results suggest that Ascaris, like other organisms, contains multiple peptidergic systems.
Connections of the subthalamic nucleus with ventral striatopallidal parts of the basal ganglia in the rat
Authors: Groenewegen Henk J. , Berendse Henk W.
Published: January 2005

The present study was undertaken to establish the precise anatomical relationship of the subthalamic nucleus (STh) with limbic lobe‐afferented parts of the basal ganglia in the rat. The anterograde tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L), injected in the STh, the globus pallidus, the ventral pallidum, the ventral striatum, and the parafascicular thalamic nucleus, and the retrograde tracers Fluoro‐Gold (FG) and cholera toxin B (CTb), injected in the globus pallidus, the ventral pallidum, the ventral striatum, and the ventral mesencephalon, were used for this purpose. The results of these tracing experiments confirm the general notion of reciprocal connections between the STh and pallidal areas. Thus the dorsomedial part of the STh is connected with the subcommisural ventral pallidum, whereas a more ventral and lateral part of the medial STh is related to the medial globus pallidus. The lateral hypothalamic area, directly adjacent to the STh, containing neurons with a morphology quite similar to those in the STh, projects to parts of the ventral pallidum related to the olfactory tubercle. The reciprocal projection from this pallidal area to subthalamic regions appears to be very sparse. The medial STh sends strong projections to the medial part of the entopeduncular nucleus and the adjacent lateral hypothalamic area. Sparser projections from the medial STh reach the rostral and medial part of the caudate‐putamen and the nucleus accumbens. The nucleus accumbens. The nucleus accumbens sends a very sparse projection back to the medial STh. The projections of the medial STh to the ventral mesencephalon appear also to be topographically organized. The lateral hypothalamus and a few cells in the most medial part of the STh project to the ventral tegmental area, whereas progressively more lateral parts of the ventral mesencephalon, in particular the substantia nigra, receive input from successively more lateral and caudal parts of the STh. In addition, a number of STh fibers reach the midbrain extrapyramidal area. The lateral part of the parafascicular thalamic nucleus projects to the lateral part of the STh, whereas parafascicular neurons medial to the fasciculus retroflexus projects to the dorsomedial portion of the STh.

The medial part of the STh and the adjacent lateral hypothalamus are intimately connected with limbic parts of the basal ganglia in a way similar and parallel to the connections of the lateral STh with motor‐related parts of the basal ganglia. These findings suggest a role for the STh in nonmotor functions of the basal ganglia.
Immunohistochemical and biochemical evidence for the putative inhibitory neurotransmitters histamine and GABA in lobster olfactory lobes
Authors: Orona Edward , Battelle Barbara‐Anne , Ache Barry W.
Published: January 2005

As an initial effort to investigate possible inhibitory interactions in the olfactory system of the spiny lobster, studies were conducted to identify and localize the putative inhibitory neurotransmitters histamine and GABA in the olfactory lobe. Biochemical studies demonstrated that olfactory lobe tissue was capable of synthesizing histamine from radioactive histidine and GABA from glutamic acid. Immunohistochemistry was used to localize histamine and GABA in brain sections, by using either avidin‐biotin conjugated peroxidase or fluorescein conjugated secondary antibody. Specific histamine‐like and GABA‐like immunoreactivity was found in soma clusters of olfactory interneurons, adjacent to the olfactory lobe. Small, putative glial cells displaying intense histamine‐like immunoreactivity were found interspersed among the glomeruli of the lobe. The accessory lobe exhibited moderate immunostaining for both histamine and GABA. Positive immunostaining for histamine and GABA was also found in the olfactory lobes, with a predominance of staining in the outer caps of the glomeruli, which are thought to be the regions where the primary afferent terminals contact the processes of second‐order olfactory neurons. These findings collectively implicate inhibition at the first synaptic level of the olfactory pathway in the spiny lobster.
Intrastriatal grafts derived from fetal striatal primordia: II. Reconstitution of cholinergic and dopaminergic systems
Authors: Liu Fu‐Chin , Graybiel Ann M. , Dunnett Stephen B. , Baughman Robert W.
Published: January 2005

Reconstitution of striatal cholinergic and dopaminergic systems was studied in intrastriatal grafts derived from embryonic day 15 rat striatal primordia and implanted into adult host rats in which unilateral ibotenic acid lesions had previously been made in the striatum. Histochemical, immunohistochemical, and ligand binding autoradiographic techniques were applied to analyze different constituents of these two systems and to study their locations relative to each other in grafts allowed to grow for 9–17 months following transplantation.

For the cholinergic system, a modular organization was found in the striatal grafts with stains for choline acetyltransferase and acetylcholinesterase, respectively the synthetic and degradative enzymes for cholinergic neurons; by autoradiographic [3H] hemicholinium binding, specific for high affinity choline uptake sites associated with cholinergic terminals; and by autoradiographic [3H] pirenzepine binding, selective for M1 receptors. For the dopaminergic system, a comparable modular organization was found in the grafts by immunostaining for tyrosine hydroxylase, the catecholamine synthetic enzyme; by autoradiographic [3H] mazindol binding for dopamine uptake sites; and by [3H] SCH23390 binding for dopamine D1 receptors and [3H] sulpiride binding for dopamine D2 receptors. The results indicate that the distributions of the cholinergic and dopaminergic markers in striatal grafts are in close anatomical register.

These markers for intracellular and membrane‐associated components of the cholinergic and dopaminergic systems were preferentially localized in the acetylcholesterase‐rich patches of the grafts in which cortical and thalamic fibers have also been found in striatal grafts, and in which output neurons projecting to the pallidum are located. This anatomical correlation suggests that the substrates for cholinergic‐dopaminergic interactions typical of the normal striatum may be reinstated in the grafts both in relation to efferent neurons establishing connections with the host brain that are typical of normal striatofugal connections, and in relation to major afferent fiber systems from the host brain originating in regions known to project densely to the normal striatum. Accordingly, the cholinergic and dopaminergic systems in such grafts may regulate the functional influence of the grafts on the behavior of host animals.
GABAergic neural elements in the rat basilar pons: Electron microscopic immunochemistry
Authors: Border B. G. , Mihailoff G. A.
Published: January 2005

Previous light microscopic immunoperoxidase studies of glutamic acid decarboxylase (GAD)‐immunoreactive neural elements in the rat basilar pontine nuclei revealed immunocytochemical reaction product in neuronal somata and axon terminals. In the present study, pre‐embedding immunoperoxidase labeling of GAD or gamma‐aminobutyric acid (GABA) and postembedding immunogold labeling of GABA allowed the ultrastructural visualization of these neural elements in the basilar pontine nuclei of colchicine‐treated animals. At the electron microscopic level, immunolabeled neuronal somata exhibited smoothly contoured nuclei, whereas some dendrites also contained reaction product after immunocytochemical treatment and were postsynaptic to both immunoreactive and nonimmunoreactive axon terminals. Synaptic boutons immunoreactive for GAD or GABA exhibited cross‐sectional areas that ranged from 0.1 to 3.8 μm2 and generally appeared round or elongated in most sections.

The majority (95%) of immunolabeled boutons contained pleomorphic synaptic vesicles and formed symmetric synapses at their postsynaptic loci; however, boutons exhibiting round vesicles and boutons forming asymmetric synapses (5%) were also immunopositive. Small (<1.5 μm2) GAD‐ or GABA‐labeled axon terminals formed synaptic contact mainly with small dendritic profiles, dendritic spines, and neuronal somata, whereas large labeled boutons (>1.5 μm2) formed synapses with all sizes of dendritic profiles. Occasionally, a single immunolabeled bouton formed synaptic contact with two separate postsynaptic dendrites.

It is suggested that the immunolabeled neuronal somata and dendrites observed in the rat basilar pontine nuclei represent a population of pontine local circuit neurons; however, it is known that GABAergic cell groups extrinsic to the pontine gray provide afferent projections to the basilar pons, and therefore at least some immunoreactive axon terminals present in the pontine nuclei are derived from these extrinsic sources. The ultrastructural observation of GABAergic neural elements in the rat basilar pontine nuclei confirms previous light microscopic findings and provides an anatomical substrate through which GABAergic neurons, whether arising from an intrinsic or extrinsic source, might exert an inhibitory influence on target cells within the pontine nuclei.
Morphology and physiology of cells in slice preparations of the posteroventral cochlear nucleus of mice
Authors: Oertel Donata , Wu Shu Hui , Garb Micah W. , Dizack Carol
Published: January 2005

In an effort to understand what integrative tasks are performed in the cochlear nuclei, the present study was undertaken to describe neuronal circuits in the posteroventral cochlear nucleus (PVCN) anatomically and physiologically. The cochlear nuclear complex receives auditory information from the cochlea through the auditory nerve. Within the cochlear nuclei, signals travel along several parallel and interconnected pathways. From the cochlear nuclei, transformed versions of the signals are passed to higher auditory centers in the brainstem. We have recorded electrophysiological responses from cells that were subsequently visualized with horseradish peroxidase (HRP). Responses to shocks to the auditory nerve root and to intracellularly injected current pulses were recorded and correlated with morphology. Two types of stellate cells and octopus cells were distinguished. T stellate cells project out of the cochlear nuclei through the T rapezoid body; D stellate cells do not. The axons of D stellate cells extend D orsalward to the dorsal cochlear nucleus (DCN) but have not been traced out of the nucleus. Both T and D stellate cells have terminal collaterals in the multipolar cell region of the PVCN and in the DCN. The endings of one T stellate cell formed a narrow band rostrocaudally in the fusiform cell layer of the DCN that resembled an isofrequency band. The endings of one D stellate cell lay closely apposed to multipolar cells in the deep layer of the DCN. The dendrites of T stellate cells are often aligned along the path of auditory nerve fibers and end in tufts, whereas those of D stellate cells extend radially in the plane of the lateral surface of the PVCN toward granule cell areas and branch sparingly. Octopus cells have dendrites oriented perpendicularly to the path of auditory nerve fibers. Their axons were cut medially in the slices; none had collateral branches.

Both T and D stellate cells were monosynaptically excited to threshold by shocks to the nerve root, indicating that they could participate in local circuits that we measure physiologically. T stellate cells have action potentials that peak at about O m V and are followed by single undershoots. The D stellate cell that was best impaled fired overshooting action potentials that were followed by double undershoots. Octopus cells were monosynaptically excited to threshold by shocks to the auditory nerve.
Fate of grafted embryonic purkinje cells in the cerebellum of the adult “purkinje cell degeneration” mutant mouse. II. Development of synaptic responses: An in vitro study
Authors: Gardette R. , Crepel F. , Alvarado‐Mallart R. M. , Sotelo C.
Published: January 2005

Solid pieces of cerebellar primordia from 12‐day‐old C57Bl embryos were implanted in the cerebellar vermis of 3–4‐month‐old “Purkinje cell degeneration” mutant mice. Ten to 22 days after grafting, mutant mice were sacrificed, and synaptic responses of grafted Purkinje cells were studied by intracellular recordings performed in 400 μm thick sagittal slices in vitro.

As early as 10 days after transplantation, grafted Purkinje cells have already completed their migration from the implant into the host molecular layer. Accordingly, inhibitory as well as excitatory responses were already elicited in these cells by electrical stimulation of the host subcortical white matter. Furthermore, a transient stage of multiple innervation of Purkinje cells by climbing fibers exists between 10 and 15 days after grafting, as revealed by the stepwise variation in amplitude of the climbing fiber‐mediated excitatory postsynaptic potentials recorded before 15 days after grafting. Thirteen days after transplantation, typical all‐or‐none climbing fiber‐mediated responses, parallel fiber‐mediated excitatory postsynaptic potentials, and inhibitory postsynaptic potentials were also already present. Finally, normal adult‐type synaptic responses were observed in all tested cells 15 to 17 days after grafting.

Together with the companion paper (Sotelo et al., 1990), these results demonstrate that grafted Purkinje cells are able to impose on host afferents a pattern of synaptogenesis which closely follows that occuring during normal development, in particular, the transient stage of multiple innervation of Purkinje cells by climbing fibers.
Organization of the auditory pathway in the thoracic ganglia of noctuid moths
Authors: Boyan George , Williams Lez , Fullard James
Published: January 2005

We describe the neuroarchitecture of the noctuid thoracic nerve cord and use this framework to interpret the organization of the auditory pathway responsible for escape behaviour in noctuid moths.

Noctuid moths possess only two auditory receptors (A1, A2), in each ear. The axon of the A1 cell projects initially to a glomerulus located ventrally and medially in the metathoracic ganglion, where it bifurcates. One branch ascends in the ventral intermediate tract to the brain, the other descends in the ventral intermediate tract into abdominal neuromeres of the metathoracic ganglion. Both axons arborize in the median ventral and ring tracts in each neuromere. The central projections of the A2 cell remain largely within the metathoracic ganglion. The axon bifurcates at the midline and directs arborizations dorsally to the dorsal intermediate and median dorsal tracts, and ventrally into the ring tract where the arborizations overlap those of the A1 afferent. The afferent projections remain ipsilateral to the ear of origin.

We describe a posterior auditory association area in the metathoracic ganglion in which the major arborizations of several identified interneurones overlap those of the A1 afferent and make monosynaptic connections with it. These interneurones all respond tonically to sound stimuli. We have also identified the projections of the A1 afferent, interneurones, and motor neurones in the segmentally equivalent anterior auditory association area of the mesothoracic ganglion. An interneurone with major arborizations in the same tracts as the A1 afferent, and receiving monosynaptic input from it, is described. The arborizations of higher order interneurones lie mainly in dorsal tracts along with those of flight motor neurones. All interneurones in this anterior centre respond phasically or phasic/tonically to sound stimuli.

The relevance of this anatomical organization for predator avoidance behaviour is considered and the organization of auditory pathways in tympanate insects compared.
Organization of the primary projections of the lateral line nerves in the lamprey lampetra japonica
Authors: Koyama Hiromichi , Kishida Reiji , Goris Richard C. , Kusunoki Toyokazu
Published: January 2005

The lateral line sensory system of Lampetra japonica is innervated by the anterior and posterior lateral line nerves. The anterior lateral line nerve innervates all electroreceptors throughout the body and mechanoreceptors of the head. The posterior lateral line nerve innervates trunk mechanoreceptors. The anterior lateral line nerve consists of two ganglia (anterior lateral line and intracapsular) and four major peripheral branches (superficial ophthalmic, buccal, hyomandibular, and recurrent nerves). The posterior lateral line nerve has one posterior lateral line ganglion and one peripheral branch. The location and central projection patterns of the primary sensory neurons of these branches of the lateral line nerves were studied with the aid of horseradish peroxidase labeling.

The ganglion cells of the buccal nerve were found in the rostral half, and those of the hyomandibular nerve were found in the caudal half of the medial part of the anterior lateral line ganglion. The lateral part of the anterior lateral line ganglion contains ganglion cells of the recurrent nerve and the superficial ophthalmic nerve. The rostral half of the intracapsular ganglion contains ganglion cells of the recurrent, hyomandibular, and buccal nerves. The ganglion cells of the posterior lateral line nerve were found in the posterior lateral line ganglion. The buccal nerve afferents terminated mainly in the lateral part of the ipsilateral mechanoreceptive medial nucleus. The peripheral part of the electroreceptive dorsal nucleus also received several afferents. The hyomandibular afferents terminated ipsilaterally in the central part of the medial nucleus and in the dorsolateral part of the dorsal nucleus. Some afferents of the hyomandibular nerve ascended and descended in the descending nucleus of the trigeminal nerve near its dorsal margin. The ventral nucleus, the primary nucleus of the VIIIth nerve, received a few fibers of the buccal and hyomandibular nerves. In the recurrent nerve, the fibers of the lateral part of the anterior lateral line ganglion terminated throughout the entire dorsal nucleus, and the fibers of the intracapsular ganglion projected to the dorsolateral part of the nucleus. The afferents of the posterior lateral line nerve terminated in the medial part of the ipsilateral medial nucleus and in the lateral part of the contralateral medial nucleus. In the cerebellar area, afferents of the anterior lateral line nerve were located laterally to those of the posterior lateral line nerve. Several fibers terminated in some branchiomotor nuclei, the cerebellar crest, and the dorsal gray near the obex level. No efferent cell bodies were found in the place where efferent neurons of the VIIIth nerve have been previously reported.
Anatomical investigation of projections from thalamus to posterior parietal cortex in the rhesus monkey: A WGA‐HRP and fluorescent tracer study
Authors: Schmahmann Jeremy D. , Pandya Deepak N.
Published: January 2005

The parietothalamic projections have been shown to be heterogeneous and appear to be a reflection of the detailed architectonic parcellation of the parietal lobe. In the present study WGA‐HRP injections were placed in the different subdivisions of the posterior parietal cortex of the rhesus monkey to determine whether a similarly complex pattern also exists in the thalamocortical pathway. Additionally, in an attempt to determine whether there is an intranuclear specificity of projections from individual thalamic nuclei to different subdivisions of the parietal lobe, multiple retrograde fluorescent tracers were injected into the rostral to caudal sectors of the parietal lobe of the same animal. Different subdivisions of the parietal lobe appear to receive different sets of thalamic input. Thus the superior parietal lobule (SPL) projections are derived from more lateral regions in the thalamus, arising predominantly from the lateral posterior (LP) and pulvinar oralis (PO) nuclei, with additional contributions from the pulvinar lateralis (PL) and pulvinar medialis (PM) nuclei. The inferior parietal lobule (IPL), by contrast, receives its projections from more medial thalamic regions, its main thalamic input originating from PM, and aided by LP, PL, and PO. Both the SPL and IPL also receive projections from the mediodorsal (MD), ventroposterior, ventrolateral, intralaminar, and limbic nuclei, albeit from different components within these nuclei.

A topographical arrangement also exists in the thalamic projections to the rostral versus the caudal subdivisions of both the SPL and the IPL. Thus, in the SPL, the ventral posterolateral nucleus, pars oralis (VPLo), ventral lateral nucleus, pars oralis (VLo), and ventral lateral nucleus, pars medialis (VLm) project to rostral, whereas the PM and limbic nuclei, anteroventral (AV), and anteromedial (AM), project to area PGm on the medial convexity of the SPL. With respect to projections to the IPL, the ventral posteromedial (VPM) and PO nuclei project to rostral regions, whereas the limbic nuclei lateral dorsal (LD), AM and AV project only to the caudalmost area, Opt. A rostrocaudal difference is reflected also within certain nuclei (LP, PO, and PM) that project to the SPL or IPL. Thus rostral parietal subdivisions receive projections from ventral regions within these thalamic nuclei, whereas caudal parietal afferents arise from the dorsal parts of these nuclei. Intervening cortical levels receive projections from intermediate positions within the nuclei.

It therefore seems that the increasing architectonic and functional complexity as one moves from rostral to caudal in the SPL and IPL appear to be reflected in the thalamic afferents. More rostral areas relate to modality‐specific thalamic nuclei, whereas more caudal regions concerned with complex functions derive their input from multimodal and limbic nuclei.
Fibre organization of the monkey's optic tract: I. Segregation of functionally distinct optic axons
Authors: Reese B. E. , Cowey A.
Published: January 2005

The fibre organization of the monkey's optic tract was examined by implanting pellets of horseradish peroxidase into different locations within the tract, or into the superior colliculus and pretectum. Retinae were examined for the distribution, size, and morphological types of retrogradely labelled ganglion cells; optic tracts were examined for the distribution of anterogradely and retrogradely labelled axonal profiles; and lateral geniculate nuclei were examined for the distribution of anterogradely labelled processes within distinct geniculate laminae.

Localized implants in the optic tract produced retrograde labelling of ganglion cells across wide regions of the retinal surface. The maximum density of labelled cells was always substantially less than the total ganglion cell density known to be present at those retinal loci. Distinct retinal ganglion cell types were labelled from differing regions within the optic tract: implants into the deep (dorsal) portion of the tract, far removed from the outer, pial, surface, retrogradely labelled predominantly Pβ retinal ganglion cells, whereas implants into the superficial (ventral), subpial, part of the tract retrogradely labelled primarily the other retinal ganglion cell types, i.e., the Pα, Pγ, and Pϵ cells. Within any given class of axon, there is a mapping of the centroperipheral retinal axis across the deep‐to‐superficial dimension of the tract, but this retinotopy is extremely coarse. Anterograde labelling of axonal terminations within the lateral geniculate nucleus showed a corresponding specificity for distinct geniculate laminae, the deep implants labelling the parvocellular laminae, superficial implants labelling the magnocellular laminae. Implants into the visual centres of the midbrain produced retrograde axonal labelling rostral to the lateral geniculate nucleus only in the superficial part of the optic tract.

These results demonstrate that the monkey's optic tract is not a simple topographic mapping of retinal eccenticity. Rather, the primary organizational principle is that of a segregation of functionally distinct optic axon classes. As fibre order in the mammalian optic tract is also a chronological index of axonal arrival during development, the present results provide specific predictions about the temporal order of ganglion call genesis and axonal addition within the visual pathway. They also provide an anatomical basis for the functionally selective visual impairments that may arise following local damage to the optic tract in humans.
Choline acetyltransferase‐like immunoreactivity in the superior colliculus of the cat and its relation to the pattern of acetylcholinesterase staining
Authors: Illing R.‐B.
Published: January 2005

Choline acetyltransferase, the biosynthetic enzyme for acetylcholine, is thought to be a marker for cholinergic neurons. This report presents an analysis of the pattern of choline acetyltransferase‐like immunoreactivity in the superior colliculus of the cat, A dense network of highly varicose immunoreactive fibers pervaded the superficial gray and optical layer. The density of the fiber network in the superficial layers was heterogeneous, forming a mosaic pattern with a period of about 400 μm. The antigen was also located in numerous small perikarya embedded in this network. This neuronal population reached a density of 2,000 cells/mm3 of the superficial gray layer and suggested the presence of a substantial cholinergic system originating in the superior colliculus. A detailed comparison was made between the pattern of choline acetyltransferase‐like immunoreactivity and the distribution of acetylcholinesterase activity. By comparisons of adjacent sections, both staining patterns were found to be similar in all collicular layers. In particular, the compartmental distribution of immunoreactivity in the intermediate collicular layers seemed to mimic the pattern of acetylcholinesterase staining. A double‐staining technique demonstrated a near‐perfect correlation between the two patterns. In conclusion, there was no indication of heightened acetylcholinesterase activity without an associated elevation in choline acetyltransferase‐like immunoreactivity throughout the superior colliculus. In this part of the brain, the presence of the putative cholinergic terminals could fully account for the distribution of acetylcholinesterase activity.
Morphology of the cells within the inferior temporal gyrus that project to the prefrontal cortex in the macaque monkey
Authors: de Lima Ana D. , Voigt Thomas , Morrison John H.
Published: January 2005

The primate neocortex possesses an extraordinary degree of regional specialization. Virtually all cortical functions are dependent upon a complex system of reciprocal connections between related cortical regions that allow for distributed information processing. Although some aspects of the organization of these corticocortical projections are understood, little is known about the morphology and afferents to the cells of origin of long corticocortical projections in primates. We combined intracellular injection of Lucifer Yellow (LY) in fixed tissue with in vivo retrograde transport of fast blue to study the dendritic morphology of neurons within the inferior temporal gyrus (ITG) and the superior temporal sulcus (STS) that furnish corticocortical projections to the prefrontal cortex. The fast blue retrogradely labeled cells formed two clearly defined bands within the inferior temporal cortex: a supragranular band that corresponded to layer III, and an infragranular band that corresponded to layers V and VI. After Lucifer Yellow intracellular filling, these retrogradely labeled cells projecting to the prefrontal cortex were found to be morphologically very heterogeneous. Although all filled cells had spiny dendrites, they presented a wide range of cell body sizes and dendritic tree morphologies. In layer III, the majority of cells were typical pyramids of various sizes. In layers V–VI, numerous typical pyramidal cells were present. In addition, significant numbers of modified pyramidal forms were found, including vertical and horizontal fusiform cells, asymmetrical pyramids and multipolar cells. The entire dendritic arbor of individual subtypes in layers III, V, and VI was restricted to a few cortical layers, but as a group these cells had dendrites spanning the whole cortical depth. We suggest that corticocortically projecting cells are distinct from subcortically projecting cells and consist of a defined set of morphological and functional subgroups, each of which is driven by a distinct set of afferents and likely possesses different response properties.
Ibotenic acid lesions of the lateral substantia nigra restore visual orientation behavior in the hemianopic cat
Authors: Wallace Steven F. , Rosenquist Alan C. , Sprague James M.
Published: January 2005

Transaction of non‐tectotectal fibers in the caudal one‐half of the commissure of the superior colliculus restores visual orienting to a cat previously rendered hemianopic by a large unilateral visual cortical lesion. Other observations related to this recovery phenomenon (i.e., the Sprague effect) have suggested that the caudal commissural fibers whose destruction produces the recovery (1) are contralateral afferents to the superior colliculus on the side of the cortical lesion, and (2) profoundly influence visuo‐motor processing in this superior colliculus. We performed anatomical and behavioral experiments to determine which of the more than 40 contralateral collicular afferents are directly involved in the Sprague effect.

To guide subsequent behavioral studies, we performed a pilot anatomical experiment in which we injected WGA‐HRP unilaterally into one superior colliculus at identical retinotopic loci in each of a pair of cats. One cat was normal (control), and the other (experimental) had previously received a caudal transection of the collicular commissure. Quantitative comparison of the retrograde labeling in collicular afferents revealed that a number of mesencephalic regions contain neurons that project to the colliculus via the caudal collicular commissure. Additional collicular injections of WGA‐HRP demonstrated the exact location and distribution of collicular afferent neurons within these nuclei.

In the behavioral experiments, we attempted to replicate the Sprague effect by destroying the neurons giving rise to the axons in the caudal collicular commissure. Ibotenic acid lesions of these neurons were performed in cats that were hemianopic following the removal of the contralateral visual cortex. Small lesions of a “critical zone” in the rostro‐lateral substantia nigra pars reticulata and possibly the overlying ventral zona incerta consistently produced a visual recovery whereas lesions, of the other collicular afferents did not. Paradoxically, large nigral lesions that also included the critical zone did not result in a recovery. A conceptual framework for these findings involving striato‐nigro‐tecto‐preoculomotor interactions is presented.
Nontopographic projection of olfactory sensory neurons in the crayfish brain
Authors: Mellon DeForest , Munger Steven D.
Published: January 2005

We have used tritiated leucine to trace the input projection pattern of olfactory sensory neurons in crayfishes. The olfactory neurons are associated with cuticular sensilla on the external antennular filaments. Each sensillum, or aesthetasc, harbors the distal dendritic segments of about 175 bipolar sensory neurons, the cell bodies for which are grouped in a subcuticular ensemble or ganglion. About 150–175 individual ganglia may be found on each antennule in an adult crayfish. When an aesthetasc is exposed to tritated leucine, the tracer is taken up by the associated olfactory sensory neurons and is transported along the axons to their central terminations within the glomeruli of the ipsilateral olfactory lobe. We tested the possibility that the sensory neurons from specific aesthetascs project to specific glomeruli. By restricting access of the leucine to small groups of aesthetascs, we exposed less than 2% of the olfactory sensory neurons to the tracer. Nonetheless, all glomeruli were labeled following such treatment. We conclude that the sensory neurons are generally distributed to the olfactory glomeruli. If each neuron terminates in a single glomerulus, these data support a divergent pattern of sensory projection from individual ganglia to all regions of the olfactory lobe.