bluuebunny/crossref_metadata_2025 huggingface dataset:
Firing Properties of Spinal Interneurons during Voluntary Movement. I. State-Dependent Regularity of Firing
Authors: Prut Yifat , Perlmutter Steve I.
Published: April 2018

The firing properties of single spinal interneurons (INs) were studied in five awake, behaving monkeys performing isometric or auxotonic flexion-extension torques at the wrist. INs tended to fire tonically at rest (mean rate, 14 spikes (sp)/sec) and during generation of static torque (mean rate, 19 sp/sec in flexion, 24 sp/sec in extension). INs exhibited regular firing, with autocorrelation functions showing clear periodic features and a mean coefficient of variation of interspike intervals (CV) of 0.55 during production of static torque. For the population, there was an inverse correlation between CV and mean rate. However, 46% of the INs had task-dependent changes in regularity that were not predicted by changes in firing rate, suggesting that their firing pattern is determined not only by the intrinsic properties of the neurons but also by the properties of its synaptic inputs. INs showed two main response types to passive wrist displacement: biphasic and coactivation. Cells with these sensory responses had different, stereotypical temporal activity profiles and firing regularity during active movement. However, INs having correlational linkages with forearm muscles, identified as features in spike-triggered averages of electromyographic activity, did not exhibit unique responses or firing properties, although they tended to fire more regularly than other INs. This suggests the lack of a precise mapping of inputs to outputs for the spinal premotor network.
Dissociable Contributions of the Human Amygdala and Orbitofrontal Cortex to Incentive Motivation and Goal Selection
Authors: Arana F. Sergio , Parkinson John A. , Hinton Elanor , Holland Anthony J. , Owen Adrian M. , Roberts Angela C.
Published: April 2018

Theories of incentive motivation attempt to capture the way in which objects and events in the world can acquire high motivational value and drive behavior, even in the absence of a clear biological need. In addition, for an individual to select the most appropriate goal, the incentive values of competing desirable objects need to be defined and compared. The present study examined the neural substrates by which appetitive incentive value influences prospective goal selection, using positron emission tomographic neuroimaging in humans. Sated subjects were shown a series of restaurant menus that varied in incentive value, specifically tailored for each individual, and in half the trials, were asked to make a selection from the menu.

The amygdala was activated by high-incentive menus regardless of whether a choice was required. Indeed, activity in this region varied as a function of individual subjective ratings of incentive value. In contrast, distinct regions of the orbitofrontal cortex were recruited both during incentive judgments and goal selection. Activity in the medial orbital cortex showed a greater response to high-incentive menus and when making a choice, with the latter activity also correlating with subjective ratings of difficulty. Lateral orbitofrontal activity was observed selectively when participants had to suppress responses to alternative desirable items to select their most preferred. Taken together, these data highlight the differential contribution of the amygdala and regions within the orbitofrontal cortex in a neural system underlying the selection of goals based on the prospective incentive value of stimuli, over and above homeostatic influences.
Major Differences in Inhibitory Synaptic Transmission onto Two Neocortical Interneuron Subclasses
Authors: Bacci Alberto , Rudolph Uwe , Huguenard John R. , Prince David A.
Published: April 2018

Locally projecting GABAergic interneurons are the major providers of inhibition in the neocortex and play a crucial role in several brain functions. Neocortical interneurons are connected via electrical and chemical synapses that may be crucial in modulating complex network oscillations. We investigated the properties of spontaneous and evoked IPSCs in two morphologically and physiologically identified interneuron subtypes, the fast-spiking (FS) and low threshold-spiking (LTS) cells in layer V of rodent sensorimotor cortex. We found that IPSCs recorded in FS cells were several orders of magnitude more frequent, larger in amplitude, and had faster kinetics than IPSCs recorded in LTS cells. GABAAreceptor α- and β-subunit selective modulators, zolpidem and loreclezole, had different effects on IPSCs in FS and LTS interneurons, suggesting differential expression of GABAAreceptor subunit subtypes. These pharmacological data indicated that the α1 subunit subtype is poorly expressed by LTS cells but makes a large contribution to GABAAreceptors on FS cells. This was confirmed by experiments performed in genetically modified mice in which the α1 subunit had been made insensitive to benzodiazepine-like agonists. These results suggest that differences in IPSC waveform are likely attributable to distinctive expression of GABAAreceptor subunits in FS and LTS cells. The particular properties of GABAergic input on different interneuronal subtypes might have important consequences for generation and pacing of cortical rhythms underlying several brain functions. Moreover, selective pharmacological manipulation of distinct inhibitory circuits might allow regulation of pyramidal cell activities under specific physiological and pathophysiological conditions.
How Selective Are V1 Cells for Pop-Out Stimuli?
Authors: Hegdé Jay , Felleman Daniel J.
Published: April 2018

Many neurons in visual area V1 respond better to a pop-out stimulus, such as a single vertical bar among many horizontal bars, than to a homogeneous stimulus, such as a stimulus with all vertical bars. Many studies have suggested such cells represent neural correlates of pop-out, or more generally figure-ground segregation. However, preference for pop-out stimuli over homogeneous stimuli could also arise from a nonspecific selectivity for feature discontinuities between the target and the background, without any specificity for pop-out per se. To distinguish between these two confounding scenarios, we compared the responses of V1 neurons to pop-out stimuli with the responses to “conjunction-target” stimuli, which have more complex feature discontinuities between the target and the surround, as in a stimulus with a blue vertical bar among blue horizontal bars and yellow vertical bars. The target in conjunction-target stimuli does not pop out, which we psychophysically verified. V1 cells in general responded similarly to pop-out and conjunction-target stimuli, and only a small minority of cells (∼2% by one measure) distinguished the pop-out and conjunction-target stimuli from each other and from homogeneous stimuli. Nevertheless, the responses of approximately 50% of the cells were significantly modulated across all center-surround stimuli, indicating that V1 cells can convey information about the feature discontinuities between the center and the surround as part of a network of neurons, although individual cells by themselves fail to explicitly represent pop-out. In light of our results, unambiguous pop-out selectivity at the level of individual cells remains to be demonstrated in V1 or elsewhere in the visual cortex.
κ-Opioid Agonists Directly Inhibit Midbrain Dopaminergic Neurons
Authors: Margolis Elyssa B. , Hjelmstad Gregory O. , Bonci Antonello , Fields Howard L.
Published: April 2018

Dopaminergic neurons of the ventral tegmental area (VTA) play a critical role in motivation and reinforcement of goal-directed behaviors. Furthermore, excitation of these neurons has been implicated in the addictive process initiated by drugs such as morphine that act at the μ-opioid receptor (MOR). In contrast, κ-opioid receptor (KOR) activation in the VTA produces behavioral actions opposite to those elicited by MOR activation. The mechanism underlying this functional opposition, however, is poorly understood. VTA neurons have been categorized previously as principal, secondary, or tertiary on the basis of electrophysiological and pharmacological characteristics. In the present study using whole-cell patch-clamp recordings, we demonstrate that a selective KOR agonist (U69593, 1 μm) directly inhibits a subset of principal and tertiary but not secondary neurons in the VTA. This KOR-mediated inhibition occurs via the activation of a G-protein-coupled inwardly rectifying potassium channel and is blocked by the selective KOR antagonist nor-Binaltorphimine (100 nm). Significantly, regardless of cell class, KOR-mediated inhibition was found only in tyrosine hydroxylase-immunoreactive and thus dopaminergic neurons. In addition, we found a subset of principal neurons that exhibited both disinhibition by a selective MOR agonist ([d-Ala2,N-Me-Phe4, Gly-ol5]-enkephalin) (3 μm) and direct inhibition by KOR agonists. These results provide a cellular mechanism for the opposing behavioral effects of KOR and MOR agonists and shed light on how KORs might regulate the motivational effects of both natural rewards and addictive drugs.
Hindbrain Noradrenergic Lesions Attenuate Anorexia and Alter Central cFos Expression in Rats after Gastric Viscerosensory Stimulation
Authors: Rinaman Linda
Published: April 2018

Behavioral, autonomic, and endocrine outputs of the CNS are subject to important feedback modulation by viscerosensory signals that are conveyed initially to the hindbrain nucleus of the solitary tract (NST). In the present study, noradrenergic (NA) neurons [i.e., those that express the NA synthetic enzyme dopamine β hydroxylase (DbH)] in the caudal NST were lesioned to determine their role in mediating anorexic responses to gastric stimulation and in conveying gastric sensory signals to the hypothalamus and amygdala. For this purpose, saporin toxin conjugated to an antibody against DbH was microinjected bilaterally into the caudal NST in adult rats. Control rats received similar microinjections of vehicle. Several weeks later, rats were tested for the ability of systemic cholecystokinin octapeptide (CCK) (0 or 10 μg/kg) to inhibit food intake. CCK-induced anorexia was significantly attenuated in toxin-treated rats. Rats subsequently were used in a terminal cFos study to determine central neural activation patterns after systemic CCK or vehicle and to evaluate lesion extent. Toxin-induced loss of DbH-positive NST neurons was positively correlated with loss of CCK-induced anorexia. Hypothalamic cFos expression was markedly attenuated in lesioned rats after CCK treatment, whereas CCK-induced neural activation in the parabrachial nucleus and amygdala appeared normal. These findings suggest that hindbrain NA neurons are an integral component of brainstem circuits that mediate CCK-induced anorexia and also are necessary for hypothalamic but not parabrachial or amygdala responses to gastric sensory stimulation.
An Adverse Role for Matrix Metalloproteinase 12 after Spinal Cord Injury in Mice
Authors: Wells Jennifer E. A. , Rice Tiffany K. , Nuttall Robert K. , Edwards Dylan R. , Zekki Hakima , Rivest Serge , Yong V. Wee
Published: April 2018

We investigated the role of matrix metalloproteinases (MMPs) in acute spinal cord injury (SCI). Transcripts encoding 22 of the 23 known mammalian MMPs were measured in the mouse spinal cord at various time points after injury. Although there were significant changes in the expression levels of multiple MMPs, MMP-12 was increased 189-fold over normal levels, the highest of all MMPs examined. To evaluate the role of MMP-12 in SCI, spinal cord compression was performed in wild-type (WT) and MMP-12 null mice. Behavioral analyses were conducted for 4 weeks using the Basso-Beattie-Bresnahan (BBB) locomotor rating scale as well as the inclined plane test. The results show that MMP-12 null mice exhibited significantly improved functional recovery compared with WT controls. Twenty-eight days after injury, the BBB score in the MMP-12 group was 7, representing extensive movement of all three hindlimb joints, compared with 4 in the WT group, representing only slight movement of these joints. Furthermore, MMP-12 null mice showed recovery of hindlimb strength more rapidly than control mice, with significantly higher inclined plane scores on days 14 and 21 after SCI. Mechanistically, there was decreased permeability of the blood-spinal barrier and reduced microglial and macrophage density in MMP-12 null mice compared with WT controls. This is the first study to profile the expression patterns of a majority of the known MMPs after spinal cord compression. The data indicate that MMP-12 expression after spinal cord trauma is deleterious and contributes to the development of secondary injury in SCI.
Single-Unit Activity Patterns in Nuclei That Control the Electromotor Command Nucleus during Spontaneous Electric Signal Production in the MormyridBrienomyrus brachyistius
Authors: Carlson Bruce A.
Published: April 2018

Mormyrid fish generate weak electric organ discharges (EODs) used for communication and navigation. EODs are initiated in the medullary command nucleus (CN), which receives dense projections from the mesencephalic precommand nucleus (PCN) and the adjacent thalamic dorsal posterior nucleus (DP), plus a minor projection from the ventral edge of the toral ventroposterior nucleus (VPv). The dorsal region of the ventroposterior nucleus (VPd) projects to DP-PCN and receives input from the electric organ corollary discharge pathway. I recorded extracellularly from single units within DP-PCN and VPd and correlated their activity patterns with electromotor output to generate hypotheses on electromotor control mechanisms.

DP-PCN neurons show an oscillatory pattern of activity, firing within a window of 10-200 msec before each EOD, while remaining silent for 50-150 msec after each EOD. VPd neurons only fire during the silent period of DP-PCN neurons, suggesting that they provide recurrent inhibition to DP-PCN. During “scallops”, only DP-PCN neurons with high baseline firing rates increase their activity, whereas during “accelerations”, only neurons with low baseline firing rates show a strong increase in activity. Thus, the generation of different displays likely results from the activation of different groups of neurons projecting to CN. The activity of VPd neurons decreases during both displays, suggesting that disinhibition plays an important role in their generation. The mormyrid electromotor network shares many functional properties with central pattern generators (CPGs) found in relatively simple motor systems, indicating that it may be an excellent model system for studying CPG function in vertebrate communication.
A Combinatorial Network of Evolutionarily ConservedMyelin Basic ProteinRegulatory Sequences Confers Distinct Glial-Specific Phenotypes
Authors: Farhadi Hooman F. , Lepage Pierre , Forghani Reza , Friedman Hana C. H. , Orfali Wayel , Jasmin Luc , Miller Webb , Hudson Thomas J. , Peterson Alan C.
Published: April 2018

Myelin basic protein (MBP) is required for normal myelin compaction and is implicated in both experimental and human demyelinating diseases. In this study, as an initial step in defining the regulatory network controllingMBPtranscription, we located and characterized the function of evolutionarily conserved regulatory sequences. Long-range human-mouse sequence comparison revealed over 1 kb of conserved noncodingMBP5′ flanking sequence distributed into four widely spaced modules ranging from 0.1 to 0.4 kb. We demonstrate first that a controlled strategy of transgenesis provides an effective means to assign and compare qualitative and quantitativein vivoregulatory programs. Using this strategy, single-copy reporter constructs, designed to evaluate the regulatory significance of modular and intermodular sequences, were introduced by homologous recombination into the mousehprt(hypoxanthine-guanine phosphoribosyltransferase) locus. The proximal modules M1 and M2 confer comparatively low-level oligodendrocyte expression primarily limited to early postnatal development, whereas the upstream M3 confers high-level oligodendrocyte expression extending throughout maturity. Furthermore, constructs devoid of M3 fail to target expression to newly myelinating oligodendrocytes in the mature CNS. Mutation of putative Nkx6.2/Gtx sites within M3, although not eliminating oligodendrocyte targeting, significantly decreases transgene expression levels. High-level and continuous expression is conferred to myelinating or remyelinating Schwann cells by M4. In addition, when isolated from surroundingMBPsequences, M3 confers transient expression to Schwann cells elaborating myelin. These observations define thein vivoregulatory roles played by conserved noncodingMBPsequences and lead to a combinatorial model in which different regulatory modules are engaged during primary myelination, myelin maintenance, and remyelination.
Processing of the Arousal of Subliminal and Supraliminal Emotional Stimuli by the Human Amygdala
Authors: Gläscher Jan , Adolphs Ralph
Published: April 2018

The amygdala is known to play an important role in conscious and unconscious processing of emotional and highly arousing stimuli. Neuroanatomical evidence suggests that the amygdala participates in the control of autonomic responses, such as skin conductance responses (SCRs), elicited by emotionally salient stimuli, but little is known regarding its functional role in such control.

We investigated this issue by showing emotional visual stimuli of varying arousal to patients with left (n= 12), right (n= 8), and bilateral (n= 3) amygdala damage and compared their results with those from 38 normal controls. Stimuli were presented both subliminally (using backward masking) and supraliminally under lateralized presentation to one visual hemifield. We collected SCRs as a physiological index of emotional responses. Subjects subsequently rated each stimulus on valence and arousal under free viewing conditions.

There were two key findings: (1) impaired overall SCR after right amygdala damage; and (2) impaired correlation of SCR with the rated arousal of the stimuli after left amygdala damage. The second finding was strengthened further by finding a positive correlation between the evoked SCR magnitude and postsurgery amygdala volume, indicating impaired autonomic responses with larger tissue damage. Bilateral amygdala damage resulted in severe impairments on both of the above measures.

Our results provide support for the hypothesis that the left and right amygdalae subserve different functions in emotion processing: the left may decode the arousal signaled by the specific stimulus, whereas the right may provide a global level of autonomic activation triggered automatically by any arousing stimulus.
Patterned Activity via Spinal Dorsal Quadrant Inputs Is Necessary for the Formation of Organized Somatosensory Maps
Authors: Jain Neeraj , Diener Pamela S. , Coq Jacques-Olivier , Kaas Jon H.
Published: April 2018

The normal development of the somatosensory system requires intact sensory inputs from the periphery during a critical window of time early in development. Here we determined how the removal of only part of the ascending spinal inputs early in development affects the anatomical and neurophysiological development of the somatosensory system. We performed spinal overhemisections in rat pups at C3/C4 levels on the third day after birth. This procedure hemisects the spinal cord on one side and transects the dorsal funiculus on the other side. When the rats were 6-8 months old, the responsiveness and somatotopy of the primary somatosensory cortex (S1) contralateral to the hemisection were determined using standard multiunit mapping techniques. Sections of the flattened cortex were processed for cytochrome oxidase activity, Nissl substance, or myelin. We found that histologically apparent modules that are normally present in the regions of the forepaw and the hindpaw representations were absent, whereas the lateral barrel field representing the face was completely normal. The neurons in the forepaw regions of S1 either did not respond to the stimulation of the skin of any region of the body or responded to the stimulation of the upper arm afferents that enter the spinal cord rostral to the site of the lesion. The results show that a lack of normal sensory inputs via ascending pathways in the dorsal spinal cord during early development results in massive anatomical and neurophysiological abnormalities in the cortex. Intact crossed spinothalamic pathways are unable to support the normal development of the forepaw barrels.
α-Melanocyte-Stimulating Hormone Stimulates Oxytocin Release from the Dendrites of Hypothalamic Neurons While Inhibiting Oxytocin Release from Their Terminals in the Neurohypophysis
Authors: Sabatier Nancy , Caquineau Céline , Dayanithi Govindan , Bull Philip , Douglas Alison J. , Guan Xiao Ming M. , Jiang Michael , Van der Ploeg Lex , Leng Gareth
Published: April 2018

The peptides α-melanocyte stimulating hormone (α-MSH) and oxytocin, when administered centrally, produce similar behavioral effects. α-MSH induces Fos expression in supraoptic oxytocin neurons, and α-MSH melanocortin-4 receptors (MC4Rs) are highly expressed in the supraoptic nucleus, suggesting that α-MSH and oxytocin actions are not independent. Here we investigated the effects of α-MSH on the activity of supraoptic neurons. We confirmed that α-MSH induces Fos expression in the supraoptic nucleus when injected centrally and demonstrated that α-MSH also stimulates Fos expression in the nucleus when applied locally by retrodialysis. Thus α-MSH-induced Fos expression isnotassociated with electrophysiological excitation of supraoptic neurons because central injection of α-MSH or selective MC4 receptor agonists inhibited the electrical activity of oxytocin neurons in the supraoptic nucleus recordedin vivo. Consistent with these observations, oxytocin secretion into the bloodstream decreased after central injection of α-MSH. However, MC4R ligands induced substantial release of oxytocin from dendrites in isolated supraoptic nuclei. Because dendritic oxytocin release can be triggered by changes in [Ca2+]i, we measured [Ca2+]iresponses in isolated supraoptic neurons and found that MC4R ligands induce a transient [Ca2+]iincrease in oxytocin neurons. This response was still observed in low extracellular Ca2+concentration and probably reflects mobilization of [Ca2+]ifrom intracellular stores rather than entry via voltage-gated channels. Taken together, these results show for the first time that a peptide, here α-MSH, can induce differential regulation of dendritic release and systemic secretion of oxytocin, accompanied by dissociation of Fos expression and electrical activity.
Electrophysiological Differentiation of New Neurons in the Olfactory Bulb
Authors: Belluzzi Ottorino , Benedusi Mascia , Ackman James , LoTurco Joseph J.
Published: April 2018

The subventricular zone produces neuroblasts that migrate to the olfactory bulb (OB) and differentiate into interneurons throughout postnatal life (Altman and Das, 1966; Hinds, 1968; Altman, 1969; Kishi et al., 1990; Luskin, 1993; Lois and Alvarez-Buylla, 1994). Although such postnatally generated interneurons have been characterized morphologically, their physiological differentiation has not been thoroughly described. Combining retroviral-mediated labeling of newly generated neurons with patch-clamp electrophysiology, we demonstrated that soon after new cells enter the layers of the olfactory bulb, they display voltage-dependent currents typical of more mature neurons. We also show that these “newcomers” express functional GABA and glutamate receptor channels, respond synaptically to stimulation of the olfactory nerve, and may establish both axodendritic and dendrodendritic synaptic contacts within the olfactory bulb. These data provide a basic description of the physiology of newly generated cells in the OB and show that such new cells are functional neurons that synaptically integrate into olfactory bulb circuitry soon after their arrival.
Distinct Roles of Kv1 and Kv3 Potassium Channels at the Calyx of Held Presynaptic Terminal
Authors: Ishikawa Taro , Nakamura Yukihiro , Saitoh Naoto , Li Wen-Bin , Iwasaki Shinichi , Takahashi Tomoyuki
Published: April 2018

Despite identification of >100 potassium channel subunits, relatively little is known about their roles in synaptic transmission. To address this issue we recorded presynaptic potassium currents (IPK) directly from the calyx of Held terminal in brainstem slices of rats.IPKwas composed of a 4-aminopyridine (4-AP)-sensitive component and a smaller 4-AP-insensitive component composed of an iberiotoxin-sensitive current and an unidentified slowly activating potassium current.IPKcould also be separated into a tetraethylammonium (TEA; 1 mm)-sensitive high-voltage-activated component and a margatoxin (10 nm)-sensitive low-voltage-activated component, which was also blocked by dendrotoxin-I (200 nm) and tityustoxin-Kα (100 nm). In outside-out patches excised from calyceal terminals, TEA (1 mm) consistently and to a large extent attenuatedIPK, whereas margatoxin attenuatedIPKonly in a subset of patches (three of seven). Immunocytochemical examination using Kv subtype-specific antibodies indicated that multiple Kv1 and Kv3 subtypes were present at the calyceal terminal. In paired presynaptic and postsynaptic whole-cell recordings, TEA (1 mm) increased both the duration and peak amplitude of presynaptic action potentials and simultaneously potentiated EPSCs. Margatoxin alone had no such effect but reduced the amount of depolarization required for action potential generation, thereby inducing a burst of spikes when the nerve terminal was depolarized for a prolonged period. Thus, at the calyx of Held terminal, Kv3 channels directly regulate evoked transmitter release, whereas Kv1 channels reduce nerve terminal excitability, thereby preventing aberrant transmitter release. We conclude that both Kv3 and Kv1 channels contribute differentially to maintaining the fidelity of synaptic transmission at the calyx of Held.
Thyroid Hormone Induces Cerebellar Purkinje Cell Dendritic Development via the Thyroid Hormone Receptor α1
Authors: Heuer Heike , Mason Carol Ann
Published: April 2018

The thyroid hormonel-3,3′,5-triiodothyronine (T3) plays an important role during cerebellar development. Perinatal T3 deficiency leads to severe cellular perturbations, among them a striking reduction in the growth and branching of Purkinje cell dendritic arborization. The molecular mechanisms underlying these effects are poorly understood. Despite the well documented broad expression of thyroid hormone receptors (TRs), analysis of different TR-deficient mice has failed to provide detailed information about the function of distinct TRs during neuronal development. The cerebellar cell culture systems offer an excellent model by which to study the effects of T3, because differentiation of cerebellar neurons in mixed and purified cultures proceeds in the absence of serum that contains T3. Addition of T3 to cerebellar cultures causes a dramatic increase in Purkinje cell dendrite branching and caliber in a dose- and time-dependent manner. Furthermore, we demonstrate for the first time that T3 acts on Purkinje cells directly through TRα1 expressed on the Purkinje cell and not on the granule cell, the presynaptic partner of Purkinje cells. In contrast, TRβ isoforms are not involved, because Purkinje cells derived from TRβ-/-mice show the same T3 responsiveness as wild-type cells. T3-promoted Purkinje cell differentiation was not mediated via neurotrophins, as suggested previously, because dendritogenesis of Purkinje cells from BDNF-/-mice could be effectively stimulatedin vitroby T3 treatment. Furthermore, the effects of T3 observed were not abolished by tyrosine kinase receptor B (TrkB)-IgG, TrkC-IgG, or K252a, agents known to block the actions of neurotrophin. These results indicate that T3 directly affects Purkinje cell differentiation through activation of the TRα1.
Critical Role of Dorsomedial Hypothalamic Nucleus in a Wide Range of Behavioral Circadian Rhythms
Authors: Chou Thomas C. , Scammell Thomas E. , Gooley Joshua J. , Gaus Stephanie E. , Saper Clifford B. , Lu Jun
Published: April 2018

The suprachiasmatic nucleus (SCN) contains the brain's circadian pacemaker, but mechanisms by which it controls circadian rhythms of sleep and related behaviors are poorly understood. Previous anatomic evidence has implicated the dorsomedial hypothalamic nucleus (DMH) in circadian control of sleep, but this hypothesis remains untested. We now show that excitotoxic lesions of the DMH reduce circadian rhythms of wakefulness, feeding, locomotor activity, and serum corticosteroid levels by 78-89% while also reducing their overall daily levels. We also show that the DMH receives both direct and indirect SCN inputs and sends a mainly GABAergic projection to the sleep-promoting ventrolateral preoptic nucleus, and a mainly glutamate-thyrotropin-releasing hormone projection to the wake-promoting lateral hypothalamic area, including orexin (hypocretin) neurons. Through these pathways, the DMH may influence a wide range of behavioral circadian rhythms.
DrosophilaAmphiphysin Functions during Synaptic Fasciclin II Membrane Cycling
Authors: Mathew Dennis , Popescu Andrei , Budnik Vivian
Published: April 2018

Recent studies have revealed that endocytosis and exocytosis of postsynaptic receptors play a major role in the regulation of synaptic function, particularly during long-term potentiation and long-term depression. Interestingly, many of the proteins implicated in exocytosis and endocytosis of synaptic vesicles are also involved in postsynaptic protein cycling. In vertebrates, Amphiphysin is postulated to function during endocytosis in nerve terminals; however, several recent reports using aDrosophila amphiphysin(damph) null mutant have failed to substantiate such a role at fly synapses. In addition, Damph is surprisingly enriched at the postsynapse. Here we used the glutamatergic larval neuromuscular junction to study the synaptic role of Damph. By selectively labeling internal and external pools of the cell adhesion molecule Fasciclin II (FasII), and by using a novelin vivosurface FasII immunocapture protocol, we show that the level of external FasII is decreased indamphmutants although the total level of FasII remains constant.In vivoFasII internalization assays indicate that the reincorporation of FasII molecules into the cell surface is severely inhibited indamphmutants. Moreover, we show that blocking solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) function in postsynaptic muscle cells interferes with FasII exocytosis. These experiments suggest that inDrosophila,Damph functions during SNARE-dependent postsynaptic FasII membrane cycling. This study challenges the notion that synaptic Amphiphysin is involved exclusively in endocytosis and suggests a novel role for this protein in postsynaptic exocytosis.
A Map of Angular Tuning Preference in Thalamic Barreloids
Authors: Timofeeva Elena , Mérette Chantal , Émond Claudia , Lavallée Philippe , Deschênes Martin
Published: April 2018

A double-labeling protocol was used to determine how cells with different angular preferences to whisker motion distribute across the dimensions of a barreloid in the ventral posterior medial nucleus of the rat thalamus. Individual barreloids were labeled retrogradely by injecting Fluoro-Gold in identified barrel columns, and single relay cells (n= 30) pertaining to the labeled barreloids were stained juxtacellularly with Neurobiotin after determination of their angular tuning preference to controlled whisker deflection. Results show that cells with like angular preference are clustered within the barreloids. Those best tuned to forward and upward directions are located principally in the dorsal sector of the barreloid, whereas those best tuned to backward and downward motion are located principally in the central and ventral sectors, respectively. The relationship between cell location and angular preference was assessed by regression, cluster, and discriminant analysis. Together, these tests indicate that barreloids contain a map of shifting angular preference that transposes along the length of a barreloid directional property imposed at the periphery by the circumferential distribution of receptors around the vibrissa follicles.
Brain-Derived Neurotrophic Factor-Induced Gene Expression Reveals Novel Actions of VGF in Hippocampal Synaptic Plasticity
Authors: Alder Janet , Thakker-Varia Smita , Bangasser Debra A. , Kuroiwa May , Plummer Mark R. , Shors Tracey J. , Black Ira B.
Published: April 2018

Synaptic strengthening induced by brain-derived neurotrophic factor (BDNF) is associated with learning and is coupled to transcriptional activation. However, identification of the spectrum of genes associated with BDNF-induced synaptic plasticity and the correlation of expression with learning paradigmsin vivohas not yet been studied. Transcriptional analysis of BDNF-induced synaptic strengthening in cultured hippocampal neurons revealed increased expression of the immediate early genes (IEGs),c-fos, early growth response gene 1 (EGR1), activity-regulated cytoskeletal-associated protein (Arc) at 20 min, and the secreted peptideVGF(non-acronymic) protein precursor at 3 hr. The induced genes served as prototypes to decipher mechanisms of both BDNF-induced transcription and plasticity. BDNF-mediated gene expression was tyrosine kinase B and mitogen-activated protein kinase-dependent, as demonstrated by pharmacological studies. Single-cell transcriptional analysis ofArcafter whole-cell patch-clamp recordings indicated that increased gene expression correlated with enhancement of synaptic transmission by BDNF. Increased expressionin vitropredicted elevationsin vivo:VGFand theIEGsincreased after trace eyeblink conditioning, a hippocampal-dependent learning paradigm. VGF protein was also upregulated by BDNF treatment and was expressed in a punctate manner in dissociated hippocampal neurons. Collectively, these findings suggested that the VGF neuropeptides may regulate synaptic function. We found a novel function for VGF by applying VGF peptides to neurons. C-terminal VGF peptides acutely increased synaptic charge in a dose-dependent manner, whereas N-terminal peptide had no effect. These observations indicate that gene profilingin vitrocan reveal new mechanisms of synaptic strengthening associated with learning and memory.
Correlated Discharge among Cell Pairs within the Oculomotor Horizontal Velocity-to-Position Integrator
Authors: Aksay Emre , Baker Robert , Seung H. Sebastian , Tank David W.
Published: April 2018

In the oculomotor system, temporal integration of velocity commands into position signals may depend on synaptic feedback among neurons of a bilateral brainstem cell assembly known as the “neural integrator.” Both ipsilateral excitatory and contralateral inhibitory projections between eye position-related integrator cells are hypothesized as a substrate for positive feedback supporting integration. Presence of feedback interactions should be evident in cross-correlation functions of neuron pairs. Here, unilateral and bilateral paired recordings were obtained during fixation behavior from neurons in goldfish brainstem area I, a key element of the integrator. During fixations, discharge of most unilateral pairs, composed of cells with eye position sensitivities of the same sign, was positively correlated with lag of 0-10 msec (n= 11 of 14 significant). Typically, a very narrow peak (mean half-width <4 msec) near zero lag was observed. Discharge of bilateral pairs, composed of cells with position sensitivities of the opposite sign, was either negatively correlated with lag of 0-10 msec (n= 5 of 13 significant) or not correlated. Troughs in negative correlations always had minima between 3 and 5 msec lag. These results are consistent with the feedback hypothesis of temporal integration, highlighting excitation unilaterally and inhibition bilaterally. Absence of visual input did not weaken correlations, but other sources of correlated input extrinsic to area I were not ruled out. Triplet recordings revealed that unilateral pairwise correlations were primarily independent. Correlation between unilateral pairs systematically decreased with increasing eye position, demonstrating that synchrony is not necessary for persistent activity at high firing rates.
Caught in the Act:In VivoMapping of Macrophage Infiltration in Nerve Injury by Magnetic Resonance Imaging
Authors: Bendszus Martin , Stoll Guido
Published: April 2018

In vivotracking of hematogenous macrophages has been a major challenge because these cells are key players in nerve injury and repair. We visualized the spatiotemporal course of macrophage infiltration after acute peripheral nerve injury in living rats by using superparamagnetic iron oxide (SPIO) particles and magnetic resonance imaging (MRI). A signal loss on MR images indicating iron accumulation was present in degenerating sciatic nerves between days 1 and 8 after a crush lesion, ceased thereafter, and corresponded to the transient presence of iron-labeled ED1-positive macrophages in tissue sections. In contrast, no SPIO accumulation was seen after optic nerve crush, which revealed microglial activation but lacked macrophage infiltration. SPIO-enhanced MRI provides a new tool to selectively visualize active periods of macrophage transmigration into the nervous system, thus enabling dynamic views on a fundamental process in a multitude of nerve disorders.
Epilepsy-Associated Dysfunction in the Voltage-Gated Neuronal Sodium Channel SCN1A
Authors: Lossin Christoph , Rhodes Thomas H. , Desai Reshma R. , Vanoye Carlos G. , Wang Dao , Carniciu Sanda , Devinsky Orrin , George Alfred L.
Published: April 2018

Mutations inSCN1A, the gene encoding the brain voltage-gated sodium channel α1subunit (NaV1.1), are associated with at least two forms of epilepsy, generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy of infancy (SMEI). We examined the functional properties of four GEFS+ alleles and one SMEI allele using whole-cell patch-clamp analysis of heterologously expressed recombinant human SCN1A. One previously reported GEFS+ mutation (I1656M) and an additional novel allele (R1657C), both affecting residues in a voltage-sensing S4 segment, exhibited a similar depolarizing shift in the voltage dependence of activation. Additionally, R1657C showed a 50% reduction in current density and accelerated recovery from slow inactivation. Unlike three other GEFS+ alleles that we recently characterized, neither R1657C nor I1656M gave rise to a persistent, noninactivating current. In contrast, two other GEFS+ mutations (A1685V and V1353L) and L986F, an SMEI-associated allele, exhibited complete loss of function. In conclusion, our data provide evidence for a wide spectrum of sodium channel dysfunction in familial epilepsy and demonstrate that both GEFS+ and SMEI can be associated with nonfunctionalSCN1Aalleles.
Action Potential Initiation and Propagation in Layer 5 Pyramidal Neurons of the Rat Prefrontal Cortex: Absence of Dopamine Modulation
Authors: Gulledge Allan T. , Stuart Greg J.
Published: April 2018

Somatic and dendritic whole-cell recording was used to examine action potential (AP) initiation and propagation in layer 5 pyramidal neurons of the rat prelimbic prefrontal cortex. APs generated by somatic current injection, or via antidromic stimulation, were reliably recorded at apical dendritic locations as far as 480 μm from the soma. Although the backpropagation of single APs into the apical dendrite was robust, frequency-dependent attenuation was observed during AP trains delivered at 10-100 Hz. APs were usually initiated close to the soma (presumably in the axon); however, strong depolarizing input to the apical dendrite could generate dendritic spikes that preceded somatic APs. AP backpropagation was dependent solely on activation of dendritic voltage-gated sodium channels and did not require activation of dendritic calcium channels. Despite not playing a role in AP backpropagation, calcium-imaging experiments demonstrated that dendritic calcium channels are activated by backpropagating APs, leading to transient increases in intracellular calcium. In addition, calcium imaging revealed that AP backpropagation into the distal apical tuft was frequency dependent. Finally, we tested whether dopamine, a prominent neuromodulator associated with prefrontal activity, could alter AP initiation or backpropagation. Bath-applied dopamine (10 or 100 μm) did not effect AP backpropagation, frequency-dependent depression, local dendritic spike initiation, or AP-induced calcium signaling. These data indicate that AP backpropagation in prefrontal layer 5 pyramidal neurons is robust but frequency dependent in the distal tuft, requires dendritic sodium rather than calcium channel activation, and, unlike other aspects of neuronal excitability, insensitive to modulation by dopamine.
Genomic Instability Promoted by Overexpression of Mismatch Repair Factors in Yeast: A Model for Understanding Cancer Progression
Authors: Chakraborty Ujani , Dinh Timothy A , Alani Eric
Published: April 2018

Increased expression of mismatch repair proteins often correlates with tumor aggressiveness. Chakraborty, Dinh, and Alani report that co-overexpression of Msh2 and Msh6 in yeast results in genome instability phenotypes that are dependent on interaction with...

Mismatch repair (MMR) proteins act in spellchecker roles to excise misincorporation errors that occur during DNA replication. Curiously, large-scale analyses of a variety of cancers showed that increased expression of MMR proteins often correlated with tumor aggressiveness, metastasis, and early recurrence. To better understand these observations, we used The Cancer Genome Atlas and Gene Expression across Normal and Tumor tissue databases to analyze MMR protein expression in cancers. We found that the MMR genes MSH2 and MSH6 are overexpressed more frequently than MSH3, and that MSH2 and MSH6 are often cooverexpressed as a result of copy number amplifications of these genes. These observations encouraged us to test the effects of upregulating MMR protein levels in baker’s yeast, where we can sensitively monitor genome instability phenotypes associated with cancer initiation and progression. Msh6 overexpression (two- to fourfold) almost completely disrupted mechanisms that prevent recombination between divergent DNA sequences by interacting with the DNA polymerase processivity clamp PCNA and by sequestering the Sgs1 helicase. Importantly, cooverexpression of Msh2 and Msh6 (∼eightfold) conferred, in a PCNA interaction-dependent manner, several genome instability phenotypes including increased mutation rate, increased sensitivity to the DNA replication inhibitor HU and the DNA-damaging agents MMS and 4-nitroquinoline N-oxide, and elevated loss-of-heterozygosity. Msh2 and Msh6 cooverexpression also altered the cell cycle distribution of exponentially growing cells, resulting in an increased fraction of unbudded cells, consistent with a larger percentage of cells in G1. These novel observations suggested that overexpression of MSH factors affected the integrity of the DNA replication fork, causing genome instability phenotypes that could be important for promoting cancer progression.
Identidades de gênero e o debate étnico-racial no direito brasileiro: autodeclaração como técnica de proteção antidiscriminatória
Authors: Resadori Alice Hertzog , Rios Roger Raupp
Published: April 2018

A autodeclaração como técnica de identificação surgiu como institutoantidiscriminatório no âmbito das relações étnico-raciais. Em matéria de sexo, gênero e sexualidade, necessita de desenvolvimento, carecendo de maior reflexão teórica e de previsão legislativa no direito brasileiro. A autodeclaração vai de encontro a classificações arbitrárias, heteronormativas e simplificadoras, informadas pelo binarismo de gênero em abordagens essencialistas, que acabam por subalternizar em vez de proteger. Partindo do debate no âmbito étnico-racial, conclui-se que a autodeclaração revela-se adequada e promissora como instrumento antidiscriminatório protetivo de identidades sexuais e de gênero.
Beleza, produção e normalização do corpo em narrativas de crianças
Authors: Da Ponte Vanessa Paula
Published: April 2018

O foco do artigo é a produção da imagem corporal de crianças entre seise doze anos, frequentadoras de salões de beleza em Brasília. Entende-se que ascrianças são agentes e intérpretes sutis de seus contextos culturais; serão priorizadas as narrativas de meninas/os, pertencentes a diferentes realidades socioeconômicas, sobre os processos de construção de sua beleza. Trata-se de um trabalho etnográfico, com perspectiva socioantropológica da infância, calcado nos estudos de gênero. Apresentam-se resultados do trabalho de campo, cujo eixo foram as experiências relacionadas ao convívio das crianças com os serviços oferecidos por salões. Discutirei como as categorias corpo e beleza – operadas nesses estabelecimentos – são manejadas pelas crianças, reverberando nos processos de produção de suas autoimagens. O artigo destaca os posicionamentos e as negociações de crianças frente às presenças incisivas, em seus cotidianos, do mercado da beleza e da valorização social de um restrito padrão estético.
O “gênero” para além de uma proposição filosófica
Authors: De Souza Ana Paula Hilgert
Published: April 2018

Resenha de: FRAISSE, Geneviève. Los excesos del género: concepto, imagéne desnudez. Madrid: Ediciones Catedra, 2016. 122 p.
Biochemical Chgaracterization of Recombinant Baculovirus 373 K/E p53 Protein
Authors: Hossein Maghsoudi, , Pati U
Published: April 2018

In this study, we expressed and purified the recombinant baculovirus 373 K/E p53 protein in a baculovirus expression system to characterize this mutant and compare it with wild type p53. Gel- filtration chromatography and chemical cross-linking experiments indicated that purified recombinant baculovirus 373 K/E p53 protein assembles into multimeric forms ranging from tetramers to polymers. Gel-mobility shift assays and protein-DNA cross-linking studies demonstrated that the recombinant protein binds, to a consensus DNA target as a dimer but that additional p53 mutant molecules may then associate with the preformed p53-dimer-DNA complexes to form a larger p53_DNA complexes. These observations suggest that the p53 mutant tetramers and polymers that forms the minimal p53 mutant complex in solution dissociated upon DNA binding to form p53 mutant dimmer DNA complexes. The DNA binding activity of this mutant was then investigated using electrophoretic mobility shift assays as well as supershift assay with anti-p53 antibodies. Binding of the anti-p53 antibody PAb421to the oligomerization promoting domain on p53 stimulated the sequential formation of both the p53_dimer DNA and larger p53-DNA complexes
Suppression of Proinflamatroy cytokine gene expression with Aqueous Extract of Berberin
Authors: Haj-allahyari Samaneh , Hossein Dr Maghsoudi,
Published: April 2018

Based on knowledge from traditional Iranian herbal medicine, this ex vitro study aims to examine the anti-inflammatory mechanism of Berberis vulgaris L by measuring the expression and release of pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), cyclooxygenase-1 (COX-1), and interleukine-18 (IL-6), IL-1β and inducible nitric oxide synthase (iNOS) in THP-1. The effects were assessed by measuring the levels of secretory proteins and mRNA of TNF-α and IL-6, the levels of nitric oxide (NO) secretion and the expression of iNOS in THP-1 cells. Cells were treated with 20 ng lipopolysaccharide/ml (LPS) in the presence and absence of concentrations of extracts from the Berberis vulgaris L. During the entire experimental period, we used extract concentrations (0.3 μg/mL) that had no cytotoxic effects, as measured with MTT, MTT and LDH assays. Berberis vulgaris extracts remarkably suppressed the LPS-induced NO release, significantly attenuated the LPS-induced transcription of iNOS and inhibited in a dose-dependent manner the expression and release of TNF-α. significant effects were observed on the release of IL-6. Taken together, these results suggest that Berberis vulgaris probably exerts anti-inflammatory effects through the suppression of TNF-α and iNOS expressions.