bluuebunny/crossref_metadata_2025 huggingface dataset:
Retinotectal map formation in dually innervated tecta: A regeneration study in Xenopus with one compound eye following bilateral optic nerve section
Authors: Straznicky Charles , Tay David
Published: January 2005

Retinotectal map formation was studied during regeneration in young adult Xenopus. Right compound double‐temporal eyes (TT) were formed in tailbud stage embryos by the fusion of two temporal halves of the eye blastema in the same orbit. In other animals right compound double‐nasal eyes (NN) were prepared. In both combinations the left eye was kept intact. After metamorphosis the right and left optic nerves were sectioned to induce optic fiber regeneration from each eye to both tecta. The patterns of retinotectal projections from the compound and normal eyes were studied from 37 to 364 days after optic nerve section, using electrophysiological recording of the visuotectal projections and 3H‐proline autoradiographic assay from one of the two eyes.

The left normal eyes projected in a retinotopic fashion, across the entire extent of the right and left dually innervated tecta. In contrast, the right compound eye projections were confined to the rostrolateral or to the caudomedial part of the right and left tecta in TT and NN animals, respectively. These tectal areas corresponded to the termination of temporal and nasal hemiretinal fibers of the normal eye. Discontinuous, interdigitating projection patterns from the right and left eyes were found in parts of the tecta where the compound and the normal eye projections overlapped.

These results indicate that the normal optic fiber projections caused the originally expanded compound eye projections to be restricted to the corresponding part of the dually innervated tecta. It is suggested that the orderliness and the extent of the retinotectal map are established by the competition and interaction of optic fibers based on stable positional programming of the retinal ganglion cells.
The organization of subcortical projections of the hamster's visual cortex
Authors: Lent Roberto
Published: January 2005

The subcortical projections of the hamster's visual cortex were determined by use of injections of tritiated proline and heat lesions placed in different cortical loci. The brains were processed for autoradiography and silver impregnation of degenerating axons. Striate cortex was shown to project ipsilaterally to the dorsocaudal region of the caudate nucleus, a dorsolateral area within the thalamic reticular nucleus (RT), a laterodorsal region of the nucleus lateralis anterior (LA), the rostral half of nucleus lateralis posterior (LP), the whole territory of the dorsal (dLGN) and ventral (vLGN) geniculate nuclei, the anterior (PA) and posterior (PP) pretectal nuclei, the superior colliculus (SC), and the precerebellar pontine nuclei. In addition, the medial visual area (18b) was shown to project to a medial band of LA and part of the caudal half of LP, while the adjoining parietal cortex was seen to terminate in a lateral part of the caudate, a ventral band of LA, and the ventral half of rostral LP. Segregation of different cortical inputs was clear in LA, LP, caudate, and pons. The projections to dLGN, vLGN, SC, LP, and PA were retinotopically organized. Clear evidence of some topography was found within RT, PP, and the pons, although a consisten map could not be derived from the data.
Reevaluation of projections from the mesencephalic trigeminal nucleus to the medulla and spinal cord: New projections. A combined retrograde and anterograde horseradish peroxidase study
Authors: Ruggiero David A. , Ross Christopher A. , Kumada Mamoru , Reis Donald J.
Published: January 2005

Microinjection of horseradish peroxidase (HRP) into the medullary parvocellular reticular formation (NPvc) resulted in retrograde labeling of neurons throughout the mesencephalic trigeminal nucleus (Mes V). Labeled cells were large and ovoid and were distributed primarily in the expanded pontine part of the nucleus. However, none of the small neurons in Mes V were labeled. Injections of HRP made into adjacent brainstem structures including the nucleus gigantocellularis, ventrolateral reticular formation, vestibular complex, and the spinal trigeminal nucleus failed to label neurons in Mes V. Injections made into the medullary raphe and into regions reported to receive inputs from Mes V–spinal cord, nucleus tractus solitarius, hypoglossal nucleus, and facial nucleus–were also not followed by transport to Mes V. Anterograde axonal transport of HRP from the region of reticular formation innervated by Mes V also labeled axons projecting to Mes V and to visceral and somatic sensorimotor nuclei in the lower brainstem. Recent reports of afferents from the amygdala to Mes V suggest that reflexes involving the mesencephlic trigeminal nucleus might be modulated by signals from limbic and autonomic as well as somatic centers in the brain.
Selective uptake of lucifer yellow by retinal cells
Authors: Sarthy P. Vijay , Johnson Steve M. , Detwiler Peter B.
Published: January 2005

When turtle retinae were incubated with the fluorescent dye, lucifer yellow, in the absence of Ca2+, the dye was selectively accumulated by cell bodies located in the inner nuclear layer (INL). The morphological features of the labeled cells suggested that they were bipolar cells. Other fluorescent dyes, Procion yellow and Primulin, were also taken up by somata in the INL, in the absence of external Ca2+, although the identity of the labeled cells was uncertain. As with turtle retina, lucifer yellow was accumulated predominantly by cell bodies in the INL of goldfish, frog, and rat retinae. Lucifer yellow uptake appeared to be independent of synaptic activity since dark‐adaptation or aspartate treatment of retinae did not alter the dye uptake. Further, retinae from dystrophic (RCS) rats showed uptake similar to that seen in normal rat retinae. After uptake, most of the dye was found intracellularly as patches or vacuoles in the somata of the labeled cells. Dye uptake was not inhibited by removal of Na+ from the incubation medium. Further, prior treatment with metabolic inhibitors, cyanide and iodoacetate, or cytochalasin B, did not block the dye uptake.
An analysis of the number and composition of the synaptic populations formed by photoreceptors of the fly
Authors: Nicol D. , Meinertzhagen I. A.
Published: January 2005

The photoreceptor terminals of newly eclosed female flies, Musca domestica, have been sampled in the first optic neuropile (or lamina) in one of two ways: first, in large number (n = 760) from single sections and second, from serial electron micrographs of the six terminals within each of three cartridges. Both sampling methods concur in assessing the number of synapses established with the two principal monopolar relay interneurons, L1 and L2, within each cartridge. Each receptor is calculated to be presynaptic at about 200 ± 40 (2 SE) synapses. This value considerably exceeds previous estimates, primarily because we took careful account of the appearance of synapses in different section planes. The number of these synapses correlates highly with the area of receptor terminal presynaptic membrane, so that each synapse is allotted, on average, about 1.6 μm2. The synapses are evenly graded in their distribution with an unexplained 23% decrease in both membrane perimeter and synapse number halfway along their receptor terminal's length. The numbers of synapses per receptor did not vary systematically within two horizontal (3 × 20 cartridge) strips of frontal, equatorial lamina sampled. Individual synapses are elongate tetrads (Burkhardt and Braitenberg, ′76) with two pairs of postsynaptic elements. The first pair is invariably contributed by the interneurons L1 and L2 (one each). The second pair comes either from the α processes of an amacrine cell or from a glial cell. In the distal lamina, however, L3 contributes one of the two postsynaptic processes, the second being αor glial. The overall ratio of postsynaptic involvement at distal synapses (α:glial:L3) is 55%, 20%, and 12% respectively, the remainder being unidentified.
Cells of origin of the spinoreticular tract in the monkey
Authors: Kevetter Golda A. , Haber Lawrence H. , Yezierski Robert P. , Chung Jin Mo , Martin Richard F. , Willis William D.
Published: January 2005

The distribution of the cells of origin of the primate spinoreticular tract was determined following injections of horseradish peroxidase (HRP) into the pontomedullary reticular formation in Macaca fascicularis. Five animals received large bilateral injections which included the raphe nuclei and seven monkeys received smaller, unilateral injections. Sections sampled were from upper cervical levels, the cervical enlargement, upper and lower thoracic levels, and lumbosacral levels. The laminar distribution of spinoreticular cells in all spinal cord levels was comparable. More than half of the labeled cells were located ventromedially, in laminae VII and VIII. HRP‐labeled cells were also found in the dorsal horn, primarily in the lateral reticulated part of lamina V. Some cells were also found in laminae I and X. Spinoreticular cells in the lumbosacral spinal cord mainly projected to the contralateral brainstem. In the cervical enlargement, however, a bilateral distribution of cells was observed following unilateral injections of HRP. Most spinoreticular cells were multipolar neurons with extensive dendritic ramifications. The distribution of spinoreticular cells is similar to the distribution of spinal cord neurons that project to the medial thalamus, but different from that of spinal neurons projecting to the ventrobasal complex. The anatomical organization of the spinoreticular tract is consistent with a role for this pathway in nociception.
Connections between the frontal eye field and pretectum in the monkey: An anterograde/retrograde study using HRP GEL and TMB neurohistochemistry
Authors: Leichnetz George R.
Published: January 2005

Horseradish peroxidase (HRP) gel implants in the frontal eye field (FEF) of macaque monkeys, processed with tetramethylbenzidine (TMB) neurohistochemistry and studied with darkfield microscopy, demonstrated bidirectional HRP labeling of the afferents and efferents of this cortical area. It was evident that among the entire scope of its inputs, the FEF received a prominent afferent projection from the nucleus of the optic tract (NOT, nucleus limitans) and the suprageniculate nucleus, and projected to a medial subdivision of NOT, sublentiform nucleus, nucleus of the pretectal area, nucleus of the posterior commissure, and the rostral periaqueductal gray. The directafferent projections to FEF from NOT could provide a route for visual inputto reach FEF via the pretectum without first going to the visual cortex. The efferents probably represent the pathway through which FEF influences pupillary dynamics known to accompany, or occur independently of, eye movements.
The corticopontine system in the rat. II. The projection pattern
Authors: Wiesendanger R. , Wiesendanger M.
Published: January 2005

The projection from various cortical areas to the pontine nuclei (PN) of rats was investigated with anterograde tracing methods. As a general topological rule, a medial to lateral succession of the PN projection fields from the motor, somatosensory, and visual cortices was observed. Apart from the main “private” projections, each cortical area was found to send fibers also to disjunctive “extra‐projection” territories which receive convergent inputs from two or more cortical areas. The sensorimotor and visual cortices provide the bulk of corticofugal fibers, but contributions from the following association areas were noted: frontal cortex, (dependent of the thalamic mediodorsal nucleus), rhinal sulcus region, and cingulate cortex.
Laminar organization of mitral and tufted cells in the main olfactory bulb of the adult hamster
Authors: Macrides Foteos , Schneider Stephen P.
Published: January 2005

Morphometric analyses of Golgi‐impregnated mitral and tufted cells in the main olfactory bulb of the hamster indicate that these second‐order neurons cannot be considered a homogeneous population. They are comprised of several categories based on differences in the sizes and spatial organizations of their dendritic fields and in their likely patterns of lateral and recurrent interactions with granule cells and/or periglomerular cells. External tufted cells have their somata in the periglomerular region or at the superficial border of the external plexiform layer (EPL) and can be subdivided into three morphological categories. Many external tufted cells lack secondary dendrites, i.e., all of their dendrites arborize within glomeruli. Most of these neurons are not in positions where they could receive synaptic contacts from granule cells and thus are likely to receive interneuronal input predominantly from periglomerular cells. Another category of external tufted cells is characterized by secondary dendrites which are highly branched and form dense but spatially restricted fields in the EPL. In contrast, external tufted cells in the third category have sparsely branched secondary dendrites which extend tangentially in the EPL and tend to be asymmetrically distributed with respect to the soma. Most of the deeperlying tufted cells, and the mitral cells, have sparsely branched secondary dendrites whose lengths and laminar distributions within the EPL are correlated with the depths of their parent somata. Internal tufted cells, which have their somata in the deep one‐third of the EPL, and mitral cells exhibit the largest secondary dendritic fields. These fields extend tangentially within the EPL in relatively symmetric radial patterns from their parent somata and envelop substantial proportions of the EPL. Middle tufted cells have their somata in the superficial two‐thirds of the EPL and exhibit secondary dendritic morphologies which are intermediate between those of internal and external tufted cells. These differences in the size and spatial organization of secondary dendritic fields are likely to be associated with differences in the amount and spatial distribution of lateral and recurrent inhibition mediated through synaptic contacts with granule cells. External tufted cells which lack secondary dendrites have large glomerular arbors that are comparable in size to those of mitral and internal tufted cells, whereas external tufted cells with secondary dendrites and middle tufted cells tend to have relatively small glomerular arbors. The morphological differences among mitral and tufted cells and the likely differences in their synaptic interactions within the olfactory bulb, together with recent evidence that these neurons differ in their pharmacology and in their patterns of interconnections with more central regions of the forebrain, suggest that the mitral and tufted cells and the central olfactory circuits may be organized as functionally defined parallel pathways.
Glutamate‐induced cellular injury in isolated chick embryo retina: Müller cell localization of initial effects
Authors: Casper Daniel S. , Trelstad Robert L. , Reif‐Lehrer Liane
Published: January 2005

The neurotoxic and gliotoxic effects of glutamate and several glutamate analogues were studied in isolated chick embryo retinas. To facilitate examination of initial pathological events, a short‐term incubation system was developed and used for light microscopic and autoradiographic investigation. Low‐dose, short‐term glutamate treatment of 12‐day retinas resulted in a glial‐specific lesion in the Müller cells, characterized by extensive cellular edema; at higher concentrations and/or longer treatment times, neurotoxic as well as gliotoxic effects were seen. The early glial damage was identical in appearance to that seen after incubation with DL‐α‐aminoadipate and other reported gliotoxins. No evidence of a similar glialspecific action was seen after administration of kainic acid, although extensive neuronal degeneration did result.

Incubation of retinas with tritiated glutamate (3H‐glu) revealed a selective uptake of the label by Müller cells. Autoradiographic grains were localized over Müller foot processes at the inner limiting membrane, and by 30 minutes labeled the entire glial system. Prior treatment with neurotoxic levels of glutamate did not alter the autoradiographic localization to glial cells.

Possible glial‐neuronal interactions and their effect on cytotoxic patterns are discussed.
Dendritic tree structure and dendritic hypertrophy during growth of the crucian carp eye
Authors: Kock Jan‐Henrik
Published: January 2005

The areas of the ganglion cell dendritic trees were determined in Golgistained, flatmounted retinas of crucian carp ranging in age from one summer to 7 years. The dendritic trees of small ganglion cells (S‐GC), forming the majority of retinal ganglion cells, add new branches as the retina grows. The increase in dendritic tree area exactly compensates for the decrease in ganglion cell density during growth of the eye so that the number of dendritic trees covering a particular point remains constant. While the retinal diameter increases by a factor of 2.5, the mean diameter of the S‐GC dendritic fields increases by a factor of 1.9 and the visual angle covered by one S‐GC dendritic tree decreases from 1.6° to 1.2°.

The number of branching points of the S‐GC dendrites is significantly higher in the ventral retina than in the dorsal. In general the dendrites of the S‐GCs tend to grow towards the retinal margin. Dendritic orientation patterns of large (LGC) and large displaced (LDGC) ganglion cells closely resemble those of the amacrines, being oriented parallel to the retinal margin over a wide peripheral region, while the SGCs rapidly lose their tangential orientation. The dendrites of the SGCs are restricted mainly to the proximal sublayer of the inner plexiform layer, suggesting they are ON‐cells, while LGC, LDGC, and amacrine cell dendrites are distributed in depth bimodally.

As determined from Golgi‐stained sections the crucian carp has the same basic IPL organization as the carp and cat.
The reticulocerebellar projection to the pyramis and copula pyramidis in the rat: An experimental study using retrograde transport of horseradish peroxidase
Authors: Eisenman Leonard M.
Published: January 2005

The organization of the lateral reticulocerebellar projection to the pyramis and copula pyramidis in the rat was studied with the use of microinjections of horseradish peroxidase (HRP). These injections were mae in different mediolateral positoins along the width of this lobule. The objective was to determine whether reticulocerebellar parasagittal zones (Chan‐Palay et al., 1977) receive differential inputs from the lateral reticular nucleus (LRN). This material has previously been used to analyze the olivo and pontocerebellar projection to this same cortical region of the rat cerebellum (Eisenman, 1981a,b). The results do not support a clear‐cut topographic organization in this projection system to the pyramis and copula pyramidis in the rat. There is some suggestion, however, of a difference in emphasis in the region of the LRN projecting to different mediolateral positions in this lobule. Injections in medial and lateral parts of this lobule result in the labeling of cells in the subtrigeminal and ventral parts of the parvicellular and magnocellular divisions. Injections in intermediate parts of this lobule result in the labeling of cells primarily in the subtrigeminal division. However, cells in each of the divisons (primarly the subtrigeminal and parvicellular) are labeled in each experiment. These results are discussed with reference to electrophysiological and other anatomical studies of the topography of the reticulocerebellar projection in the cat.
A wide field electron microscopic analysis of the fiber constituents of the major splanchnic nerve in cat
Authors: Kuo David C. , Yang Grace C. H. , Yamasaki Dwayne S. , Krauthamer George M.
Published: January 2005

The fiber compositio of the left major splanchnic nerve was studed in cats by electron microscopy. Comparisons were made between normal and partically degenerated nerve specimens following ventral rhizotomy (T3‐L1), or spinal nerve division (T3‐L1). Normal, major splanchnic nerves contained 2,500–4,000 myelinated and 10,000–15,000 unmyelinated fibers. Preganglionic fibers included approximately 90% of the finely myelinated (1–7μm) and over 50% of the unmyelinated fibers. Removal of the sensory and preganglionic components by spinal nerve division revealed a third, postganglionic fiber category. This included 13–38 small myelinated (1–5μm) and 1,645‐7,619 unmyelinated fibers. Finally, a comparison of normal and partially degenerated nerve specimens of both groups (ventral rhizotomy and spinal nerve cut) indicated that splanchnic afferents are made up of virtually all of the 120–350 large myelinated (8‐14μm) and 10% of the small myelinated (1–7μm) fibers. A preliminary estimate indicated that about 10–20% of the unmyelinated fibers were sensory. The implications of these findings are discussed.
Synapse‐to‐neuron ratios in the visual cortex of adult rats undernourished from about birth until 100 days of age
Authors: Warren M. A. , Bedi K. S.
Published: January 2005

Male rats undernourished from the 18th day of gestation until 100 days of age were nutritionally rehabilitated until 200 days of age. Six control and six experimental rats at each of 100 and 200 days of age were killed by perfusion with buffered 2.5% glutaraldehyde. Pieces of visual cortex from each rat were postfixed in osmium tetroxide and embedded in resin. Stereological procedures at the light and electron microscope levels were used to estimate the synapse‐to‐neuron ratios in cortical layers II to IV.

Rats undernourished until 100 days of age had a mean ± S.E. of 10,350 ± 470 synapses associated with each neuron. This represented a 13% deficit (P < 0.05) when compared to the control value of 11,950 ± 530.

Following nutritional rehabilitation till 200 days of age it was found that the previously undernourished rats had about 23% more (P < 0.05) synapses‐per‐neuron than their age‐matched controls. This was due almost entirely to a substantial increase in the ratio in the previously undernourished animals; the value of controls did not alter significantly between the two age groups.

It appears that the deficit in the synapse‐to‐neuron ratio seen after a lengthy period of undernutrition is not permanent, at least in rats subsequently allowed nutritional rehabilitation. In fact, such animals seem to be capable of not only “catching‐up” but “overshooting” the values found in age‐matched controls.
Distribution of cholinergic neurons in rat brain: Demonstrated by the immunocytochemical localization of choline acetyltransferase
Authors: Armstrong David M. , Saper Clifford B. , Levey Allan I. , Wainer Bruce H. , Terry Robert D.
Published: January 2005

The neuroanatomical location and cytological features of cholinergic neurons in the rat brain were determined by the immunocytochemical localization of the biosynthetic enzyme, choline acetyltransferase (ChAT). Perikarya labeled with ChAT were detected in four major cell groups: (1) the striatum, (2) the magnocellular basal nucleus, (3) the pontine tegmen‐tum, and (4) the cranial nerve motor nuclei. Labeled neurons in the striatum were observed scattered throughout the neostriatum (caudate, putamen) and associated areas (nucleus accumbens, olfactory tubercle). Larger ChAT‐labeled neurons were seen in an extensive cell system which comprises the magnocellular basal nucleus. This more or less continuous set of neuronal clusters consists of labeled neurons in the nucleus of the diagonal band (horizontal and vertical limbs), the magnocellular preoptic nucleus, the substantia innominata, and the globus pallidus. Labeled neurons in the pontine tegmentum were seen as a group of large neurons in the caudal midbrain, dorsolateral to the most caudal part of the substantia nigra, and extended in a caudodorsal direction through the midbrain reticular formation into the area surrounding the superior cerebellar peduncle. The neurons in this latter group constitute the pedunculopontine tegmental nucleus (PPT). An additional cluster of cells was observed medially adjacent to the PPT, in the lateral part of the central gray matter at the rostral end of the fourth ventricle. This group corresponds to the laterodorsal tegmental nucleus. Large ChAT‐labeled neurons were also observed in all somatic and visceral motor nerve nuclei. The correspondence of the distribution of ChAT‐labeled neurons identified by our methods to earlier immunocytochemical and acetylcholinesterase histochemical studies and to connectional studies of these groups argues for the specificity of the ChAT antibody used.
Projections of nucleus caudalis and spinal cord to rrainstem and diencephalon in the hedgehog (Erinaceus europaeus and Paraechinus aethiopicus): A degeneration study
Authors: Ring George , Ganchrow Donald
Published: January 2005

In the light of hypotheses related to the evolution of pain‐carrying systems in mammals, terminal projection fields in brainstem and diencephalon of efferents of nucleus caudalis (NC) of the spinal trigeminal complex and spinal cord were determined in hedgehog by using Nauta‐Gygax and Fink‐Heimer silver techniques for degeneration.

Unilateral NC lesions resulted in medullary degeneration in the ventral portion of NC contral a ter ally and bilaterally in cuneate nucleus (CU) and reticular formation. Pontine degeneration was noted ipsilaterally in medial (PBM) and lateral (PBL) parabrachial, facial motor (VII), and interpolar, oral, and main sensory trigeminal nuclei; degeneration in reticular formation was bilateral. Midbrain degeneration was seen bilaterally in caudal superior colliculus (SO), inferior colliculus (IC), periaqueductal gray, and tegmentum. In thalamus, projections to ventroposterior nucleus (VP) were contralateral and concentrated in a crescent extending along the lateral one‐third‐to‐one‐halfand ventral border of the nucleus. Bilateral degeneration fields were noted in a dorsomedial sector of the “ventral nuclear field,” posterior complex (PO), and mediodorsal nucleus (MD), the degeneration always heavier contralaterally in these nuclei. Sparse degeneration was noted in the medialmost portions of the medial geniculate nuclei bordering PO and VP. In rostral diencephalon, bilateral degeneration was traced from the inferior thalamic peduncle to the lateral hypothalamic area (LH).

Unilateral spinal cord lesions made between C7 and Tl vertebrae resulted in medullary degeneration in NC contralaterally, ipsilaterally in CU and lateral cuneate nucleus, and bilaterally in gracile nucleus, inferior olivary complex, and reticular formation. Pontine degeneration was limited to ipsilateral PBL and bilaterally to VII. Midbrain degeneration was found bilaterally in IC, SC, nucleus sagulum, and tegmentum; a minor projection was noted in interpeduncular nucleus. In thalamus, projections were confined to ipsilateral PO and zona incerta. In rostral diencephalon bilateral fields were noted in LH.

NC terminations in PO and VP parallel results of research in hedgehogs on thalamic projections of the dorsal column nuclei (Jane and Schroeder, 1971), and particularly the location in VP of most cells responsive to stimulation of the face (Erickson et al., 1967). This suggests that somatic input from NC, some of which may be pain‐specific, reaches thalamic areas, a portion of whose neurons are characterized as polymodal and at least partially convergent for somatotopy. These results are consistent with the thesis that specific sensothalamic nuclei evolved from a diffuse sensory region. Response properties of neurons in the dorsomedial portion of the ventral nuclear field, an area which also received NC efferents, are not known. Last, NC projections to MD and LH implicate the role of “limbic” aspects of nociception.
The acoustic and lateral line nuclei are distinct inthe premetamorphic frog, Rana catesbeiana
Authors: Jacoby Jean , Rubinson Kalman
Published: January 2005

The transition from aquatic to terrestrial hearing in the frog occurs during metamorphosis and during the disappearance of the lateral line system. The coincidence in time of these two processes and morphological similarities between the acoustic and lateral line systems has led to the suggestion (Larsell, 1934) that the lateral line nuclei are transformed into the acoustic nuclei. The relation between the acoustic and lateral line systems was investigated by studying the distribution of primary afferents, the dendritic patterns of the cells in the primary nuclei, and the development of the nuclei in the premetamorphic bullfrog, Rana catesbeiana

The posterior and anterior lateral line roots distribute to a neuropil located medial to the dorsal medullary nucleus. Horseradish peroxidase (HRP) injections into the contralateral tegmentum fill cells in the periventricular region whose dendrites ramify within the neuropil. These cells constitute the lateral line nuclei. The amphibian and basilar papillary roots of the acoustic system distribute to the more lateral nuclear region. The dendrites of these cells arborize within the nucleus and not in the lateral line neuropil. The dorsal medullary nucleus is, therefore, the acoustic nucleus (AcN). [3H]‐thymidine labeling reveals that newly generated cells occupy the AcN within a few hours of their formation throughout the period when anatomical analysis shows the parallel growth and diminution of the lateral line neuropil and nuclei

This study indicates that the lateral line and acoustic systems are morphologically independent at the level of the primary afferents and primary nuclei throughout early development.
Nucleus rotundus in a snake, Thamnophis sirtalis: An analysis of a nonretinotopic projection
Authors: Dacey Dennis M. , Ulinski Philip S.
Published: January 2005

Nucleus rotundus, a tectorecipient thalamic nucleus in reptiles and birds, is described for the first time in a snake. The morphology of rotunda neurons and tectorotundal axons was studied at the light microscopic level by using anterograde and retrograde filling with horseradish peroxidase (HRP)

Injections of HRP in the dorsal ventricular ridge retrogradely fill neurons in rotundus. Rotundus is situated centrally in the caudal diencephalon medial to the cell plate of the retinorecipient geniculate complex and ventrolateral to the lentiform thalamic nucleus. The dendrites of rotundal neurons are long and radiate, but are confined within the cytoarchitectonically defined borders of the nucleus. Injections of HRP into the optic tectum anterogradely fill axons that project to rotundus bilaterally via the tectothalamic tract. Small injections show that axons arising from a single tectal locus distribute to all sectors of rotundus. Thus, this projection may not be retinotopically organized. However, single axons reconstructed through serial sections form spatially restricted, sheetlike terminal fields that pass caudorostrally through the entire extent of rotundus.

Several hypotheses on the functional significance of such organized but nonretinotopic visual projections are discussed.
Anatomy and electrophysiology of individual neurosecretory cells of an insect brain
Authors: Zaretsky Malcolm , Loher Werner
Published: January 2005

The structure and electrophysiological properties of individual neurose‐cretory cells of the pars intercerebralis, medial neurosecretory cells (MNSCs), in the brain of an insect, the cricket Teleogryllus commodus, were investigated by means of intracellular injections of the dye Lucifer Yellow and electrophysiological recordings. Action potentials recorded from these cells were of long duration, 8–50 msec. In the pars intercerebralis there are both neurosecretory cells with axons that join one of the tracts of the nervi corpori cardiaci I (NCC I) and cells without an axon or collateral that leaves the brain, local neurosecretory cells. MNSCs with axons that join NCC I and terminate in the anterior corpus cardiacum arborize extensively in the proto‐cerebrum and to a lesser degree in the deutocerebrum. Other MNSCs have axons that pass through the corpus cardiacum and hypocerebral ganglion and join one of the oesophageal nerves. These MNSCs have sparse collateral arborizations in the protocerebrum but do have extensive terminal arborizations in the tritocerebrum. This type of cell is dye‐coupled to other MNSCs. Among the local MNSCs, some have an unusual loop shape. These cells branch extensively in the protocerebrum and have massive terminal arborizations in a posterior ventromedial region of the brain. Both the long curved axons of the loop‐shaped cells and their ventromedial branches are of large diameter, suitable for storage of neurosecretory material.
Central organization of the electrosensory lateral line system in bullhead catfish Ictalurus nebulosus
Authors: Tong Shang‐Liang , Finger Thomas E.
Published: January 2005

The connections of the electrosensory lateral line lobe (ELL) of ictalurid catfish were examined by means of horseradish peroxidase tracing methods. The ELL receives direct input from the anterior and posterior lateral line nerves. Some of these nerve fibers continue through the ELL to end as mossy fibers in the lateral portion of the eminentia granularis. Granule cells in this area as well as those in lobus caudalis of the cerebellum project back to the ELL as parallel fibers in the upper molecular layer. The lower molecular layer of the ELL receives its input from the n. praeeminentialis.

The ELL projects via the lateral lemniscus to the n. praeeminentialis and torus semicircularis bilaterally, but more heavily on the contralateral side. In addition, the n. praeeminentialis receives the bulk of its input from the ipsilateral torus semicircularis. The caudal lobe of the cerebellum both projects to the electrosensory portion of the torus semicircularis and receives indirect input from the torus semicircularis via the inferior olivary nucleus. In summary, the central organization of this ampullary receptor electrosensory system in catfish is similar to that of the ampullary‐tuberous receptor elec‐trosense of mormyrids and gymnotids.
Immunohistochemical localization of avian pancreatic polypeptide‐like immunoreactivity in the rat hypothalamus
Authors: Card J. Patrick , Brecha Nicholas , Moore Robert Y.
Published: January 2005

The distribution of avian pancreatic polypeptide‐like (APP) immuno‐reactivity within the rat hypothalamus was investigated with the indirect immunoperoxidase method. APP immun ore active perikarya are found in largest numbers in the retrochiasmatic area, the arcuate nucleus, and the supracommissural portion of the interstitial nucleus of the stria terminalis. Small clusters of immunoreactive neurons are also consistently observed in the ventral aspect of the medial preoptic area and lateral hypothalamic area, immediately dorsolateral to the optic chiasm and tracts. These neurons are apparent in all animals but are more intensely stained and occur in larger numbers following colchicinepretreatment. Other immunoreactive neurons are visible only in colchicine‐treated rats and are scattered throughout the anterior and lateral hypothalamic areas and the supramammillary nucleus. Immunoreactive axons and terminal fields present an extensive and highly characteristic distribution throughout the hypothalamus, which in many instances exhibits differential distribution within specific subfields of hypo‐thalamic nuclei and areas. The heaviest concentrations of APP immuno‐reactive axons are present in the periventricular nucleus throughout the ros‐trocaudal extent of the hypothalamus, the ventrolateral portion of the suprachiasmatic nucleus, the retrochiasmatic area, the parvocellular para‐ventricularnucleus, the ventral supraopticnucleus, theperifornical nucleus, the ventral dorsomedial nucleus, and the arcuate nucleus. Moderate plexuses of immunoreactive fibers are also present in the medial preoptic area, the anterior and lateral hypothalamic areas, the nucleus circularis, the median eminence, and the ventral premammillary area. Other areas, such as the ventromedial nucleus, contain virtually no immunoreactive axons but are encapsulated by a dense plexus of immunoreactive terminals. The distribution of a major component of APP immunoreactive fibers exhibits a marked similarity to that of previously described norepinephrine‐containing hypothalamic afferents. Other groups of APP immunoreactive perikarya and fibers appear to represent components of intrinsic diencephalic systems.
Localization of cholecystokininlike immunoreactivity in the rat spinal cord, with particular reference to the autonomic innervation of the pelvic organs
Authors: Daa Schrøder Henrik
Published: January 2005

The distribution of cholecystokinin in the spinal cord was investigated by immunohistochemistry. Throughout the length of the spinal cord cholecystokinin immunoreactivity was found in laminae I and II, in the spinal re‐ticular nucleus, and in the surroundings of the central canal. On the basis of the cholecystokinin pattern lamina II could be divided into a dorsal and ventral part.

In the lumbar and sacral spinal cord additional terminal fields of cholecystokinin immunoreactive boutons unique to these levels were found. They corresponded to the intermediolateral nucleus and to the medial lumbar sympathetic nucleus dorsal to the central canal in the first and second lumbar segment. Also the intermediolateral nucleus in L6–S1 received a dense cholecystokinin positive input. Moreover, the area surrounding the central canal in L6–S1, contained many cholecystokinin immunoreactive structures. Combined retrograde tracing and immunocytochemistry revealed that the two cholecystokinin terminal fields characteristic for L1–L2 and that sur‐rounding the intermediolateral nucleus in L6–S1 were situated corresponding to preganglionic neurons innervating pelvic organs through the hypo‐gastric nerve or the pelvic nerves.

It thus appears that the unique lumbosacral cholecystokinin is related to nuclei influencing pelvic structures, pointing to a special need for regulation of the organs involved in evacuation and sexual functions. Moreover, it is demonstrated that the caudal part of the spinal sympathetic system differs from the more cranial part with respect to type of afferent connections.

The origin of the spinal cholecystokinin was investigated and it was found that neither complete transection of the spinal cord nor ipsilateral sectioning of three or four dorsal roots induced visible changes in the cholecystokinin staining pattern. Treatment of the caudal spinal cord with colchicine revealed the presence of cholecystokinin immunoreactive neurons in the intermediate gray, at the lateral border of the dorsal horn, in the dorsal horn proper, and in the substantia gelatinosa. These findings indicate that the majority of spinal cholecystokinin has a spinal origin.
Modifications in the laminar organization of peptide‐like immunoreactivity in the anuran optic tectum following retinal deafferentation
Authors: Kuljis Rodrigo O. , Karten Harvey J.
Published: January 2005

Substance P (SP)‐, leucine‐enkephalin (LENK)‐, cholecystokinin octa‐peptide (CCK8)bombesin (BOM)‐, and avian pancreatic polypeptide (APP)‐like immunoreactiyities were analyzed in the optic tectum of Rana pipiens 5–99 days after unilateral eye enucleation, or optic nerve ligation, by means of the peroxidase‐antiperoxidase and indirect fluorescence single and double labeling methods. The normal pattern (Kuljis and Karten, 1981, 1982c) of peptide‐like immunoreactivity was observed ipsilaterally to the operation. Contralateral deafferented tectae displayed conspicuous modifications in the normal pattern of peptide‐like immunoreactivity unique to each of the substances studied. The modifications of peptide‐like immunoreactivity observed varied depending both on the survival time and on the particular peptide analyzed, with either increment or diminution or disappearance–or combinations thereof–in the staining intensity of some of the peptide‐positive bands in the superficial one‐third (superficial neuropil) of the tectum. The onset of these changes is detectable immunocytochemicahy between the sixth and tenth day following deafferentation. By 2–4 weeks full expression of the long‐term changes is reached with no apparent further modification up to the 99th postoperative day. The rapid onset of these phenomena suggests the existence of a previously unrecognized retinal ganglion cell terminal peptidergic contribution to the tectum and/or rapid transsynaptic effects. The former possibility is suggested by recent observations demon‐strating peptide‐like immunoreactivity for SP, LENK, CCK8 and BOM in the retinal stump of ligated optic nerves (Kuljis and Karten, 1982b). The fact that no vertebrate retinal ganglion cells have been shown to contain any of these peptides (Brecha et al., 79; Famiglietti et al., 1980; Eldred and Karten, 1981; Karten et al., 1982), however, argues against the possibility of a retinal terminal contribution to peptide‐like immunoreactivity in the tectum and suggests that transsynaptic phenomena are involved.
Comparisons of directionally selective with other ganglion cells of the turtle retina: Intracellular recording and staining
Authors: Jensen Ralph J. , Devoe Robert D.
Published: January 2005

Directionally selective (DS) and other ganglion cells of the turtle retina were studied in in vitro eyecup preparations by using intracellular recording and staining techniques. DS ganglion cells responded to moving gratings with periodic, depolarizing synaptic potentials in both preferred and null directions. Although depolarizations were usually larger in the preferred than in the null directions, in a few cells spike discharges were directional but depolarizations were not. Directionality could disappear if inappropriate field sizes or grating spatial frequencies were used.

Unlike non‐DS cells, one‐half of the DS cells penetrated showed two sizes of action potentials upon photostimulation. It is proposed that the smaller spikes originated at axonal initial segments and failed to invade the somas actively. DS cells also exhibited postspike depolarizations (PSDs).

Three types of DS ganglion cells (ON‐OFF, OFF center, and ON center) were identified morphologically with Lucifer yellow injection. Other ganglion cells, which were also recorded from and stained intracellularly, are compared to the DS cells.
The effects of lesions of telencephalic visual structures on visual discriminative performance in turtles (Chrysemyspicta picta)
Authors: Reiner Anton , Powers Alice Schade
Published: January 2005

Ascending thalamotelencephalic visuaJ pathways that terminate in specific telencephalic regions have been described in all reptiles studied. Although the anatomical data suggests that such telencephalic regions may play a role in visual processing in reptiles, few behavioral data are available. In the present study, the effects of destruction of either the core nucleus (CN) of the dorsal ventricular ridge (telencephalic terminus of the tectothal‐amofugalpathway) or the dorsal cortex (telencephalic terminus of the retino‐thalamofugal pathway) on visual discriminative performance in the turtle were examined. Following extensive bilateral destruction of the CN, turtles were severely impaired in their performance of both a simultaneous pattern discrimination and a simultaneous visual intensity discrimination. The extent of the discriminative impairment was found to be specifically correlated with the amount of CN damage. In contrast to the effects of CN lesions, lesions of the dorsal cortex had no evident effect on the performance of either a simultaneous pattern discrimination or a simultaneous visual intensity discrimination. The present results suggest that, as in birds and mammals, telencephalic visual areas play an important role in visual functions in reptiles. As in at least some birds (such as pigeons), the telencephalic terminus of the tectothalamofugal visual pathway appears to play a larger, or at least more readily measurable, role in visual discrimination than does the telencephalic terminus of the retinothalamofugal pathway.
The termination of primary afferents within the rat dorsal horn: Evidence for rearrangement following capsaicin treatment
Authors: Nagy J. I. , Hunt S. P.
Published: January 2005

The mode of termination of primary afferent fibres within the superficial dorsal horn of the spinal cord was studied with anterograde tracing methods in normal rats and in animals which had been treated with capsaicin (50 mg/kg. s.c.) shortly after birth. In normal animals following injections of horseradish peroxidase (HRP) into lumbar dorsal root ganglia L4, L5, L6, a Golgi‐like filling of primary afferent fibres was seen consistently within laminae I, II, and III of the dorsal horn. Several types of lamina related arborisations were observed, depending upon the survival time after HRP injection. At the earliest survival time (1–2 days) a punctate granular labelling was found in laminae I and II inner (IIi). At 3 days survival a Golgi like labelling of primary afferent axons occurred and three tiers of arborisation were seen within laminae I, II outer (IIO), and II inner (IIi), respectively. By 7 days after injection this pattern was considerably reduced and there was coarser fibre labelling within laminae I, IIO, and III.

When these tracing experiments were repeated in capsaicin‐treated rats in which up to 90%of unmyelinated fibres had been destroyed, evidence for a considerable loss of some inputs and rearrangement of the remaining fibres was found. At 3–5 days survival the axonal labelling within laminae I and IIi was severely depleted yet some input, particularly to lamina IIO, was present. At 7 days survival deep fibre labelling within lamina III now extended well into lamina II.

Mapping of the primary afferent input following 3H‐proline injections into the dorsal root ganglion and subsequent autoradiographic processing confirmed that primary afferents terminated throughout the dorsal horn but most heavily in two bands within laminae I and IIi. These two dense layers of termination were not present in capsaicin‐treated animals, suggesting that they corresponded to areas of unmyelinated primary afferent fibre input.

These data, taken together with histochemical observations on the distribution of substance P and fluoride‐resistant acid phosphatase (FRAP)‐containing primary afferents, suggests that the earliest‐labelled fibre systems (3days) were unmyelinated and replaced at 7 days by predominantly A6 myelinated fibres. It is further suggested that of the three tiers of C fibre terminations seen at 3 days, the most superficial corresponds in part to those primary afferents that can be stained for substance P within lamina I while the most ventral tier within lamina IIi are those primary afferents containing FRAP. The presence of the two temporally distinct fibre systems also suggests that laminae I and IIo, receive both C and A6 primary afferent input while lamina IIi, receives only C fibre input.