bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of primary axosomatic endings in the anteroventral cochlear nucleus of the cat: A study of the endbulbs of Held
Authors: Ryugo D. K. , Fekete D. M.
Published: December 2004

The central axons of Type I spiral ganglion neurons travel in the auditory nerve and terminate in the cochlear nucleus. The ascending branches of these axons innervate the anteroventral cochlear nucleus and give rise to large axosomatic endings, called the endbulbs of Held, and smaller boutons. This paper reports a study of the endbulbs of Held, stained by horseradish peroxidase and variants of the Golgi method in kittens 2, 5, 10, 20, and 45 days postnatal and adult cats. Endbulbs tend to fall into two extreme groups with some endbulbs having an intermediate appearance; consequently, we have defined three descriptive stages of endbulbs that are conceived of as representing a developmental sequence. One group of endbulbs is found mostly in kittens younger than 10 days postnatal and is similar to the classic description of endbulbs by Ramón y Cajal ('09). The other extreme group of endbulbs is found mostly in adult cats. In these cases, the parent axonal trunk divides into several thick, gnarled branches that in turn branch again, sometimes repeatedly. These branches display irregular varicosities and form a cup‐shaped arborization into which the postsynaptic cell body nestles. A chronology of postnatal endbulb development has been inferred from the relative proportions of the different endbulb stages at various ages. Maturation transforms the endbulb of Held from a large, spoon‐shaped swelling having many filipodia into an elaborate tree with broad trunks and many smaller branches. Some implications of the proposed developmental sequence are discussed.
Spontaneous regeneration of cut axons in adult rat brain
Authors: Foerster Anne P.
Published: December 2004

Lesions with precisely defined boundaries were made, in adult rat brains, with a new type of cutting device that remained implanted during various survival times. The subsequent events were followed histologically in silverstained (including Fink‐Heimer) horizontal sections, with myelin and nuclear counterstains. The devices, inserted vertically through the dorsal surface of the brain until they met the floor of the skull, consisted of a horizontal cutting wire (0.9–2.6 mm long) between two vertical support wires, all 90 μm diameter. Following fixation of the brain, the device was removed from its ventral surface; thus, the channels left by the support wires appeared as two holes in horizontal sections, clearly marking the limits of the cut. The extents of the tissue cut by, and that passively deflected around, such devices were charctrized from measurments of brains examined immediately after an incision was made and from degeneration studies after 3‐day implantations. After implantations of 18–230 days, the severed axons no longer abutted the line of such lesions, as seen initially; now axons were often observed to extend alongside the lesion, then to bend and course around the support wire. Such “detours” curved back into the injured tracts, seeming to reconnect them appropriately. Detours had begun by 3–8 days, and end‐swellings were frequently seen on their reoriented axons. Neither collateral sprouting of spared axons nor passive deformation of brain tissue was consistent with the findings. It is concluded that a massive and reconstructive regeneration of cut axons occurred around the ends of lesions made by the cutting devices.
Immunocytoehemical localization of substance P in the spinal trigeminal nucleus of the rat: A light and electron microscopic study
Authors: Priestley John V. , Somogyi Péter , Cuello A. Claudio
Published: December 2004

The neuropeptide substance P is a transmitter candidate for certain primary afferent fibers which terminate in the substantia gelatinosa. In this study the light and electron microscopic localization of substance P in the substantia gelatinosa of the spinal trigeminal nucleus of the rat has been studied using immunocytochemical procedures.

Substance P immunoreactive fibers were observed mainly in lamina I and outer lamina II. Ultrastructural analysis revealed immunoreactivity in unmyelinated fibers and in axon terminals which contained agranular spherical vesicles and large dense‐cored vesicles and which made predominantly simple asymmetric axodendritic synaptic contacts. Immunoreactive terminals only rarely formed the central terminal of synaptic glomeruli and in only one example was a stained terminal possibly postsynaptic to an unstained terminal. The majority of synapses were onto small dendrites in outer lamina II and in some cases these dendrites were themselves presynaptic to other dendrites. Immunoreactive terminals also synapsed with the soma and proximal dendrites of large neurons on the border of laminae I and II.

The results show that there are at least two distinct targets for substance P immunoreactive terminals in the substantia gelatinosa, namely the large lamina I neurons and lamina II probable intemeurons. Some of the former may be projection neurons while some of the latter may correspond to the inhibitory islet cells described by Gobel and colleagues in the cat. In addition the results indicate that few substance P immunoreactive terminals receive axoaxonic synapses and emphasize instead the role of postsynaptic interactions. In particular the results suggest several sites at which substance P might interact postsynaptically with the neuropeptide enkephalin.
A comparative histological and electrophysiological study of some neurotoxins in the rat hippocampus
Authors: Lancaster Barrie , Wheal Howard V.
Published: December 2004

It has been proposed that the neurotoxic action of kainic acid is a result of the seizure activity which it induces. In this study intraventricular injection of kainic acid, and three other putative neurotoxins, was used in an attempt to investigate the role of electrical seizure activity and neurotoxicity in the rat hippocampus, Two separate groups of experiments were performed. First, & histological study of the neurotoxic potency of the compounds under investigation was carried out, and second, an electrophysiological study of those compounds which displayed neurotoxicity. In these experiments, extracellular recordings were made in the hippocampus ipsilateral to infusion during and after administration of the neurotoxin.

Kainic acid (5.0 μg) produced unilateral lesions of the CAB and C A4/ hilus cells of the hippocampus, but CA1 and granule cells remained intact. Electrical seizure activity could be recorded from both CS3 and CA1 regions after kainic acid infusion. Dihydrokainic acid displayed no neurotoxicity. α‐ketokainic acid (5.0 μg) only produced minor toxic effects such as small areas of pyknosis, but electrical seizure activity was produced in both CA3 and CA1 cell regions. Cis 1‐amino 1,3‐dicarboxycyclopentane (cis‐ADCP), (5.0 μg) produced unilateral lesions of the CA3 area without any extension into the CA4/hilus cell layer. There was no electrical seizure activity associated with the action of this compound.

These results show that the presence of seizure activity in the hippocampus is not invariably followed by loss of pyramidal cells. As cis‐ADCP produces a discrete lesion in the absence of any seizure activity, this compound may prove to be a more useful neurotoxin for producing experimental models of disease states in the central nervous system.
Peripheral organization and central projections of the electrosensory nerves in gymnotiform fish
Authors: Carr Catherine E. , Maler Leonard , Sas Emilia
Published: December 2004

The electrosensory system of weakly electric gymnotiform fish is described from the receptor distribution on the body surface to the termination of the primary afferentsin the posterior lateral line lobe (PLLL). There are two types of electroreceptor(ampullary and tuberous) and a single type of lateral line mechanoreceptor (neuromast). Receptor counts in Apteronotus albifronsshow that (1) neuromasts are distributed as in other teleosts; (2) ampullary receptors number 151 on one side of the head and 208 on one side of the body; (3) tuberous receptors were estimated to number 3,000‐3,500 on one side of the head and 3,500‐5,000 on one side of the body. The distribution of each receptor type is described.

Each receptor is innervated by a single primary afferent. Electro‐sensory afferents have myelinated cell bodies in the ganglion of the anterior lateral line nerve (ALLN). The distribution of these ganglion cell diameters is strongly bimodal in Apteronotus and Eigenmannia: The smaller‐diameter cells may be those which innervate ampullary electroreceptors, the larger‐diameter tuberous electroreceptors.

Transganglionic HRP transport techniques were used to determine the first‐order connections of the anterior lateral line nerve in six species of gymnotiform fish. Small branches of the ALLN were labeled so as to determine the somatotopic organization in the PLLL. The PLLL is divided into four segments from medial to lateral, termed medial, centromedial, centrolateral, and lateral segments (Heiligenberg and Dye, '81). Representations of the head are found rostrally in each zone, and the trunk is mapped caudally in each zone. Thus there are four body maps in the PLLL. The medial segment receives ampullary input (Heiligenberg and Dye, '82) and maps the dorsoventral body axis mediolaterally, as does the tuberous centrolateral segment. The tuberous centromedial and lateral segments map the dorsoventral axis lateromedially. Thus the medial and centromedial segments meet belly to belly, the centromedial and centrolateral segments meet back to back, and the centrolateral and lateral segments meet belly to belly. Adjacent electrosensory maps within the PLLL are therefore always mirror images.
Representations of the body surface in cortical areas 3b and 1 of squirrel monkeys: Comparisons with other primates
Authors: Sur Mriganka , Nelson R. J. , Kaas J. H.
Published: December 2004

Microelectrode multiunit mapping techniques were used to determine the somatotopic organization of postceritral parietal cortex in the squirrel monkey Saimiri sciurus. Recordings were largely confined to architectonic areas 3b and 1. Results were compared to those from similar studies of owl (Merzenich et al., '78) and macaque (Nelson et al., '80) monkeys. As in these previous investigations, separate representations of the body surface were found in areas 3b and 1 of squirrel monkeys. These representations were organized in parallel, so that both proceeded from the tail on the medial wall of the cerebral hemisphere, to the lips and oral cavity on the lateral margin of these areas along the sylvian fissure. The representations were also roughly mirror images of each other so that whatever skin surface was represented rostrally in area 3b was represented caudally in area 1, and similar skin surfaces were represented along the common border. However, the representations were not identical. For example, the split representations of the leg differed so that the distal leg was represented in cortex lateral to that devoted to the foot in area 1 and medial to the foot in area 3b. Remarkably, the representations of some body parts were reversed in orientation in both area 3b and area 1 in squirrel monkeys as compared to owl and macaque monkeys. The face, arm, trunk, and leg representations were all reversed in squirrel monkeys, while the orientations of the hand and foot representations were the same. For example, the dorsal trunk is represented rostrally in area 3b and caudally in area 1 and the ventral trunk is represented at the 3b/l border in owl and macaque monkeys, while the ventral trunk is represented rostrally in area 3b and caudally in area 1 and the dorsal trunk is represented at the 3b/1 border in squirrel monkeys. These reversals of somatotopic organization in part but not all of the representations in areas 3b and 1 suggest that both fields are divided into sectors where the basic somatotopic orientation is independently determined, that the orientation of some of these sectors is subject to reversal in evolution, and that matching sectors in areas 3b and 1 are not independent in somatotopic organization.
The origin of lipid phagocytes in the central nervous system: I. The intrinsic microglia
Authors: Brierley J. B. , Brown A. W.
Published: December 2004

The potential for the transformation of the normal microglial cell to a lipid phagocyte was studied by light and electron microscopy in the brains of rodents and by light microscopy only in primates. All were subjected to some form of hypoxia‐ischemia and the microglial response was examined in regions of selective neuronal destruction (SND) so that infarction was deliberately excluded. In vivo perfusion‐fixation was employed in all animals and light microscopic examination was carried out on paraffin‐ and sometimes celloidin‐embedded material. Semithin plastic sections from several regions of the rodent brains were used for light microscopy but ultrastructural studies were confined to the hippocampus.

In all animals the microglia were activated and transformed into rod cells exhibiting phagocytic properties but only a minority gave rise to lipid phagocytes. Blood vessels were normal in all animals and no hematogenous elements were identified in the parenchyma. As neuronal ghosts could be identified for up to 3 weeks it was concluded that the capacity of the microglia for phagocytic activity was limited.
Volume densities and specific surfaces of neuronal and glial tissue elements in the rat supraoptic nucleus
Authors: Pilgrim Ch. , Reisert I. , Grab D.
Published: December 2004

The present study was undertaken to provide an explanation for previous autoradiographic results suggesting a several times higher rate of synthesis of glycoconjugates per unit volume of hypothalamic glia than of neurons. Volume densities, specific surfaces (surface:volume ratios), and relative surfaces (contribution of the surface of a tissue element to the total surface of the tissue) were assessed.

Neuronal elements occupy about 74% and glial elements about 8% of the total volume. The specific surface, i.e., the amount of plasma membrane per unit volume of structure, is more than 30 times higher in the neuropil than in the neuronal perikaryal fraction. The largest specific surface is found with (unmyelinated) axons and astroglial processes. The specific surface of the average astrocyte is about twice that of the average neuron. If the surface of the entire cell is considered in relation to the perikaryal volume only, this ratio is about seven times as large for glial cells as for neurons. It follows that an astrocyte perikaryon has to renew a several times larger plasma membrane than a neuron, which can account for the above differences in perikaryal synthesis rates of glycoconjugates.
Insula of the old world monkey. Architectonics in the insulo‐orbito‐temporal component of the paralimbic brain
Authors: Mesulam M.‐Marsel , Mufson Elliott J.
Published: December 2004

The insula of the rhesus monkey has a surface area of approximately 160 mm2 and can be divided into three architectonic sectors. The agranular sector is coextensive with prepiriform allocortex and is characterized by three agranular cellular strata, a zonal layer of myelinated fibers, and a high level of intracortical acetylcholinesterase (AChE). The dysgranular sector adjoins the agranular sector and shows first the emergence of a granular L4 and then a gradual differentiation of L2. Cortical myelin is low and mostly within deep layers; the AChE level is less than in the agranular sector. The third and granular sector covers the posterior aspect of the insula and contains granular L4 and L2, incipient sublamination of L3, increased cortical myelin with an emergent outer line of Baillarger, and a very low density of AChE. These observations indicate that AChE histochemistry can be used for the architectonic analysis of cortex.

The lateral orbital cortex and the temporal pole can also be subdivided into agranular, dysgranular, and granular regions. In the insula as well as in lateral orbital and temporopolar areas, the agranular sector is directly contiguous with prepiriform cortex. When these three brain regions are considered jointly, they are seen to be organized in the form of increasingly more differentiated agranular, dysgranular, granular, and hypergranular sectors arranged concentrically around prepiriform allocortex.

The term paralimbic is suggested as a generic term for all regions where such transitions occur from allocortex to granular isocortex. The insula, lateral orbital surface, and temporal pole are paralimbic areas with an olfactory allocortical focus. The parahippocampal, retrosplenial, cingulate, and subcallosal regions constitute a second group of paralimbic areas with a hippocampal‐induseal focus. In the most general sense, the functional specializations of paralimbic areas are predominantly for behaviors which require an integration between extrapersonal stimuli and the internal milieu.

The human insula has a plan of organization virtually identical to that in the rhesus monkey. In the human, the insulo‐orbito‐temporopolar component of the paralimbic brain may become involved in conditions which range from epilepsy to psychosomatic disease.
The motor cortex of the rat: Cytoarchitecture and microstimulation mapping
Authors: Donoghue John P. , Wise Steven P.
Published: December 2004

The first motor (MI) cortex of the rat was identified as the region from which movements could be evoked by the lowest intensity of electrical stimulation. The location of this region was correlated with Cytoarchitecture in the frontal and parietal cortex. Two frontal areas can be discerned in Nissl‐stained sections: (1) the medial agranular field, marked by a pale‐staining layer III and a compact layer II, and (2) the lateral agranular field, which has more homogeneous superficial layers and a broad layer V containing large, densely staining cells. Both of these regions project to the spinal cord and can therefore be included in the somatic sensorimotor cortex. MI in the rat coincides with the lateral agranular field but also overlaps with part of the adjacent granular cortex of the first somatic sensory (SI) representation. We conclude that the rat MI cortex can be identified by microstimulation techniques and by cytoarchitecture in the rat.
The distribution of vasotocin and isotocin in the brain of the rainbow trout
Authors: van den Dungen H. M. , Buijs R. M. , Pool C. W. , Terlou M.
Published: December 2004

The distribution of vasotocin and isotocin in the brain of the rainbow trout Salmo gairdneri was investigated by the unlabeled antibody enzyme method, by using purified antisera against arginine vasotocin and isotocin. In the preoptic nucleus no clear differences were observed in the distribution of vasotocinand isotocin containing cells. Vasotocin and isotocin innervation was found in most brain regions, though in general isotocin fibers were much more abundant. The area dorsalis pars medialis of the telencephalon, the saccus dorsalis, and the basal part of the nucleus recessus posterioris were found to be innervated by vasotocin and scarcely by isotocin fibers. In the nucleus habenularis, the nucleus recessus lobus lateralis, the nucleus preglomerulosus pars medialis, and the tectum mesencephali isotocin fibers prevailed. These findings in the trout brain are compared with the vasopressin and oxytocin innervation of the rat brain.
Retinal degeneration in the pcd cerebellar mutant mouse. II. Electron microscopic analysis
Authors: Blanks Janet C. , Mullen Richard J. , Lavail Matthew M.
Published: December 2004

The cerebellar ataxia in Purkinje cell degeneration pcd mutant mice results from the rapid loss of Purkinje cells between 3 and 5 weeks after birth. The loss of photoreceptors in these mutants begins about the same time but proceeds slowly, with most photoreceptors being lost by 1 year of age. In this study the retinas of pcd/pcd mice and their littermate controls from the age of 10 postnatal days to 15 months were analyzed by electron microscopy. The first signs of photoreceptor cell degeneration are apparent in the region of photoreceptor inner segments as early as postnatal day 13, and more prominently at day 18. During this time, the degeneration is characterized by a large number of vesicles, ranging in diameter from 150 to 350 nm, which are located in the extracellular space adjacent to the photoreceptor inner segments. Analysis of serial sections shows that most of these membrane‐bound degeneration profiles are tubular in shape and some are continuous with the cell membrane of the inner segment. There‐lore, these [profiles] are thought to arise from tubular outpocketings of the inner segments which cleave off to form isolated membrane‐bound profiles. This represents a new and unusual form of photoreceptor degeneration. While the most obvious abnormality in the retina is degeneration of photoreceptor cells, Müller cells also appear to be affected, with swollen apical processes often seen coursing through the outer nuclear layer.
Cytoarchitecture, neuronal morphology, and some efferent connections of the interstitial nucleus of cajal (INC) in the cat
Authors: Zuk A. , Gwyn D. G. , Rutherford J. G.
Published: December 2004

This study describes the Cytoarchitecture and neuronal morphology of the interstitial nucleus of Cajal (INC) in the cat. In addition, the efferent projections of this nucleus to the spinal cord and inferior olive were studied by retrograde labelling with horseradish peroxidase (HRP).

The INC was shown to extend rostrocaudally for slightly more than 2 mm. Caudally, the nucleus consists of a small number of loosely aggregated neurons lying lateral to the ventral periaqueductal gray matter at a rostrocaudal level corresponding to the rostral one‐fifth of the somatic cell columns of the oculomotor nucleus. Rostrally, the INC increases in size and reaches its maximum development in its rostral half, where it lies ventro‐lateral to the nucleus of Darkschewitsch (ND). Rostrally the INC is bounded by the dorsoventrally aligned fibres of the fasciculus retroflexus.

Two groups of neurons could be distinguished within the INC in both normal and HRP‐injected material. One group consists of a relatively small number of large, oval, pyramidal, fusiform, or multipolar neurons with mean dimensions of 40 × 26 μm The second group consists of numerous small to medium‐sized neurons with mean dimensions of 20 × 14 μm. Large neurons and some cells of the second group contain substantial amounts of Nissl substance throughout their perikarya. Some medium‐sized to small neurons exhibit indentations in their nuclei, and glial cells are often apposed to their cell membranes. Golgi‐Kop sch preparations taken from kitten showed that INC neurons possess sparsely branched, radiating dendritic trees with few spinous processes. The majority of INC neurons retrogradely labelled with HRP exhibited similar dendritic patterns.

Injections of HRP into lesions at cervical, thoracic, or lumbar levels of the spinal cord resulted in retrograde labelling of neurons of all sizes and shapes throughout the entire length of the INC. However, the greatest number of HRP‐labelled cells in INC were observed subsequent to injections of the enzyme into cervical levels of the cord. Following injections of HRP into the inferior olive only small to medium‐sized neurons were labelled in the nucleus, the majority of which are located in rostral levels of the INC. A substantial olivary projection was observed to originate in the nucleus of Darkschewitsch (ND) and the nucleus parafascicularis (NPF). The sizes of the projections from these two nuclei to the inferior olive appeared to be much larger than that from the INC. Smaller numbers of neurons were also observed in the rostral parvocellular red nucleus (RN) and mesencephalic reticular formation (MRF).
Physiological response properties of cells labeled intracellularly with horseradish peroxidase in cat dorsal cochlear nucleus
Authors: Rhode W. S. , Smith P. H. , Oertel D.
Published: December 2004

The physiology and morphology of fusiform cells in the dorsal cochlear nucleus were studied using extracellular and intracellular recording and intracellular injection of horseradish peroxidase. Fusiform cells displayed a variety of responses to tone pips presented at the characteristic frequency; most often these cells exhibited the pauser/buildup pattern defined in earlier studies. The response pattern of each neuron was dependent on frequency and sound‐pressure level. Tone pips evoked short‐lasting depolarizations of about 10 mV and long‐lasting hyperpolarizations of about 10 mV in cells whose resting potentials were −50 to −65 mV. The time courses of both the excitation and the inhibition depended on frequency and sound‐pressure level. Generally the depolarization was sustained for the duration of the tone pip, whereas the hyperpolarization could last as long as 600 ms after the end of the tone pip. Often a neuron exhibited a sustained chopper pattern after microelectrode impalement. This was probably a result of a decrease in membrane potential which altered the relative effectiveness of the excitatory and inhibitory inputs. The large, bitufted fusiform cells had many apical dendrites, which branched one to five times and were covered with spines, and fewer basal dendrites, which exhibited little branching and had few appendages. The morphology of fusiform cells varied systematically as a function of location within the dorsal cochlear nucleus. Response patterns for tone pips were not exclusive to individual cell types as two nonfusiform cells were found to exhibit a buildup pattern. Axons of injected neurons left the nucleus via the dorsal acoustic stria and 14 of 15 had collaterals within the dorsal cochlear nucleus.
Morphology and origin of axonal endings in nucleus laminaris of the chicken
Authors: Parks Thomas N. , Collins Patricia , Conlee John W.
Published: December 2004

The axonal endings on the somata and dendrites of third‐order auditory neurons in nucleus laminaris (NL) were measured and classified in thin‐sectioned material from adult chickens. Two methods were used to deter‐mine which ending types arise from second‐order auditory neurons in nu‐cleus magnocellularis (NM): (1) degeneration of axonal endings in NL after transection of the crossed dorsal cochlear tract (CTrX) carrying the axons of each NM to the contralateral NL, and (2) injection of horseradish per‐oxidase (HRP) into NM or the CTrX to label endings in NL by anterograde transport. About 42% of the perikaryl surface of NL neurons and 63% of the dendritic surface are apposed by axon terminals arising from NM; these endings are also prevalent on the axon hillock and initial segment. The NM endings are characterized by round, clear synaptic vesicles‐distributed at an average density of 76/μm2 behind small punctate synaptic junctions with thick synaptic densities. These endings degenerate preferentially after tran‐section of the CTrX and are the only endings consistently labeled after HRP injections. About 31% of the perikaryl surface of NL and 10% of the distal dendritic surface are apposed by a prominent non‐NM axonal ending type This ending is characterized by a synaptic vesicle density of 135/ μm2 a single large area of synaptic contact which bears very slight densities on both pre‐ and postsynaptic membranes. On the perikaryon, about 80% of these non‐NM terminals end on the cell body proper, with the rest found on proximal dendrites or capping the short somatic processes or spines occasionally seen in NL. The distribution of the two ending types does not differ significantly along the posterior‐to‐anterior axis of NL.
Effects of visual deprivation upon the geniculocortical W‐cell pathway in the cat: Area 19 and its afferent input
Authors: Leventhal Audie G. , Hirsch Helmut V. B.
Published: December 2004

We studied the receptive field properties of 206 single units in area 19 of normal cats and 228 single units in area 19 of cats deprived of vision for 9‐14 months by monocular lid suture. The ocular dominance of a sample of cells in area 17 of normal cats was studied for comparison. In some of these monocularly deprived animals, we also studied the sizes of relay cells in the parvocellular C laminae of the dorsal lateral geniculate nucleus labeled by electrophoretic injections of horseradish peroxidase into area 19.

In area 19 of normal cats, the large majority of cells, regardless of their laminar location and the retinal eccentricity of their receptive fields, were binocular. Most responded equally well to the two eyes. In area 17, (see also Leventhal and Hirsch, ′78, ′80) but not in area 19, the cells which had the narrowest receptive fields tended to be activated unequally by the two eyes.

In area 19 of monocularly deprived cats, virtually all cells (97%), re‐gardless of their laminar location and receptive field eccentricity, responded only to stimulation of the normal eye. Thus, the effects of monocular dep‐rivation upon area 19 are apparently more severe than those reported for area 17. In area 17 significant numbers of neurons in layer 4 can be activated by the deprived eye (Shatz and Stryker, ′78). Within the limits of our tech‐nique, measurements of relay cells in the parvocellular C laminae labeled by injections into area 19 of deprived cats indicated that cell size in the deprived C laminae was unaffected by the deprivation. In contrast, cells in the deprived A laminae of these cats were severely shrunken.

These findings suggest that the types of relay found in the parvocellular C laminae (referred to collectively as W‐cells) are not affected by visual deprivation as severely as are the X‐ and Y‐cells in the A laminae. Since laminar location and receptive field width are related to binocularity in area 17 but not in area 19 and the sizes of relay cells in the parvocellular C laminae (see also Hickey, ′80) are not seriously affected by monocular deprivation, it is suggested that binocular interactions in area 19aremninly determined by connections among cortical cells.
Origin of various enzymes released from the substantia nigra and caudate nucleus: Effects of 6‐hydroxydopamine lesions of the nigro‐striatal pathway
Authors: Greenfield Susan A. , Grünewald R. A , Foley P. , Shaw S. G.
Published: December 2004

Various enzymes are released from the nigro‐striatal pathway. The hypothesis that these enzymes–i.e., acetylcholinesterase, nonspecific cho‐linesterase, aminopeptidase, and lactate dehydrogenase–originate from do‐paminergic nigro‐striatal neurons was investigated. Following a 6‐hydrox‐ydopamine lesion of the rat nigro‐striatal pathway, the spontaneous release of all four enzymes was reduced, in both the caudate nucleus and substantia nigra. In both structures the reduction in release of aminopeptidase and lactate dehydrogenase was less marked than that seen for acetylcholines‐terase and nonspecific cholinesterase. In nonlesioned rats, application of 50 mM KC1 to the substantia nigra led to an increase in enzyme release locally, accompanied by a decrease in release from the caudate nucleus. These changes were observed in release of acetylcholinesterase, aminopeptidase, and lac‐tate dehydrogenase, but nonspecific cholinesterase remained unchanged. In rats with 6‐hydroxydopamine lesions, nigral application of potassium no longer induced a significant decrease in release from the caudate nucleus in any of the enzymes. In perfusates of the treated group, however, a po‐tassium‐evoked increase in nigral aminopeptidase and lactate dehydrogen‐ase release was still detectable. Nigral acetylcholinesterase release was not affected by potassium in animals with 6‐hydroxydopamine lesions. It ap‐pears that lactate dehydrogenase and aminopeptidase are released together from both dopamine‐ and non‐dopamine‐containing cells in the caudate nucleus and substantia nigra; this release may be related to neuronal de‐polarization. A high proportion of nonspecific cholinesterase is released from nigro‐striatal dopamine‐containing cells but appears not to be dependent on depolarization. Acetylcholinesterase, which is released in the caudate nucleus and substantia nigra following neuronal depolarization, originates almost exclusively from dopamine‐containing nigro‐striatal neurons.
Dendritic reorganization in the denervated dentate gyrus of the rat following entorhinal cortical lesions: A Golgi and electron microscopic analysis
Authors: Caceres Alfredo , Steward Oswald
Published: December 2004

The organization of the dendritic tree and the morphology of individual dendrites of the dentate granule cell were analyzed qualitatively and quantitatively by means of the rapid Golgi technique 2, 4, 8, 10, 14, 30, 60, and 250 days after unilateral lesions of the entorhinal cortex (EC). Three dendritic field parameters were analyzed from camera lucida drawings of de‐nervated granule cells at each survival time: (1) dendritic field spread, (2) dendritic length, and (3) dendritic branching. Cells in the contralateral dentate gyrus served as controls. Spines were counted at each postlesion interval from material stained with a modification of the Golgi‐Kopsch method. The amount of tissue occupied by dendritic shafts at different postlesion intervals was also evaluated in samples of the ventral leaf of the dentate gyrus prepared for electron microscopy. After unilateral lesions of the EC, dendrites of the granule cells undergo modifications which appear to represent deterioration and recovery. When the dendrites reach the denervated zone, they abruptly change their orientation and tend to follow a course parallel to the granule cell layer. In contrast to normal dendrites, those in the denervated neuropil only occasionally reach the outer boundaries of the molecular layer. At the time of maximal denervation there is often a sudden reduction in dendritic diameter as the dendrite enters the denervated zone. Varicosities are also prominent. The alterations in individual dendrites are not evident 2 days after the lesion, are fully developed 10 days after deafferentation; and disappear for the most part by 30 days postlesion. The quantitative analysis of Golgi‐stained granule cells reveals that there is a 40% reduction in the total length of the granule cell dendritic tree. Electron microscopic analysis confirms the Golgi observations, indicating that the amount of neuropil occupied by dendritic shafts in the denervated zone is initially reduced and later recovers to values close to those observed in control animals. While the apparent dendritic loss is mainly restricted to the denervated zone, significant modifications occur in the inner npnde‐nervated molecular layer; there is an increase in the length of primary dendrites as evidenced by an increase in the distance to the first branch point. There is also a polarized redistribution of 1st, 2nd, 3rd, and 4th branch points toward the middle and outer molecular layer that persists even 30 days after the lesion. The results are discussed in terms of the capabilities of the granule cells of the dentate gyrus to reorganize and remodel their dendritic surface after partial deafferentation.
Neural basis of developing salt taste sensation: Response changes in fetal, postnatal, and adult sheep
Authors: Mistretta Charlotte M. , Bradley Robert M.
Published: December 2004

To learn whether salt taste responses change during mammalian development, we recorded from multifiber preparations of the chorda tympani while stimulating the anterior tongue in sheep fetuses, lambs, and adults. Stimuli were 0.5 M NH4C1, KC1, NaCl, and LiCl, and 0.05–0.75 M concentration series of the first three salts. Ultrastructural studies were made of taste buds at different ages to determine whether morphological elements such as microvilli and tight junctions are present in young fetuses.

Substantial changes occur in relative salt taste responses, throughout development. In fetuses that are beginning the last third of gestation, NaCl and LiCl elicit much smaller response magnitudes than NH4C1 and KC1. Throughout the rest of gestation and postnatally, the NaCl and LiCl responses gradually increase in magnitude relative to NH4C1 and KCL In adults, NaCl, LiCl, and NH4Cl all elicit similar response magnitudes and KC1 is less effective as a taste stimulus. At ages when response ratios for the 0.5 M salts are changing, there are no changes in shapes of the response/concentration functions for individual salts. Furthermore, microvilli are present on taste bud cell apices and tight junctions are found between cells in the youngest fetuses studied. Therefore, initial stimulus‐receptor membrane contacts are probably similar to those in adults.

Our data suggest that different membrane components interact with the various monochloride salts and that taste receptors contain different proportions of these various membrane components at different developmental stages. Therefore young taste bud cells do not have the same salt response characteristics as mature cells, and a changing neural substrate underlies development of salt taste function, both pre‐ and postnatally.
The morphology of intracellularly labeled rat subthalamic neurons: A light microscopic analysis
Authors: Kita H. , Chang H. T. , Kitai S. T.
Published: December 2004

Light microscopic analysis of rat subthalamic (STH) neurons which were intracellularly labeled with horseradish peroxidase, following the acquisition of electrophysiological data, revealed the following: (1) The somata of STH neurons were polygonal or oval with occasionally a few somatic spines. Uusally three or four primary dendrites arose from the soma. Dendritic trunks tapered slightly and divided into long, thin, sparsely spined branches. Dendrites of some STH neurons extended into the cerebral peduncle. (2) Reconstruction of the dendritic field was made in three different planes. In either sagittal or frontal planes, the dendritic field was usually oval and the long axis was parallel to the main axis of STH. In the horizontal plane, the dendritic field of all neurons was polygonal. (3) The axons of all the neurons analyzed originated from the soma and were traced beyond the borders of STH, thus indicating that they were projection neurons. All the parent axons bifurcated at least once. After bifurcation, one axon branch coursed dorsolaterally within the cerebral peduncle and terminated in the globus pallidus. The other branch coursed caudally or mediocaudally and arborized in the substantia nigra. Frequently, the axon branches projecting toward the globus pallidus emitted fine axon collaterals within the entope‐duncular nucleus. (4) About one‐half of the analyzed STH neurons had intranuclear axon collaterals. The neurons with intranuclear collaterals had a higher dendritic tips/stems ratio than neurons without intranuclear collaterals. This observation indicated that STH neurons could be divided into two groups according to their axonal morphology. (5) The axonal terminal arborization observed in all the target sites (i.e., globus pallidus, entopeduncular nucleus, STH, and substantia nigra) were formed with varicose collateral branches which also gave rise to short filaments with beaded endings. Some of these projection neurons could therefore communicate with the target neurons in the globus pallidus, substantia nigra, entopeduncular nucleus, as well as STH through their collateral system.
Cytology of periolivary cells and the organization of their projections in the cat
Authors: Adams Joe C.
Published: December 2004

Projections of cells located near principal nuclei of the superior olive, periolivary cells, were studied by injecting horseradish peroxidase or fluorescent tracers into the cochlea, cochlear nucleus, and inferior colliculus. At least two distinct cytological classes of periolivary cells were found to project to each of these structures. “Large” and “small” olivocochlear cells were labelled. Their cytology and locations were found to be as had been previously described. Some olivocochlear cells also project to the cochlear nucleus. Other major periolivary cell classes that project to the cochlear nucleus include a lateral group of multipolar cells whose members are located around the ipsilateral lateral superior olive and have coarse, darkly staining Nissl substance. The other major periolivary cell class that projects to the cochlear nucleus is the small cell of the ventral nucleus of the trapezoid body. This cell is characterized by its size and by only one or two intensely staining clumps of Nissl substance. Projections of these cells to the cochlear nucleus is from both sides. Periolivary cells that project to the inferior colliculus include medial and lateral groups. Cells of the lateral group project from both sides. These cells are multipolar in shape and contain lightly staining, floccu‐lent Nissl substance. They are predominantly located immediately ventral to the lateral superior olive. Projections from the medial group are predominantly ipsilateral and arise from the region medial to the medial superior olive. The cells are multipolar and contain clumped Nissl substance. They often lie near “large” olivocochlear cells, which they resemble in Nissl material, but are distinguished from the latter in Protargol material by having ring‐type axosomatic endings. The appearance and locations of these six classes of periolivary cells make it possible to recognize them in nonexperi‐mental material and to infer with confidence what their projections are. These results show considerable organization of these previously little understood structures.
Language functions explored in normal subjects by positron emission tomography: A critical review
Authors: Démonet J. F. , Wise R. , Frackowiak R. S. J.
Published: December 2004

Recent advances in positron emission tomography techniques provide a way of studying the functional anatomy of language processes in the normal brain. A large amount of data have already been acquired using the subtractive activation method, which consists of comparing regional metabolic brain activities between two experimental conditions, a reference condition and an active condition (e. g., a language task). In spite of the potential interest of such results, their interpretation may be obscured by conflicting theoretical issues on the nature of brain‐language relationships and by various methodological problems, which are described in this review paper. The exact nature of the language task and stimuli used in the activation paradigms appear to be critical for this topic. Moreover, the strictly hierarchical, unidimensional subtractive method, previously described by Petersen et al. ([1988]: Nature 331:585–589) seems not to be adequate for generating appropriate contrasts between activation conditions in most language paradigms. Further progress in the analysis of task‐related changes in distribution of cerebral activities, are expected from: (1) other methods that should complement the subtractive approach, such as analysis of interregional correlations of cerebral activity which would account for the distributed anatomy of language functions; and (2) single‐subject studies in which issues of anatomical and cognitive interindividual variability may be addressed. © 1993 Wiley‐Liss, Inc.
Preoperative assessment of the cerebral hemispheric dominance for language with CBF PET
Authors: Pardo José V. , Fox Peter T.
Published: December 2004

This study evaluated whether cerebral blood flow positron emission tomography (CBF PET) could provide assessments of language dominance comparable to the invasive reference method, the Wada test (selective intracarotid injection of amytal with cognitive testing subsequent to the anesthesia of each hemisphere). In 9 of 11 patients with partial complex epilepsy who were operative candidates, the Wada test lateralized unequivocally; in two subjects Wasa results were indeterminate (no speech arrest following injection of either carotid). Of four brain regions selected a priori for PET analysis based on techniques developed from studies of normal volunteers, anterior frontal cortex (AFC) was most consistently detectable and lateralized. AFC laterality agreed with Wada laterality in eight of the nine subjects lateralized by Wada. In both subjects having an indeterminate Wada, PET demonstrated clear laterality. In one subject both PET and Wada lateralized, but in disagreement; anterior temporal lobectomy in the hemisphere indicated by PET as language‐dominant caused long‐lasting language impairment. We conclude that CBF PET: (1) provides an effective, noninvasive adjunct to the Wada test; and (2) permits assessment of language dominance in normal research volunteers. © 1993 Wiley‐Liss, Inc.
Etudes sur les matières végétales volatiles. XLV. — Présence d'ionones dans l'essence concrète de Boronia megastigma Nees
Authors: Naves Y. R. , Parry G. R.
Published: December 2004

L'essence concrète de Boronia megastigma Nees., préparée par l'un de nous, renferme, outre de l'eugénol, un mélange de β‐ionone, de d‐α‐ionone et de d,l‐α‐ionone.
Recherches sur l'action chimique des décharges électriques XXXII. Rectifications à apporter aux déterminations, par la méthode oscillographique, des rendements énergétiques des synthèses chimiques au moyen de l'arc à haute fréquence; emploi de méthodes photométrique et calorimétrique
Authors: Briner E. , Höfer H. , Kundig J. J.
Published: December 2004

Une étude critique de la méthode oscillographique, utilisée dans les recherches précédentes pour la détermination des puissances mises en jeu dans l'arc électrique, a mis en évidence certaines causes d'erreurs qui affectent cette méthode en haute fréquence (lo7), et les précautions qu'il y a lieu de prendre pour les atténuer.
The Absolute Configuration of the Glutarimide Antibiotics Streptimidone and 9‐Methylstreptimidone
Authors: Becker Anna Maria , Rickards Rodney W.
Published: December 2004

Chemical and spectroscopic studies have established the absolute configuration of the glutarimide antibiotics streptimidone and 9‐methylstreptimidone, which can now be represented as the (2R,5S,6E)‐structures 14 and 15, respectively.
Die Epoxysulfoncyclofragmentierung, eine neue Ringerweiterungsmethode. Synthese von rac.‐Muskon
Authors: Fischli Albert , Branca Quirico , Daly John
Published: December 2004

A new ring expansion method using the cyclofragmentation of epoxysulfones; a synthesis of rac. muscone.

Starting from the readily available cyclododecanone 1 the hydroxy sulfone 5 has been prepared using standard procedures. Subsequent dehydration followed by an acidic equilibration resulted in a mixture of two endocyclic olefines, from which the olefin 7 showing the (E)‐configuration could be isolated by fractional crystallization. Oxidation of 7 produced the epoxy sulfones 8 and 9. The epoxy sulfone 8 was cyclized to the hydroxy sulfone 10 without any detectable amount of the corresponding epimer 11. Fragmentation of the intermediate 10 using KOTB produced pure (E)‐4‐muscenone 12. The epoxy sulfone 9 was cyclized to a mixture of the two epimeric hydroxy sulfones 14 and 15. Fragmentation of the two crystalline hydroxy sulfones 14 or 15 with KOTB produced a mixture of 12 and 16. The ‘one‐pot’ preparation of (E)‐4‐muscenone 12 starting from 8 could also be accomplished. The configurational assignements within this serie are based upon the data of an X‐ray analysis of the hydroxy sulfone 10.
Anil‐Synthese. 14. Mitteilung. Über die Darstellung von heterocyclisch substituierten Styryl‐Derivaten des 2H‐1,2,3‐Triazols
Authors: Siegrist Adolf Emil , Kormány Géza , Kabas Guglielmo
Published: December 2004

Preparation of heterocyclic substituted styryl derivatives of 2H‐1,2,3‐triazole.

Anile aus 2‐Phenyl‐4‐formyl‐2H‐1,2,3‐triazolen und o‐oder p‐Chloranilin können mit p‐tolyl‐substituierten aromatischen Heterocyclen in Gegenwart von Dimethylformamid und Kaliumhydroxid bzw. Kalium‐t‐butylat in die entsprechenden heterocyclisch substituierten Styryl‐Verbindungen übergeführt werden («Anil‐Synthese»). Zur Erzielung guter Ausbeuten muss das Reaktionsgemisch anfänglich mit ultraviolettem Licht bestrahlt werden. Die Darstellung heterocyclisch substituierter 4‐(2H‐1,2,3‐Triazol‐2‐ bzw. ‐4‐yl)‐styrol‐Verbindungen gelingt mit Natriummethylat ohne UV.‐Licht.