bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of the angle of gaze upon the excitability of the light- sensitive neurons of the posterior parietal cortex
Authors: Andersen RA , Mountcastle VB
Published: March 2018

The responses of parietal visual neurons are markedly increased during attentive fixation, as compared to those evoked in relaxed wakefulness, an effect specific for directed attention and unrelated to putative differences in the general level of arousal. Those responses are also strongly influenced by the angle of gaze, an effect observed only during directed visual attention. The change in response is smoothly graded along a meridian for about one-half the neuron population; the average spatial gradient from maximum to minimum is 78% response for a 20 degrees shift in eye position. No lateral preference was observed. For the remaining half, responses were either maximal or minimal for fixations dead ahead, and changes occurred with deviations in any direction. Angle of gaze effects were observed for neurons with foveal as well as eccentrically located receptive fields, all of which were organized in retinotopic not spatial coordinates. Control experiments showed that the effect was not produced by changes in visual background with changes in the angle of gaze, nor to changes in fixation distance, nor to variations in the intensity of stimuli viewed from different angles. The effect depends upon the position of the eye in the orbit, but is unlikely due to a direct central action of changes in nonretinal orbital afferent activity at different angles of gaze, for the effect was rarely observed with changes in the angle of gaze during relaxed wakefulness without directed visual attention. The evidence supports the interpretation that the effect is produced by a central influence of the systems controlling directed visual attention and the angle of gaze upon those linking the retinae to the parietal lobe.
Electromyographic response to displacement of different forelimb joints in the squirrel monkey
Authors: Lenz FA , Tatton WG , Tasker RR
Published: March 2018

The electromyographic (EMG) reflex response evoked in muscles stretched by imposed angular joint displacement has previously been studied in a variety of muscles and species. In most muscles studied, the EMG response consists of an initial burst of activity at latencies comparable to tendon tap responses followed by one or more bursts of EMG activity occurring at latencies less than somatosensory reaction time. The longer latency bursts or peaks of activity have often been assumed to be of similar origin in functionally diverse muscles. The present experiments were performed to examine the EMG response to imposed joint displacement in several different muscles of the squirrel monkey forelimb. The EMG was studied in muscles stretched by elbow, wrist, and metacarpophalangeal joint extension. Early (M1) and long (M2) latency peaks of activity could be observed in the EMG responses of short head of biceps (SHB), flexor carpi ulnaris (FCU), and flexor digitorum profundus (FDP), at latencies which are similar to those reported in other primate species allowing for differences in the size of the animals. The intervals between these peaks did not correspond to the period of oscillations in tension which occurred after the onset of the joint extension. The M2 peak consistently occurred later in SHB than in FCU and FDP. The M1 peak was smaller in distal than in proximal muscles and was frequently absent in FDP at resting levels of EMG activity. The ratio of M1 to M1 + M2 activity for different muscles revealed that proximal muscles had prominent early with less prominent long latency activity, whereas distal muscles had minimal early latency activity with prominent long latency activity. The onset of EMG activity approached tendon tap latencies in FCU at high base line EMG levels but in most cases occurred at approximately twice tendon tap latencies in FDP at high base line EMG levels. The results demonstrate the presence of significant differences between the EMG response to joint displacement in the proximal-distal series of forelimb flexors. Differences in the reflex response to joint displacement are discussed in view of twitch times and motor unit composition of the muscles studied.
Ganglioside composition is regulated during differentiation in the neuroblastoma X glioma hybrid cell line NG108-15
Authors: Dahms NM , Schnaar RL
Published: March 2018

Cellular differentiation of the neuroblastoma X glioma hybrid cell line NG108–15 was measured and correlated with quantitative changes in the cells' ganglioside composition. The degree of differentiation was measured using an enzymatic marker, choline acetyltransferase (CAT), which is responsible for neurotransmitter synthesis in this cell line. Differentiation of these cells is commonly induced by agents such as dibutyryl cyclic adenosine 3′:5′-monophosphate (Bt2cAMP). However, in our studies, we observed that these cells “self-differentiated,” in the absence of chemical inducers, when the cells became dense in culture. The differentiation marker, CAT specific activity, rose from 150 to more than 400 pmol/min/mg of protein as cell density increased, attaining a level higher than that achieved by treatment with Bt2cAMP. Differentiation of sparse cultures could be induced by conditioned medium removed from dense cultures. This effect was not due to depletion of a serum component from the medium by the cells, since it was not mimicked by serum depletion or inhibited by addition of fresh serum to the conditioned medium. These data suggest that cell density- dependent differentiation was caused by release of a factor from the cells which induced differentiation in a concentration-dependent manner. Gangliosides, therefore, were purified from sparse control cultures, dense cultures, and cultures treated with the differentiating agents Bt2cAMP, prostaglandin E1 (plus theophylline), or butyric acid. Quantitative thin layer chromatography revealed that all of the cultures contained the four gangliosides GM3, GM2, GM1, and GD1a. The concentration of one of the gangliosides, GM2, increased markedly (up to 12-fold) during differentiation. The GM2 concentration correlated closely with the level of CAT activity in the different cultures (r = 0.99). These data demonstrate that the ganglioside concentration in these cells is regulated during differentiation, a finding consistent with a possible role for gangliosides in the differentiated phenotype.
Telencephalic enkephalinergic systems in the rat brain
Authors: Khachaturian H , Lewis ME , Hollt V , Watson SJ
Published: March 2018

The comparative distribution of Leu-enkephalin and an enkephalin precursor fragment, BAM-22P, was studied in the rat telencephalon using immunocytochemical procedures. Although the enkephalins have previously been localized to telencephalic neurons, the use of high doses of colchicine in the present study has permitted the visualization of widespread enkephalin-containing systems in cortical-limbic regions. Rats were treated intraventricularly with colchicine (300 to 400 micrograms) to enhance the visualization of neuronal perikarya. Leu- enkephalin immunoreactivity was noted in perikarya as well as processes of neurons in many telencephalic regions including the olfactory bulb, parolfactory areas, olfactory tubercle, basal ganglia, nucleus accumbens, septal nuclei, amygdala, hippocampal formation, and several paleocortical regions such as the piriform, entorhinal, and cingulate cortex, as well as regions of the frontal, parietal, and occipital neocortex. In the majority of regions investigated, analysis of sections adjacent to those processed for Leu-enkephalin histochemistry showed BAM-22P immunoreactivity to be localized to perikarya and processes in the same region. These results suggest that brain enkephalin-positive neurons may possess mechanisms for enkephalin biosynthesis similar to those found in adrenal medullary enkephalin cells.
Nicotine stimulates secretion of both catecholamines and acetylcholinesterase from cultured adrenal chromaffin cells
Authors: Mizobe F , Livett BG
Published: March 2018

There is conflicting evidence from studies on sympathetic ganglia and the adrenal medulla concerning the morphological and biochemical localization and physiological role(s) of the enzyme acetylcholinesterase (AChE). Furthermore, the origin of the AChE released from the adrenal medulla (whether from chromaffin cells or splanchnic nerve, or both) has not been firmly established. We have examined the efficacy of cholinergic agonists to release endogenous AChE and catecholamines (CA) from monolayer cultures of purified bovine adrenal chromaffin cells. The nicotinic agonist (nicotine), but not the muscarinic agonist (methacholine), released both AChE and CA from the adrenal chromaffin cells. The concomitant release of CA and AChE evoked by nicotine was Ca++ dependent with a correlation coefficient r = 0.82 (p less than 0.001). The results show that adrenal chromaffin cells in vitro, a system free of splanchnic nerve elements, can still release AChE. The finding that concomitant release of AChE and catecholamines occurs on exposure of the cells to nicotinic agonists suggests that released AChE may have a physiological role at neuroeffector junctions.
Evidence for periaqueductal cholecystokinin-substance P neurons projecting to the spinal cord
Authors: Skirboll L , Hokfelt T , Dockray G , Rehfeld J , Brownstein M , Cuello AC
Published: March 2018

Using indirect immunofluorescence techniques combined with retrogradely transported fluorescent dyes, cholecystokinin (CCK)-like and substance P immunoreactive cell bodies in the periaqueductal central grey of the rat brain were studied. Data from both adjacent sections and elution- restaining techniques indicated that some of these central grey cells contain both a CCK-like peptide and substance P. Injection of the fluorescent dye, Fast Blue, into the cervical spinal cord indicated that this CCK-substance P cell group is a descending system. These findings provide evidence for two peptides in a single neuron, and the possible functional significance of such an occurrence is discussed.
Changes in [3H]muscimol binding in substantia nigra, entopeduncular nucleus, globus pallidus, and thalamus after striatal lesions as demonstrated by quantitative receptor autoradiography
Authors: Pan HS , Frey KA , Young AB , Penney JB
Published: March 2018

A quantitative autoradiographic technique for measuring the binding of [3H]muscimol to central nervous system GABA receptors is described using tritium-sensitive film. [3H]Muscimol binding was studied in primary and secondary striatal projection areas of rat brain following kainic acid lesions of the striatum. Seven days after the lesion, binding affinities in the striatum and its projection areas were not altered significantly. There was a loss of [3H]muscimol receptors in the striatum. Receptors increased in numbers in the ipsilateral globus pallidus (19%), entopeduncular nucleus (22%), and substantia nigra pars reticulata (38%). [3H]Muscimol binding was decreased in the ipsilateral anteroventrolateral and ventromedial (8%) thalamic nuclei. [3H]Muscimol binding in other brain areas (layer IV of the cerebral cortex, central gray, superior colliculus, and stratum moleculare of hippocampus) was not affected. The findings suggest that a loss of striatal innervation resulted in increased numbers of GABA receptors in striatal projection sites. It is further suggested that loss of inhibitory striatal inputs to neurons in the entopeduncular nucleus and substantia nigra pars reticulata may activate GABAergic projections to thalamus and thus result in decreased numbers of thalamic GABA receptors.
Interactions between the sympathetic and sensory innervation of the iris
Authors: Kessler JA , Bell WO , Black IB
Published: March 2018

The interaction between peptidergic, sensory nerves and sympathetic fibers was examined in the rat iris. The putative peptide neurotransmitter, substance P, was used as an index of the sensory innervation, because the peptide is exclusively localized in the iris to trigeminal sensory fibers. Extirpation of the sympathetic, superior cervical ganglion resulted in an increase in iris content of substance P-like immunoreactivity (henceforth SP), suggesting that sympathetic terminals influence the peptidergic sensory innervation of the iris. The increase in iris peptide after sympathetic ganglionectomy was reversed by implantation of sympathetic ganglia into the anterior chamber of the eye. Pharmacological stimulation or blockade of sympathetic nerve impulse activity and pharmacological blockade of sympathetic axonal transport did not alter iris peptide, suggesting that these procedures did not mediate the sympathetic-sensory interaction. However, injection of nerve growth factor (NGF) systemically or into the anterior chamber increased iris peptide, reproducing the effects of ganglionectomy. Conversely, injection of antiserum to NGF (anti-NGF) into the anterior chamber decreased iris SP suggesting that endogenous trophic protein normally regulates sensory peptide. The effects of anti-NGF were transitory; iris peptide returned to normal after cessation of treatment. Consequently, anti-NGF administration apparently did not lead to sensory neuron destruction, but rather altered either the number of sensory fibers in the iris or the amount of peptide per fiber. Finally, injection of anti-NGF into the anterior chamber reversed the effects of sympathetic ganglionectomy, suggesting that NGF may mediate the sympathetic-sensory interaction. Our observations suggest that competition for target NGF may result in reciprocal regulation of the iris sympathetic and sensory innervation.
Axotomy-induced parallel increases in electrical and dye coupling between identified neurons of Helisoma
Authors: Murphy AD , Hadley RD , Kater SB
Published: March 2018

The electrically coupled buccal ganglion neurons 4R and 4L of the snail, Helisoma, display predictable plasticity. The strength of the electronic synapse between them increases significantly following axotomy. Synaptic strength was assayed by measurements of electrical coupling coefficients and by assessment of dye coupling (passage of dye into the uninjected neuron) following injection of Lucifer Yellow CH into one neuron. Within 3 to 5 days, axotomy induced an increase in electrical coupling coefficients between neurons 4R and 4L from 0.54 +/- 0.11 (n = 13) in normal preparations to 0.72 +/- 0.14 (n = 24). A parallel axotomy-induced increase in the probability of dye coupling occurred. Only 27% (n = 27) of normal neuron 4 pairs were dye coupled, compared with 87% (n = 15) of axotomized neuronal pairs. Irrespective of treatment, electrical and dye measurements in the same neuron 4 pairs showed a consistent correlation between the magnitude of the electrical coupling coefficients and the probability of detectable dye coupling. No dye coupling was observed in neuronal pairs with electrical coupling coefficients less than 0.50. Dye coupling always occurred when coupling coefficients were greater than 0.70. Sixty-seven percent of neuronal pairs with intermediate coupling (0.50 to 0.70) coefficients displayed dye coupling. The results show that axotomy evokes a predictable enhancement of communication at an “identified” electronic synapse and suggests that electrical and dye coupling are mediated by similar mechanisms.
The peptidergic organization of the cat periaqueductal gray. II. The distribution of immunoreactive substance P and vasoactive intestinal polypeptide
Authors: Moss MS , Basbaum AI
Published: March 2018

Despite the important contribution of the midbrain periaqueductal gray (PAG) to endogenous pain suppression systems, little is known about the neuroanatomical basis of its functional organization. In a previous study of the distribution of the endogenous opiate leucine-enkephalin (ENK) in the PAG (Moss, M. S., E. J. Glazer, and A. I. Basbaum (1983) J. Neurosci. 3: 603–616), we found that immunoreactive ENK-containing neurons and terminals are clustered in discrete populations. In this study we have extended our analysis of the neurochemical organization of the PAG by using immunocytochemistry to map the distribution of two non-opiate peptides that produce potent analgesia when administered at central gray levels: substance P (Sub P) and vasoactive intestinal polypeptide (VIP). Immunoreactive Sub P neurons and terminal fields are clustered in discrete populations throughout the PAG. The distribution pattern of these populations changes at different rostral-caudal levels of the PAG. For example, there is a ventral-to-dorsal shift in the location of Sub P-like immunoreactivity from the caudal to the rostral PAG. Few immunoreactive Sub P neurons are found in the nucleus raphe dorsalis although moderately dense terminal field staining is present. The staining pattern of immunoreactive VIP is totally different from that of Sub P. Regardless of the rostral-caudal level examined, VIP- containing neurons are found tightly clustered in the subependymal neuropil of the ventromedial PAG. Only a few immunoreactive VIP- containing neurons are found in the ventral PAG or nucleus raphe dorsalis. The striking differences between the distribution of Sub P- and VIP-like immunoreactivity in the PAG indicates that the neural circuitry underlying pain suppression by Sub P and VIP may also differ.
Tyrosine hydroxylase activity decreases with induction of cholinergic properties in cultured sympathetic neurons
Authors: Wolinsky E , Patterson PH
Published: March 2018

Establishment of transmitter phenotype is an essential step in neuronal development. Studies on rat sympathetic neurons both in vivo and in vitro have provided evidence that mature cholinergic sympathetic neurons arise from previously noradrenergic neurons. Cultured rat superior cervical ganglion neurons can be influenced by their environment to remain noradrenergic, to acquire dual transmitter function, or to become predominantly cholinergic. Several other neuronal traits, such as a variety of surface molecules and released proteins, change simultaneously with levels of catecholamine and acetylcholine production, suggesting that various components of transmitter phenotype are regulated in concert. In this report, tyrosine hydroxylase levels are compared in neurons cultured under noradrenergic, dual function, or cholinergic conditions. Both enzyme activity in cell extracts and immunocytochemical staining were measured. These methods showed significantly less tyrosine hydroxylase enzyme activity and immunoreactive material in cholinergic cultures compared to noradrenergic and dual function cultures. These data support the interpretation that a switch in transmitter status from noradrenergic to cholinergic has occurred. This interpretation contrasts with that of Iacovitti et al. (Iacovitti, L., T. H. Joh, D. H. Park, and R. P. Bunge (1981) J. Neurosci. 1: 685–690), who conducted their experiments under critically different culture conditions.
An analysis of axon caliber within the optic nerve of the cat: evidence of size groupings and regional organization
Authors: Williams RW , Chalupa LM
Published: March 2018

Axon size in the optic nerves of three adult cats was measured using an accurate planimetric method. A sample of the axon complement was obtained from sets of more than 125 electron micrographs taken at each nerve. In contrast to previous reports, the distribution of axon diameter, as estimated from measurements of axonal cross-sectional area was clearly bimodal. The group of finest axons had a mode at approximately 1 micrometer, and the mode of the group of intermediate size axons was approximately 2 micrometers. Fibers with diameters larger than 3.5 micrometers formed the extensive tail of the distribution. The proportions of large, intermediate, and small axons were estimated to be 5%, 45%, and 50%. These groups probably correspond to the alpha, beta, and gamma classes of retinal ganglion cells. Regional distributions of axon caliber were also bimodal and, in a few instances, even trimodal. A peripheral crescent of each nerve contained a large number of fine fibers. Mean fiber diameter within discrete regions of the optic nerve varied inversely with the density of axon packing. The thickness of the myelin sheath was highly correlated with the inner fiber diameter, hence, myelin sheath width was also distributed in a bimodal manner. These results furnish the first clear evidence that the distribution of fiber caliber within the cat's optic nerve mirrors the principal classes of retinal ganglion cells.
The neural signal for skin indentation depth. I. Changing indentations
Authors: Burgess PR , Mei J , Tuckett RP , Horch KW , Ballinger CM , Poulos DA
Published: March 2018

Psychophysical tests on human subjects showed that judgments of skin indentation depth made when the fingertip was indented at rates from 0.2 to 16 mm/sec were quite insensitive to changes in indentation velocity. Similar results were obtained on the forearm at indentation velocities of 0.4 to 16 mm/sec. Recordings were made from mechanoreceptors in the monkey's hand that were able to respond over the same range of velocities and at comparable depths to determine how skin indentation depth might be signaled (coded) at the receptor level and to examine the rate sensitivity of the possible depth codes. It was found that most of the receptors with foci under the stimulator were recruited relatively early during an indentation, especially at velocities of 1.6 mm/sec and higher, making it improbable that the full range of indentation depths is signaled by the “subsurface” recruitment of different receptors at different indentation depths. A subsurface recruitment code involving subcutaneous receptors is not likely since subjects could feel virtually none of the stimuli after skin anesthesia. Progressive recruitment with depth of receptors whose foci lie further and further away from the stimulator (“lateral” recruitment) was considered an unlikely depth code because changing the area of the stimulator had little effect on its perceived depth. Also, it was shown that subjects could sense the curvature of the indentation (the profile of the depth at right angles to the skin surface), which requires information about the depth of individual patches of skin beneath the stimulator. There is no obvious way that a lateral recruitment code can provide this information. Thus it is probable that the discharge rate of some or all of the receptors excited by the indentation is involved in indicating its depth. Both impulse frequency and receptor recruitment at any given depth increased as the velocity of the indentation increased. The demonstrated reliability of information about skin indentation depth in humans indicates that the central neural circuitry responsible for judgments of skin indentation depth is able to compensate for the rate-sensitive receptor signals.
The representation of the body surface in S-I of cats
Authors: Felleman DJ , Wall JT , Cusick CG , Kaas JH
Published: March 2018

In both cats and monkeys, the traditional region of the first somatosensory area of cortex, S-I, has been described as containing four strip-like architectonic fields, areas 3a, 3b, 1, and 2. In monkeys, a number of recent studies have provided evidence that each of these architectonic fields constitutes a separate representation of the body. Because of the observations in monkeys, we decided to re-examine the S-I region of cats to determine whether the evidence supported the traditional concept of a single representation, or the existence of several representations related to the described architectonic fields. Microelectrode multiunit mapping techniques were used to determine the somatotopic organization of the S-I region of 10 cats. The results indicate that a single representation of the body surface occupies most or all of the traditional S-I region including cortex defined as area “3b,” area “1,” and much of area “2,” but excluding area “3a.” Neurons throughout this single representation were activated by cutaneous stimuli, indicating that all parts of S-I receive input from cutaneous receptors. Neurons in area 3a were activated by inputs from deep receptors, as reported by others. Neurons caudal to S-I were activated by cutaneous stimuli and appeared to constitute the additional body surface representations of S-II and possibly S-III. Thus, the significance of the architectonic fields “3b,” “1,” and “2” is quite different in cats than in monkeys. We propose that most or all of these three fields, as described in cats, constitute the homologue of area 3b in monkeys.
Compartmental relationships between anuran primary spinal motoneurons and somitic muscle fibers that they first innervate
Authors: Moody SA , Jacobson M
Published: March 2018

The compartmental and clonal relationships between primary motoneurons and the myotubes they innervate have been studied in Xenopus laevis embryos by initiating clones at blastula stages (32 to 512 cells) with intracellular injections of horseradish peroxidase (HRP). Primary motoneurons and ventral myotome belong to the posterior-ventral compartment, whereas sensory neurons and dorsal myotome belong to the posterior-dorsal compartment (Jacobson, M. (1983) J. Neurosci. 3: 1019–1038). The pathways of HRP-labeled primary motor axons, which pioneer the peripheral pathway to the adjacent myotome beginning at stage 21/22, were traced. Within the spinal cord, the axons remained in the posterior-ventral compartment. Upon leaving the cord they were confronted with both dorsal and ventral myotome; they remained almost exclusively in the ventral myotome. At late embryonic stages (40/42) primary motoneurons could be retrogradely labeled by applying HRP to the dorsal myotome, indicating that their axons or a branch had crossed the compartmental boundary. The primary motor axon also displayed a highly significant preferred association with clonally related myotubes within the ventral myotome. Axon growth only in the compartmentally related myotome and preferred association with clonally related myotubes suggest that the guidance of pioneer axons in the periphery may be based upon factors derived from common ancestry and lineage.
Simultaneous expression of neuronal and glial properties by chick ciliary ganglion cells during development
Authors: Rohrer H , Sommer I
Published: March 2018

Autoradiographic methods were used to show that non-neuronal cells from dissociated chick ciliary ganglia grown in cell culture for 1 day exhibit high affinity uptake for norepinephrine (NE) and/or specific receptors for nerve growth factor (NGF). Using immunofluorescence procedures, it was demonstrated that these cells reacted neither with the neuron-specific marker tetanus toxin nor with antibodies to the fibroblast marker fibronectin. The cells were, however, positive for 04 antigen, which is present on Schwann cells and oligodendrocytes and is recognized by a monoclonal antibody (Schachner, M., S. K. KIm, and R. Zehnle (1981) Dev. Biol. 83: 328–338). At all stages studied between embryonic day 6 (E6) and embryonic day 14 (E14), about 80% of the non- neuronal cells were positive for 04 antigen, the other non-neuronal cells being identified as fibroblasts or fibroblast-like cells by staining with antibodies to fibronectin. The proportion of cells with NGF receptors and cells with NE uptake decreased during development between E6 and E14. The percentage of 04-positive cells which have NGF receptors decreased from about 95% at E6 to about 35% at E14. The proportion of 04-positive cells with NE uptake decreased from about 57% at E6 to about 15% at E14. Thus, a considerable proportion of the non- neuronal cell population in embryonic ciliary ganglia displays neuronal properties. We suggest that those cells exhibiting biochemical properties of both differentiated glial cells and neurons are precursor cells which have the potential to develop either into glial cells or neurons.
Regeneration of an identified central neuron in the cricket. II. Electrical and morphological responses of the soma
Authors: Roederer E , Cohen MJ
Published: March 2018

The cell body of the medial giant interneuron (MGI) in the cricket normally does not spike in response to injected depolarizing currents. When axotomized 1 mm or more from the cell body (distant axotomy), the membrane properties of the soma remain unchanged. However, after axotomy close to the cell body (200 to 500 micron), the soma membrane becomes capable of generating action potentials by 6 hr after lesion. These regenerative spikes are 1 to 1.5 msec in duration and may reach 100 mV in peak amplitude. Ion substitutions indicate that these action potentials are primarily sodium dependent. A calcium-dependent component of soma membrane excitability that is normally present appears to be unaffected by axotomy. By 48 hr, the close axotomized MGI somata have lost the ability to generate action potentials and the membrane electrical properties return to normal. By 2 days after axotomy close to the soma, large, membrane-bound, electron-lucent vacuoles appear in the cytoplasm of the MGI cell body. Such vacuoles then disappear from axotomized MGI somata by 10 days. In addition, numerous arrays of densely packed, darkly staining microtubules are observed in the cell body, especially concentrated near the initial neurite. Neither of these specialized structures is observed in control, intact MGI somata. We propose that close axotomy disrupts the mechanisms which regulate the stability of the fully mature, differentiated neuron. The characteristic morphological and physiological stability of the MGI is lost: the dendritic arborization has been shown previously to be altered by extensive new outgrowth (Roederer, E., and M. J. Cohen (1982) J. Neurosci. 3: 1835–1847); there is a transient increase in soma membrane excitability, and new cytoplasmic organelles are induced.
Dissociated neurons from normal and mutant Drosophila larval central nervous system in cell culture
Authors: Wu CF , Suzuki N , Poo MM
Published: March 2018

A primary dissociated cell culture of Drosophila larval central nervous system is reported. Divisions of neuroblasts and vigorous outgrowth of neurites could be observed in culture. Within 24 hr cultured cells exhibited characteristic neuronal morphology and unimpaired ability to synthesize and accumulate acetylcholine. This cell culture system renders easy access to experimental analysis of normal neuronal properties and the altered mechanisms in neurological mutants. Single- channel currents induced by acetylcholine and regenerative action potentials were studied in the somata of the dissociated neurons. The appearance of Na channels in these cultured neurons was demonstrated by the cell lethality induced by veratridine and inhibition of the effect by tetrodotoxin. Dissociated neurons from a temperature-sensitive paralytic mutant napts, in which nerve conduction fails at high temperature, were studied in culture. Neuronal growth was not affected by this mutation, nor by tetrodotoxin. However, napts neurons showed greatly reduced sensitivity to veratridine even at 21 degrees C, a temperature at which napts individuals behave normally. This finding indicates expression of the napts phenotype at a level of isolated single cells and provides independent evidence that napts affects Na channel function.
Connections of the multiple visual cortical areas with the lateral posterior-pulvinar complex and adjacent thalamic nuclei in the cat
Authors: Raczkowski D , Rosenquist AC
Published: March 2018

The present report describes the patterns of cat thalamocortical interconnections for each of the 13 retinotopically ordered visual areas and additional visual areas for which no retinotopy has yet emerged. Small injections (75 nl) of a mixture of horseradish peroxidase and [3H]leucine were made through a recording pipette at cortical injection sites identified by retinotopic mapping. The patterns of thalamic label show that the lateral posterior-pulvinar complex of the cat is divided into three distinct functional zones, each of which contains a representation of the visual hemifield and shows unique afferent and efferent connectivity patterns. The pulvinar nucleus projects to areas 19, 20a, 20b, 21a, 21b, 5, 7, the splenial visual area, and the cingulate gyrus. The lateral division of the lateral posterior nucleus projects to areas 17, 18, 19, 20a, 20b, 21a, 21b, and the anterior medial (AMLS), posterior medial (PMLS), and ventral (VLS) lateral suprasylvian areas. The medial division of the lateral posterior nucleus projects to areas AMLS, PMLS, VLS, and the anterior lateral (ALLS), posterior lateral (PLLS), dorsal (DLS) lateral suprasylvian areas, and the posterior suprasylvian areas. In addition, many of these visual areas are also interconnected with subdivisions of the dorsal lateral geniculate nucleus (LGd). Every retinotopically ordered cortical area (except ALLS and AMLS) is reciprocally interconnected with the parvocellular C layers of the LGd. The medial intralaminar nucleus of the LGd projects to areas 17, 18, 19, AMLS, and PMLS. Finally, each cortical area (except area 17) receives a projection from thalamic intralaminar nuclei. These results help to define the pathways by which visual information gains access to the vast system of extrastriate cortex in the cat.
Synaptic responses and electrical properties of cells in brain slices of the mouse anteroventral cochlear nucleus
Authors: Oertel D
Published: March 2018

Intracellular recordings were made from cells in brain slices of the anteroventral cochlear nucleus. Responses to electrical stimulation of the stump of the auditory nerve were: (1) all-or-none, following the stimulus with no delay, and insensitive to the removal of extracellular Ca2+, probably representing the firing of directly stimulated auditory nerve fibers, or (2) graded, excitatory postsynaptic potentials, with synaptic delays of about 0.7 msec, which were often followed by graded, inhibitory synaptic potentials with synaptic delays of 1.2 msec or longer. The excitatory and inhibitory synaptic potentials were abolished by the removal of extracellular Ca2+. The result that delays of inhibitory synaptic responses were at least 2 times as long as those of excitatory ones indicates that probably an additional synapse was interposed. Responses to intracellularly injected current pulses show that cells in the anteroventral cochlear nucleus have one of two types of electrical characteristics. Type I properties are characterized by linear current-voltage relationships in the subthreshold voltage range and large, regularly firing action potentials in the suprathreshold range. Type II properties are characterized by nonlinear current- voltage relationships; suprathreshold depolarization elicits only one or two small action potentials. Type II characteristics are particularly well suited for maintaining the information contained in the timing and patterns of firing of the auditory nerve fibers.
Neurotrophic regulation of the phosphorylation of a soluble cytosolic protein in skeletal muscle
Authors: Held IR , Squinto SP , McLane JA
Published: March 2018

Neural influences are exerted not only by propagation of nerve impulses, but also by trophic actions of the motor neuron upon its contiguous muscle cell. Previously, we found that the in vitro phosphorylation of soluble protein catalyzed by an endogenous protein kinase is increased in cytosolic fractions from denervated soleus muscles. This alteration occurred within several hours after the loss of some neural influence, but not as an immediate consequence of denervation (Squinto, S. P., J. A. McLane, and I. R. Held (1980) Neurosci. Lett. 20: 295–300; Squinto, S. P., J. A. McLane, and I. R. Held (1981) Neurochem. Res. 6: 203–211). In this paper, we further define the cytosolic protein substrates and demonstrate a nerve stump length-dependent phosphorylative modulation of the predominate substrate in rat soleus muscles which were denervated for 1, 3, and 6 hr and then at 6-hr intervals to 78 hr by unilaterally cutting the sciatic nerve to leave either a short (2 mm or less), intermediate (17 to 20 mm), or long (32 to 35 mm) distal nerve stump attached to the muscle. The results are compared with those obtained from sham- operated, contralateral solei and unoperated muscles. We found that the times of onset and of maximal increase of the in vitro phosphorylation of soluble cytosolic protein in denervated solei are directly related to the lengths of the distal nerve stumps; i.e., 1.4 hr/mm and 1.3 hr/mm, respectively, based upon linear regression analysis. Also, this alteration could be accounted for by an increased phosphorylation of a 56-kilodalton soluble cytosolic protein which was resolved as a minor protein-staining band after SDS slab PAGE. Although gel autoradiographs clearly showed that other soluble cytosolic proteins were also phosphorylated, approximately 80% of the incorporated 32P label was bound to the 56-kilodalton substrate. The transfer of 32PO4 from [gamma- 32P]ATP to the 56-kilodalton protein during the assay was markedly inhibited by cAMP, but was not affected by Ca2+, cGMP, or a specific inhibitor of cAMP-dependent protein kinase. The possibility that the 56- kilodalton protein substrate is the autophosphorylatable regulatory subunit of protein kinase type II is discussed. The temporal relationship of the increased phosphorylation of the 56-kilodalton protein with the denervation period and nerve stump length suggests this change is mediated by some neurotrophic regulation of skeletal muscle.
Benzodiazepine receptors: localization in rat amygdala
Authors: Niehoff DL , Kuhar MJ
Published: March 2018

Behavioral, electroencephalographic, and evoked potential studies, as well as experiments utilizing the direct intracerebral injection of benzodiazepines (BZs), have implicated the amygdala, particularly its basolateral nuclear division, as an important locus of the therapeutic actions of these drugs. BZ receptor localization within the amygdala could further define which amygdaloid nuclei are important for BZ action and suggest neuroanatomical pathways especially sensitive to these drugs. Using a quantitative light microscopic autoradiographic technique, this study has localized type 1 and type 2 BZ receptors within the amygdaloid nuclear complex of the rat. BZ receptors were labeled with [3H]flunitrazepam, and type 1 BZ receptor binding was preferentially displaced by CL218,872 in 8-micron coronal sections of rat brain. Autoradiograms were generated by the apposition of emulsion- coated coverslips and quantified by standardized procedures. Ten amygdaloid nuclei were examined at nine levels over the rostrocaudal extent of the amygdala. Total BZ receptor density was highest in the basolateral nuclear complex, and the majority of these receptors were of the type 2 subclass. Type 1 receptors were concentrated in the anterior aspects of the amygdala, particularly the anterior cortical nucleus. These results are consistent with an important role for the basolateral amygdala in anxiogenesis and seizure induction. Furthermore, a larger circuit which includes the amygdala, ventromedial hypothalamus, mammillary body, anterior thalamus, and frontal cortex could be involved in the anxiolytic actions of the BZ drugs.
Regional distribution of dynorphin and neo-endorphin peptides in rat brain, spinal cord, and pituitary
Authors: Cone RI , Weber E , Barchas JD , Goldstein A
Published: March 2018

Five products of the dynorphin gene--alpha-neo-endorphin, beta-neo- endorphin, dynorphin A, dynorphin A-(1-8), and dynorphin B--were measured in various regions of rat brain and in rat spinal cord and pituitary. Specific antisera were used, supplemented by gel permeation analysis and high performance liquid chromatography, confirming the presence of dynorphin-32, dynorphin A, and dynorphin B in rat brain. In whole brain, alpha-neo-endorphin, dynorphin A-(1-8), and dynorphin B are present in much greater amounts than beta-neo-endorphin or dynorphin A. Although a general parallelism was found in the distribution of the five peptides, there were also noteworthy exceptions, suggesting that differential processing may occur.
Retrograde transport of nerve growth factor in lesioned goldfish retinal ganglion cells
Authors: Yip HK , Johnson EM
Published: March 2018

Previous experiments have shown that nerve growth factor (NGF) enhances regeneration of goldfish optic nerve after local application of NGF at the site of the lesion. However, the site and mechanism of action of NGF are not yet known. One possibility is that NGF is taken up at the site of the lesion and retrogradely transported to the cell bodies of the retinal ganglion cells and thereby exerts its trophic effects. The present work was carried out to assess the role of retrograde transport of NGF in this enhanced regeneration of goldfish retinal ganglion cells. In intact retinal ganglion cells of the goldfish, 125I-labeled NGF was found not to be retrogradely transported from the optic tectum to the retina, suggesting that retinal ganglion cells do not possess specific NGF receptors. However, if [125I]NGF was injected at the site of an optic nerve lesion at the time of lesion, [125I]NGF was retrogradely transported from the site of a lesion of the optic nerve to the cell body of retinal ganglion cells. The accumulated radioactivity was shown to be intact NGF by SDS-PAGE. The ability of NGF to decrease the time required for recovery of visual function was observed only when NGF was administered at the time of the injury. Likewise, no transport of [125I]NGF was observed when it was injected at the crush site 16 hr or longer after crush. Thus, there is a temporal correlation between the ability of intact [125I]NGF to be retrogradely transported from a lesion site to the retina and the regenerative effect of NGF. Autoradiography showed that the [125I]NGF accumulated only in retinal ganglion cells. The transport of NGF in the lesioned goldfish visual system was not specific for NGF in that other proteins (cytochrome c, bovine serum albumin) were transported equally well. Likewise, transport of [125I]NGF was not prevented by concomitant administration of excess unlabeled NGF. The retrograde transport of [125I]NGF therefore was not selective and did not appear to be mediated by specific NGF receptors in this system. This nonspecific transport of [125I]NGF did not occur in the axotomized spinal motor neurons in the neonatal or adult rat or in the newt. However, receptor-mediated transport is seen in lesioned sensory neurons in both species.(ABSTRACT TRUNCATED AT 400 WORDS)
Tetanus toxin: convulsant action on mouse spinal cord neurons in culture
Authors: Bergey GK , MacDonald RL , Habig WH , Hardegree MC , Nelson PG
Published: March 2018

The effects of direct application of tetanus toxin on fetal mouse spinal cord neurons in culture are described. Tetanus toxin produces increased excitation characterized by paroxysmal depolarizing events (PDE). In contrast to the abrupt onset of convulsant action produced by postsynaptic glycine antagonist strychnine, the convulsant action of tetanus occurs after a dose-dependent latent period. The onset of the convulsant action of tetanus toxin is paralleled by a reduction in observed spontaneous inhibitory synaptic potentials. Excitatory synaptic events can be identified as components of some tetanus-PDE. The toxin does not alter postsynaptic responses to the inhibitory amino acids glycine and gamma-aminobutyric acid. The latency and convulsant action of tetanus toxin are consistent with an irreversible presynaptic membrane interaction that reduces inhibitory transmission, a mechanism of action distinct from those of convulsants that antagonize inhibitory transmitters at the postsynaptic membrane.
Nerve fiber growth in culture on fibronectin, collagen, and glycosaminoglycan substrates
Authors: Carbonetto S , Gruver MM , Turner DC
Published: March 2018

In an initial report (Carbonetto, S. T., M. M. Gruver, and D. C. Turner (1982) Science 216: 897–899) we described the use of 2- hydroxyethylmethacrylate (HEMA) in preparing defined culture substrates for studying nerve fiber growth. In those studies fibronectin and collagen were conspicuous, among a variety of HEMA-embedded proteins, in supporting fiber growth of embryonic neurons from chick dorsal root ganglia. Here we further document and extend our preliminary studies, especially with regard to the interaction of growing nerve fibers with fibronectin. HEMA substrates were prepared with proteolytic fragments of fibronectin, each of which had one or more of the functional sites of the intact molecule. Only those fragments of fibronectin that retained the region of the molecule known to mediate myoblast attachment were active in supporting nerve fiber growth. When added in excess to the culture medium, the smallest of the active fragments inhibited fiber growth on substrates that contained intact fibronectin. In culture medium depleted of serum fibronectin, HEMA gels containing collagens purified from connective tissues (types I and III) or from basement membranes (type IV) were about as effective as HEMA substrates containing fibronectin in supporting fiber growth. Nerve fiber growth on collagen substrates proceeded in the absence of fibronectin in the culture medium. Several glycosaminoglycans (heparin, chondroitin sulfate, hyaluronic acid) were ineffective as substrates for fiber growth. Treatment of HEMA/ fibronectin gels with heparin or incorporation of heparin along with fibronectin in the gel profoundly diminished the efficacy of fibronectin in supporting nerve fiber growth. Our studies suggest that the growth of nerve fibers on fibronectin substrates results from direct interaction with a specific portion of the fibronectin molecule and that this interaction can be inhibited by heparin and possibly other glycosaminoglycans.
Formation of the receptive fields of leech mechanosensory neurons during embryonic development
Authors: Kramer AP , Kuwada JY
Published: March 2018

We have charted the embryonic development of the epidermal receptive fields of the PV and PD mechanosensory neurons present in each segmental ganglion of the ventral nerve cord of the glossiphoniid leech Haementeria ghilianii. The receptive field of either of these neurons is established by several peripheral axons, each of which grows into its own skin territory, so that the receptive field is subdivided into a quiltwork of contiguous, mutually exclusive subfields of various sizes. The largest subfield develops first from the primary peripheral axon of the PD or PV neuron. The PD and PV primary axons grow directly to their respective territories and begin to innervate them at approximately the same time (see also Kuwada, J.Y., and A.P. Kramer (1983) J. Neurosci. 3: 2098–2111). The smaller secondary and minor subfields develop later from the secondary and intersegmental peripheral axons, respectively. These axons, too, grow directly to their appropriate skin territories. The arborizations of the peripheral axons expand until the adult receptive field pattern is established late in embryogenesis; they do not appear to initially overgrow and later trim down to the normal boundaries of the adult receptive field. The receptive field of the PV neuron develops from a stereotyped skeletal branching pattern of the peripheral axons that is elaborated in a regular way to form a grid-like pattern that matches the arrangement of muscle fibers in the body wall. Thus, this branching pattern may be the result of axon growth along prespecified pathways, perhaps delineated by the muscles. Throughout embryonic development, as in the adult leech, axon branches of neighboring homologous P neurons overlap considerably, but separate axon branches of the same neuron are virtually non-overlapping. These observations suggest that developing branches of a neuron are excluded from territory occupied by other branches of the same cell, in contrast to branches belonging to different neurons which can occupy the same territory.