bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatotopic organization of inputs from the hand to the spinal gray and cuneate nucleus of monkeys with observations on the cuneate nucleus of humans
Authors: Florence S. L. , Wall J. T. , Kaas J. H. 
Published: January 2005

AbstractCentral termination patterns of primary afferents from the hand and forelimb were studied following subdermal injections of HRP conjugates in macaque monkeys. In the middle layers of the dorsal horn of the spinal cord, afferents from digits 1–5 terminated in a rostrocaudal sequence in separate, elongated columns at cervical levels 5–7. Afferents from teh glabrous digits extended to the medial margin of the dorsal gray, while afferents from the dorsal skin of the digits terminated more laterally. Afferents from the dorsal hand and palm terminated lateral to those from the digits, while inputs from the forearm occupied tissue rostral and caudal to the representation of the hand. In the cuneate nucleus, terminations from each digit formed an elongated column that was densely labelled in the central pars rotunda and sparsely labelled in both the rostral and caudal reticular poles. Within the pars rotunda, digits 1–5 were represented in order from lateral to medial. Inputs from the digit tips terminated ventral to inputs from the proximal digits. Afferents from the dorsal skin of the digits terminated in an even more dorsal position, while the most dorsal portion of the pars rotunda related to the glabrous and dorsal hand. Within the pars rotunda, terminations from specific parts of the hand overlapped parcellated clusters of neurons. These clusters were densely reactive for cytochrome oxidase (CO) and were surrounded by myelinated fibers. Much sparser label in the reticular poles was found consistently only after injections in the glabrous digits. Inputs to the poles appeared diffuse and overlapping while preserving some somatotopic order. When treated for CO or stained for Nissl substance or myelin, the pars rotunda of humans showed parcellation patterns that closely resembled the patterns seen in monkeys. From the relationship of inputs to the CO dense cell clusters in monkeys, it was possible to postulate in detail the somatotopic organization of inputs to pars rotunda of humans.The present results provide a comprehensive description of the somatotopic patterns of termination of afferents from the skin of the hand and forearm in the spinal cord and cuneate nucleus of macaque monkeys. A direct relationship of afferent somatotopy and identifiable cell clusters in the pars rotunda of the cuneate nucleus is further demonstrated. Finally, the patterns of cell clusters in the pars rotunda of macaque monkeys and humans suggest that the somatotopic organization of the cuneate nucleus may be very similar in human and nonhuman primates.
Histochemistry of acetylcholinesterase and immunocytochemistry of an acetylcholine receptor‐like antigen in the brain of the honeybee
Authors: Kreissl Sabine , Bicker Gerd 
Published: January 2005

AbstractA histochemical staining method for acetylcholinesterase (AChE) and an antiserum raised against nicotinic acetylcholine receptors (AChR) of locust nervous tissue were applied in order to reveal certain candidates of cholinergic pathways in the brain of the honeybee. The AChE staining marked layers in the optic lobes, fibers connecting the two brain hemispheres, and fiber tracts as well as soma clusters within the protocerebrum. The calycal input regions of the mushroom bodies were labelled, whereas the intrinsic Kenyon cells showed no staining. Although the antennal afferents projecting into the dorsal lobe showed strong AChE activity, projections into the antennal lobe showed rather weak staining.Application of the antiserum against the AChR showed immunoreactivity in neuropiles, tracts, somata, and the antennal nerve. The immunoreactivity of the optic lobes coincided with the banding pattern of the AChE staining. A particularly striking overlap of AChR immunoreactivity and AChE staining was found in the lip neuropile of the mushroom bodies, which would suggest a cholinergic input into this neuropile via fibers of the median antennoglomerular tract. Because the antiserum against locust AChR binds in neuropiles displaying AChE activity, we conclude that this antiserum also cross‐reacts with the bee's receptor. This interpretation is supported by experiments showing α‐bungarotoxin (α‐BTX) binding sites in some areas of strong immunoreactivity.
Mormyromast electroreceptor organs and their afferent fibers in mormyrid fish: I. Morphology
Authors: Bell C. C. , Zakon H. , Finger T. E. 
Published: January 2005

AbstractMormyromast electroreceptor organs are the most numerous type of electroreceptor organs in mormyrid electric fish and provide the sensory information necessary for active electrolocation. Mormyromast organs and their primary afferent fibers have not been studied very extensively. Both morphological and physiological questions remain to be answered before the neural basis of active electrolocation in mormyrids can be understood. This paper examines four different aspects of the morphology of mormyromast organs and afferent fibers: (1) Mormyromast organs in the skin. The innervation patterns for the two types of separately innervated sensory cells in the mormyromast organ are described on the basis of silver‐stained whole mounts of skin. The number of sensory cells per mormyromast organ increases linearly with fish growth for both types of sensory cells. (2) Relation between peripheral sensory cell innervated and central zone of termination for mormyromast afferent fibers. The afferent fibers arising from the two types of sensory cell in the mormyromast organ project to separate zones of the electrosensory lateral line lobe, as shown by using retrograde labeling with horseradish peroxidase. (3) Central trajectories and terminal arbors of mormyromast afferent fibers. These aspects of mormyromast fibers are described by using intracellular staining of individual fibers as well as whole nerve staining of an electrosensory nerve. (4) Fine structure of mormyromast afferent terminals in the electrosensory lateral line lobe. Afferent fibers make various synaptic contacts, including contacts of a mixed type, gap junction‐chemical, onto a restricted class of granule cells. The fine structure is described based on electron microscopy of horseradish‐peroxidase‐labeled fibers.The results provide an anatomical base for current physiological studies on mormyromast afferent fibers.
Visual area MT in the Cebus monkey: Location, visuotopic organization, and variability
Authors: Fiorani Mario , Gattass Ricardo , Rosa Marcello G. P. , Sousa Aglai P. B. 
Published: January 2005

AbstractThe representation of the visual field in the dorsal portion of the superior temporal sulcus (ST) was studied by multiunit recordings in eight Cebus apella, anesthetized with N2O and immobilized with pancuronium bromide, in repeated recording sessions. On the basis of visuotopic organization, myeloarchitecture, and receptive field size, area MT was distinguished from its neighboring areas.MT is an oval area of about 70 mm2 located mainly in the posterior bank of the superior temporal sulcus. It contains a visuotopically organized representation of at least the binocular visual field. The representation of the vertical meridian forms the dorsolateral, lateral, and ventrolateral borders of MT and that of the horizontal meridian runs across the posterior bank of ST. The fovea is represented at the lateralmost portion of MT, while the retinal periphery is represented medially.The representation of the central visual field is magnified relative to that of the periphery in MT. The cortical magnification factor in MT decreases with increasing eccentricity following a negative power function. Receptive field size increases with increasing eccentricity. A method to evaluate the scatter of receptive field position in multiunit recordings based on the inverse of the magnification factor is described. In MT, multiunit receptive field scatter increases with increasing eccentricity.As shown by the Heidenhain‐Woelcke method, MT is coextensive with two myeloarchitectonically distinct zones: one heavily myelinated, located in the posterior bank of ST, and another, less myelinated, located at the junction of the posterior bank with the anterior bank of ST.At least three additional visual zones surround MT: DZ, MST, and FST. The areas of the dorsal portion of the superior temporal sulcus in the diurnal New World monkey Cebus are comparable to those described for the diurnal Old World monkey, Macaca. This observation suggests that these areas are ancestral characters of the simian lineage and that the differences observed in the owl monkey may be secondary adaptations to a nocturnal ecological niche.
Brainstem facial‐motor pathways from two distinct groups of stapedius motoneurons in the cat
Authors: Guinan John J. , Joseph Michael P. , Norris Barbara E. 
Published: January 2005

AbstractTo determine the brainstem origins and axonal routes of stapedius motoneurons, we labeled motoneurons by injecting cat stapedius muscles with horseradish peroxidase. Some injections were made in normal cats and some in cats in which the middle segment of the internal facial genu had been cut. By tracing labeled axons and by comparing the locations of labeled cell bodies in normal and lesioned cats, we divided stapedius motoneurons into two groups: “perifacial” and “accessory.” Perifacial stapedius motoneurons have cell bodies located around the motor nucleus of the facial nerve and axons which follow the classical course of facial motor axons through the internal genu of the facial nerve. Accessory stapedius motoneurons have cell bodies near the descending facial motor root and axons which ascend to the rostral tip of the internal facial genu, abruptly reverse direction, and then join the descending facial motor root. The sharply hooked course of axons of accessory stapedius motoneurons is similar to the course of axons from other accessory nuclei of cranial nerves V‐VII. Our present results, with those of McCue and Guinan (J. Neurophysiol. 60:1160–1180, '88), demonstrate that cats have two groups of stapedius motoneurons which can be separated anatomically by the locations of their cell bodies or by the courses of their axons, and which, on the average, have different response properties.
Enkephalin‐immunoreactive neuronal projections from the medulla oblongata to the intermediolateral cell column: Relationship to substance P–immunoreactive neurons
Authors: Sasek Cathrine A. , Helke Cinda J. 
Published: January 2005

AbstractThe present study investigated the ventral medullary distribution of enkephalin‐immunoreactive neurons that project to the intermediolateral cell column and the relationship of these neurons to substance P–immunoreactive neurons. Neurons that projected to the intermediolateral cell column were identified by the presence of rhodamine‐labeled microspheres within the neuronal cell body after an injection of the microspheres into the intermediolateral cell column of the third thoracic spinal cord segment. Enkephalin‐ and substance P‐immunoreactivities were identified by dual‐color immunohistochemistry. Enkephalin‐immunoreactive neurons that projected to the intermediolateral cell column were present in the raphe magnus, the nucleus reticularis magnocellularis pars alpha, the paragigantocellular reticular nucleus, and the parapyramidal region. These neurons were present throughout the rostrocaudal extent of each of these nuclei. However, in the raphe magnus the greatest number was present at more rostral levels of the nucleus. The morphology and distribution of enkephalin‐immunoreactive neurons that projected to the intermediolateral cell column were similar to those of enkephalin‐immunoreactive neurons that were not observed to contain rhodamine‐labeled microspheres. Substance P– and enkephalin‐immunoreactive neurons that projected to the intermediolateral cell column were present in similar distributions in each of the nuclei studied, except the raphe magnus. The raphe magnus contained more enkephalin‐ than substance P–immunoreactive neurons at rostral levels and more substance P‐immunoreactive neurons than enkephalin‐immunoreactive neurons at caudal levels. Coexistence of substance P‐ and enkephalin‐immunoreactivities in ventral medullary neurons that projected to the intermediolateral cell column was rarely seen. These studies support the hypothesis that ventral medullary enkephalinergic neurons project to the intermediolateral cell column where they could act to modulate preganglionic sympathetic activity.
Modulation of disk margin structure during renewal of cone outer segments in the vertebrate retina
Authors: Corless Joseph M. , Worniałło Ewa , Fetter Richard D. 
Published: January 2005

AbstractIn the process of disk renewal in retinal cone outer segments (COSs), apical displacement of disks must be coupled to systematic reductions in disk area and perimeter in order to retain overall conical geometry. We have quantified these changes in disk area and perimeter segment lengths by morphometric analyses of cross sections of fully formed disks taken from basal to apical ends of COSs. Specifically excluded from these analyses are data arising from partial or incomplete disks within the COS, which do not conform to the conical geometry and which constitute a minor fraction of the COS disk population. Thus, our results address the long‐range pattern of structural changes affecting the major population of disks along the length of the COS. Our data indicate that decreases in total disk margin length associated with apical displacement of fully formed disks are due to decreases in the length of the margin opposite the cilium, i.e., the open margin segment. In contrast, the average length of the closed margin segment remains constant or increases slightly in the apical direction.The open margins of frog COS disks have recently been shown to possess a distinctive lattice of membrane‐associated components (Fetter and Corless: Invest. Ophthalmol. Vis. Sci. 28:646–657, '87). We have also examined COSs by the freeze‐fracture, deep‐etch technique for evidence of a mechanism whereby measured changes in open margin length may be accommodated while maintaining the overall organization of the open margin segments. In regions of membrane continuity between open margins and the COS plasma membrane, we have observed elevated ridges on the plasma membrane that (1) tend to lie parallel to the open margin segments, (2) have a similar axial spacing, (3) occasionally demonstrate interconnecting filaments similar to those of the open margin lattice, and (4) appear to have a particulate substructure. The mechanism proposed for reducing open margin length involves tangential displacement of the lateral edges of the open margin lattice to the adjacent plasma membrane. These shifted lattice domains initially give rise to the plasmalemmal ridges, which subsequently disassemble, and whose components become redistributed in the COS plasma membrane. These structural features of COS open margins suggest several revisions of our earlier model of disk morphogenesis (Corless and Fetter: J. Comp. Neurol. 257:24–38, '87), which was based on the margin structure of ROS disks alone.Eckmiller (J. Cell Biol. 105:2267–2277, '87) has recently proposed that partial disks observed within the COS represent sites of new disk formation. We evaluate the consequences of partial disk geometries for local remodelling of the open margin lattice and briefly outline an alternative interpretation of the partial COS disks that is fully consistent with available morphological data.
Photoreceptor topography of the retina in the adult pigtail macaque (Macaca nemestrina)
Authors: Packer Orin , Hendrickson Anita E. , Curcio Christine A. 
Published: January 2005

AbstractIn spite of the crucial role retinal photoreceptors play in mapping optical images into a pattern of neural excitation, there are no complete studies of photoreceptor topography in any primate retina. We have measured the spatial density and inner segment areas of cones and rods across the whole mounted retinas of three adult pigtail macaques (Macaca nemestrina) and constructed maps of photoreceptor density and inner segment diameter.These retinas contain an average of 3.1 million cones (2.8–3.3 million), with an average peak foveal cone density of 210,000 cones/mm2 (190,000–260,000 cones/mm2). Cone density falls steeply with increasing eccentricity, to 100,000 cones/mm2 at 200 μm from the fovea, and to 50,000 cones/mm2 at 750 μm. Imposed on this gradient is a “streak” of higher cone density along the horizontal meridian. At equivalent eccentricities, cone density is higher in nasal and inferior retina. Cone inner segments increase in diameter from 2.3 μm at the foveal center to 11 μm in far temporal retina and 10 μm in far nasal retina.These retinas contain an average of 60.1 million rods (44.9–75.3 million). Rod density is zero within 20 μm of the foveal center, increases to the crest of a “rod ring” at the eccentricity of the optic disk, and then declines. Central rod topography is asymmetric, with higher densities in superior retina. Density along the crest of the rod ring peaks in superior retina at 177,000 rods/mm2, dips as low as 120,000 rods/mm2 along the horizontal meridian, and increases to about 150,000 rods/mm2 in inferior retina. Far peripheral rod topography is relatively symmetric around the fovea. Rod inner segment diameter ranged from 1.5 μm in the fovea to 4 μm at the temporal edge and 3.4 μm at the nasal edge of the retina. At eccentricities exceeding 6 mm, rod inner segment diameter was greater temporally than nasally.Cone inner segments cover 85–90% of the central fovea, with extrareceptor space accounting for the remainder. Cone coverage declines with increasing eccentricity to 20% at the temporal edge and 35% at the nasal edge of the retina. In contrast, rod coverage increases from zero at the foveal center to a maximum of 65% in temporal retina and 50% in nasal retina.The photoreceptor topography of the pigtail macaque is qualitatively similar to that of other macaques and to humans. Photoreceptor topography is formed by a complex interaction between regional changes in cone and rod density and inner segment diameter.
Terminal arbors of single ON‐center and OFF‐center X and Y retinal ganglion cell axons within the ferret's lateral geniculate nucleus
Authors: Roe Anna W. , Garraghty Preston E. , Sur Mriganka 
Published: January 2005

AbstractThe lateral geniculate nucleus of the ferret contains not only eye‐specific layers, but a further subdivision of layers A and A1 into inner and outer sublaminae that contain, respectively, ON‐center and OFF‐center cells (Stryker and Zahs, '83). To study how the arbors of single retinal ganglion cell axons correlate with these cellular divisions, we have examined the morphology of physiologically classified retinal axons in the ferret's lateral geniculate nucleus.As in cats, we could classify retinal axons as X or Y on the basis of a number of physiological criteria. X and Y axons have distinct patterns of termination in the lateral geniculate nucleus. Contralateral X axons innervate lamina A and ipsilateral axons lamina A1. X axons are further segregated in these laminae so that ON‐center axons terminate in the inner sublamina, and OFF‐center axons in the outer sublamina. We did not observe any branches of X axons innervating the medial interlaminar nucleus or the midbrain. Y axons have much larger terminal arbors and exhibit greater variation in their terminations. Generally, within layers A and A1, ON‐center Y axons innervate the inner sublamina and OFF‐center Y axons innervate the outer sublamina. However, they often innervate both sublaminae, and occasionally have a few boutons in the inappropriate lamina as well. Y axons also terminate in the dorsal C laminae, the interlaminar zones, and the medial interlaminar nucleus; branches of these axons course toward the midbrain, presumably to innervate the superior colliculus. Thus, whereas the Y pathway in the ferret is one of high divergence, the X pathway appears to be the substrate for segregated ON and OFF channels through the lateral geniculate nucleus.
Primate spinothalamic pathways: I. A quantitative study of the cells of origin of the spinothalamic pathway
Authors: Apkarian A. Vania , Hodge Charles J. 
Published: January 2005

AbstractIn six monkeys spinothalamic (STT) cells were retrogradely labeled by injecting 2% wheat germ agglutinin–conjugated horseradish peroxidase into the somatosensory thalamus. Following a 5‐day survival period, the animals were perfused and the tissue was removed and processed with the tetramethyl benzidine technique. In all animals there were HRP‐labeled STT cells in all segments of the spinal cord. In one old world monkey, the injection included most of the thalamus and resulted in 18,235 estimated total number of STT cells. Of this total, 35% were located in the upper cervical segments (C1–C3), 18% were located in C4–C8, 19% were in the thoracic spinal cord with most found in T1–T3; 6% were in L1–L3, 13% were in L4–L7, and 7% were in the coccygeal segments. Of the total labeled STT cells, 17% were found in the spinal cord ipsilateral to the thalamic injection; 53% of these cells were located in C1–C3 primarily in lamina VIII. The percentage of label found in the contralateral lower cervical region laminae I–III (43–50%), IV–VI (33–48%), and VII–X (8–17%) was similar among three animals with similar thalamic injections.The distributions of the shapes of the labeled STT cells were similar for each lamina between the lower cervical and lower lumbar regions. The mean diameter of the labeled STT cells varied with spinal cord segment and lamina. The lamina I STT cells were the smallest. In the cervical spinal cord, lamina VIII STT cells had the largest diameters, while in the lumbar region laminae IV–VI had the largest STT cells.
Development of location‐specific hair cell stereocilia in denervated embryonic ears
Authors: Corwin Jeffrey T. , Cotanche Douglas A. 
Published: January 2005

AbstractThe developmental mechanisms that allow physiological coding of acoustic pitch have remained unexplained. Cochlear hair cells that have different structures respond to different sound frequencies and synapse with neurons that project to different locations in the brain. How do these hair cells develop appropriate structures, and how are the connections between specific hair cells and the neurons that code for their pitch sensitivities matched? We have investigated one aspect of this by denervating embryonic chicken ears, before the time of hair cell production, and then transplanting them to the aneural chorioallantoic membrane of host embryos where they have continued to develop. We report that vestibular and auditory hair cell phenotypes differentiate appropriately and that correct gradients of hair cell structural phenotypes, as expressed in stereocilia bundles, develop in the cochleae of these denervated ears. Therefore, the normal development of gradients in hair cell stereocilia properties must be controlled by location‐specific cues originating in the ear itself. Neuronally directed modification of target cell phenotypes is not required for the quite specific phenotype development represented by the stereocilia bundles of individual hair cells and the connectional matching in the numerous distinct peripheral information lines of the auditory system.