bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytogenesis in the monkey retina
Authors: la Vail Matthew M. , Rapaport David H. , Rakic Pasko
Published: January 2005

Time of cell origin in the retina of the rhesus monkey (Macaca mulatto) was studied by plotting the number of heavily radiolabeled nuclei in autoradiograms prepared from 2‐ to 6‐month‐old animals, each of which was exposed to a pulse of 3H‐thymidine (3H‐TdR) on a single embryonic (E) or postnatal (P) day. Cell birth in the monkey retina begins just after E27, and approximately 96% of cells are generated by E120. The remaining cells are produced during the last (∼ 45) prenatal days and into the first several weeks after birth. Cell genesis begins near the fovea, and proceeds towards the periphery. Cell division largely ceases in the foveal and perifoveal regions by E56.

Despite extensive overlap, a class‐specific sequence of cell birth was observed. Ganglion and horizontal cells, which are born first, have largely congruent periods of cell genesis with the peak between E38 and E43, and termination around E70. The first labeled cones were apparent by E33, and their highest density was achieved between E43 and E56, tapering to low values at E70, although some cones are generated in the far periphery as late as E110. Amacrine cells are next in the cell birth sequence and begin genesis at E43, reach a peak production between E56 and E85, and cease by E110. Bipolar cell birth begins at the same time as amacrines, but appears to be separate from them temporally since their production reaches a peak between E56 and E102, and persists beyond the day of birth. Müller cells and rod photoreceptors, which begin to be generated at E45, achieve a peak, and decrease in density at the same time as bipolar cells, but continue genesis at low density on the day of birth. Thus, bipolar, Müller, and rod cells have a similar time of origin. The maximal temporal separation of cell birth is between cones and amacrine cells so that cell generation exhibits two relatively distinct phases: the first phase gives rise to ganglion, horizontal, and cone cells, and the second phase to amacrine, bipolar, rod, and Müller cells. In addition, cells of the first phase are generated faster than the second phase cells, and there are differences in the topography of spread of labeled cells between the two phases.

Each cell class displays a central‐to‐peripheral gradient in genesis, although the spatiotemporal characteristics of the gradients differ between the classes. Heavily labeled ganglion cells, horizontal cells, and cone photoreceptors (phase 1) are found near the retinal margin much sooner than amacrine, bipolar, Müller, and rod photoreceptor cells (phase 2). As a consequence, genesis of phase 1 cells generally occurs over a more extensive retinal area, extending to the retinal margin, while phase 2 cell genesis ceases centrally by the time cell birth begins near the margin. The site of initial cessation of cell division is more variable than it is for the beginning of cytogenesis, although for all cell classes it is roughly centered on the fovea.
Glutamate‐like immunoreactivity in retinal terminals in the nucleus of the optic tract in rabbits
Authors: Cardozo Bob Nunes , Buijs Ruud , van der Want Johannes
Published: January 2005

The ultrastructural organization of retinal terminals within the nucleus of the optic tract of rabbits was investigated with a combination of anterograde tracing and immunocytochemistry. The anterogradely transported WGA‐HRP injected in the vitreous of the eye was visualized with the sensitive gold‐substituted silver peroxidase (GSSP) method. Glutamate and GABA immunoreactivity were identified with postembedding colloidal gold particles.

Retinal ganglion cell terminals (R‐terminals) in the nucleus of the optic tract formed asymmetric synapses and contained spherical vesicles and electron lucent mitochondria. R‐terminals were observed in large clusters in the neuropil and in synaptic contact with large initial dendrites and somata. Within the clusters of neuropil the R‐terminals formed two types of glomeruluslike arrangements: (1) an R‐terminal centrally located and surrounded by small dendritic and axonal profiles and (2) several R‐terminals surrounding a single dendrite or a group of dendritic profiles, presumably of interneuronal origin. All R‐terminals identified with WGA‐HRP as well as those exhibiting similar ultrastructural characteristics showed high levels of glutamate immunoreactivity, but no GABA immunoreactivity. The presence of glutamate and the absence of GABA in R‐terminals suggest that glutamate is involved in neurotransmission in the pathway from retina to the nucleus of the optic tract of rabbits.
An electron microscopic description of glutamate‐like immunoreactive axon terminals in the rat principal sensory and spinal trigeminal nuclei
Authors: Clements Jane R. , Beitz Alvin J.
Published: January 2005

The spinal and principal sensory trigeminal nuclei relay noxious and nonnoxious stimuli from the orofacial region to the thalamus. Physiological studies have implicated glutamate as an important neurotransmitter in this region. Despite its importance as a potential transmitter, few studies have examined the anatomical distribution of glutamate within these nuclei. We therefore chose to use a monoclonal antibody raised against glutamate conjugated to a carrier protein to identify and describe glutamate‐like immunoreactive processes at the electron microscopic level.

Glutamate‐like immunoreactive axon terminals were identified throughout the spinal trigeminal and principal sensory trigeminal nucleus. In. subnucleus caudalis glutamate‐like immunoreactive terminals occurred frequently in all laminae and were morphologically heterogeneous. In lamina I, glutamate‐like immunoreactive terminals were primarily ovoid, contained spherical synaptic vesicles, and participated in synaptic complexes with both dendritic and axonal profiles. In laminae II and III many glutamate‐like immunoreactive axon terminals were identified as the central element in synaptic glomeruli. Within discrete patches of lamina II, large numbers of glutamate‐like immunoreactive terminals contained dense core vesicles.

The majority of glutamate‐like immunoreactive terminals in subnucleus interpolaris, subnucleus oralis, and principal sensory trigeminal nucleus were similar in morphology and synaptic interaction to the glutamate‐like immunoreactive terminals found in subnucleus caudalis, Glutamate‐like immunoreactive terminals that were the central presynaptic element in glomerular complexes were seen in all subnuclei. In sections from subnucleus interpolaris and subnucleus oralis central glutamate‐like immunoreactive terminations within glomerular complexes had much smoother profiles, and in subnucleus interpolaris participated primarily in axodendritic synaptic junctions. In the principal sensory trigeminal nucleus central glutamate‐like immunoreactive terminations were highly scalloped and participated in numerous axoaxonic synaptic junctions.

The above observations are consistent with the hypothesis that glutamate‐like immunoreactivity is present in some primary afferent terminations and functions as an important excitatory transmitter involved in the relay of sensory information to the spinal trigeminal and principal sensory trigeminal nucleus.
Rat tooth pulp projections to spinal trigeminal subnucleus caudalis are glutamate‐like immunoreactive
Authors: Clements J. R. , Magnusson K. R. , Hautman J. , Beitz A. J.
Published: January 2005

It has been shown that glutamate‐like immunoreactive axon terminals are present within the spinal trigeminal nucleus, including subnucleus caudalis. The morphology of many of these terminations is consistent with their identification as primary afferents. To establish whether primary afferent projections to subnucleus caudalis are glutamate‐like immunoreactive, we injected an anterograde tract tracer into rat incisor tooth pulp, histochemically visualized this tracer within subnucleus caudalis, and then used an immunocytochemical technique to label glutamate‐like immunoreactive profiles within these same sections.

The anterograde tract tracer used, the B subunit of cholera toxin conjugated to horseradish peroxidase (B‐HRP), is transported transganglionically and can be used to localize tooth pulp projection fibers in the spinal trigeminal nucleus. A majority of B‐HRP projection fibers from rat lower incisors terminated ipsilaterally in axon terminals in the dorsal region of subnucleus caudalis. Labeled axon terminals were both scallop‐shaped and smooth in profile. Small numbers of fibers containing B‐HRP extended into laminae I‐III caudally and were present in both the border zone between laminae IV and V and the most lateral region of lamina V rostrally. Approximately 75% of the B‐HRP‐labeled projection fibers were glutamate‐like immunoreactive, providing evidence that the excitatory amino acid glutamate functions as a neurotransmitter in a subpopulation of these fibers. Terminals reactive for both B‐HRP and glutamate‐like immunoreactivity contained small, spherical round vesicles, formed asymmetric synapses, and participated in axoaxonic and axodendritic synaptic junctions. These results support the hypothesis that glutamate may be a transmitter of A delta and C fibers involved in relaying nociceptive information from the tooth pulp.
The bed nucleus‐amygdala continuum in human and monkey
Authors: Price Donald L. , Martin Lee J. , Powers Richard E. , Dellovade Tammy L.
Published: January 2005

The cytoarchitecture and distributions of seven neuropeptides were examined in the the bed nucleus of the stria terminalis (BST), substantia innominata (SI), and central and medial nuclei of the amygdala of human and monkey to determine whether neurons of these regions form an anatomical continuum in primate brain. The BST and centromedial amygdala have common cyto‐ and chemo‐architectonic characteristics, and these regions are components of a distinct neuronal complex. This neuronal continuum extends dorsally, with the stria terminalis, from the BST and merges with the amygdala; it extends ventrally from the BST through the SI to the centromedial amygdala. The cytoarchitectonics of the BST‐amygdala complex are heterogeneous and compartmental. The BST is parcellated broadly into anterior, lateral, medial, ventral, supracapsular, and sublenticular divisions. The central and medial nuclei of the amygdala are also parcellated into several subdivisions. Neurons of central and medial nuclei of the amygdala are similar to neurons in the lateral and medial divisions of the BST, respectively. Neurons in the SI form cellular bridges between the BST and amygdala. The BST, SI, and amygdala share several neuropeptide transmitters, and patterns of peptide immunoreactivity parallel cytological findings. Specific chemoarchitectonic zones were delineated by perikaryal, peridendritic/perisomatic, axonal, and terminal immunoreactivities. The results of this investigation demonstrate that there is a neuronal continuity between the BST and amygdala and that the BST‐amygdala complex is prominent and discretely compartmental in forebrains of human and monkey.
Peptidergic and serotoninergic innervation of the rat dura mater
Authors: Keller Jeffrey T. , Marfurt Carl F.
Published: January 2005

The peptidergic and serotoninergic innervation of the rat dura mater was investigated by reacting dural wholemounts immunohistochemically with antibodies to calcitonin gene‐related peptide (CGRP), substance P (SP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), and serotonin (5‐HT). CGRP and SP innervations of the dura were robust and the patterns of distribution of these neuropeptides were essentially the same. The majority of the fibers were perivascular and distributed to branches of the anterior and middle meningeal arteries and to the superior sagittal and transverse sinuses. Other CGRP/SP fibers appeared to end “free” within the dural connective tissue. NPY‐immunoreactive fibers were extremely numerous and also distributed heavily to the branches of the meningeal arteries, the venous sinuses, and to the dural connective tissue. The pattern of NPY innervation resembled in many ways that of CGRP/SP; however, NPY innervation of the sinuses was greater and NPY perivascular fibers supplying the meningeal arteries formed more intimate contacts with the walls of the vessels. The pattern of VIP innervation was, in general, similar to that observed for the three previous neuropeptides; however, the overall density was considerably less. Small to moderate numbers of serotoninergic nerve fibers were observed in some, but not all, of the duras processed for 5‐HT. The latter fibers were almost exclusively perivascular in distribution. Dural mast cells were prominently stained in the 5‐HT preparations because of their serotonin content. Mast cells were also labeled in a nonspecific fashion in some of the tissues reacted immunohistochemically for neuropeptides; some of them were located in close apposition to passing nerve fibers.

This study represents, to our knowledge, the first comprehensive work on the peptidergic and serotoninergic innervation of the mammalian dura mater. The results should increase our understanding of the roles that these fibers play in normal dural physiology and of their potential interactions in the pathogenesis of vascular headache.
Glycine‐receptor immunoreactivity in retinal bipolar cells is postsynaptic to glycinergic and GABAergic amacrine cell synapses
Authors: Yazulla Stephen , Studholme Keith M.
Published: January 2005

Glycinergic innervation of the synaptic terminals of mixed rod‐cone bipolar cells in the goldfish retina was investigated by electron microscopical immunocytochemistry with presynaptic and postsynaptic markers for glycinergic neurons: a monoclonal antibody (mAb 7A) against the 93 kDa subunit of the strychnine‐sensitive glycine receptor and polyclonal antisera against a glycine/BSA conjugate. Conventional “glycinergic” synaptic contacts, made by amacrine cell processes, accounted for 7–10% of the input to the bipolar cell terminals, whether determined by glycine receptor immunoreactivity (GlyR‐IR) or glycine‐IR. In addition to the conventional synapses, the large bipolar cell terminals in the proximal inner plexiform layer (type Mb) gave rise to spinules (spine‐like protrusions) that invaginated into presynaptic amacrine cell processes. Although 85% of the spinules were GlyR‐IR, no spinules were postsynaptic to glycine‐IR processes; yet 86% of the spinules were postsynaptic to GAD‐IR processes, suggesting that the GlyR‐IR spinules were postsynaptic to GABAergic terminals. Furthermore, a single amacrine cell process could make two synapses with an Mb terminal: a GlyR‐IR contact onto a spinule and a conventional synapse that was not GlyR‐IR. We suggest that glycinergic innervation of bipolar cell terminals involves conventional glycinergic synapses as well as an unconventional situation in which GABA and glycine may interact in as yet undetermined manner, perhaps by potentiatio.
Rod‐signal interneurons in the rabbit retina: 1. Rod bipolar cells
Authors: Young Heather M. , Vaney David I.
Published: January 2005

The cellular morphology and topographic distribution of the rod bipolar cells in the rabbit retina have been investigated by selective labelling with protein kinase C‐immunohistochemistry (Negishi et al., Neurosci. Lett. 94:247–252, 1988) and by Lucifer Yellow injection of microscopically identified cells in a superfused retinal preparation. The distribution of the rod bipolar cells parallels that of their input neurons, the rod photoreceptors, in that the rod bipolars reach maximum densities of 5,000–7,000 cells/mm2 on the inferior and superior flanks of the visual streak, dropping to slightly lower densities at the peak visual streak. The centre‐to‐periphery density gradient of the rod bipolars is about 2.5:1, and the density ratio of rods to rod bipolars shows little variation across the retina, ranging from 43:1 in superior retina to 58:1 in inferior retina. The dendritic field area of the rod bipolar cells increases from 600 μm2 on the visual streak to 1,200 μm2 in the far‐superior retina, with each point on the retina overlapped by 2.5–3.5 dendritic fields. The axonal field area of the rod bipolar cells increases from about 100 μm2 at the peak visual streak to about 250 μm2 at the retina edge, and the axonal field coverage ranges from 0.55 in the visual streak to about 0.8 in peripheral retina. Although there appear to be gaps in the local array of rod bipolar somata, these areas are covered by the axonal arbours of neighbouring rod bipolar cell.
Immunocytochemical localization of phosphatase inhibitor‐1 in rat brain
Authors: Gustafson Eric L. , Girault Jean‐Antoine , Hemmings Hugh C. , Nairn Angus C. , Greengard Paul
Published: January 2005

The localization of phosphatase inhibitor‐1 was investigated in rat brain by use of immunocytochemistry. Studies were performed with an affinity purified IgG raised against purified rabbit skeletal muscle inhibitor‐1. In rat brain tissue homogenates, this antibody reacted only with a 29 kDa protein corresponding to inhibitor‐1. Immunocytochemical studies with this antibody revealed numerous immunoreactive cell bodies and fibers. The highest concentration of immunoreactive perikarya was observed in the caudate‐putamen and nucleus accumbens, and these appeared to be exclusively medium‐sized neurons. Other areas containing substantial populations of immunoreactive neurons included the suprachiasmatic nucleus of the hypothalamus, lateral hypothalamus, horizontal limb of the diagonal band of Broca, dentate gyrus of the hippocampal formation, habenula, superior colliculus, claustrum, endopiriform nuclei, and neocortex. The distribution of terminals containing inhibitor‐1 coincided with the distribution of terminal fields known to originate from the above regions. Thus, plexuses of immunoreactive axons were seen in the globus pallidus, substantia nigra pars reticulata, para ventricular hypothalamus, dorsal thalamus, CA3 region of the hippocampus, and interpeduncular nucleus. These results demonstrate that phosphatase inhibitor‐1, a cyclic AMP‐regulated inhibitor of phosphatase‐1, is differentially distributed in the rat CNS. Given the widespread role of protein phosphorylation and dephosphorylation in intracellular signal transduction, these results suggest that neurons containing high levels of inhibitor‐1 may share common, hitherto unrecognized, properties in terms of neurotransmitter regulation and/or responsivenes.
Transient retinal axon collaterals to visual and somatosensory thalamus in neonatal hamsters
Authors: Langdon Ronald B. , Frost Douglas O.
Published: January 2005

We have studied the postnatal development of individual axons in the optic tract and thalamus of the Syrian hamster, concentrating attention on retinal ganglion cell axons that make a transient projection to the main somatosensory nucleus, the ventrobasal complex. We bulk‐filled axons with horseradish peroxidase in hemithalami maintained en bloc, in vitro. After processing and reaction with diaminobenzidine, we reconstructed individual axons from serial sections. In hamsters and other rodents, the optic tract is composed of superficial and internal components, either or both being possible sources of the retino‐ventrobasal projection. Both project to the midbrain, but in normal adults only the superficial optic tract maintains collaterals in the thalamus. We found that the axons of the internal component bear numerous transient thalamic collaterals on postnatal days 0, 1, and 2, and some of these extend into the ventrobasal complex. Axons in the superficial optic tract also bear collaterals on days 0 to 2, but these are confined to the superficial half of the dorsal lateral geniculate nucleus. Thus the transient retino‐ventrobasal projection comprises solely transient collaterals originating from axon trunks in the internal optic tract. On days 1 and 2, some collaterals from the superficial optic tract appear to have begun to arborize in the lateral geniculate nucleus. In contrast, collaterals from internal optic tract axons to the ventrobasal complex branch little if at all as they traverse the lateral geniculate nucleus, and at no time prior to their elimination do they develop an appreciable terminal arbor. These long collaterals often terminate in growth cones that include lamellopodia. Our HRP‐impregnation method also revealed some transient non‐retinofugal axons that pass medially from the ventral lateral geniculate nucleus to the ventrobasal complex but then return without terminating or branching. By day 4, they are absent, as are collaterals from the internal optic tract to the ventrobasal comple.
Immunolocalization studies of putative guidance molecules used by axons and growth cones of intersegmental interneurons in the chick embryo spinal cord
Authors: Shiga Takashi , Oppenheim Ronald W.
Published: January 2005

The earliest developing interneurons in the chick spinal cord can be divided into two groups: neurons in the ventral region whose axons pioneer the primitive longitudinal pathway (PL‐cells) and neurons whose axons project circumferentially (C‐cells) along the lateral marginal zone and join the ipsilateral or contralateral ventrolateral longitudinal pathways. To begin to examine the molecular cues for axonal pathway formation of these interneurons, we screened a variety of molecules from embryonic day (E) 2 to E6.5 [stage 14–30 of Hamburger and Hamilton (1951) J. Morphol. 88:49–92]. These include cell adhesion and related molecules (G4, F11, neurofascin, N‐cadherin, TAG‐1‐like molecule), extracellular matrix (ECM) molecules (laminin, fibronectin, heparan sulfate proteoglycan, laminin‐heparan sulfate proteoglycan complex, and collagen type IV), and receptors for ECM molecules (β1‐class integrin). PL‐cells first expressed neurofascin at stage 14+ before the onset of axonogenesis. When the PL‐cells began to extend their axons at stage 15, they expressed G4 and avian TAG‐1‐like molecules, as well as neurofascin, on both cell bodies and longitudinal axons. In the following stages, PL‐cells continued to strongly express neurofascin and G4 on their fasciculating axons, suggesting the involvement of these glycoproteins in growth and fasciculation. C‐cells began to express G4 and TAG‐1‐like molecules on cell bodies and axons at stage 15–16 shortly after axonal growth. In the following stages, C‐cells expressed several cell adhesion molecules differentially on their axonal segments. The proximal segment of C‐axons in the circumferential pathway strongly expressed a TAG‐1‐like molecule, whereas the distal segment in the longitudinal pathway strongly expressed G4 and neurofascin. The commissural axonal segment in the floor plate expressed TAG‐1‐like molecule, neurofascin, N‐cadherin, and β‐class integrin. The basement membrane around the spinal cord was enriched with ECM glycoproteins (laminin, fibronectin, heparan sulfate proteoglycan, and collagen type TV) during the stages examined (stage 15–27), and commissural C‐cell axons became strongly integrin positive in the floor plate where they contacted the basement membrane. These data indicate that interneurons may use multiple molecules during axonal pathway formation, depending on cell type, pathway position, and developmental stag.
Acoustic chiasm III: Nature, distribution, and sources of afferents to the lateral superior olive in the cat
Authors: Glendenning K. K. , Masterton R. B. , Baker B. N. , Wenthold R. J.
Published: January 2005

The outcomes of seven experiments are reported, each directed to the nature and sources of the excitation and inhibition impinging on the lateral superior olive (LSO) in cats. In the first experiment, we used conventional 14C 2‐DG methods to determine the specificity, precision, and extent of symmetry in the stimulation reaching LSO from the ipsilateral and contralateral ears. In Experiment 2, we sought the presence of GABA and glycine receptors in LSO using conventional, in vitro receptor‐binding methods. On the basis of these results, we used in vitro high‐affinity uptake methods in Experiment 3 to seek evidence that some of the terminals as well as the receptors in LSO are glycinergic. In Experiment 4, we used immunocytochemical methods to show that the somata known to supply the contralateral projections to LSO, and their terminals in LSO, are each immunoreactive with an antibody directed to a glycine‐protein conjugate. In Experiment 5, we made use of a glycinergic neuron's avidity for transporting glycine retrogradely to label the likely sources of the glycinergic terminals in LSO. In Experiment 6, we used immunocytochemical methods to show that the spherical and globular cells of the ventral cochlear nucleus and terminals, in LSO and in MTB are glutamatergic and/or aspartergic. In Experiment 7, we used receptor binding methods to determine whether the glutamate/aspartate receptors in LSO are probably of the kainate or of the quisqualate typ.

The results of the several experiments suggest that probably ghitamate‐quisqualate synapses mediate LSO's ipsilaterally driven excitatory responses and glycinergic synapses mediate its contralaterally driven inhibitory responses. The two types of input appear to be well matched in LSO's medial and middle limbs with glycinergic terminals mostly perisomatic and glutamatergic terminals mostly peridendritic. However, LSO's low frequency lateral limb appears to be somewhat different; it receives less stimulation from the contralateral ear. Instead, LSO's lateral limb may receive some of its glycinergic input directly from the ipsilateral ventral cochlear nucleus and/or indirectly via the juxtaposed lateral nucleus of the trapezoid body.
Myelo‐ and cytoarchitecture of the granular frontal cortex and surrounding regions in the strepsirhine primate Galago and the anthropoid primate Macaca
Authors: Preuss Todd M. , Goldman‐Rakic Patricia S.
Published: January 2005

As the first part of a comparative investigation of primate frontal cortex, we compared the frontal architectonic organization of Galago, a small‐brained, strepsirhine (or “prosimian”) primate, to that of an anthropoid primate, Macaca, by using myelin‐ and Nissl‐stained material. We were able to distinguish many more areas in both taxa than have been recognized in most previous studies of the primate frontal lobe. In particular, we were able to subdivide many of the areas shown in the commonly cited architectonic map of Walker (J. Comp. Neurol. 73:59–86. 1940). Delineation of areas was greatly facilitated by the use of the Gallyas technique for staining myeli.

The areal organization of much of frontal cortex (specifically, the premotor, orbital, and medial regions) appears to be very similar in Galago and Macaca. In these regions, we were able to recognize the same complement of areas in both taxa, with few exceptions. In the granular frontal cortex (GFC), by contrast, we were able to distinguish about twice as many areas in Macaca as in Galago. For most of the GFC areas of Galago, there are architectonically similar areas in Macaca; the areas shared by both taxa correspond mainly to the arcuate and superior areas of Macaca (i.e., the region encompassed by Walker's areas 45, 8A, and 8B). However, there are many additional, more rostral, areas in Macaca for which there are no obvious homologues in Galago. In particular, Galago lacks cortex resembling the distinctive, lightly myelinated cortex of the Macaca principal sulcus (Walker's area 46 and its subdivisions)

Our results are difficult to reconcile with the view that frontal lobe organization varies little across taxa. Rather, they suggest that granular frontal cortex underwent considerable change during primate evolution, including the addition of new areas in anthropoids.
Ipsilateral cortical connections of granular frontal cortex in the strepsirhine primate Galago, with comparative comments on anthropoid primates
Authors: Preuss Todd M. , Goldman‐Rakic Patricia S.
Published: January 2005

Modern studies of granular frontal cortex (GFC) in large‐brained, anthropoid primates, such as Macaca, indicate that this region is comprised of many areal subdivisions. These areas vary in their architectonic appearance and each has a distinctive, diverse set of corticocortical connections. The great extent of the GFC region in anthropoids, and its high degree of areal parcellation, suggest that some GFC areas may be specializations of anthropoids, not found in other mammals. To investigate this possibility, we studied the corticocortical connections of GFC in the relatively small‐brained, strepsirhine primate Galago, with a series of eight tracer injections in the frontal cortex, and an additional eight injections of parietal and temporal cortex. Tracers used were wheat‐germ agglutinin conjugated to horseradish peroxidase and tritiated amino acid.

Our results indicate that Galago GFC has strong, reciprocal connections with the parietal area‐7 complex and with higher‐order temporal areas; there are additional connections with extrastriate visual cortex, parahippocampal, and cingulate areas, and frontal cortex. Thus GFC has an extremely diverse array of cortical connections in Galago, as in Macaca. However, we also found that the pattern of parietofrontal connections is simpler in Galago than in Macaca. Specifically, parietal areas project to fewer discrete zones within the GFC of Galago, consistent with the view that these animals have fewer GFC areas than Macaca. In addition, Galago GFC possesses connections that specifically resemble those of Macaca arcuate cortex, but lacks connectional patterns that are characteristic of principals cortex. These results are in accord with our previous architectonic studies, which indicated that Galago does not possess homologues of principalis areas. We conclude that the arcuate areas are common elements of primate GFC organization, while the areas located within and adjacent to the principal sulcus are anthropoid specializations.
Origin of neuronal inputs to the region of the tuberomammillary nucleus of the rat brain
Authors: Ericson Hans , Blomqvist Anders , Köohler Christer
Published: January 2005

The origin of afferent connections of the hypothalamic tuberomammillary nucleus has been examined by using retrograde and anterograde tracing techniques. Retrogradely labeled neurons were found in about 70 cell groups of the forebrain and brainstem after injection of tracer into the ventral subgroup of the tuberomammillary nucleus. The majority of the labeled neurons were seen in the forebrain, with particularly large numbers in the infralimbic cortex, lateral septal nucleus, and preoptic region.

The anterograde tracing experiments supported the general results of the retrograde tracing experiments. However, we did not observe any single cell group that selectively projected to the cell‐rich core of the nucleus. In general, only a few fibers entered the core, whereas many labeled fibers seemed to terminate immediately adjacent to the cell group. Thus the target for the afferents is not primarily the perikarya of the neurons of the tuberomammillary nucleus, but either dendrites radiating out from the nucleus or neurons not belonging to the tuberomammillary nucleus.

The results of the present study demonstrate that the histaminergic tuberomammillary nucleus derives its main input from the limbic forebrain. Through their widespread projections, the histaminergic neurons may transmit information originating from the limbic system to most if not all parts of the brain.
Thyrotropin‐releasing hormone‐immunoreactive projections to the dorsal motor nucleus and the nucleus of the solitary tract of the rat
Authors: Lynn Richard B. , Kreider Margaret S. , Miselis Richard R.
Published: January 2005

Thyrotropin‐releasing hormone‐immunoreactive nerve terminals heavily innervate the dorsal motor nucleus and nucleus of the solitary tract, whereas cell bodies containing thyrotropin‐releasing hormone reside most densely in the hypothalamus and raphe nuclei. By using double‐labeling techniques accomplished by retrograde transport of Fluoro‐Gold following microinjection into the dorsal motor nucleus/nucleus of the solitary tract combined with immunohistochemistry for thyrotropin‐releasing hormone, it was demonstrated that thyrotropin‐releasing hormone‐immunoreactive neurons projecting to the dorsal motor nucleus/nucleus of the solitary tract reside in the nucleus raphe pallidus, nucleus raphe obscurus, and the parapyramidal region of the ventral medulla, but not in the paraventricular nucleus of the hypothalamus. The parapyramidal region includes an area along the ventral surface of the caudal medulla, lateral to the pyramidal tract and inferior olivary nucleus and ventromedial to the lateral reticular nucleus. Varying the position of the Fluoro‐Gold injection site revealed a rostral to caudal topographic organization of these raphe and parapyramidal projections.
Corticomotoneuronal connections in the rat: Evidence from double‐labeling of motoneurons and corticospinal axon arborizations
Authors: Liang Pengyi , Moret Véronique , Wiesendanger Mario , Rouiller Eric M.
Published: January 2005

In order to investigate the possibility of direct corticomotoneuronal (CM) connections in the rat, an anterograde‐retrograde double‐labeling method was developed. Phaseolus vulgaris‐leucoagglutinin (PHA‐L) anterograde tracing of corticospinal axons was combined with retrograde labeling of spinal motoneurons either by a conjugate of choleragen subunit B with horseradish peroxidase (CB‐HRP) or by wheat germ agglutinin (WGA). The location of PHA‐L injection unilaterally in the forelimb area of sensorimotor cortex and the CB‐HRP or WGA injections in corresponding contralateral wrist or digit extensors or flexors were determined and matched on the basis of movement responses elicited by intracortical microstimulation.

Light microscopic observation showed, in addition to the main contralateral dorsal corticospinal tract (CST), the presence of four other CST minor components in the contralateral lateral, ipsilateral ventral, and ipsilateral dorsal funiculi of the cervical spinal white matter and at the base of contralateral dorsal horn of the gray matter, respectively, PHA‐L‐labeled CST axonal arbors were observed from Rexed's lamina I through lamina X of contralateral spinal gray matter, most extensively in laminae VI and VII; some CST axons reached the zone of motoneuronal somata in lamina IX and a few of them also entered the lateral and occasionally the ventral funiculi, ramifying in the white matter. Between the zones of PHA‐L‐labeled CST axonal arbors on the one hand and CB‐HRP/WGA labeled spinal motoneuronal somata with their extensive dendritic trees on the other, there was a large overlap, covering partly both the gray and the white matter. PHA‐L‐labeled axonal boutons (en passant or terminaux) were seen to contact the dendrites or even the somata of motoneurons in the gray matter, according to light‐microscopic criteria for identification of synaptic contacts. Axodendritic CM contacts were occasionally observed in the lateral funiculus of the white matter as well. In general, only a single contact was observed between an individual PHA‐L‐labeled CST axon and a given retrogradely labeled motoneuron. In contrast to the common notion that direct CM connections are a specialty of primates, the present morphological data support the presence of direct CM connections also in some other mammals, such as the rat.
Amacrine cells in the tiger salamander retina: Morphology, physiology, and neurotransmitter identification
Authors: Yang Chen‐Yu , Lukasiewicz Peter , Maguire Greg , Werblin Frank S. , Yazulla Stephen
Published: January 2005

Amacrine cells of the vertebrate retina comprise multiple neurochemical types. Yet details of their electrophysiological and morphology properties as they relate to neurotransmitter content are limited. This issue of relating light responsiveness, dendritic projection, and neurotransmitter content has been addressed in the retinal slice preparation of the tiger salamander. Amacrine cells were whole‐cell clamped and stained with Lucifer yellow (LY), then processed to determine their immunoreactivity (IR) to GABA, glycine, dopamine or tyrosine hydroxylase (TOH), and glucagon antisera.

Widefield, ON‐OFF amacrine cells were glycine‐IR. The processes of these cells extended laterally in the inner plexiform layer (IPL) from 250–600 μm. They were either multistratified in the IPL or monostratified near the IPL midline. Three multistratified ON‐OFF narrowfield glycine‐IR cells also were found.

Four types of ON amacrine cells were found to be GABA‐IR; all types had their processes concentrated in the proximal IPL (sublamina b). Type I cells were narrowfield (∼ 100 μm) with a compact projection. Type II cells were widefield (220–300 μm) with a sparse projection. Type III cells had an asymmetrical projection and varicose processes. Type IV cells were pyriform and monostratified in sublamina b. One narrowfield ON‐OFF amacrine cell, with processes broadly distributed in the middle of the IPL, was GABA‐IR. This cell appeared similar to an ON‐OFF cell that was glycine‐IR and may comprise a type in which GABA and glycine colocalize.

Another class of amacrine cell, with processes forming a major plexus along the distal border of the IPL and a lesser plexus in the proximal IPL, produced slow responses at light ON and OFF; these cells were dopamine/TOH‐IR. A narrowfield class of transient ON‐OFF amacrine cell, with processes ramifying throughout both sublaminae a and b of the IPL, were glucagon‐IR; these cells appeared to be dye‐coupled at the soma.

We have shown that, with respect to GABA, glycine, dopamine, and glucagon, salamander amacrine cells fall into rather discrete groups on the basis of ramification patterns in the IPL and responses to photic stimulation. The physiological, structural, and neurochemical diversity of amacrine cells is indicative of multiple and complex roles in retinal processing.
Neurosecretory cells in the honeybee brain and suboesophageal ganglion show FMRFamide‐like immunoreactivity
Authors: Eichmüller Stefan , Hammer Martin , Schäfer Sabine
Published: January 2005

Immunocytochemical analysis of the brain and suboesophageal ganglion of the honeybee Apis mellifera L. was combined with Lucifer Yellow backfilling from the corpora cardiaca and intracellular staining of single neurons. It is shown that more than one third of the cells that display FMRFamide‐like immunoreactivity (F‐LI) project to the corpora cardiaca, suggesting they are neurosecretory. Among the ca. 120 median neurosecretory cells (MNCs) in the pars intercerebralis about 32 show F‐LI. The number of immunoreactive MNCs is highly variable and may depend on age and/or diet. Seven of at least 40 lateral neurosecretory cells display F‐LI. They project through the brain via the medial branch of the bipartite nervus corporis cardiaci II. In the suboesophageal ganglion three types of immunoreactive neurosecretory cells were identified. Together with the median and the lateral neurosecretory cells in the brain these cells project through a single pair of nerves into the corpora cardiaca suggesting that the nervus corporis cardiaci (NCC) of the honeybee is a fusion of NCC I, II, and III described in other insects.
Functionally distinct subdivisions of the macroglomerular complex in the antennal lobe of the male sphinx moth Manduca sexta
Authors: Hansson Bill S. , Christensen Thomas A. , Hildebrand John G.
Published: January 2005

Each antennal lobe in the brain of a male moth has a distinctive neuropil structure, the macroglomerular complex (MGC), which is specialized for primary processing of information about the conspecific female sex‐pheromone blend. Olfactory interneurons with dendritic arborizations in the MGC were examined by means of tandem intracellular recording and staining with Lucifer Yellow. Neurons that responded selectively to stimulation of the antenna with the major pheromone component, (E,Z)‐10,12‐hexadecadienal, had arborizations that were restricted to a toroidal subdivision (the “toroid”) of the MGC. Similarly, neurons that responded selectively to antennal stimulation with (E,Z)‐11,13‐pentadecadienal, a more stable mimic of a second essential but chemically unstable pheromone component, (E,E,Z)‐10, 12, 14‐hexadecatrienal, had arborizations confined to a globular subdivision (the “cumulus”) of the MGC situated more proximally to the antennal nerve input. One neuron that responded to both of these stimuli clearly had arborizations in both subdivisions of the MGC. These anatomically distinct subdivisions of the MGC thus appear also to be functionally separate regions of pheromone‐processing neuropil.
Somatotopy of spinal nociceptive processing
Authors: Bullitt Elizabeth
Published: January 2005

Relatively little is known about the spatial organization of spinal nociceptive processing. This study has employed the expression of c‐fos‐like protein as a marker for neuronal activity and has analyzed the patterns of immunoreactivity seen within the rodent spinal cord following noxious mechanical stimulation of various portions of one hindlimb.

The results indicate that noxious mechanical stimulation induces distinct, somatotopic patterns of immunolabeling in laminae I‐IV. Individual digits of a foot are represented medially in the dorsal horn over a short rostrocaudal distance, with the most lateral digit represented approximately one segment caudal to the most medial digit. Representation of the hip region is more lateral, is centered at L2, and extends rostrocaudally over many segments.

The patterns of neuronal excitation seen in laminae V‐IX following noxious peripheral stimulation were similar to those noted in laminae I‐IV but were less tightly organized. C‐fos‐like immunoreactivity was noted both medially and laterally in the deeper laminae following stimulation of any portion of the hindlimb, but stimulation of different areas produced different columns of labeled cells extending from the superficial dorsal horn into lamina VII. In the rostrocaudal direction, immunolabeling in lamina V‐IX was maximal at the same segmental level as in laminae I‐IV, but the more ventral laminae exhibited increases in c‐fos‐like immunoreactivity over longer rostrocaudal distances.

Experiments in spinally transected animals indicated that long, descending pathways contributed little or nothing to the pattern of immunolabeling.

The results of this study imply that spinal nociceptive processing is spatially organized not only in laminae I‐IV, but also in more ventral regions of the spinal cord.
Somatotopic component of the multisensory map in the deep laminae of the cat superior colliculus
Authors: Meredith M. Alex , Clemo H. Ruth , Stein Barry E.
Published: January 2005

The topographic organization of the somatosensory representation in the deep layers of the cat superior colliculus was reexamined using methods previously used to examine the visuotopy in these layers. This technique identified the distribution of neurons in the superior colliculus that represent a designated region of the body surface (i.e., a dermal image), as well as assessed the differential distribution of deep layer neurons representing different body regions (e.g., face, forelimb, hindlimb, etc.). When the area of densest representation within a dermal image was considered, a well‐ordered somatotopy was evident that was similar to the one previously described (Stein et al., '76: J. Neurophysiol. 39:401–419). Each region of the body surface, however, was represented within a surprisingly broad area of the deep layers, which often had considerable overlap with the representations of adjacent body regions. This organization was similar to that of the deep layer visuotopy and emphasizes that the representation of a peripheral stimulus is accomplished by the simultaneous activation of a large population of deep layer neurons. Furthermore, an examination of the convergence patterns on somatosensory‐responsive neurons demonstrated that the somatotopy was formed primarily by multisensory neurons. These data indicate that the somatosensory representation is best considered as a component of a comprehensive multisensory functional unit that plays a critical role in effecting behavioral responses to a wide variety of stimuli.
The visually related posterior pretectal nucleus in the non‐percomorph teleost Osteoglossum bicirrhosum projects to the hypothalamus: A Dil study
Authors: Wullimann Mario F. , Meyer Dietrich L. , Northcutt R. Glenn
Published: January 2005

This study was done to elucidate the ancestral (plesiomorphic) condition for visual pathways to the hypothalamus in teleost fishes. Three patterns of pretectal organization can be discerned morphologically and histochemically in teleosts. Their taxonomic distribution suggests that the intermediately complex pattern (seen in most teleost groups) is ancestral to both the elaborate pattern (seen in percomorphs) and the simple pattern (seen in cyprinids). The pretectal nuclei involved can be demonstrated with acetylcholinesterase histochemistry selectively and reliably in different species of teleosts, suggesting that the same‐named nuclei are homologous in representatives of the three different patterns.

Whereas there are visual pathways to the hypothalamus in both the elaborate (percomorph) and the simple (cyprinid) patterns, different pretectal and hypothalamic nuclei are involved. Thus visual hypothalamic pathways in these two patterns would not appear to be homologous.

In this study, circuitry within the third, i.e., the intermediately complex, pattern is investigated. It is demonstrated that visual pathways project via the pretectum to the hypothalamus in Osteoglossum bicirrhosum and that they are very similar to the visual pathways in the elaborate pattern. This suggests that the circuitry in the intermediately complex pattern, as represented by Osteoglossum, is plesiomorphic (evolutionarily primitive) and the circuitry in both the simple pattern (seen in cyprinids) and the elaborate pattern (seen in percomorphs) is apomorphic (evolutionarily derived) for teleosts.
Gliosis during optic fiber regeneration in the goldfish: An immunohistochemical study
Authors: Levine R. L.
Published: January 2005

Antisera directed against the 48 kDa and 50 kDa cytoskeletal antigens were used to examine changes in the astroglial fabric of the goldfish visual pathways following optic nerve crush. Several major‐ observations are described. First, an optic nerve crush lesion in these animals appears to be devoid of glial cells for at least the first month after surgery. As a corollary, regenerating axons that grow across the lesion may do so over an aglial substrate. Once the axons cross the lesion, their growth is confined to the astroglial domains of the proximal nerve stump. In the optic nerve, gliosis comprises hypertrophy of astrocytic processes such that the open framework characterizing the normal nerve is obscured. In addition, during regeneration, optic nerve glia express large amounts of the 50 kDa cytoskeletal protein, which they ordinarily express at only minimal levels. In the optic tract, gliosis is reflected in a markedly increased expression of the 50 kDa protein as well as an apparent increase in the number and complexity of glial processes. In addition, optic tract glia begin to express the 48 kDa antigen during regeneration. This protein is ordinarily confined for the most part to the optic nerve and is not seen in the tract glia. Finally, no obvious changes were seen in the glia of the optic tectum.

These results demonstrate many points of similarity between gliosis in the goldfish and in mammals. However, in some particulars the two responses differ, and it is possible that these differences are related to the differing ability of central axons to regenerate in the two groups of organisms.