bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of neurons in the thalamic reticular nucleus (TRN) of mammals as revealed by intracellular injections into fixed brain slices
Authors: Lübke J.
Published: January 2005

I have investigated the morphology of neurons in the thalamic reticular nucleus (TRN) by means of intracellular injections in fixed tissue in order to study whether neurons in visual (dorsocaudal part), somatosensory (intermediate part), or limbic/motor (rostral part) sectors in the rat, rabbit, and cat differ morphologically in relation to their different sensory cortical or thalamic inputs. In addition, I have compared the different mammalian species to ask whether there is a morphological difference of TRN neurons according to reported differences in the intrinsic thalamic organisation, for example, due to the presence of GABAergic local circuit neurons in the majority of thalamic nuclei in the cat and the lack of those neurons in most of the rat thalamic nuclei, and presynaptic dendrites in the cat but not in the rat. In all animals investigated so far, neurons in the caudal (visual) and intermediate (somatosensory) part of the TRN have an elongated dendritic morphology in all three species, but some neurons in the rostral part, in particular in dorsal sections, have a distinctive multipolar morphology. Neurons have round, ovoid, or elongated somata ranging in area between 150 and 860 μm2. In general 4–8 first order dendrites emerge directly from the two poles of the soma or from a thick stem segment. Most of the dendrites then run parallel to the borders of the nucleus extending for relatively long distances, up to 450 μm, but remain inside the border of the nucleus. Only a few (1–3) dendrites could be observed to run perpendicular to the border of the nucleus and generally only for a short distance (20–70 μm). Some of the smooth first order dendrites give rise to second order dendrites (up to 200 μm in length), which then branch into short (15–70 μm) third order dendrites. Dendritic spines and varicosities, spine‐like protusions and/or hair‐like processes are mainly found on second and third order dendrites. Surprisingly, the shape, arrangement, and the size of the dendritic field are not strictly related to the shape and size of the nucleus. In mammalian species with a comparatively narrow TRN (rat and cat) the dendritic field size was similar to that in the rabbit with a broad TRN. There was considerable variability in dendritic morphology in the caudal and intermediate parts of TRN. However, in contrast to two recent studies in the rat TRN I have found no obvious basis for classification of neurons in the mammalian TRN according to dendritic morphology. In addition, there seems to be no difference in neuronal morphology of TRN neurons in relation to different intrinsic thalamic organisation within or between species. © 1993 Wiley‐Liss, Inc.
Heterogeneity and selectivity of the degeneration of cholinergic neurons in the basal forebrain of patients with Alzheimer's disease
Authors: Lehéricy Stéphane , Hirsch Étienne C. , Cervera‐Piérot Pascale , Hersh Louis B. , Bakchine Serge , Piette François , Duyckaerts Charles , Hauw Jean‐Jacques , Javoy‐Agid France , Agid Yves
Published: January 2005

Cholinergic neurons were studied by immunohistochemistry, with an antiserum against choline acetyltransferase (ChAT), in the basal forebrain (Ch1 to Ch4) of four patients with Alzheimer's disease (AD) and four control subjects. ChAT‐positive cell bodies were mapped and counted in Ch1 (medial septal nucleus), Ch2 (vertical nucleus of the diagonal band), Ch3 (horizontal nucleus of the diagonal band) and Ch4 (nucleus basalis of Meynert). Compared to controls, the number of cholinergic neurons in AD patients was reduced by 50% on average. The interindividual variations in cholinergic cell loss were high, neuronal loss ranging from moderate (27%) to severe (63%). Despite the small number of brains studied, a significant correlation was found between the cholinergic cell loss and the degree of intellectual impairment. To determine the selectivity of cholinergic neuronal loss in the basal forebrain of AD patients, NPY‐immunoreactive neurons were also investigated. The number of NPY‐positive cell bodies was the same in controls and AD patients. The results (1) confirm cholinergic neuron degeneration in the basal forebrain in AD and the relative sparing of these neurons in some patients, (2) indicate that degneration of cholinergic neurons in the basal forebrain contributes to intellectual decline, and (3) show that, in AD, such cholinergic cell loss is selective, since NPY‐positive neurons are preserved in the basal forebrain.
Chiasmatic course of temporal retinal axons in the developing ferret
Authors: Baker Gary E. , Reese Benjamin E.
Published: January 2005

Recent studies on the distribution of optic axons in the mature visual pathways, as well as on the genesis of their ganglion cells of origin, suggest that the time of axonal arrival at the optic chiasm determines the side of the brain to which a temporal retinal axon will project. The present study has examined this issue directly in fetal ferrets, by determining the projection of the temporal retina at different developmental stages. Fetuses of known gestational age were fixed with paraformaldehyde and subsequently implanted with crystals of the carbocyanine dye, DiI, into eithe the temporal retina, or into one optic tract. The lipophilic diffusion of the dye within the plasma membrane of the axons revealed the course of temporal retinal fibers through the fetal chiasm, as well as the distribution of ganglion cells across the two retinae projecting to one optic tract.

During early fetal stages, the temporal retina extends axons preferentially into the ipsilateral optic tract: the early retinal projection shows a classical partial decussation pattern. During later fetal stages, temporal retinal axons can be traced into both optic tracts, and the distribution of cells with crossed and uncrossed optic axons in the temporal retina is overlapping. These results indicate that the mature decussation patterns of retinal ganglion cell classes are not primarily the consequence of regressive phenomena such as cell death; rather, they are formed as axons navigate the chiasmatic region during development. The differences in decussation pattern between cell classes arise from the fact that the mechanisms producing the segregation of nasal and temporal retinal axons at the chiasm must change as development proceeds.
OKN‐related neurons in the rat nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system receive a direct cortical input
Authors: Schmidt M. , Zhang H.‐Y. , Hoffmann K.‐P.
Published: January 2005

It has been previously assumed that the asymmetry of the monocular optokinetic nystagmus (OKN) of lateral‐eyed mammals is caused by an absence of visual cortex projections to directional selective neurons in the pretectal nucleus of the optic tract and dorsal terminal nucleus of the accessory optic system (NOT‐DTN). In contrast to this generally accepted hypothesis, we present multiple evidence that OKN‐related neurons in the rat NOT‐DTN in fact do receive input from the visual cortex.

We studied the corticofugal projection to NOT‐DTN physiologically, with extracellular single unit recording and electrical stimulation of the optic chiasma and the visual cortex, and anatomically, using retrograde and anterograde tracing techniques. In particular we focussed our attention on the NOT‐DTN neurons, which control eye movements during OKN. All OKN‐related NOT‐DTN cells were activated after optic chiasma stimulation. Forty‐five percent of these neurons were also activated after stimulation of the visual cortex (VC). The majority of neurons activated from VC (80%) also responded to monocular stimulation of either eye. On the contrary, most of the neurons that responded to stimulation of the contralateral eye only were not activated from VC. After injection of fluorescent latex microspheres into the NOT‐DTN, retrogradely labeled neurons were found in areas 17, 18, and 18A of the visual cortex. Phaseolus vulgaris leucoagglutinin injected into the visual cortex anterogradely labeled fibres and terminals throughout the NOT‐DTN complex. Labeled boutons were found in close proximity to OKN‐related NOT‐DTN cells, selectively stained after horseradish peroxidase (HRP) injections into the inferior olive. Our results demonstrate that NOT‐DTN cells in the rat, which are involved in the generation of horizontal OKN, receive a direct input from the ipsilateral visual cortex.
Quantitative synaptology of functionally different types of cat medial gastrocnemius α‐motoneurons
Authors: Brännström Thomas
Published: January 2005

The aim of this ultrastructural investigation was to study quantitatively the synaptology of the cell bodies and dendrites of cat medial gastrocnemius (MG) α‐motoneurons of functionally different types. In electrophysiologically classified and intracellularly HRP‐labelled MG α‐motoneurons of the FF (fast twitch, fatigable), FR (fast twitch, fatigue resistant) and S (slow twitch, very fatigue resistant) types, the synaptic covering of the soma as well as that of dendritic segments located within 100 μm and at 300, 700, and 1,000 μm distance, respectively from the soma, was analyzed.

The synaptic boutons were classified into the L‐(apposition length > 4 μm) and S‐types (<4 μm) with spherical synaptic vesicles, and the F‐type with flat or pleomorphic synaptic vesicles. The length of apposition towards the motoneuron membrane was measured for each bouton profile. Approximately 1,000 boutons contacted the soma and a similar number of boutons contacted the proximal dendrites within 50 μm from the soma. The number of dendritic boutons was larger at the 300 μm distance than at the 100 and 700 μm distances.

The three types of motoneurons showed similar values for percentage synaptic covering and synaptic packing density in the proximal dendrites, while in the most distal dendritic regions the S motoneurons had more than 50% higher values for percentage covering, packing density and total number of boutons. The S motoneurons also exhibited a larger preponderance of F‐type boutons on the soma. The ratio between the F‐ and S‐types of boutons decreased somatofugally along the dendrites in the type FF and FR motoneurons, while in the S motoneurons it remained fairly constant.
Development of the principal sensory nucleus of the trigeminal nerve of the rat and evidence for a transient synaptic field in the trigeminal sensory tract
Authors: Al‐Ghoul Walid M. , Miller Michael W.
Published: January 2005

The early development of the principal sensory nucleus of the trigeminal nerve (PSN) was examined to determine whether spatiotemporal patterns of synaptogenesis coincide with patterns in neuronal generation, migration, and death. The morphogenesis of PSN neurons during the period from G16 to P14 was studied with a Golgi method. Prenatally, PSN neurons had dendrites that extended into the sensory tract of the trigeminal nerve (s5), and from as early as G18, these dendrites were studded with spines. The dendrites in the s5 degenerated or regressed in the early postnatal period so that the s5 was free of dendrites by P14. The development of anti‐synapsin I immunoreactivity was traced from G14 to P10. Immunoreactive puncta (synaptic boutons) appeared in the medial third of the s5 transiently between G18 and P5. On the other hand, puncta in the PSN did not appear until G20, at which time they were confined to the lateral margin of the PSN. By P0, puncta were distributed throughout the PSN. Cytochrome oxidase activity in the PSN was low and unpatterned prenatally. Postnatally, cytochrome oxidase activity intensified and a segmented pattern of barreloids appeared in the ventral PSN on the day of birth. By P5, the complete pattern of barreloids, spanning the full width of the ventral PSN, was evident. The development of cytochrome oxidase activity in the PSN followed the lateral‐to‐medial gradient of synaptogenesis revealed by the development of synapsin 1 immunoreactivity. This gradient is opposite of that for neuronal generation, migration, and death. Moreover, the s5 serves as a transient synaptic field.
Distribution of calbindin‐D28k immunoreactivity in the monkey temporal lobe: The amygdaloid complex
Authors: Pitkänen Asla , Amaral David G.
Published: January 2005

Calbindin‐D28k is a calcium‐binding protein located in a variety of neuronal cell types in many regions of the central nervous system. In the present study, we describe the distribution of calbindin‐D28k‐immunoreactive cells, fibers, and terminals in the monkey amygdaloid complex. Calbindin‐D28k‐immunoreactive neurons could be divided into four major cell types. Neurons of the first three cell types demonstrated clearly stained dendrites that were either aspiny or had a few spines on their distal portions. Type 1 cells were small, stellate, or multipolar and found throughout the amygdala. Type 2 cells were large, multipolar and were most commonly found in the deep nuclei, particularly in the lateral nucleus, intermediate division of the basal nucleus, accessory basal nucleus and in the periamygdaloid cortex. Type 3 cells were fusiform, of various sizes, and were found throughout the amygdala. Type 4 cells were quite large and lightly stained; the dendrites of these cells were usually unstained. The size, shape, and location of Type 4 labeled cell bodies suggested that they might be the large, modified pyramidal cells that constitute the projection neurons of the amygdala. Type 4 cells were observed primarily in the lateral, basal, and accessory basal nuclei and in the periamygdaloid cortex. Calbindin‐D28k‐immunoreactive fibers and terminals were difficult to observe in the amygdala partly because of a diffuse, finely granular neuropil labeling that was particularly dense in the anterior cortical and medial nuclei, in the central nucleus, and in the periamygdaloid cortex. The neuropil labeling was substantially lighter in the lateral, basal, and accessory basal nuclei. Conspicuous linear profiles resembling the “calbindin bundles” of the neocortex were evident in large numbers in the accessory basal nucleus, the medial portion of the parvicellular division of the basal nucleus, in the amygdalohippocampal area, and in the periamygdaloid cortex. There were calbindin‐D28k‐positive fibers in the stria terminalis and in the ventral amygdalofugal pathway. When the distributions of calbindin‐D28k and parvalbumin immunoreactivity in the monkey amygdaloid complex were compared, it appeared that the overall distribution of these two calcium‐binding proteins was generally complementary rather than overlapping. © 1993 Wiley‐Liss, Inc.
Selective sparing of later‐born ganglion cells after neonatal transection of the infraorbital nerve
Authors: White Fletcher A. , Chiaia Nicolas L. , McCann Patricia , Enfiejian Howard L. , Macdonald Gordon J. , Bennett‐Clarke Carol A. , Rhoades Robert W.
Published: January 2005

A combination of [3H]thymidine labelling and retrograde tracing with either horseradish peroxidase (HRP) or true blue (TB) was used to determine whether V primary afferent neurons born on different embryonic (E) days were differentially susceptible to neonatal transection of the infraorbital nerve (ION). In one experiment, rat fetuses were exposed to [3H]thymidine on E‐8.5, 9.5, 10.5, 11.5, 12.5, 13.5, 14.5, or 15.5, the left infraorbital nerve (ION) was transected on the day of birth, and both the regenerate and intact IONs were labelled with HRP when the animals reached adulthood. The percentage of HRP labelled cells that were also heavily labelled by [3H]thymidine was calculated for both the intact ganglion and that ipsilateral to the damaged nerve for each animal. A consistently higher percentage of double labelled cells on the lesioned rather than on the intact side for a given E‐day was taken as an indication that cells born on the day in question had an increased probability of survival relative to the entire population of V ganglion cells that contributed axons to the ION. Cells born late in gestation on E‐12.5 through 14.5 were significantly more likely than early born (E‐9.5 through 11.5) cells to survive neonatal axotomy. In a second experiment, fetuses were exposed to [3H]thymidine on either E‐9.5, E‐10.5, or E‐14.5, the vibrissa pads on both sides of the face were injected with TB within 6 hours of birth, and the ION was transected 6–8 hours later. When these rats reached at least 60 days of age, ganglia were processed for the visualization of both TB and [3H]thymidine labelled neurons. Cells labelled with both tracers would have been born on a given E‐day, projected to the vibrissa pad via the ION at the time of nerve transection, and survived any naturally occurring or lesion‐induced cell death. As in the HRP tracing experiment, ganglion cells born on E‐14.5 were significantly more likely to survive neonatal ION transection than those born on either E‐9.5 or E‐10.5. © 1993 Wiley‐Liss, Inc.
Immunohistochemical studies on neurofilamentous hypertrophy in degenerating retinal terminals of the olivary pretectal nucleus in the rat
Authors: Meller D. , Schmidt‐Kastner R. , Eysel U. T.
Published: January 2005

Following section of the optic nerve, degenerating retinal terminals reveal an accumulation of neurofilaments (neurofilamentous hypertrophy) as demonstrated by silver impregnation techniques or electron microscopy. The present study examined degenerating retinal terminals by means of immunohistochemistry and antibodies specific for the triplet of neurofilament proteins of low (NF‐L), medium (NF‐M), and high (NF‐H) molecular weight class. Following unilateral optic nerve section in the rat and survival 1,2,4,8, and 21 days, brains were perfused with aldehyde fixative, sliced on a vibratome and stained for neurofilaments by using the peroxidase‐antiperoxidase technique. Other brains were frozen, cut in the native state, and slid‐mounted sections were fixed by acetone. Side comparisons in visual pathways were made in frontal sections, taking advantage of the near complete crossing of retinal fibers in the rat. Anterograde degeneration of axons occurred in the optic tract and brachium colliculi. Changes of terminals were investigated in the olivary pretectal nucleus, which contains a dense aggregation of retinal terminals in the core region. The optic tract and brachium coliculi showed a reduction in imunostaining for neurofilament proteins following axotomy. Within the core region of the olivary pretectal nucleus, strong increases of immunoreactivity of NF‐L and NF‐M were detected begining at 2 days postlesion and persisting at 8 days. No changes in NF‐H proteins were found in the terminal regions with three different antibody probes. The increase in immunostaining reflects the accumulation of neurofilament proteins in the degenerating retinal terminals, i.e., neurofilamentous hypertrophy. A combination of increased influx of neurofilaments into the terminals and decreased local degradation by calciumactivated neutral protease might explain the accumulations. The selective occurrence of NF‐L and NF‐M suggests molecular specificity of the degenerative process, which may be related to differences in axonal transport, integration into the stationary cytoskeleton, and phosphorylation state of different neurofilament proteins. © 1993 Wiley‐Liss, Inc.
Efferent projections of the suprachiasmatic nucleus in the golden hamster (Mesocricetus auratus)
Authors: Kalsbeek Andries , Teclemariam‐Mesbah Rebecca , Péavet Paul
Published: January 2005

The efferent projections of the suprachiasmatic nucleus (SCN) in the golden hamster have been examined by using the anterograde tracer Phaseolus vulgaris leucoagglutinin (Pha‐L). SCN projections were further localized through a combination of restricted SCN‐lesions and immunocytochemistry for three well‐known peptidergic transmitters contained in SCN neurons, viz. vasopressin (VP), vasoactive intestinal peptide (VIP), and gastrin‐releasing peptide (GRP). Thus, major terminal fields of SCN‐derived VP were detected in the medial preoptic nucleus, the anterior part of the paraventricular nucleus of the thalamus (PVA), the medial parvicellular part of the paraventricular nucleus of the hypothalamus (PVN), and the medial part of the dorsomedial nucleus of the hypothalamus (DMH). VIP‐containing projections from the SCN were discovered in the PVA, anterior and dorsal parvicellular divisions of the PVN, subparaventricular area, and medial DMH. Efferent fibers from the SCN containing GRP were restricted to the subparaventricular area, medial DMH, and supraoptic nucleus. In addition, Pha‐L tracing indicated the existence of SCN projections which could not be ascribed to one of the presently investigated peptides. Furthermore, a pronounced innervation of the contralateral SCN was observed, of which the neurotransmitter remains to be established.

The results of the present study indicate that the different neuronal populations in the SCN, as characterized by their transmitter content, also show a clear diversity in their preferential target areas. © 1993 Wiley‐Liss, Inc.
Quantitative analysis of central terminal projections of visceral and somatic unmyelinated (C) primary afferent fibers in the guinea pig
Authors: Sugiura Y. , Terui N. , Hosoya Y. , Tonosaki Y. , Nishiyama K. , Honda T.
Published: January 2005

In guinea pigs, intracellular labeling of the dorsal root ganglion (DRG) cells with Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was used to demonstrate the central projections of somatic and visceral afferent C‐fibers. The terminations of the afferent fibers were analyzed qualitatively and quantitatively with the aid of camera lucida drawings. Terminal branches of C‐fibers of both somatic and visceral origin were, in general, distributed in accord with the organization of the neuropil in lamina of the spinal cord. Terminal boutons arranged from longitudinally coursing fibers were distributed in lamina I, while boutons in lamina II were scattered in an apparent random fashion. The synaptic enlargements were counted in gray matter of the spinal dorsal horn and measured on each terminal branch of a fiber. All synaptic boutons (over one thousand) of somatic fibers were found in the superficial dorsal horn (laminae I and II). More than 60% of the synaptic enlargements of the visceral afferents also were localized superficially (lamina I and adjacent dorsal funiculus) while 10–20% of the visceral enlargements appeared in deeper layers of the spinal cord. Boutons of somatic C‐fibers were larger than those of visceral orgin. Quantitative data of the unmyelinated afferent fibers are discussed in the context of the sensory functions of myelinated afferent fibers. © 1993 Wiley‐Liss, Inc.
The central nucleus of the inferior colliculus in rat: A Golgi and computer reconstruction study of neuronal and laminar structure
Authors: Malmierca Manuel S. , Blackstad Theodor W. , Osen Kirsten K. , Karagülle Tevfik , Molowny Roberto L.
Published: January 2005

The cellular basis for the laminar structure of the central nucleus of the inferior colliculus has been investigated by computer‐assisted 3‐D reconstruction of Golgi impregnated dendritic arbors, sampled from serial sections of resin embedded material of adult rat. Two types of flattened neurone, defined here as flat (F) and less flat (LF), are described as contributing to the pattern. The dendritic arbors of F neurones had a smaller absolute thickness (mean about 50 μm) and a denser arbor. They were strikingly parallel regionally and formed laminae mostly one cell thick. The laminae appeared to be separated by interlaminar compartments populated by the LF neurones. The arbors of the latter were thicker (mean about 100 μm) and less dense than those of the F neurones. The different density of the two types may, at least in part, be responsible for the corresponding difference in density of oriented dendrites within the laminae and interlaminar compartments. The orientation planes of F and LF arbors were roughly similar, but a consistent, slight difference in orientation between F and LF arbors is not excluded. Most of the F and LF arbors were elongated in parallel with the ventrolaterally to dorsomedially oriented long axis of the laminae. A few were instead oriented rostrocaudally or in intermediate directions. The interlaminar compartments appeared less distinct in the low than in the high frequency region. The latter region also differed from the former by having F neurones with a higher number of intermediate and terminal segments and a denser arbor. It is discussed whether the observed F and LF cells constitute two distinct cell types or are varieties of one type of neurone, with the morphological differences reflecting differences in location. Further characterization of the neurones on histochemical, hodological, and other criteria is required to settle this question. © 1993 Wiley‐Liss, Inc.
Immunochemical heterogeneity in the tecto‐LP pathway of the rat
Authors: Lane Richard D. , Bennett‐Clarke Carol A. , Allan Dawn M. , Mooney Richard D.
Published: January 2005

The projection from the rat's superior colliculus (SC) to the lateral posterior nucleus of the thalamus (LP) has previously been described as arising from a morphologically homogeneous population of neurons in the stratum opticum (SO). The present study combined immunocytochemistry with retrograde tracing and lesion techniques to determine whether or not the SC → LP projection arose from neurons that were also neurochemically homogeneous. The combination of retrograde tracing and immunocytochemistry with an antibody directed against calbindin‐D 28K (CBD) showed that 64.4% of the neurons that project from SC to LP contain this calcium‐binding protein. Retrograde tracing and immunocytochemistry for adenosine deaminase (ADA) showed that a smaller number of tecto‐LP cells (15.7%) were immunoreactive (IR) for this enzyme. Moreover, nearly all (93.0%) of the ADA‐IR tecto‐LP cells also contained CBD‐IR. Adenosine deaminase‐IR axons in LP were restricted to the dorsomedial portion of the nucleus and their density was substantially reduced after ablation of the ipsilateral superficial SC laminae. The lateral posterior nucleus contained numerous CBD‐IR cells and fibers throughout its extent and it was thus difficult to determine the extent to which the extra‐perikaryal CBD‐IR in this nucleus was dependent upon the tecto‐LP pathway. Nevertheless, destruction of the ipsilateral SC did reduce the density of CBD‐IR in LP. These results suggest that the SC → LP projection in rat arises from at least four neurochemically distinct cell groups: (1) those that contain CBD, (2) those that contain both CBD and ADA, (3) a very small population that contains only ADA, and (4) a group that is not recognized by either of these markers. Our results further suggest that ADA containing fibers may have a more restricted terminal distribution in LP than axons that contain only CBD. © 1993 Wiley‐Liss, Inc.
JUN, FOS, KROX, and CREB transcription factor proteins in the rat cortex: Basal expression and induction by spreading depression and epileptic seizures
Authors: Herdegen T. , Sandkühler J. , Gass P. , Kiessling M. , Bravo R. , Zimmermann M.
Published: January 2005

The expression of the nuclear c‐JUN, JUN B, JUN D, c‐FOS, FOS B, KROX‐24, and CREB transcription factors was investigated in the cortex of adult rats by immunocytochemistry. The expression patterns were studied in untreated rats and up to 24 hours following topical application of 1 M KCl to the cortical surface (KCl) or i.v. injection of bicuculline (BIC). Topical KCl induced cortical spreading depression and systemic injection of bicuculline evoked generalized tonic‐clonic seizures.

In untreated rats, JUN B, c‐FOS, and FOS B were expressed in a small number of neurons in the piriform, perirhinal, entorhinal, and insular cortex and in layers II, III, and VI of all neocortical areas. In contrast, c‐JUN, JUN D, and KROX‐24 were expressed in all cortical layers but with different intensities of immunoreactivity (IR): c‐JUN‐IR was generally weak and predominantly present in layers II, III, and VI. JUN D‐IR was equally strong in all layers. KROX‐24 showed a prominent expression in layers II, IV, and VI. The CREB protein exhibited a high and fairly homogeneous constitutive expression throughout the cortex with a slight preponderance in layer II and piriform cortex.

Following KCl or BIC, a strong induction was seen for c‐FOS, JUN B, and KROX‐24, whereas c‐JUN, JUN D, and FOS B showed only a moderate increase compared to basal levels. Changes of CREB‐IR could not be detected. The localization of induced JUN, FOS, and KROX proteins reflected the pattern of labelling in untreated animals but demonstrated a higher intensity of labelling and an increased number of immunoreactive nuclei. The intensity and persistence of IR as well as the number of labelled cells following BIC exceeded those following KCl. Following BIC, increased levels of FOS B and JUN D were still present after 24 hours. Counterstaining with cresyl‐violet and GFAP, a marker for astrocytes, revealed that JUN, FOS, and KROX proteins were expressed in neurons but not in glial cell populations.

The present data demonstrate that CREB, JUN, FOS, and KROX transcription factors exhibit a layer‐specific expression in the cerebral cortex with only slight area‐specific differences both in untreated rats and following stimulation with KCl and BIC. The expression of transcription factor proteins indicate complex molecular genetic changes in cortical neurons due to pathophysiological events such as seizure activity and spreading depression. © 1993 Wiley‐Liss, Inc.
Immunohistochemical analyses of the human olfactory bulb
Authors: Smith Robin L. , Baker Harriet , Greer Charles A.
Published: January 2005

These studies explore the distribution of putative neuroactive peptides in the human olfactory bulb. Localization of synaptophysin‐, serotonin‐, cholecystokinin‐, substance P‐, and somatostatin‐like staining was examined by immunocytochemical protocols. The results provide new insights into the composition and laminar segregation of subpopulations of neurons and neuronal processes in the human olfactory bulb.

The prominent synaptophysin‐like immunoreactivity observed in the glomeruli of the human olfactory bulb is consistent with the notion that the density of synapses, and hence the density of synaptic vesicles, is highest in the glomeruli. Serotonin‐like immunoreactivity suggested a variable innervation of glomeruli ranging from a dense tangled ball of fibers within the glomerulus to a sparse innervation by a single immunoreactive fiber. There was no evidence of serotonin‐like immunoreactive cell bodies in either the olfactory bulb proper, anterior olfactory nucleus, or proximal regions of the lateral olfactory tract. Cholecystokinin‐like immunoreactivity was limited to fibers found largely in the juxtaglomerular region of the glomerular layer. In the deeper layers of the olfactory bulb, cholecystokinin‐like immunoreactive fibers did not show any of branching or arborization that was evident in the juxtaglomerular region. Substance P‐like immunoreactivity was seen in varicose fibers distributed in all of the human olfactory bulb laminae. In addition, stained multipolar neurons were found in the area of the anterior olfactory nucleus. Somatostatin‐like immunoreactivity was similar to that of substance P in that a plexus of stained fibers was found in all laminae of the olfactory bulb. Also, somatostatin‐like immunoreactive cell bodies were found in the area of the anterior olfactory nucleus. However, as compared to substance P, somatostatin had a less dense plexus of immunoreactive fibers in the olfactory bulb.

These results increase our understanding of the fundamental organization of the human olfactory system. The current data, coupled with prior studies, provide a foundation from which to study the cellular pathology of diseases with known olfactory system sequelae such as Alzheimer's, Parkinson's, and schizophrenia. © 1993 Wiley‐Liss, Inc.
Axon dependent glial changes during optic fiber regeneration in the goldfish
Authors: Levine R. L.
Published: January 2005

During optic fiber regeneration in the goldfish, astrocytes in the visual system undergo a number of changes. These include hypertrophy of cell processes, increased reactivity with anti‐intermediate filament antisera, and expression of cytoskeletal antigens not usually seen in these cells. In the present study, I have asked how much of this response might be due to interactions of glial cells with regenerating optic axons. Animals with and without a retina (regenerating and nonregenerating animals, respectively) had their optic nerve crushed and were then examined at various postoperative times with immunohistochemical methods. Three major differences between these two groups of animals were observed. First, in nonregenerating animals the crush lesion is not repopulated by immunoreactive glial cells while in regenerting animals it is. Second, the nature of the glial hypertrophy in the optic nerve is different in regenerating and nonregenerating animals. Finally, there is marked submeningeal swelling in regenerating nerves that is absent from nonregenerating nerves. Thus, these three aspects of the cellular response to optic nerve crush in the goldfish‐–wound healing, optic nerve gliosis, and non‐neural cellular responses–‐appear to depend on interactions between regenerating optic axons and astrocytes or other non‐neuronal cells of the visual paths for their expression. © 1993 Wiley‐Liss, Inc.
Development of blobs in the visual cortex of macaques
Authors: Purves Dale , Lamantia Anthony
Published: January 2005

We have examined the area of the primary visual cortex and the number and size of blobs within it in 10 neonatal and 11 adult rhesus monkeys. The average area of the primary visual cortex (V1) increases from 919 mm2 in newborns to 1,069 mm2 in adult animals (16%). The number of blobs decreases per unit area from an average of 5.2/mm2 at birth to 4.3/mm2 in maturity (18%). As a consequence, the number of blobs remains approximately the same during maturation, at about 4,800/hemisphere. These observations correct a preliminary report on a subset of the animals studied here (Purves and LaMantia: Proc Natl Acad Sci 87:5765, '90), in which it appeared that blob number might increase between birth and maturity. As in other regions of the developing postnatal brain, we found no net loss of modular circuitry. © 1993 Wiley‐Liss, Inc.
Qualitative and quantitative analyses of the patterns of retinal input to neurons in the dorsal lateral geniculate nucleus of the cat
Authors: Robson John A.
Published: January 2005

In the visual system of the cat the projection from the retina to the lateral geniculate nucleus has been studied extensively. However, the patterns of synaptic contacts made by individual axons onto individual cells have not been described. In this study these patterns have been examined for class 1 cells (Guillery: J. Comp. Neurol. 128:21, '66). Retinogeniculate axons and lateral geniculate neurons are labeled with horseradish peroxidase (HRP) via injections into the optic tracts and optic radiations, respectively. Sections are then processed for combined light and electron microscopic analysis. They are examined with the light microscope to identify labeled lateral geniculate neurons that appear to be contacted by labeled retinal axons. These cells and axons are then analyzed by a computerized microscope system, and sites of apparent synaptic contact are recorded. This light microscopic analysis indicates that individual class 1 cells are contacted by many retinogeniculate axons (> 10) and that each of these axons contacts many lateral geniculate neurons (> 20). Some axons make numerous contacts that are concentrated onto a few dendrites, while others make only a few contacts, which are spread over several dendrites. In all cases, the majority of contacts are on the dendritic shafts of relatively thick secondary and tertiary dendrites. Electron microscopic analysis confirms that most of the contacts identified with the light mciroscope are synaptic. It also reveals that labeled and unlabeled retinal axons can innervate the same dendritic segment. Finally, one cell was studied that had its soma and most of its dendrites in lamina A1 but some of its dendrites extended into lamina A. This cell received input from retinal axons in both layers, thus suggesting that it may have been binocularly excitable. © 1993 Wiley‐Liss, Inc.
Distribution of prosaposin‐like immunoreactivity in rat brain
Authors: Kondoh Keiji , Sano Akira , Kakimoto Yasuo , Matsuda Seiji , Sakanaka Masahiro
Published: January 2005

Prosaposin is the precursor for saposins A, B, C, and D, which are small lysosomal proteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. With a monospecific anti‐saposin C antibody, which cross‐reacts with prosaposin but not with saposin A, B, or D, the present immunoblot experiments showed that the rat brain expresses an unprocessed ∼ 72 kDa protein (possibly prosaposin) and little saposin C. Regional analysis demonstrated that prosaposin is abundant in the brainstem, hypothalamus, cerebellum, striatum, and hippocampus, and less abundant in the cerebral cortex. Consistent with this finding, prosaposin‐like immunoreactive neurons and fibers as revealed by immunohistochemistry were observed frequently in subcortical regions. The medial septum, diagonal bands, basal nucleus of Meynert, ventral striatum, medial habenular nucleus, and motor nuclei of cranial nerve had significant numbers of immunoreactive neurons. There were also nerve fibers with prosaposin‐like immunoreactivity in several projection fields of the above nuclei. Other brain areas that contained prosaposin‐like immunoreactive neurons and/or processes were: several brain nuclei (nucleus caudate putamen, globus pallidus, substantia nigra, red nucleus) constituting the so‐called extrapyramidal system, reticular thalamic nucleus, entopeduncular nucleus, mammillary nuclei, auditory relay nuclei, cerebellum, sensory cranial nerve nuclei, and the reticular formation. The distribution pattern of prosaposin is apparently different from that of other neuroactive substances so far examined, and thus prosaposin may be involved in novel central events. © 1993 Wiley‐Liss, Inc.
Effects of aging on the size, density, and number of rhesus monkey lateral geniculate neurons
Authors: Ahmad Aneeq , Spear Peter D.
Published: January 2005

Visual abilities decline during aging, and many of these declines are due to neural changes in the retina or brain. We have begun studies of the monkey visual system to investigate the location and nature of these changes as well as to answer general questions about the effects of aging on neural structure and function. We began with the dorsal lateral geniculate nucleus (LGN) because it is the main structure through which visual information passes on the way to cortex and because the parallel parvicellular and magnocellular pathways are most easily identified and studied in the LGN. In the present experiment, we determined the sizes, densities, and numbers of LGN neurons in young‐adult (5 to 12.5 years) and old (23 to 27.5 years) rhesus monkeys. The measures were corrected for tissue shrinkage, and stereological procedures were used that yield unbiased estimates.

In young‐adult monkeys, neuron densities were lower in the magnocellular layers (about 14,000/mm3) than in the parvicellular layers (23,000/mm3). Neuron density increased about 28% from anterior to posterior in both types of layers. There was an average of approximately 1,267,000 neurons in the parvicellular layers and 148,000 neurons in the magnocellular layers; however, there was substantial variability (1.9‐fold) among five brains studied.

Aging produced a statistically significant decrease in neuron density in both the magnocellular (29% average decrease) and parvicellular (41% average decrease) layers. However, there was no significant loss of neurons. Rather, the density decrease was due to a small (nonsignificant) decrease in the number of neurons combined with a small (nonsignificant) increase in LGN volume. The increase in LGN volume was due to a significant increase in neuron soma‐size and proportional increases in the volume of glial cells, blood vessels, and neuropil. These results, together with those of other studies, suggest that the effects of aging on the primate visual pathway from retina through striate cortex are relatively subtle. It is possible that the major neural changes occur more centrally. Alternatively, individual differences in the effects of aging may require much larger samples or prior screening to observe consistent changes. © 1993 Wiley‐Liss, Inc.
Projections of the suprachiasmatic nucleus to stress‐related areas in the rat hypothalamus: A light and electron microscopic study
Authors: Buijs Ruud M. , Markman Marry , Nunes‐Cardoso Bob , Hou Yang‐Xun , Shinn Susan
Published: January 2005

The purpose of the present study was to investigate the sites in the hypothalamus where the suprachiasmatic nucleus (SCN) may influence corticosteroid secretion. In spite ofthe well established, SCN‐mediated, daily rhythms in adrenocorticotrophic hormone (ACTH) and corticosteroid secretion, previous studies determining the projections of the suprachiasmatic nucleus faiied to illustrate direct connections with corticotrophin‐releasing hormone neurons (CRH).

In order to identify where in the central nervous System the SCN may influence corticosteroid secretion, areas were selected that contained SCN efferents contacting neurons involved in the stress response. To achieve this in the present study, SCN efferents were visualized by Pha‐L tract‐tracing, together with the neurons involved in the stress response by immunocytochemical staining for c‐fos protein.

The sites where these efferents contacted c‐fos‐positive neurons were established by light microscopic double staining and electron microseopic immunocytochemical studies. It appeared that apart from the medial parvocellular area of the paraventrieular nucleus (PVN) of the hypothalamus, many more regions showed fos‐positive neurons. Sites where SCN efferents contacted such neurons are limited only to areas immediately adjacent to these putative CRH neurons but are not concentrated on these neurons themselves. These areas consist of the periventricular and rostral PVN together with the dorsomedial hypothalamus: all three regions are known to project into the PVN. Therefore, it is concluded that the SCN transmits its Information related to corticosteroid secretion via interneurons in and around the PVN to the CRH‐containing neurons, rather than by a direct interaction with these neurons themselves. © 1993 Wiley‐Liss, Inc.
Heterogeneity of rat corticospinal neurons
Authors: Tseng Guo‐Fang , Prince David A.
Published: January 2005

In order to examine the degree of diversity within a population of cortical projection neurons, rat corticospinal cells were retrogradely labeled in vivo by injocting rhodamine‐tagged microspheres into the cervical spinal cord, and subsequently studied electrophysiologically and anatomically in neocortical slices maintained in vitro, by use of Standard current clamp techniques and a double‐labeling protocol (Tseng et al, J. Neurosci. Meth. 37′. 121–131, 1991). Three different subgcroups were distinguished on the basis of their spiking behavior: (l) Adapting cells had a marked fast (50 ms) and slow phase (200 ms) of spike frequency adaptation; (2) regulr spiking (RS) cells had only a period offast adaptation; (3) some regulr spiking neurons had prominent depolarizing afterpotentials (DAPs) and could generate bursts of Spikes, often in repetitive fashion (RSoAp cells). Subgroups of RSc.Ap cells had different patterns of burst responses to depolarizing current pulses, suggesting differences in the types and/or sites ofunderlying ionic conduetances.

Adapting cells had a slightly higher membrane input resistance and more prominent slow hyperpolarizing afterpotentials than RS and RSDAP neurons; however, the activation of presumed anomalous rectifier current by intracellular hyperpolarizations was less prominent in adapting neurons. Orthodrornic Stimulation in layer l evoked presumed excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) in all three types of cells, but prominent short‐latency IPSPs were found in a higher percentage of adapting neurons.

The morphology of electrophysiologically characterized corticospinal neurons was studied following intracellular injection of biocytin. All three spiking types were typical layer V pyramids with apical dendrites reaching layer l, basal dendrites in infragranular layers, and deep‐directed axons that had a moderate density oflocal collaterals in lower cortical layers. The profuseness of dendrites, examined by Sholl's analysis of two‐dimensional, camera lucidareconstructed neurons was comparable in the three neuronal subgroups, although a smaller somatic area and more siender apical dendritic trunk were found in adapting neurons.

Our results suggest that corticospinal cells in rats are a heterogeneous population of projection neurons with respect to their spiking behavior, membrane properties, synaptic connections, and, to a lesser extent, their morphology. This diversity revealed in vitro adds new complexity to the classification of corticospinal neurons. © 1993 Wiley‐Liss, Inc.
Development of gemculocortical projections to visual cortex in rat: Evidence for early lngrowth and synaptogenesis
Authors: Kageyama Glenn H. , Robertson Richard T.
Published: January 2005

Anterograde movement of Dil and transneuronal transport of wheat germ aghitinin‐horseradish peroxidase (WGA‐HRP) were used to study the temporal and laminar patterns of ingrowth of the geniculocortical projection to visual cortex in fetal and postnatal rats. The development of this projection was compared to patterns of migration and settling of L HJ‐thymidine‐labeie neurons destined for cortical layer IV, and to geniculocortical synapse formation. Dil‐labeied geniculocortical axons were found in the intermediate zone beneath the lateral cerebral mantle at embryonic day (E) 17 and in the subplate layer underlying visual cortex by EIS. On E 19 they appeared to accumulate and grow radially into an expanding subplate layer and into the deep part ofdeveloping cortical layer VI. By postnatal day (P)0, Dil or WGA‐HRP‐labeled geniculocortical axons were found in developing cortical layers VI and V. By P l, they invaded the deep portion ofthe cell‐dense cortical plate, where they were in position to make initial contact with neurons that would later form layer IV. A few xons traversed the cortical plate to reach the marginal zone. Layer IV became an identifiable layer on P2, and s clear projection to layer IV was evident by P3. These results suggest that geniculocortical afferents grow continuously from the intermediate zone, initially into an expanding subplatt layer and then sequentially into each of the developing cortical layers without evidence of “waiting”. Electron microscopic data suggest that geniculocortical axons begin to form immature synapses with dendrites and neuronal perikaryas they first encounter cortical neurons, first in the subplate layer and then in developing layers VI, V and marginal zone, in addition to the primary target layer IV. The precise targetmg and overall temporal and laminar patterns of ingrowth and synaptogenesis suggest that geniculocortical axons are directed to the visual cortex by guidance cues within the internal capsule and subplate. Further, they reach the occipital pole early enough to influence the specification and histogenesis of cortical area 17, perhaps by exerting an influence on the deep‐to‐superficial “wave” of neuronal differentiation in sequentially developing subplate and cortical layers VI, V and IV. © 1993 Wiley‐Liss, Inc.