bluuebunny/crossref_metadata_2025 huggingface dataset:
Mirarse a uno mismo: Acerca de la afectación como engranaje clave de las políticas de reforma curricular
Authors: Villagran Carla Andrea
Published: April 2018

En este artículo se presentan resultados de un trabajo de investigación que procura describir y analizar las políticas curriculares de reforma en la cotidianeidad de la vida escolar atendiendo aquí específicamente a los procesos de regulación y auto-regulación que producen en los sujetos. A partir de la noción Foucaultiana de gubernamentalidad entendemos a las políticas curriculares como tecnologías de regulación de las conductas que producen efectos performativos (Ball, 2002, 2012), que afectan de manera neurálgica no solo la vida de las instituciones sino también de los sujetos (Ahmed, 2004; Berlant, 2011). De modo que, la pregunta que orienta este escrito se teje en torno a la articulación del gobierno de los otros y el gobierno del sí (Foucault, 1988, 2009) en tanto que un modo clave de las tecnologías de reforma escolar y los modos de afectación social. Los procesos de reforma atraviesan a los sujetos a través de tecnologías performativas (Ball, 2002) y configuran parte de aquello que Rose (2012) dio en llamar las ethopolíticas. Esto es, actúan a nivel de los sentimientos, las creencias donde el sí mismo es puesto en jaque. A modo de hipótesis se plantea que el juzgamiento, la reflexión sobre sí y la auto-responsabilización se aglutinan en las preguntas que los docentes se realizan a sí en el llamado a volverse mejor de lo que se es.
Halaman Belakang
Authors: Belakang Halaman
Published: April 2018

Pedoman Penulisan, Cover Belakang
An ethnobotanical study of plants used by forest fringe communities of Lwali village (Pauri Garhwal, Uttarakhand)
Authors: Bisht Nidhi , Verma Praveen Kumar , Negi Ranjana , Chandra Anup
Published: April 2018

The paper provides information on traditional knowledge of plants used by fringe forest communities of village Lwali (District Pauri Garhwal). The paper deals with 35 plant species belonging to 34 genera of 29 families, that find mention in the local folklore. The plants have been provided with botanical names, vernacular names, parts used and ethnobotanical uses.
Opioid peptide immunoreactivity in spinal and trigeminal dorsal horn neurons projecting to the parabrachial nucleus in the rat
Authors: Standaert DG , Watson SJ , Houghten RA , Saper CB
Published: April 2018

The parabrachial nucleus (PB) is the major relay for ascending visceral afferent information from the nucleus of the solitary tract to the forebrain. We have recently found that PB in the rat also receives a substantial afferent projection from neurons in the marginal zone of the entire length of the spinal and trigeminal dorsal horn. Immunoreactive perikarya stained with antisera against several neuropeptides--including dynorphin, enkephalins, and substance P--have been identified in the marginal zone. We therefore investigated the chemical specificity of the spinoparabrachial projection by combining fluorescent retrograde tracing with immunofluorescence for substance P, dynorphin A1-17, met-enkephalin, and two enkephalin precursor fragments (proenkephalin 192–203 and peptide E). Following PB injections of fluorescent dyes, about half of the retrogradely labeled neurons in the marginal zone stained with antisera against either dynorphin or enkephalin series peptides. Elution-restaining experiments indicated that the dynorphin- and enkephalin-immunoreactivities were contained within separate populations of marginal zone neurons. We could not identify any substance P-immunoreactive perikarya in the marginal zone, but substance P-immunoreactive fibers were seen in close apposition to retrogradely labeled, opioid-immunoreactive cell bodies and dendrites. These results indicate that the dynorphin- and enkephalin- immunoreactive perikarya in the marginal zone of the dorsal horn represent independent neuronal populations. These opioid-immunoreactive neurons, which are believed to have extensive local collateral connections, are the main source of a long ascending projection to the parabrachial nucleus in the rat. Furthermore, opioid neurons in the marginal zone may receive substance P-immunoreactive primary sensory afferents.
Effect of a uniform partial denervation of the periphery on the peripheral and central vibrissal system in guinea pigs
Authors: Sikich L , Woolsey TA , Johnson EM
Published: April 2018

In some rodents, somatotopically organized architectonic patterns corresponding precisely to the arrangement of the vibrissae on the face are found in each of the central stations of the trigeminal (V) pathway. Two lines of evidence indicate that these architectonic patterns reflect the level of peripheral innervation. First, in normal mice, the sizes of the individual units within the cortical representation are proportional to the number of fibers supplying the corresponding vibrissal follicles. Second, complete surgical denervation of groups of vibrissae can severely attenuate the sizes of and alter the patterns of their central representations. However, previous studies in this system do not distinguish the effects of the absolute and the relative levels of peripheral innervation on central representations. To address this question, we have studied guinea pigs in which all vibrissae are partially deafferentated before birth by fetal exposure to antibodies against NGF. This approach reduces the absolute level of peripheral innervation in a graded way, and does so uniformly, without changing the pattern of vibrissal innervation. In the most severely affected animals, only 18% of the normal number of V ganglion neurons survive. The effect of this loss on the V system was assessed by comparing the peripheral and central components of the vibrissal system in normal and NGF-deprived animals. Peripheral fibers from the V ganglion neurons, including those to the vibrissae, are less reduced in number (50%) than expected. The number of peripheral fiber fascicles is also decreased. In contrast, neither the patterns nor the areas of the central representations in medulla and cortex differ from those of normal animals. We conclude that 18% of the normal number of V ganglion cells is sufficient to establish normal central architectonic patterns and the size of the central vibrissal representations is independent of the absolute magnitude of peripheral innervation. These observations are of relevance to understanding the role of NGF on the morphogenesis of central somatosensory pathways, the effects of “mismatches” between peripheral innervation, and the development of projections to central targets in the mammalian brain, and provide new data for understanding competitive interactions in the developing central and peripheral trigeminal system.
Immunofluorescent localization of two different Na,K-ATPases in the rat retina and in identified dissociated retinal cells
Authors: McGrail KM , Sweadner KJ
Published: April 2018

Two isozymes of the Na,K-ATPase are made in the brain and retina. Antisera have been produced that contain antibodies specific for each of the catalytic subunits of the two isozymes, alpha and alpha(+) (Sweadner & Gilkeson, 1985a). To determine which classes of cells express which form of the Na,K-ATPase, and whether cells can express both forms, the antisera were used to stain sections of the rat retina and dissociated retinal cells by indirect immunofluorescence. In sections of the retina, bright stain specific for both isozymes was seen in the inner segments of the photoreceptor cells, the outer and inner plexiform layers, and in the ganglion cell axons. Cell bodies were outlined in the inner nuclear layer. Stain specific for the alpha isozyme was seen in adhering pigment epithelium and at the position of the apical processes of the Muller glial cells. In sections of the optic nerve, the nerve itself stained for both isozymes, although the stain for the alpha(+) isozyme was stronger. The sheath, in contrast, stained selectively for the alpha isozyme. Cells were dissociated from the retina, and they were identified by their morphology and by cell class-specific monoclonal antibodies. Muller glial cells were found to stain brightly for only the alpha isozyme, while horizontal and ganglion cells stained brightly for both isozymes. Bipolar cells stained faintly for only the alpha(+) isozyme, while amacrine cells stained faintly for both isozymes. The evidence indicates that different kinds of neurons can express one or both isozymes of the Na,K- ATPase, and at quantitatively different levels.
Analysis of the carbohydrate composition of axonally transported glycoconjugates in sciatic nerve
Authors: Hart CE , Wood JG
Published: April 2018

Glycosidase enzyme digestion in combination with postembedding lectin cytochemistry was used to study the carbohydrate composition of axonally transported glycoproteins. A cold block procedure for the interruption of axonal transport was employed to increase selectively the population of anterograde moving components on the proximal side of the transport block. Electron-microscopic observations revealed that a cold block applied to the sciatic nerve of an anesthetized rat produced an increase in axonal smooth membrane vesicles at a site directly proximal to the cold block. Postembedding lectin cytochemistry of the sciatic nerve demonstrated a substantial increase in concanavalin A (Con A), wheat germ agglutinin (WGA), and succinylated WGA binding sites in axons directly proximal to the cold block. Endoglycosidase H (endo H) digestion prior to lectin cytochemistry characterized a large population of the axonally transported Con A binding sites as polymannose and/or hybrid N-linked oligosaccharides (endo H- susceptible). A distinct population of neuraminidase-resistant WGA binding sites was also found in axons directly proximal to the transport block. The concomitant increase in smooth membrane vesicles and lectin binding sites in axons at the transport block supports the hypothesis that a system(s) of smooth membrane inside the axon is involved in the transport of glycoproteins from the cell soma to their cell surface destinations. Results of glycosidase digestions and lectin cytochemistry experiments suggest that many of the axonally transported glycoprotein carbohydrates are polymannose and/or hybrid N-linked oligosaccharides. This observation is especially interesting in relation to our previous reports, which indicated that most lectin binding sites on the neuronal cell surface are composed of complex oligosaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)
Interchange of callosal and association projections in the developing visual cortex
Authors: Innocenti GM , Clarke S , Kraftsik R
Published: April 2018

Neurons projecting transitorily into the corpus callosum from area 17 of the cat were retrogradely labeled by the fluorescent tracer Fast Blue (FB) injected into contralateral areas 17 and 18 on postnatal days 1–5. During the second postnatal month these neurons were still labeled by the early injection, although they had eliminated their callosal axon. At this time, 15–20% of these neurons could be retrogradely relabeled by injections of Diamidino Yellow (DY) into ipsilateral areas 17 and 18, but few or none by similar injections in the other areas that receive from area 17 (19, 21a, PMLS, 20a, 20b, DLS). Similarly, area 17 neurons projecting transitorily to contralateral area PMLS during the first postnatal week could be relabeled by DY injections in ipsilateral areas 17 and 18 but not in PMLS. Already around birth, many transitorily callosal neurons in area 17 send bifurcating axons both to contralateral areas 17 and 18 and ipsilateral area 18. It is probable that during postnatal development some of these neurons selectively eliminate their callosal axon collaterals and maintain the projection to ipsilateral area 18. In fact, some transitorily callosal neurons in area 17 can be double-labeled by simultaneous perinatal injections of FB in contralateral areas 17 and 18 and of a new long-lasting retrograde tracer, rhodamine-conjugated latex microspheres, in ipsilateral area 18. The same neurons can then be relabeled by reinjecting ipsilateral area 18 with DY during the second postnatal month. This finding, however, does not exclude the possibility that some transitorily callosal neurons send an axon to ipsilateral area 18 after eliminating their callosal axon. In conclusion, area 17 neurons that project transitorily through the corpus callosum later participate, probably permanently, in ipsilateral corticocortical projections but selectively to areas 17–18. The mechanism responsible for this selectivity is unknown, but it may be related to the differential radial distribution (i.e., to birth date) of area 17 neurons engaged in the various corticocortical projections. The problems raised by the use of long-lasting retrograde fluorescent tracers in neurodevelopmental studies and by the quantification of results of double- and triple-labeling paradigms are also discussed.
Development of glutamic acid decarboxylase immunoreactivity in the cat's lateral geniculate nucleus
Authors: Shotwell SL , Shatz CJ , Luskin MB
Published: April 2018

The development of glutamic acid decarboxylase (GAD) immunoreactivity in the cat's dorsal LGN was studied during fetal and postnatal life. In the adult, inhibitory interactions within the LGN are known to be mediated by GABA. Here we have used an antiserum to GAD, the rate- limiting synthetic enzyme for GABA, to examine the development of the anatomical substrate for this inhibitory system. The pattern of immunostaining observed in the adult cat LGN was similar to that reported by Fitzpatrick et al. (1984), with heavily stained somata and proximal dendrites located within the LGN layers and the adjacent perigeniculate nucleus (PGN). The LGN also contained a complex array of terminal staining. In development, specific staining was seen about 2 weeks before birth and was confined to PGN somata and, to a lesser extent, to somata located in the future ventral C-layers. A similar pattern of immunostaining was seen using GABA antiserum. Not until birth did the A-layers of the LGN show appreciable staining of both somata and terminals; however, even then the pattern of immunostaining was far from mature. Furthermore, excessive numbers of PGN neurons appeared to stain. By 5 weeks after birth, the intensity of both soma and terminal staining within the A-layers of the LGN increased substantially relative to that of the PGN and ventral C-layers. The first glomerular clusters of terminal staining could also be seen, and the number of stained PGN neurons had diminished to levels similar to those seen in the adult. The pattern of immunostaining was almost adultlike by 2 months after birth, except within the C-complex, where the staining did not yet show the distinct difference in staining intensity present in the adult between dorsal layer C and ventral layers C1 and C2. The final adult pattern of GAD immunoreactivity appeared by 3 months after birth. These results suggest that during fetal life the PGN and ventral C-layers of the LGN may supply the first source of GABA-mediated inhibition to the nucleus, with the major portion of the inhibition supplied by intrinsic LGN neurons arising postnatally. Thus, PGN neurons may provide part of the anatomical substrate for the inhibitory interactions seen physiologically during late fetal development (Shatz and Kirkwood, 1984). Finally, the relatively late appearance of the adultlike pattern of GAD immunostaining suggests that intrageniculate inhibitory circuitry continues to develop well after birth.
Operant conditioning of head-waving in Aplysia. II. Contingent modification of electromyographic activity in identified muscles
Authors: Cook DG , Carew TJ
Published: April 2018

Aplysia can readily exhibit operant conditioning of their head-waving response when bright light is used as aversive reinforcement (Cook and Carew, 1986). In the first paper of this series (Cook and Carew, 1989a), we showed that the electromyographic (EMG) activity of a discrete band of neck muscles, the lateral columellar muscles (LCMs) of Aplysia is significantly correlated with the component of head-waving (the horizontal component) that is modified during operant conditioning. In the present paper, we asked whether the EMG activity of the LCMs themselves could also be contingently modified, using the same procedures that produce operant conditioning of the behavioral response. Differential EMG from the LCMs was recorded in freely behaving animals with chronically implanted muscle cuff electrodes. Animals receiving aversive reinforcement (bright light) that was contingent upon specific patterns of LCM activity readily learned to alter their differential EMG output. Like operant conditioning of the head-waving response, this operant modification of LCM activity was rapidly acquired and was specific to the contingencies of reinforcement. These results show that a restricted group of muscles, the LCMs, exhibit the essential features of the head-waving system observed at the behavioral level: (1) their activity is significantly correlated with head-waving behavior, and (2) the LCMs are capable of operant modification of their output. Thus, this restricted response system provides a useful preparation for examining the neural mechanisms of operant conditioning of head-waving in Aplysia.
Interganglionic axonal transport of neuropeptides in Aplysia
Authors: Lloyd PE
Published: April 2018

The transport of neuropeptides between central ganglia was studied in Aplysia. Peptide transport was determined by incubating ganglia with 35S-methionine and measuring the appearance of labeled peptides in connected ganglia. Selected interganglionic connectives were left intact and passed through a diffusion barrier separating the ganglia. Labeled peptides transported between ganglia included FMRFamide, myomodulin, and pedal peptide. Each of these peptides has been shown to be physiologically active in Aplysia. In addition to these previously characterized neuropeptides, a number of other as yet uncharacterized labeled peptides were also transported. All the peptides were transported by fast axonal transport as judged by the distance transported and/or the sensitivity to colchicine. Overall, FMRFamide and several unidentified peptides were the predominant transported peptides. However, the nature and amount of the peptides transported differed for each ganglia. These results support the proposition that the labeled peptides have transmitterlike actions and suggest that there are a number of neuropeptides that are likely to have central actions that have not yet been characterized in Aplysia.
Intrastriatal grafts derived from fetal striatal primordia. I. Phenotypy and modular organization
Authors: Graybiel AM , Liu FC , Dunnett SB
Published: April 2018

Fetal striatal grafts display a striking modularity of composition. With acetylcholinesterase (AChE) histochemistry, the tissue of such grafts can be divided into regions with strong AChE staining of the neuropil and regions in which AChE staining of the neuropil is weak. In the experiments reported here, we reexamined the nature of this modularity. Striatal grafts were made by injecting dissociated cells of E15 ganglionic eminence into the striatum of adult rats, which 7 days before had recived intrastriatal deposits of ibotenic acid. Some donors had been exposed to 3H-thymidine at E11-E15. After 9–17 month survivals, the anatomical organization of the grafts was studied by histochemistry, immunohistochemistry, and autoradiography. In every graft, the AChE-rich regions formed patches (P regions) in a larger AChE-poor surround (NP regions). Neurons labeled with 3H-thymidine appeared in both P and NP regions, suggesting that donor cells were distributed in each type of region and that neither type of tissue, P or NP, was composed exclusively of host tissue. In the AChE-rich P regions, markers characteristic of normal perinatal and mature rat striatum were expressed by medium-sized cells: calcium-binding protein (calbindin D28k) immunostaining, metenkephalin (mENK) immunostaining, and, more rarely, somatostatin (SOM) immunostaining. In the NP regions, however, medium-sized cells expressing calbindin and mENK immunostaining were very rare, and there was an abundance of neuronal types not found in normal mature striatal tissue. These included (1) large, multipolar, calbindin-positive neurons with well-ramified, densely stained dendrites, (2) large, SOM-positive neurons with prominent dendritic trees, and (3) mENK-positive cells smaller than typical striatal, medium-sized, mENK-immunoreactive neurons. In Nissl stains, the AChE-rich P regions resembled the normal striatum of mature animals, whereas the AChE-poor NP regions did not. These findings suggest that the P regions of fetal striatal grafts achieve a phenotypy similar to that of normal striatum at maturity and during much of postnatal development. The dominant expression of perikaryal calbindin- like immunoreactivity in the P regions further suggests that these zones have a high proportion of tissue resembling striatal matrix. By contrast, expression of marker antigens in the NP zones of the grafts suggests that these zones are predominantly composed of nonstriatal tissue or that they have the phenotypy of immature striatum intermixed with some nonstriatal cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Evidence that L-dopa-induced rotational behavior is dependent on both striatal and nigral mechanisms
Authors: Robertson GS , Robertson HA
Published: April 2018

Parkinson's disease results from the death of the dopamine-containing neurons in the substantia nigra pars compacta (SNC). This is accompanied by a loss of dopamine in brain regions, such as the corpus striatum, which receives input from dopaminergic neurons in the substantia nigra (SN). Since the corpus striatum is the primary target for these dopaminergic neurons, it has long been thought that the corpus striatum is the principal region affected. It was, therefore, natural to assume that replenishing dopamine in the striatum might be an effective treatment for Parkinson's disease. In fact, the dopamine precursor L-dihydroxyphenylalanine (L-dopa), the current drug of choice for treatment of Parkinson's disease, is believed to exert its therapeutic effect by replenishing dopamine levels in the corpus striatum via enzymatic decarboxylation within the synaptic terminals of surviving nigrostriatal neurons (Hornykiewicz, 1974). However, dopamine is also synthesized, stored, and released from the dendrites of SNC neurons that arborize in the substantia nigra pars reticulata (SNR) (Cheramy et al., 1981). Using a classic animal model for Parkinson's disease (rats with a unilateral 6-hydroxydopamine lesion of the SN), we show that L-dopa is also converted to dopamine in significant amounts within the 6-OHDA-lesioned SN. Furthermore, in contrast to the situation in the striatum where dopamine levels are only elevated for a short time, dopamine levels in the SN remain elevated until the behavioral effects of L-dopa have subsided. This elevation of nigral dopamine levels produces rotation that can be blocked by injecting a selective D1 dopamine receptor antagonist (SCH 23390, 2 micrograms in 1 microliter) directly into the SN pars reticulata. Infusion of SCH 23390 into the ipsilateral striatum produced only a modest reduction in L- dopa-induced circling behavior. These results suggest that D1 dopamine receptors in the SN may be at least as important as D1 dopamine receptors in the striatum as a site for the effects of L-dopa. This may have important implications for the therapy of Parkinson's disease.
The physiology of substance P in the rabbit retina
Authors: Zalutsky RA , Miller RF
Published: April 2018

The neuropeptide substance P (SP) has been localized to amacrine and ganglion cells in the rabbit retina. We have examined the effects of SP and related peptides on rabbit retinal neurons using bath application and intra- and extra-cellular electrophysiological methods in an in vitro retina eyecup preparation. Substance P, at concentrations as low as 25 nM, moderately excited most brisk ganglion cells. SP excited some ganglion cells directly during cobalt block of synaptic transmission. Intracellular recordings from amacrine cells demonstrated that some, but not all, were depolarized by SP; pharmacological evidence suggested GABAergic amacrines were probably among those sensitive to SP. SP did not affect horizontal cells or the ERG, suggesting that the effects of this peptide are confined to the inner retina. The effects of SP were strongly potentiated by peptidase inhibitors, raising the possibility that endogenously released SP may act quite locally in the rabbit retina. The relative potencies of SP and the related peptides substance K and eledoisin on different cells suggest that more than one tachykinin receptor subtype is present in the rabbit retina. The responses of ganglion cells to SP desensitized with repeated or prolonged applications. Comparison of a cell's light responses before and after the receptors were desensitized revealed no qualitative changes in receptive field characteristics, but quantitative changes in excitability were apparent. SP antagonist analogs, although not potent, specifically blocked the effects of SP on some ganglion cells. The effects of these antagonists on light responses reinforced the inferences from desensitization paradigms regarding the role of endogenous SP.(ABSTRACT TRUNCATED AT 250 WORDS)
Cardioactive neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) and novel related peptides are encoded in multiple copies by a single gene in the snail Lymnaea stagnalis
Authors: Linacre A , Kellett E , Saunders S , Bright K , Benjamin PR , Burke JF
Published: April 2018

The neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide) is a potent cardioactive neuropeptide in Lymnaea stagnalis. Isolation and sequencing of 2 cDNAs and a genomic clone shows that a single gene encodes a precursor protein which contains 9 copies of the FMRFamide peptide, 2 copies of the related peptide Phe-Leu-Arg-Phe-NH2 (FLRFamide), and single copies of the putative pentapeptides Gln-Phe- Tyr-Arg-lle-NH2 (posttranslationally modified to pQFYRlamide) and Glu- Phe-Leu-Arg-lle-NH2 (EFLRlamide). The gene is transcribed in the CNS and gives rise to a single RNA of 1.7 kb in size. The organization of the Lymnaea gene is significant with respect to the evolution of FMRFamide and related peptides in other organisms.
Suppressive control of the crustacean pyloric network by a pair of identified interneurons. I. Modulation of the motor pattern
Authors: Cazalets JR , Nagy F , Moulins M
Published: April 2018

A pair of identified neuromodulatory neurons, the pyloric suppressor (PS) neurons, can individually and strongly modify the activity of the pyloric network in the stomatogastric nervous system of the lobster Homarus gammarus. The PS neurons are identified by the location of their somata in the inferior ventricular nerve, their axonal projections, and their effects on pyloric network activity in vitro. Discharge of a PS neuron evokes large EPSPs in the pyloric dilator (PD) neurons and a long-lasting cessation of rhythmic activity in the neurons that control movements of the pyloric filter: PD, lateral pyloric (LP), and pyloric (PY). This cessation of rhythmic activity can outlast by several 10s of seconds a brief discharge of PS lasting only a few seconds. The different neurons of the pyloric filter do not exhibit the same sensitivity to the suppressive effects of PS, with the LP neuron being the most sensitive. Tonic discharge in PS induces graded alterations in the pyloric pattern, depending on its firing frequency. At low (less than 5 Hz) discharge frequencies, PS provokes changes in phase relationships and duration of bursting in pyloric neurons. A slight increase in PS frequency suppresses the rhythmic activity of some pyloric neurons, resulting in a switch from a triphasic to a biphasic pattern. At higher (greater than 10 Hz) PS firing frequencies, rhythmic activity in all the pyloric neurons, including the pacemakers (PD, anterior burster), is abolished, except in cells (ventricular dilator, inferior cardiac) controlling the pyloric valve. We conclude that a central pattern generator is not only subject to activating modulatory control, but may also be the target of suppressive inputs that are themselves able to provoke functional reconfigurations of the network.
Suppressive control of the crustacean pyloric network by a pair of identified interneurons. II. Modulation of neuronal properties
Authors: Cazalets JR , Nagy F , Moulins M
Published: April 2018

In the lobster Homarus, the 2 identified PS neurons have a strong suppressive modulatory effect on the activity of the pyloric network in the STG (Cazalets et al., 1990). In the present paper, we consider the effects of PS on individual pyloric neurons isolated from their partners in the network by cell photoinactivation and synaptic blockade. Three types of PS action are described: (1) a transient, EPSP- mediated depolarization of the PD, VD, and AB neurons; (2) a long- lasting hyperpolarization concomitant with a loss of oscillatory properties in the PD and LP neurons; (3) a long-lasting depolarization without modification of oscillatory properties in the PY and IC neurons. The various effects of PS on isolated pyloric cells were consistent with the overall effects of PS on the intact pyloric network.
Distribution of a putative kainic acid receptor in the frog central nervous system determined with monoclonal and polyclonal antibodies: evidence for synaptic and extrasynaptic localization
Authors: Dechesne CJ , Oberdorfer MD , Hampson DR , Wheaton KD , Nazarali AJ , Goping G , Wenthold RJ
Published: April 2018

A frog brain kainic acid receptor (KAR) was studied using monoclonal and polyclonal antibodies against the affinity-purified receptor. Immunocytochemistry was done on sections of the frog CNS, and the distribution of immunostaining was compared with the distribution of high- and low-affinity 3H-kainic acid (3H-KA) binding sites determined with in vitro receptor autoradiography. These studies showed (1) similar distributions of high- and low-affinity 3H-KA binding sites, (2) identical patterns of immunostaining with the polyclonal antibodies and 2 monoclonal antibodies, and (3) an antibody binding distribution which closely matched that of 3H-KA binding, suggesting that the antibodies recognize the primary KAR in frog brain. In the frog brain, an anteroposterior gradient of immunostaining was observed, with the telencephalon intensely and uniformly immunoreactive. Other areas intensely immunoreactive included the cerebellum, the infundibulum, the tectal and posterior commissures, and the laminar nucleus of the torus semicircularis. The optic tectum showed selective staining of the plexiform layers 3 and 5–7. The pattern of staining was punctate and appeared to be associated with nerve fibers, among them dendritic arborizations. Electron microscopic observations showed staining at the cytoplasmic side of postsynaptic membranes. Extra-synaptic staining was observed as patches on the surface of unmyelinated nerve processes.
Identification of a functional glucocorticoid response element in the phenylethanolamine N-methyltransferase promoter using fusion genes introduced into chromaffin cells in primary culture
Authors: Ross ME , Evinger MJ , Hyman SE , Carroll JM , Mucke L , Comb M , Reis DJ , Joh TH , Goodman HM
Published: April 2018

The rat gene encoding phenylethanolamine N-methyltransferase (PNMT) was cloned and a consensus sequence for a glucocorticoid response element (GRE) was found at -513 bp, 5′ to the transcriptional start site. In order to define the function of this element, fusion genes containing the PNMT promoter and a chloramphenicol acetyltransferase (CAT) reporter gene were constructed. These constructs did not express after transfection into any of 7 continuous cell lines, none of which endogenously produce PNMT. A system for transfecting chromaffin cells in primary culture was therefore devised using constructs containing 200 bp of the proenkephalin (ENK) promoter, whose expression characteristics are well known. pENK beta GAL-1, containing the ENK promoter with a lac Z reporter, was introduced into these cells and beta-galactosidase activity was visualized in situ. Approximately 90% of cells transfected were chromaffin; transfection efficiency was 5%. High levels of CAT activity were measured in chromaffin cells transfected with pENKAT12, possessing a CAT reporter. In contrast to tumor cell lines, pENKAT12 induction in these cells by forskolin and phorbol esters did not require a phosphodiesterase inhibitor. In this chromaffin system, both basal and regulated expression of the PNMT fusion genes were detected. Dexamethasone (dex) induced expression of pPNMT3000 and pPNMT900, containing the putative GRE and 3000 bp or 863 bp of PNMT promoter sequence, 4- to 10-fold. Expression of pPNMT300 and pPNMT100, which lack the GRE and contain 273 bp or 99 bp of PNMT promoter sequence, was unaffected by dex. Addition of the PNMT region spanning -490 to -863 bp conferred full dex responsiveness to a thymidine kinase promoter. Deletion of the putative GRE sequence by site-directed mutagenesis abolished the dex response. These data identify the sequence at -513 bp in the rat PNMT gene as a functional, positively acting GRE. Primary cultures of bovine chromaffin cells provide a biologically relevant expression system for transcriptional studies of catecholamine genes and their related neuropeptides.
Positron emission tomographic measurements of pulvinar activity during an attention task
Authors: LaBerge D , Buchsbaum MS
Published: April 2018

Positron emission tomographic scans were recorded from human subjects following an object-identification task, one version of which required attentional selection and the other version of which did not. In one experimental session, the attention-demanding displays were presented in the left visual field and the nonattention displays were presented in the right visual field. In a second session, the sides of the displays were reversed. Analysis of the scans indicated that, averaged across the 2 sessions, the pulvinar showed greater glucose uptake when it was contralateral to the display of the selective attention task than when it was contralateral to the display of the nonattention task. The pattern of the data indicated that the degree of the attention task effect on pulvinar glucose uptake may differ between the hemispheres. In view of known connections between the pulvinar and cortical areas that mediate object identification, the present finding suggests that the pulvinar operates interactively with these cortical structures when an identification process demands selective attention.
A monoclonal antibody that recognizes somatic motor neurons in the mature rat nervous system
Authors: Urakami H , Chiu AY
Published: April 2018

In order to obtain markers selective for motor neurons, an in vitro immunization was carried out using a crude homogenate of embryonic rat ventral spinal cord. We have generated a monoclonal antibody, MO-1, that binds selectively to the cell bodies of somatic motor neurons in the brain stem and spinal cord of the adult rat nervous system. In a survey of both peripheral and central nervous systems, intense labeling by MO-1 appears exclusive to this class of cholinergic neuron. Immunoreactivity is predominantly intracellular and is detectable within the somata as well as the proximal regions of processes but is absent along fiber tracts and at neuromuscular junctions. This staining pattern indicates that MO-1 does not recognize other molecules known to be present in motor neurons, such as choline acetyltransferase, acetylcholinesterase, agrin, or the calcitonin-gene-related-peptide. In the spinal cord, antibody binding begins to be detectable in motor neurons late in development, during the second postnatal week. Thus, MO- 1 appears to recognize a novel cellular component that accumulates in somatic motor neurons during terminal stages of differentiation.
Axon overproduction and elimination in the corpus callosum of the developing rhesus monkey
Authors: LaMantia AS , Rakic P
Published: April 2018

We have studied the cytological and quantitative aspects of axon addition and elimination in the corpus callosum of the developing rhesus monkey. Electron microscopic analysis reveals that during fetal development the number of callosal axons increases from 4 million at embryonic day 65 (E65) to 188 million at birth (E 165). Thus, the number of callosal axons in newborn monkeys exceeds the number present in the adult (an average of 56 million; LaMantia and Rakic, 1990a) by at least 3.5 times. Although there is some variability among the 11 fetal and newborn monkeys examined, there appears to be a progressive increase in the total number of callosal axons from midgestation through birth. The presence and numbers of growth cones from E65 through birth suggests that axon addition occurs exclusively during this period. There is no ultrastructural or quantitative indication of postnatal axon addition. After birth, about 70% of the axons in the callosum are eliminated in 2 phases. During the first phase, which includes the first 3 postnatal weeks, approximately 80 million axons are lost at an estimated rate of 4.4 million/d or 50/sec. During the second phase, which continues for the following 3 months, an additional 50 million axons are eliminated at a rate of 0.5 million/d or 5/sec until the adult value is reached. A discontinuous distribution of different classes of axons along the anterior-posterior axis of the tract reminiscent of the pattern seen in the adult is detectable before the onset of the first phase of axon elimination. Since the basic topography and terminal field patterns of callosal projections are well established before birth in all regions of the monkey cortex examined so far (Goldman-Rakic et al., 1983; Killackey and Chalupa, 1986; Dehay et al., 1988; Schwartz and Goldman-Rakic, 1990), we conclude that the massive postnatal elimination of callosal axons described here is unlikely to play a significant role in the development of discretely patterned callosal projection zones or their columnar terminations. The coincidence of axon elimination and the increase in synaptic density throughout the primate cerebral cortex during the first 6 postnatal months (Rakic et al., 1986), however, suggests that supernumerary axons may be lost during a process that results in the local proliferation of synapses from a subset of initial interhemispheric projections.
Color and contrast sensitivity in the lateral geniculate body and primary visual cortex of the macaque monkey
Authors: Hubel DH , Livingstone MS
Published: April 2018

We tested color and contrast sensitivity in the magnocellular and parvocellular subdivisions of the lateral geniculate body and in layers 2, 3, 4B, and 4C alpha of visual area 1 to obtain physiological data on the degree of segregation of the 2 pathways and on the fate of the color and contrast information as it is transmitted from the geniculate to the cortex. On average, magnocellular geniculate cells were much less responsive than parvocellular cells to shifts between 2 equiluminant colors. Nevertheless, many magnocellular cells (though not all) continued to give some response at equiluminance. As expected from previous studies, luminance contrast sensitivity differed markedly between magnocellular and parvocellular layers. In V-1, the properties of cells in the magnorecipient layers 4C alpha and 4B faithfully reflected the properties of magnocellular geniculate cells, showing no evidence of any parvocellular input. Like magnocellular geniculate cells, they showed high contrast sensitivity, and with color contrast stimuli they showed large response decrements at equiluminance. In the interblob regions of cortical layers 2 and 3, which anatomically appear to receive most of their inputs from parvorecipient layer 4C beta, contrast sensitivities of some of the cells were compatible with a predominantly parvocellular input. Other interblob cells had sensitivities intermediate between magno- and parvocellular geniculate cells, suggesting a possible contribution from the magnocellular system. Many cells in cortical layers 2 and 3 responded to color- contrast borders equally well at all relative brightnesses of the 2 colors, including equiluminance. We recorded from many direction- and disparity-selective cells in V-1: most of the direction-selective and all of the clearly stereo-selective cells were located in layer 4B.
Neural model of stereoacuity and depth interpolation based on a distributed representation of stereo disparity [published erratum appears in J Neurosci 1991 Mar;11(3):following Table of Contents]
Authors: Lehky SR , Sejnowski TJ
Published: April 2018

We have developed a model for the representation of stereo disparity by a population of neurons that is based on tuning curves similar in shape to those measured physiologically (Poggio and Fischer, 1977). Signal detection analysis was applied to the model to generate predictions of depth discrimination thresholds. Agreement between the model and human psychophysical data was possible in this model only when the population size representing disparity in a small patch of visual field was in the range of about 20-200 units. Interval encoding and rate encoding were found to be inconsistent with these data. Psychophysical data on stereo interpolation (Westheimer, 1986a) suggest that there are short-range excitatory and long-range inhibitory interactions between disparity- tuned units at nearby spatial locations. We extended our population model of disparity coding at a single spatial location to include such lateral interactions. When there was a small disparity gradient between stimuli at 2 locations, units in the intermediate, unstimulated position developed a pattern of activity corresponding to the average of the 2 lateral disparities. When there was a large disparity gradient, units at the intermediate position developed a pattern of activity corresponding to an independent superposition of the 2 lateral disparities, so that both disparities were represented simultaneously. This mixed population pattern may underlie the perception of depth discontinuities and transparent surfaces. Similar types of distributed representations may be applicable to other parameters, such as orientation, motion, stimulus size, and motor coordinates.
Membrane properties and discharge characteristics of guinea pig dorsal cochlear nucleus neurons studied in vitro
Authors: Manis PB
Published: April 2018

Intracellular recordings were made from neurons of the guinea pig dorsal cochlear nucleus in an in vitro brain slice preparation. The membrane properties of the cells were studied, and the membrane potentials were manipulated by current injection to determine how intrinsic conductances might alter the cell discharge patterns. Eleven cells were marked with Lucifer yellow. Ten of these cells were identified as the large pyramidal cells of layer 2 of this nucleus, and 1 cell was identified as a “vertical” cell in layer 3. Two kinds of action potentials were observed: simple spikes and complex spikes. This report discusses only cells with simple spikes. Simple spiking cells (60/72 recorded cells; all stained cells were simple spiking cells) discharged in a regular fashion with depolarization, and had linear frequency-current relationships up to 2 nA with a mean slope of 116 Hz/nA. The discharge rate was approximately constant throughout the current pulse. Responses of simple spiking cells to depolarizing current steps superimposed on a steady-state membrane hyperpolarization were studied. When the membrane has been held hyperpolarized, small current pulses produce a long-latency regular train of action potentials. Larger current pulses superimposed on membrane hyperpolarization can produce a short-latency action potential followed by a long silent interval (i.e., a long first interspike interval), and finally a regular train of spikes. It is concluded that the membrane conductances of DCN pyramidal cells are capable of generating at least 3 discharge patterns (regular firing, long first spike latency, and long first interspike interval) depending on the state of the membrane potential prior to a depolarizing current step. These responses are similar to the “chopper,” “buildup,” and “pauser” discharge patterns reported for these cells in vivo in response to tone bursts. The modulation of the intrinsic membrane conductances by membrane polarization and the possible contribution of these conductances to the generation of DCN discharge patterns provide new insights into the mechanisms underlying the responses of DCN cells to acoustic stimuli.
Kainate receptors in the rat hippocampus: a distribution and time course of changes in response to unilateral lesions of the entorhinal cortex
Authors: Ulas J , Monaghan DT , Cotman CW
Published: April 2018

The response of kainate receptors to deafferentation and subsequent reinnervation following unilateral entorhinal cortex lesions was studied in the rat hippocampus using quantitative in vitro autoradiography. The binding levels of [3H]kainic acid (KA) and changes in the distribution of KA sites were investigated in the dentate gyrus molecular layer (ML) and in various terminal zones in the CA1 field at 1, 3, 7, 14, 21, 30, and 60 d postlesion. The data from both the ipsilateral and contralateral hippocampus were compared with those from unoperated controls. The first changes in KA receptor distribution were observed 21 d postlesion when the dense band of KA receptors occupying the inner one-third of the ML expanded into the denervated outer two- thirds of the ipsilateral ML. The spreading of the KA receptor field into previously unoccupied zones continued 30 and 60 d postlesion. At these time points, the zone enriched in [3H]KA binding sites became significantly (on average 50%) wider than in unoperated controls. No changes were observed in either the distribution or binding levels in other hippocampal areas or in the contralateral hippocampus at any studied time point. Saturation analysis of binding in the ipsilateral ML 60 d postlesion revealed changes in the maximum number of receptor sites (Bmax) without changes in KA receptor affinity (Kd). The data suggest that the elevation of the [3H]KA binding in the outer two- thirds of the ML reflects an increase in the number of both low and high affinity receptor binding sites. The pattern of KA receptor redistribution was similar to the well-characterized pattern of sprouting of commissural/associational systems from the inner one-third into the outer two-thirds of the ML after entorhinal lesions (Zimmer, 1973; Lynch et al., 1975). This supports the hypothesis (Geddes et al., 1985) that the KA receptor response observed in the present study reflects postlesion reorganization of inputs within the denervated ML and may be relevant to functional recovery of the damaged circuits.