bluuebunny/crossref_metadata_2025 huggingface dataset:
Cingulate gyrus of the cat receives projection fibers from the thalamic region ventral to the ventral border of the ventrobasal complex
Authors: Yasui Yukihiko , Itoh Kazuo , Kamiya Hiroto , Ino Tadashi , Mizuno Noboru
Published: January 2005

Direct projections to the cingulate gyrus from the thalamic region lying just ventrally to the ventral border of the ventrobasal complex (VB) were found in the cat by two sets of experiments that used WGA‐HRP (wheat germ agglutinin‐horseradish peroxidase conjugate).

In the first set of experiments, WGA‐HRP was injected into the thalamic region around the ventral border of the VB. When the site of injection involved the thalamic region lying ventrally to the ventral border of the VB at the levels of the caudal two thirds of the VB. The cerebral cortex in the rostral part of the cingulate gyrus ipsilateral to the WGA‐HRP injection contained fine HRP‐positive granules, which indicated anterograde labeling of axon terminals. These labeled presumed axon terminals were mainly distributed to the superficial part of layer I, deep part of layer II, layer IV, and the most superficial part of layer V in the cingulate cortex.

In the second set of experiments, WGA‐HRP was injected into the cerebral cortex of the rostral part of the cingulate gyrus. When the site of injection involved the region of the cingulate gyrus, where presumed axon terminals had been labeled in the first set of experiments, the thalamic region just ventral to the ventral margin of the caudal two‐thirds of the VB ipsilateral to the WGA‐HRP injection contained neuronal cell bodies labeled retrogradely.

The results indicate that some neurons that are located in the thalamic region just ventral to the ventral border of the caudal two‐thirds of the VB send their axons to the cerebral cortex in the rostral part of the cingulate gyrus.

The possible significance of the thalamocingulate projection found in the present study is discussed with relation to nociceptive behavior and function.
Somatostatin‐like immunoreactivity and glycine high‐affinity uptake colocalize to an interplexiform cell of the Xenopus laevis retina
Authors: Smiley John F. , Basinger Scott F.
Published: January 2005

Antibodies directed against somatostain have been used to label a population of interplexiform cells (IPCs) in the Xenopus laevis retina. These cells have spherical soma which lie in the inner nuclear layer (INL), adjacent to or one cell distal to the inner plexiform layer (IPL). Processes from these cells project throughout the IPL, with a fairly dense accumulation of labeled dendrites in the upper two‐fifths of the IPL and a dense, narrow band of labeled dendrites adjacent to the ganglion cell layer. These cells also have finer processes, originating at the cell body, that traverse the INL and ramify in the outer plexiform layer (OPL). Double label experiments show that all of the cells that contain somatostatin‐like immunoreactivity (SOMLI) in the INL are also labeled by high‐affinity uptake with 3H‐glycine. Immunocytochemistry of retinal whole mounts shows that these cells are evenly distributed across the retina at a density of 542 ± 65 cells/mm2. On the basis of the colocalization experiments and the morphological homogeneity of these cells, we suggest that they represent a single cell type.

Interplexiform cell processes were further characterized by electron microscopy after immunocytochemistry or 3H‐glycine autoradiography. In the IPL, IPC processes are seen to be postsynaptic at both ribbon and conventional synapses. This input is found almost entirely in the distal two‐fifths of the IPL. Interplexiform cell processes are presynaptic to unlabeled processes in both the distal and proximal IPL. In the OPL, labeled processes are found near or contiguous with photoreceptor bases, and are often presynaptic to small‐diameter processes. The postsynaptic processes have been identified as bipolar cell dendrites in six cases. Interplexiform cell processes may also contact horizontal cell processes in the OPL.
Lack of central sprouting of primary afferent fibers after ricin deafferentation
Authors: Pubols Lillian M. , Bowen David C.
Published: January 2005

A new deafferentation technique, the application of ricin to peripheral nerves, was used to test for collateral sprouting of undamaged primary afferent fibers within the adult mammalian spinal cord dorsal horn. The right sciatic nerves in rats were injected with ricin 14 to 57 days prior to bilateral labelling of dorsal rootlets with horseradish peroxidase. To equate the number of surviving dorsal root fibers on the two sides, the left sciatic nerves were injected 5 days prior to labelling. In each animal, horseradish peroxidase was applied to a bilateral pair of lumbar or low thoracic dorsal rootlets 18 hours prior to sacrifice to test for sprouting by labelling primary afferent fibers and terminals in the right (experimental) and left (control) dorsal horns.

Although there is overlap of degenerated and intact primary afferent fields in this preparation, a postulated precondition for sprouting (Murray and Goldberger: J. Neurosci. 6: 3205‐3217, '86), we found no evidence for sprouting of undamaged, myelinated afferent fibers in the experimental dorsal horns. The pattern of labelling was symmetrical in all animals, and the density of labelling was not consistently greater on the experimental side. These results support the conclusions of Rodin et al. (J. Comp. Neurol. 215: 187‐198, '83) and Rodin and Kruger (Somatosens. Res. 2: 171‐192, '84), who also found no sprouting in the rat's dorsal horn after surgical deafferentation, and do not support the assertion that the difference between the results of those studies and earlier studies in cats was due to a lack of overlap of degenerated and intact dorsal roots in the rat.
Neuroanatomical distribution of receptors for three potential inhibitory neurotransmitters in the brainstem auditory nuclei of the cat
Authors: Glendenning Karen K. , Baker Barbara N.
Published: January 2005

In order to visualize the relative abundance of each of three potentially inhibitory neurotransmitters in the nuclei of the brainstem auditory pathway, receptor sites for glycine, GABA‐A, and muscarinic acetylcholine (ACh) have been localized in the cat's brainstem auditory system. Conventional autoradiographic receptor‐binding procedures were used and the distributions of the receptors were inferred from the respective distributions of tritiated strychnine, muscimol, and quinuclidinyl benzilate (QNB) binding sites.

The results show that glycine may be the major inhibitory neurotransmitter in the auditory system as it ascends to the midbrain in that relatively high levels of strychnine binding are present in every major nucleus of the system. In contrast, high levels of muscimol binding of high‐affinity GABA‐A receptors are confined mostly to the dorsal cochlear nucleus, the dorsal nucleus of the lateral lemniscus, and the central and cortical regions of the inferior colliculus, while high levels of QNB binding of muscarinic ACh receptors are seen only in the central and cortical regions of the inferior colliculus.
Immunocytochemical localization of luteinizing hormone‐releasing hormone (LHRH) in the brain and nervus terminalis of the adult and early neonatal gray short‐tailed opossum (Monodelphis domestica)
Authors: Fukuda Marlene Schwanzel , Fadem Barbara H. , Garcia Maria Soledad , Pfaff Donald W.
Published: January 2005

Luteinizing hormone‐releasing hormone (LHRH) was detected by immunocytochemical procedures in cells and fibers in the brain and in the nervus terminalis of the adult and neonatal gray, short‐tailed opossum (Monodelphis domestica). As in several species of eutherian mammals, LHRH‐immunoreactive cells and fibers were seen in the medial septal nuclei, nucleus, and tract of the diagonal band and olfactory tubercle. Surprisingly, few LHRH‐immunoreactive cells were found in the hypothalamus or in the preoptic area in either the adult or neonate. LHRH‐immunoreactive fibers were seen in these regions and were numerous in the median eminence.

The nervus terminalis in the gray opossum showed several distinctive characteristics. Immunoreactive and nonreactive cells, in ganglia along the fascicles of LHRH fibers and frequently lay adjacent to blood vessels. No LHRH‐immunoreactive branches of the nervus terminalis were found in contact with the vomeronasal nerves as they traversed the medial surfaces of the main olfactory bulbs en route to the accessory olfactory bulbs. The LHRH‐immunoreactive fibers in the central roots of the nervus terminalis formed a compact bundle on either side of midline, which coursed obliquely from clusters of ganglion cells on the ventromedial surface of the olfactory bulbs into the septum. Traced through serial sagittal sections, LHRH‐immunoreactive fibers, in continuity with those in the triangular nucleus of the septum, ran down and around the rostal face of the anterior commissure and fanned out into the medial preoptic area.

As previously observed in the fetal guinea pig and rat, LHRH was detected in ganglion cells of the nervus terminalis of the newborn gray opossum preceding its detection in any other area of the brain.
Primary projections and efferent cells of the VIIIth cranial nerve in the monitor lizard, Varanus exanthematicus
Authors: Barbas‐Henry Heleen A. , Lohman Anthony H. M.
Published: January 2005

In order to describe the central relations of both the afferent and efferent components of the VIIIth cranial nerve in one reptile, the methods of anterograde and retrograde axonal transport and anterograde degeneration were used to study the vestibular and cochlear projections and the efferent system of this nerve in Varanus exanthematicus. On the basis of cresyl violet and Klüver‐Barrera staining, five vestibular nuclei, four cochlear nuclei, and two clusters of small cells which could not be designated as strictly auditory or vestibular are distinguished. The vestibular nuclei include the nucleus dorsolateralis, nucleus ventrolateralis, nucleus tangentialis, nucleus ventromedialis, and nucleus descendens. The well‐developed cochlear nuclear complex includes the nucleus angularis, nuclei magnocellulares medialis and lateralis, and nucleus laminaris. The two cell clusters are located dorsolaterally in the brainstem just ventrolateral to the acoustic tubercle.

The primary afferent vestibular fibers coursing in the anterior VIIIth nerve root distribute to the ventral portions of all vestibular nuclei except nucleus ventromedialis, whereas the fibers coursing in the posterior root project to the dorsal portions of these nuclei. In nucleus ventromedialis fibers of both roots do not segregate into ventral and dorsal portions. Other targets of the vestibular fibers are the two cell clusters, the granular layer of the ipsilateral cerebellum, the reticular formation, and the descending trigeminal tract and its nucleus. The primary cochlear fibers coursing in the posterior root terminate in nucleus angularis, nuclei magnocellulares medialis and lateralis, and the inner cell strand of nucleus laminaris. The efferent system is, ipsi‐ and contralaterally in the brainstem, composed of ventral and dorsal cell groups that extend from the level of the principal abducens nucleus caudally where they overlap with the facial motor nucleus. The fibers, which originate from the contralaterally located efferent cells, course beneath the IVth ventricle to exit the brainstem on the ipsilateral side.
Basal forebrain efferents to the medial dorsal thalamic nucleus in the rhesus monkey
Authors: Hreib Kinan K. , Rosene Douglas L. , Moss Mark B.
Published: January 2005

Thalamic efferent connections of the basal forebrain (BF); medial septal nucleus (MS), vertical limb of the diagonal band (VDB), horizontal limb of the diagonal band (HDB), nucleus basalis (NB), and ventral pallidum (VP) were investigated in twelve rhesus monkeys. In five animals, injections of radioactively labeled amino acids were placed in the BF. In four animals, the injections involved different divisions of the NB, HDB, and the most ventral part of the VDB. In those four cases, labeled fibers in the medial forebrain bundle were observed traveling caudally towards the hypothalamus where some turned dorsally to enter the inferior thalamic peduncle. These fibers terminated in the ventral half of the magnocellular part of the medial dorsal thalamic nucleus (MDmc). In a fifth case, the amino acid injection involved most of the MS and the VDB. Labeled fibers traveled caudally from the injection site and entered the stria medullaris. These fibers then traveled caudally before turning ventrally to terminate in the dorsal half of MDmc. To determine which of the diverse neuronal types in the BF gives rise to these thalamic projections, in two monkeys injections of horseradish peroxidase (HRP) were placed into MDmc. Labeled neurons were observed throughout the full extent of the NB, the VDB, the MS, and part of the VP. In order to determine the extent of the cholinergic input to MDmc from the BF, one of the HRP cases was processed for the simultaneous visualization of HRP, and acetylcholinesterase (AChE), the hydrolytic enzyme for acetylcholine, and a second case was processed for simultaneous visualization of HRP, and choline acetyltransferase (ChAT), the synthetic enzyme for acetylcholine. We observed that 30–50% of the HRP‐labeled neurons were putatively cholinergic. In order to determine if the NB projection to MD is a collateral of the NB projection to orbital frontal cortex, one fluorescent retrograde tracer was injected into the orbital frontal cortex and one into MD. This case showed that approximately 5% of the BF neurons that project to MDmc also project to the orbital frontal cortex. These results confirm a significant subcortical projection by which the cholinergic system of the basal forebrain may influence higher cortical functions through the thalamus.
Regenerated optic fibers in goldfish reestablish a crude sectoral order in the visual pathway
Authors: Bernhardt Robert , Easter Stephen S.
Published: January 2005

The goldfish optic pathway is regenerated after an optic nerve crush. We have examined the axonal topography of the regenerated pathway by labeling, with horseradish peroxidase (HRP), axons originating from retinal sectors or annuli. The positions of the labeled axons in the cross section of the pathway were compared to the normal and related to the factors that may influence axonal pathfinding.

The positions of retinal axons in the cross section of the normal pathway are predictable from the retinal addresses of the ganglion cells described by the polar coordinates r (the distance from the optic disc) and θ (the sectoral or clockface position). The two coordinates map orthogonally onto the cross section of the pathway; r varies monotonically along one axis; θ varies along a perpendicular axis.

The normal r‐order, present in the nonregenerated stump of the experimental nerve, was severely degraded and perhaps lost entirely in the regenerated optic nerve, tract, and brachia. Sectoral order was also lost as the axons passed the crush site, but it was reestablished, albeit crudely, in the regenerated tract and brachia where axons tended to occupy positions appropriate to their dorsal, ventral, nasal, and temporal retinal origins. The exit sequence of the regenerated axons from the stratum opticum into the tectal neuropil was normal: temporal first, nasal last.

These results suggest that the regenerating fibers followed some θ specific cue located in the nonaxonal environment. It seems likely that the original axons probably followed the same cue. In contrast, the absence of r‐order suggests that there is no r‐specific cue for the regenerates to follow. It seems likely that the original r‐order was a consequence of nonspecific influences—the orderly spatiotemporal growth of the retina and the existence of a permissive region for axonal growth.
Postnatal development of cat hind limb motoneurons. I: Changes in length, branching structure, and spatial distribution of dendrites of cat triceps surae motoneurons
Authors: Ulfhake Brun , Cullheim Staffan , Franson Peter
Published: January 2005

The postnatal development of length, branching structure, and spatial distribution of dendrites of triceps surae motoneurons, intracellularly stained with horseradish peroxidase, was studied from birth up to 44–46 days of postnatal (d.p.n.) age in kittens and compared with corresponding data from adult cats.

The number of dendrites of a triceps surae motoneuron was about 12, and the arborization of each dendrite generated an average of 12–15 terminal branches. There was no net change in the number of dendrites of a neuron or in the degree of branching of the dendrites despite the occurrence of both a transient remodeling of the dendritic branching structure and changes of the spatial distribution of the dendritic branches during postnatal development.

The perisomatic territory in the transverse plane occupied by the dendritic branches of a motoneuron increased in parallel with the overall growth of the spinal cord. Thus, the relative size of the dendritic territory in this plane was kept almost constant, whereas dendritic branches projecting in the rostrocaudal direction grew much faster than the spinal cord and also became more numerous. At birth the rostro‐caudal dendritic span of individual motoneurons bridged 1:6 to 1:5 of the L7 spinal cord segment length; this figure was 1:3 at 22–24 d.p.n. Hence, in this direction, the growing dendritic branches invaded novel dendritic territories.

The change in dendritic branch length from birth to 6 weeks of age corresponded to an average growth rate of 2 to 4 μm per dendritic branch and day, which implies that the total increase in length of the dendrites of a neuron could amount to 1 mm/day. The increase in branch length did not occur in a uniform or random manner; instead, it followed a spatiotemporal pattern with three phases: From birth to 22–24 d.p.n., growth was particularly prominent in ⩾3rd order preterminal and 2nd through 6th order terminal branches. From 22–24 to 44–46 d.p.n., a large increase in branch length confined to terminal branches of ⩾3rd branch orders was observed. As indicated by topological analysis, this length increase was probably due in part to a resorption of peripheral dendritic branches during this stage of development. From 44–46 d.p.n. to maturity, the increase of dendritic branch length was restricted to preterminal branches of low (⩽4th) branch order.

Topological analysis revealed that the arborization pattern of triceps surae motoneuron dendrites resembled most a tree structure generated by an outgrowth of branches from terminal segments, but also that a transient change in dendritic branching structure appeared to occur during postnatal development.
Distribution and central projections of primary afferent neurons that innervate the masseter muscle and mandibular periodontium: A double‐label study
Authors: Capra Norman F. , Wax Tim D.
Published: January 2005

A double‐label strategy was used to determine the distribution and central projections of primary afferent neurons that innervate the periodontium and muscles of mastication in cats. Central injections of either Fast Blue (FB) or a mixture of wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP) and HRP were made into one of three cytoarchitectonically distinct regions of the spinal trigeminal nucleus. These regions included the subnucleus oralis (Vo), the subnucleus interpolaris (Vi), and the medullary dorsal horn (MDH). In each case, injections were also made into the periodontium of the ipsilateral mandibular teeth or into the ipsilateral masseter muscle. FB injections preceded the peroxidase injections by at least 48 hours and total survival time ranged from 72 to 96 hours. Animals were perfused with phosphate‐buffered paraformaldehyde (4%; pH 7.2). Serial frozen sections were made through the brainstem and trigeminal ganglion. Tetramethylbenzidine was used as a chromagen to demonstrate HRP and sections were viewed with brightfield and epifluorescent illumination. Cells containing peripherally injected tracer were observed in the lateral portion of the ganglion and in the mesencephalic nucleus (Vmes). Double‐labeled ganglion cells were observed in most cats that received periodontal injections in combination with central injections in the dorsal part of spinal trigeminal nucleus regardless of the rostrocaudal level of the central injection. In the animals that received intramuscular injections, double‐labeled ganglion cells were observed only in the animals that received central injections caudal to the Vo. Double‐labeled Vmes perikarya were observed in cats that received either intramuscular or periodontal injections in combination with central injections into the MDH and Vo but not in animals that received injections into the Vi. These results demonstrate that ganglion cell periodontal afferents project to the three major rostrocaudal subdivisions of the spinal trigeminal nucleus while ganglion cell muscle afferents have more limited central projections to caudal regions of the nucleus. Masseter and periodontal Vmes afferents also project to the spinal trigeminal nucleus‐specifically, to the Vo and MDH. These findings are consistent with physiological observations regarding the role of periodontal and masseteric afferents in oral and facial reflexes and somethetic mechanisms.
Regional specialisation for synaptic input and output on a locust intersegmental interneurone with multiple spike‐initiating zones
Authors: Watson A. H. D. , Pflüger H.‐J.
Published: January 2005

A4I1 is a long intersegmental interneurone whose soma lies in the fourth abdominal ganglion and whose axon ascends through, and branches in the thoracic and suboesophageal ganglia and the brain. It receives sensory input in the prothoracic ganglion from wind‐sensitive hairs on the head and prosternum and in the fourth abdominal ganglion from cercal afferents (Pflüger: J. Comp. Neurol. 223:343–357, '84). Spikes can be initiated from both of these ganglia. In the present study the neurone was stained by intracellular injection of cobalt salts for light microscopy and of horseradish peroxidase for electron microscopy. The morphology of its neurites in the thoracic and fourth abdominal ganglia and the distribution of synapses upon them could then be observed and correlated. In the fourth abdominal ganglion the neurone receives input synapses but makes no outputs. In each thoracic ganglion the neurone has fine, varicose ventral neurites and thicker dorsal neurites. The ventral neurites are most abundant in the prothoracic ganglion where they receive only input synapses. In the meso‐ and metathoracic ganglia the ventral neurites also receive inputs, but in addition they make output synapses. In all three thoracic ganglia output synapses are abundant on the dorsal branches, but in the meso‐ and metathoracic ganglia a small number of inputs are also received here. The possibility that the function of the interneurone may not be the same in all of the thoracic ganglia is discussed in the light of its known physiological properties.
In situ localization of myosin and actin in dendritic spines with the immunogold technique
Authors: Morales Marisela , Fifková Eva
Published: January 2005

The in situ detection of macromolecules by means of immunoelectron microscopy provides information about their ultrastructural localization in cellular compartments. With this technique, we have demonstrated that the contractile proteins actin and myosin are both localized in dendritic spines at densities exceeding those of other neuronal compartments. Myosin was associated with actin filaments, with spine plasma membrane, and with membranes of the spine apparatus. Given the dynamic properties of actin and myosin, these data suggest that these proteins may be involved in the mechanism of synatpic plasticity in general and in morphometric change resulting from intense synaptic activation in particular.
Peripheral patterns of calcitonin‐gene‐related peptide general somatic sensory innervation: Cutaneous and deep terminations
Authors: Kruger Lawrence , Silverman James D. , Mantyh Patrick W. , Sternini Catia , Brecha Nicholas C.
Published: January 2005

The distribution of calcitonin‐gene‐related peptide (CGRP) immunoreactivity (IR) was studied in peripheral tissues of rats. The ganglionic origin, somatosensory nature, and anatomic relations of this thin‐axon population were evaluated with particular emphasis on possible nociceptive roles. In animals untreated with colchicine, CGRP‐IR is found in a vast proportion of small‐ and medium‐diameter sensory ganglion cells that give rise to numerous thinly myelinated and unmyelinated axons that display CGRP‐IR throughout the body.

The integumentary innervation consists, in part, of an extensive subpapillary network largely traced to dermal blood vessels, sweat glands, and “free” nerve endings, some of which are found within regions containing only mast cells, fibroblasts, and collagen. Dermal papillae contain CGRP‐IR axons surrounding each vascular loop; other papillary axons end freely or occasionally surround Meissner corpuscles. Intraepithelial axons enter glabrous epidermal pegs, branching and exhibiting terminals throughout the stratum spinosum. A similar pattern is found in hairy skin with additional innervation entering the base and surrounding the lower third of each hair follicle, but apparently not supplying sebaceous glands and arrector pili muscle. Axons innervating nonkeratinized oral epithelium are similar or greater in number and distribution compared to epidermis, often with more extensive branching. The high density of intraepithelial CGRP‐IR innervation does not appear to correlate with the sensitive mechanoreceptor‐based increase in spatial sensory discriminative capacities in the distal portions of the limb.

In deep somatic tissues, CGRP‐IR is principally related to vasculature and motor end plates of striated muscle, but there is an extensive network of thin axons within bone, principally in the periosteum, and focally in joint capsules, but not in relation to muscle spindles or tendon organs.

These findings, together with the distribution in cranial tissues described in an accompanying paper (Silverman and Kruger: J. Comp. Neurol. 280:303–330, '89), are considered in the context of a “noceffector” concept incorporating the efferent role of these sensory axons in various tissues. It is suggested that involvement in tissue maintenance and renewal during normal function, as well as following injury, may predominate over the relatively infrequent nociceptive role of this peptidergic sensory system.
Distribution of neuropeptide y‐containing perikarya and axons in various neocortical areas in the macaque monkey
Authors: Kuljis Rodrigo O. , Rakic Pasko
Published: January 2005

The laminar and areal distribution of neuropeptide Y (NPY)‐containing perikarya and their processes was analyzed immunocytochemically in Brodmann's neocortical areas 17, 18, 7, 22, 3, 4, 24, and 9 (Walker's area 46) in seven macaque monkeys. Most NPY‐containing cells are distributed in two broad bands in layers II–III and V–VI in all areas; relatively few cells can be found in layer I and virtually none in layer IV. Numerous NPY‐containing cells are situated in the white matter immediately subjacent to the cortical gray. Severalfold regional and individual differences in the density of NPY‐positive somata were found in supra‐ and infragranular layers. However, the interareal variations in the density of NPY‐containing somata do not conform to a universal pattern, because of either individual variability or inherent difficulties in standardizing immunocytochemical labeling. In contrast, the laminar differences in the distribution of NPY‐containing axons among cortical areas are consistent in all animals. In general, primary sensory and motor areas have a lesser density of NPY‐containing axons than association and limbic areas. Within this general pattern, area‐specific laminar segregation of NPY‐containing axons occurs. The regional differences in the distribution of NPY‐like immunoreactivity in the neocortex may reflect innate characteristics of local neuronal circuits serving specialized functions.
Localization of Drosophila neurons that contain choline acetyltransferase messenger RNA: An in situ hybridization study
Authors: Barber Robert P. , Sugihara Hidemitsu , Lee Mariko , Vaughn James E. , Salvaterra Paul M.
Published: January 2005

In situ hybridization with radiolabeled complementary RNA (cRNA) probes was used to determine the location of the messenger RNA (mRNA) encoding choline acetyltransferase (ChAT) in Drosophila nervous system. Areas in the cell‐rich cortical regions of the cerebrum and optic lobes hybridized with substantial concentrations of the probe. This contrasted with the cell‐sparse neuropil areas where no significant concentrations of probe were observed. Although most of the cortical regions were substantially labeled, there were regions within all of the areas where labeling was sparse or nonexistent. For example in the lamina, even though the monopolar cell layer appeared to be heavily labeled, there were some neuronal profiles that were not associated with the probe. Moreover, the epithelial glia that form an arch of cell profiles subjacent to the monopolar cells were not labeled, nor were amacrine neurons in the apex of the lamina near the external optic chiasma. The highest concentration of probe (∼140 grains/400 μm2) was observed in the laminar monopolar cell region and the cerebral cortical rind. The next most heavily labeled region (∼90 grains/400 μm2) occurred over cortical cells of the medulla‐lobula. In the peripheral nervous system, label over the antennal sensory neurons amounted to about 75 grains/400 μm2, and the retinular cell layer of the compound eye exhibited about 60 grains/400 μm2. The control probe did not hybridize in significant quantities in either cellular or noncellular regions. This study presents evidence that large numbers of Drosophila cortical and primary sensory neurons contain the messenger RNA necessary for the production of ChAT, the acetylcholine‐synthesizing enzyme. Further, our findings provide baseline information for use in ontogenetic studies of cholinergic neurons in Drosophila, and they also provide normative data for studying the effects of mutant alleles at the Cha or Ace loci upon the transcription of ChAT messenger RNA.
Physiological, morphological, and cytochemical characteristics of a layer 1 neuron in cat striate cortex
Authors: Martin Kevan A. C. , Friedlander Michael J. , Alones Vinessa
Published: January 2005

We have recorded from a small neuron in layer 1 of the striate visual cortex in a 34‐day‐old kitten. It had a simple, orientation‐selective receptive field that was nondirectional and showed length summation. The neuron was injected intracellularly with horseradish peroxidase. Computer‐aided reconstruction revealed that it had a dense axonal plexus confined to layer 1, elongated in the anteroposterior dimension. By means of an antibody directed against a GABA‐like antigen, and postembedding immunocytochemistry, the neuron was found to be strongly immunoreactive. The main input to soma and dendrites of the neuron was from synapses that were not GABA‐L‐immunoreactive, and probably originated from pyramidal cells. The axon of the cell formed synapses on dendritic shafts and spines, whose most likely sources were the apical tufts of pyramidal cell dendrites. These data suggest that such neurons may be involved in local circuits that contribute to the formation of pyramidal cell receptive fields.
Structure‐Function relationships in the rat brainstem subnucleus interpolaris: VI. Cervical convergence in cells deafferented at birth and a potential primary afferent substrate
Authors: Jacquin Mark F. , Chiaia Nicolas L. , Klein Bradley G. , Rhoades Robert W.
Published: January 2005

Possible substrates for peripheral injury‐induced receptive field (RF) changes were assessed in the trigeminal (V) subnucleus interpolaris (SpVi). In adult rats with infraorbital nerve section at birth, 449 cells were studied ipsilateral to the lesion by using electrophysiological methods. Of these, 33 (7.4%) had RFs that included facial vibrissae, guard hairs, and skin, as well as ipsilateral regions normally innervated by cervical primary afferents (ear, neck, shoulder, arm, forepaw). Such non‐V convergence was never seen in 373 normal SpVi cells or in 641 V ganglion cells ipsilateral to the lesion. SpVi cells with cervical RFs discharged to V ganglion shocks and their latencies (1.6 ± 0.7 ms, mean ± s.d.) did not differ from normal (1.4 ± 0.5). Most (71%) projected to the thalamus. None were nociceptive‐biased, and many had unusually discontinuous RFs (48%).

Possible pathways by which cervical inputs might reach SpVi neurons were investigated in additional anatomical and electrophysiological experiments. Eight SpVi cells with cervical RFs were intracellularly labeled with HRP. Although all had dendrites that were polarized toward SpVi regions containing spared mandibular and/or ophthalmic primary afferents, none had dendrites which extended out of SpVi. In other neonatally nerve‐damaged adults, WGA‐HRP was injected bilaterally into forepaw, arm, and shoulder regions. Transganglionic transport was restricted to normal targets. However, WGA‐HRP injections into SpVi retrogradely labeled a total of 46 ± 20 (mean ± s.d.) cells in ipsilateral C1–3 dorsal root ganglia, and 24 ± 8 cells in C4–8 ganglia. In controls, labeled cells were seen only in C1–3 ganglia (32 ± 9). The distribution and number of labeled cells in the somatosensory cortex did not differ in experimental and control cases. No labeled cells were visible in the dorsal column nuclei of either the normal or experimental rats. Thus, retrograde labeling studies suggest that a cervical primary afferent projection to SpVi is a potential substrate for cervical convergence expressed in neonatally deafferented SpVi cells.
Axon‐myelin relationships in rat cranial nerves III, IV, and VI: A morphometric study of large‐ and small‐fibre classes
Authors: Fraher John P.
Published: January 2005

The primary objectives of this study were to determine (1) if quantitative axon‐myelin relationships are similar for large‐ and for small‐fibre classes within individual nerves and (2) if the same axon‐myelin relationships hold for equivalent fibre classes in closely similar nerves. The oculomotor, trochlear, and abducent nerves of the rat were examined since they each contain distinct large‐ and small‐fibre classes and are similar in a wide range of anatomical and developmental respects. Accordingly, morphometric analyses of axon‐myelin relationships were performed separately on large and small fibres of each of the three nerves.

Withineach nerve, the setting of the relationship between the two parameters was found to be different for the two fibre classes: Scatterplots relating sheath thickness to axon perimeter for large fibres were shifted upwards relative to those for small fibres. These differences were also reflected in the positions of the regression lines fitted to the plots and in the g‐ratios.

Significant differences were foundbetweennerves in relation to their large fibres: Those of the abducent nerve had significantly thicker sheaths, those of the oculomotor nerve had significantly smaller axon perimeters, and the myelin sheath–axon perimeter relationship of the abducent nerve differed significantly from that of the other two.

This study therefore shows that morphometric axon‐myelin relationships may differ significantly between equivalent fibre classes of nerves that are closely similar in respect of morphological class, central origin, peripheral distribution, developmental environment, and function.
Deafferentation‐induced expansion of saphenous terminal field labelling in the adult rat dorsal horn following pronase injection of the sciatic nerve
Authors: LaMotte Carole C. , Kapadia Shanta E. , Kocol Christine M.
Published: January 2005

We have examined the effect of the degeneration of sciatic nerve afferents on the distribution of saphenous terminals in the adult rat dorsal horn. Deafferentation was produced by injection into the sciatic nerve of pronase, a combination of proteolytic enzymes, which causes death of ganglion cells and degeneration of their terminal fields. The saphenous terminal fields were labelled by exposing the cut nerve to a combination of horseradish peroxidase (HRP) and wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). Terminals were mainly found in the superficial dorsal horn, indicating that small‐diameter afferents were heavily labelled. In one group of control animals, the normal sciatic and normal saphenous terminal fields were shown to be bilaterally symmetrical. In the experimental group, the initial injection of one sciatic nerve with pronase was followed 4 months later by bilateral HRP/WGA‐HRP labelling of both saphenous nerves. In each animals, the terminal field of the saphenous nerve on the lesioned side was expanded in the medial, lateral, and caudal directions. Medially and laterally, the expanded terminal field overlapped more of the sciatic territory than normal; caudally, saphenous terminals were found in the rostral portion of the L5 segment, in an area normally filled by sciatic terminals and devoid of saphenous terminals. The expansion resulted in a total saphenous area 26% larger than the control side. Electron microscopy demonstrated that the label in both the normal and expanded territories was primarily contained in axons and terminals, with minor transneuronal labelling. Labelled terminals in the expanded areas were both simple terminals with round, clear vesicles, and glomerular terminals with multiple synaptic contacts; these terminal types resemble those previously described for primary afferents in the superficial dorsal horn. Although the preexistence of “silent” synaptic terminals in the expanded areas cannot be disproven, the data support the hypothesis that primary afferents in the adult have the potential to sprout and establish synapses when the conditions of the deafferentation are favorable.
Organization of actin filaments and immunocolocalization of alpha‐actinin in the connecting cilium of rat photoreceptors
Authors: Arikawa Kentaro , Williams David S.
Published: January 2005

A small discrete concentration of actin filaments in the connecting cilium of vertebrate photoreceptors appears to have a role in the morphogenesis of the phototransductive disk membranes (Williams et al., '88). We have visualized these actin filaments in rat rod photoreceptors by decorating them with myosin subfragment‐1. At the site of disk morphogenesis, we observed a cluster of short filaments, with various orientations and their faster growing (barbed) ends at the ciliary plasma membrane. Their association with the liplike structure of an early nascent disk is consistent with their apparent involvement in the initiation of disk môrphogenesis. A few longer decorated filaments extended along the core of the connecting cilium, away from the site of disk morphogenesis, implying that they might have some function other than the shaping of a new disk. Most of the antiactin label was found in the region of the short filaments. The alpha‐actinin immunolabel coincided with that of actin, suggesting that the filaments may be crosslinked by alpha‐actinin.
Anatomical investigation of projections to the basis pontis from posterior parietal association cortices in rhesus monkey
Authors: Schmahmann Jeremy D. , Pandya Deepak N.
Published: January 2005

The projections to the basis pontis from cytoarchitectonically defined subregions of the superior (SPL) and inferior (IPL) parietal lobules were investigated in 14 rhesus monkeys by using the anterograde tracing techniques of autoradiography and horseradish peroxidase histochemistry. The results of our study confirm and complement available information regarding the parietopontine projections. The projections are found in clusters distributed in lamellae approximately concentric to the peduncle. They are directed most heavily towards the peripeduncular and lateral nuclei of the pons. There are also lesser, but nevertheless substantial projections to other nuclei including the intrapeduncular, ventral, dorsolateral, extreme dorsolateral, and dorsal nuclei. The dorsomedial, paramedian, and NRTP nuclei receive only minor projections. The SPL projections are relatively widespread with respect to the more focussed IPL projections. The IPL projections are, in general, situated more laterally and at more rostral levels of the pontine nuclei than are those of the SPL.

The sulcal cortex of the SPL (area PEa) favors the dorsolateral, extreme dorsolateral, and ventral nuclei compared to the light projections to these nuclei from the convexity of the SPL. The sulcal cortex of the IPL, area POa, differs from the gyral cortex in favoring the ventral and extreme dorsolateral nuclei. The rostral IPL differs from the caudal IPL in that the intrapeduncular nucleus receives projections only from rostral regions, while the lateral nucleus receives projections preferentially from caudal regions. The pontine projections from the medial SPL, area PGm, are unique in the parietal lobe in that they include the paramedian nucleus. Projections arising from multimodal regions located caudally in the SPL (areas PEa and PGm) and IPL (areas PG and Opt) are more strongly represented and more laterally placed within the pontine nuclei than projections arising from more rostral, unimodal, posterior parietal regions.

The heavy projections to the pontine nuclei from the posterior parietal cortex, and particularly from those caudal parietal regions that have prominent associative and limbic connections, seem to suggest that the corticopontocerebellar pathways permit a cerebellar contribution not only to the coordination of movement, but also to the modulation and integration of higher function.
A subpopulation of dorsal unpaired median neurons in the blood‐feeding insect Rhodnius prolixus displays serotonin‐like immunoreactivity
Authors: Orchard Ian , Lange Angela B. , Cook Heather , Ramirez Jan‐Marino
Published: January 2005

We describe, for the first time in insects, the presence of serotonin‐like immunoreactive dorsal unpaired median (DUM) neurons. In unfed, untreated Rhodnius prolixus, the cell bodies of these DUM neurons displayed only faint serotonin‐like immunofluorescence without any detectable fluorescence in the axons. There was, however, an extensive serotonin‐like immunoreactive peripheral complex. We have enhanced the immunostaining of the cell bodies and axons of these DUM neurons by using 5,7‐dihydroxytryptamine (5,7‐DHT) and nerve transection, and have further defined their morphology with cobalt backfilling and Lucifer yellow injection.

Injection of 5,7‐DHT resulted in enhanced serotonin‐like immunostaining, after 24 hours, of five DUM neurons in the mesothoracic ganglionic mass. Each DUM neuron possessed bifurcating serotonin‐like immunoreactive axons projecting to the periphery via one of the five bilaterally paired abdominal nerves. Concomitant with the enhanced immunostaining in the cell body and axons of these DUM neurons was the depletion of a serotonin‐like immunoreactive neurohaemal area lying on each of the abdominal nerves and the depletion of serotonin‐like immunoreactive processes on the body wall. Enhancement of cell body and axon immunostaining was also observed in preparations in which the abdominal nerves had been transected 24 hours previously.

The location and morphology of these DUM neurons were studied in further detail by using cobalt backfilling of the abdominal nerves and intracellular injection of Lucifer yellow followed by immunohistochemistry. The five serotonin‐like immunoreactive DUM neurons were found to represent a sub‐population in a group of ten DUM neurons located in the mesothoracic ganglionic mass and associated with the abdominal nerves. Each abdominal nerve received projections from two DUM neurons, only one of which was serotonin‐like immunoreactive.

Electrophysiological recordings revealed that the serotonin‐like immunoreactive DUM neurons of Rhodnius had similar properties to previously described octopaminergic DUM neurons of insects.

The five DUM neurons in Rhodnius appear to represent a subpopulation of DUM neurons containing serotonin.
Modality‐specific axonal projections in the CNS of the flies Phormia and Drosophila
Authors: Murphey R. K. , Possidente Debra , Pollack Gerald , Merritt D. J.
Published: January 2005

There is a rich history of behavioral and physiological studies on the leg sensory systems of flies. Here we examine the anatomy of the sensory axons of two species of fly and demonstrate that the location of the axonal projections in the CNS can be correlated with the modality they encode. We studied receptors associated with proprioceptive, tactile, and multimodal hairs. Proprioceptive hairs occur in clusters, called hair plates, and are situated near joints. The neuron innervating each proprioceptive hair has a large axon and coarse arborization in the intermediate neuropil. Tactile receptors have smaller arbors, which are located in a ventral region of the thoracic neuromere. Finally, the multimodal hairs are each innervated by one tactile and four chemosensory neurons. The single tactile neuron has a central arbor that is indistinguishable from those of the tactile hairs; the four chemosensory neurons project to yet a third region of neuropil near the ventral surface of each neuromere. Thus there is a clear modality‐specific segregation of axonal arbors in the CNS. This organization is identical in Phormia and Drosophila and thus apparently highly conserved within the Diptera. We presume that, as in other insect sensory systems, this anatomical specificity is linked to synaptic specificity.