bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal Activity in the Primate Motor Thalamus During Visually Triggered and Internally Generated Limb Movements
Authors: van Donkelaar P. , Stein J. F. , Passingham R. E. , Miall R. C.
Published: December 2017

Single-unit recordings were made from the basal-ganglia- and cerebellar-receiving areas of the thalamus in two monkeys trained to make arm movements that were either visually triggered (VT) or internally generated (IG). A total of 203 neurons displaying movement-related changes in activity were examined in detail. Most of these cells (69%) showed an increase in firing rate in relation to the onset of movement and could be categorized according to whether they fired in the VT task exclusively, in the IG task exclusively, or in both tasks. The proportion of cells in each category was found to vary between each of the cerebellar-receiving [oral portion of the ventral posterolateral nucleus (VPLo) and area X] and basal-ganglia-receiving [oral portion of the ventral lateral nucleus (VLo) and parvocellular portion of the ventral anterior nucleus (VApc)] nuclei that were examined. In particular, in area X the largest group of cells (52%) showed an increase in activity during the VT task only, whereas in VApc the largest group of cells (53%) fired in the IG task only. In contrast to this, relatively high degree of task specificity, in both VPLo and VLo the largest group of cells (∼55%) burst in relation to both tasks. Of the cells that were active in both tasks, a higher proportion were preferentially active in the VT task in VPLo and area X, and the IG task in VLo and VApc. In addition, cells in all four nuclei became active earlier relative to movement onset in the IG task compared with the VT task. These results demonstrate that functional distinctions do exist in the cerebellar- and basal-ganglia-receiving portions of the primate motor thalamus in relation to the types of cues used to initiate and control movement. These distinctions are most clear in area X and VApc, and are much less apparent in VPLo and VLo.
Changes in the Calcium Dependence of Glutamate Transmission in the Hippocampal CA1 Region After Brief Hypoxia-Hypoglycemia
Authors: Ouanonou A. , Zhang Y. , Zhang L.
Published: December 2017

Using the model of hypoxia-hypoglycemia (HH) in rat brain slices, we asked whether glutamate transmission is altered following a brief HH episode. The HH challenge was conducted by exposing slices to a glucose-free medium aerated with 95% N2-5% CO2, for ∼4 min, and glutamate transmission in the hippocampal CA1 region was monitored at different post HH times. In slices examined ≤8 h post HH, CA1 synaptic field potentials are comparable in amplitude to controls, but are less sensitive to experimental manipulations designed to attenuate intracellular Ca2+ signals, as compared with controls. Reducing calcium influx, by applying a nonspecific calcium channel blocker Co2+ or lowering external Ca2+, attenuated CA1 synaptic potentials much less in challenged slices than in controls. Buffering intracellular Ca2+ by bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid-AM (BAPTA-AM) attenuated CA1 synaptic potentials in control but not in slices post HH. Furthermore, minimally evoked excitatory postsynaptic currents displayed a lower failure rate in post-hypoxic CA1 neurons compared with controls. Based on these convergent observations, we suggest that evoked CA1 glutamate transmission is altered in the first several hours after brief hypoxia, likely resulting from alterations in intracellular Ca2+homeostasis and/or Ca2+-dependent processes governing transmitter release.
Saccade-Related Inhibitory Input to Pontine Omnipause Neurons: An Intracellular Study in Alert Cats
Authors: Yoshida Kaoru , Iwamoto Yoshiki , Chimoto Sohei , Shimazu Hiroshi
Published: December 2017

Omnipause neurons (OPNs) are midline pontine neurons that are thought to control a number of oculomotor behaviors, especially saccades. Intracellular recordings were made from OPNs in alert cats to elucidate saccade-associated postsynaptic events in OPNs and thereby determine what patterns of afferent discharge impinge on OPNs to cause their saccadic inhibition. The membrane potential of impaled OPNs exhibited steep hyperpolarization before each saccade that lasted for the whole period of the saccade. The hyperpolarization was reversed to depolarization by intracellular injection of Cl− ions, indicating it consisted of temporal summation of inhibitory postsynaptic potentials (IPSPs). The duration of the saccade-related hyperpolarization was almost equal to the duration of the concurrent saccades. The time course of the hyperpolarization was similar to that of the radial eye velocity except for the initial phase. During the falling phase of eye velocity, the correlation between the instantaneous amplitude of hyperpolarization and the instantaneous eye velocity was highly significant. The amplitude of hyperpolarization at the eye velocity peak was correlated significantly with the peak eye velocity. The time integral of the hyperpolarization was correlated with the radial amplitude of saccades. The initial phase disparity between the hyperpolarization and eye velocity was due to the relative constancy of peak time (∼20 ms) of the initial steep hyperpolarization regardless of the later potential profile that covaried with the eye velocity. The initial steep hyperpolarization led the beginning of saccades by 15.9 ± 3.8 (SD) ms, which is longer than the lead time for medium-lead burst neurons. These results demonstrate that the pause of activity in OPNs is caused by IPSPs initiated by an abrupt, intense input and maintained, for the whole duration of the saccade, by afferents conveying eye velocity signals. We suggest that the initial sudden inhibition originates from central structures such as the superior colliculus and frontal eye fields and that the eye velocity-related inhibition originates from the burst generator in the brain stem.
GABAA-Dependent Chloride Influx Modulates GABAB-Mediated IPSPs in Hippocampal Pyramidal Cells
Authors: Lopantsev Valeri , Schwartzkroin Philip A.
Published: December 2017

The relationship between postsynaptic inhibitory responses [the fast GABAA-mediated inhibitory postsynaptic potential (IPSP) and the slow GABAB-mediated IPSP] were investigated in hippocampal CA3 pyramidal cells. Mossy fiber-evoked GABAB-mediated IPSPs were, paradoxically, of greater amplitude in cells with resting membrane potential of −62 mV (13.6 ± 0.5 mV; mean ± SE) as compared with cells with resting membrane potential of −54 mV (7.0 ± 0.8 mV). In addition, when a cell’s membrane potential was artificially manipulated, GABAB-mediated IPSPs were reduced at relatively depolarized levels (−55 mV) and enhanced at relatively hyperpolarized potentials (at least −60 mV). In contrast, the preceding GABAA-mediated IPSPs were larger at the more positive membrane potentials and smaller as the cell was hyperpolarized. Similar voltage dependency was obtained when monosynaptic GABAA- and GABAB-mediated IPSPs were isolated in the presence of glutamatergic receptor antagonists. However, monosynaptic GABAB-mediated IPSPs isolated in the presence of glutamatergic and GABAA receptor antagonists were not reduced at the more positive membrane potentials, and were significantly larger in amplitude than GABAB-mediated IPSPs preceded by a monosynaptic GABAA-mediated IPSP. The amplitude of the isolated monosynaptic GABAB-mediated IPSPs recorded with potassium chloride-containing microelectrodes was significantly smaller than the comparable potential recorded with potassium acetate microelectrodes without chloride. We conclude that voltage-dependent chloride influx, via GABAA receptor-gated channels, modulates postsynaptic GABAB-mediated inhibition in hippocampal CA3 pyramidal cells.
Modulation of Radula Opener Muscles inAplysia
Authors: Evans Colin G. , Vilim Ferdinand S. , Harish Orna , Kupfermann Irving , Weiss Klaudiusz R. , Cropper Elizabeth C.
Published: December 2017

We observed fibers immunoreactive (IR) to serotonin (5-HT), the myomodulins (MMs), and FMRFamide on the I7-I10 complex in the marine mollusk Aplysia californica. The I7–I10 muscle complex, which produces radula opening, is innervated primarily by one motor neuron, B48. B48 is MM-IR and synthesizes authentic MMA. When B48 is stimulated in a physiological manner, cAMP levels are increased in opener muscles. cAMP increases also are seen when the MMs are applied to opener muscles but are not seen with application of the B48 primary neurotransmitter acetylcholine (ACh). Possible physiological sources of 5-HT and FMRFamide are discussed. When modulators are applied to resting opener muscles, changes in membrane potential are observed. Specifically, 5-HT, MMB, and low concentrations of MMAall depolarize muscle fibers. This depolarization is generally not sufficient to elicit myogenic activity in the absence of neural activity under “rest” conditions. However, if opener muscles are stretched beyond rest length, stretch- and modulator-induced depolarizations can summate and elicit contractions. This only occurs, however, if “depolarizing” modulators are applied alone. Thus other modulators (i.e., FMRFamide and high concentrations of MMA) hyperpolarize opener muscle fibers and can prevent depolarizing modulators from eliciting myogenic activity. All modulators tested affected parameters of motor neuron-elicited contractions of opener muscles. MMBand 5-HT increased contraction size over the range of concentrations tested, whereas MMApotentiated contractions when it was applied at lower concentrations but decreased contraction size at higher concentrations. FMRFamide decreased contraction size at all concentrations and did not affect relaxation rate. Additionally, the MMs and 5-HT increased muscle relaxation rate, decreased contraction latency, and decreased the rate at which tension was developed during motor neuron-elicited muscle contractions. Thus these modulators dramatically affect the ability of opener muscles to follow activity in the opener motor neuron B48. The possible physiological significance of these findings is discussed.
Miniature Inhibitory Postsynaptic Currents in CA1 Pyramidal Neurons After Kindling Epileptogenesis
Authors: Wierenga Corette J. , Wadman Wytse J.
Published: December 2017

Miniature inhibitory postsynaptic currents (mIPSCs) were measured in CA1 pyramidal neurons from long-term kindled rats (>6 weeks after they reached the stage of generalized seizures) and compared with controls. A large reduction in the number of mIPSCs was observed in a special group of large mIPSCs (amplitude >75 pA). The frequency of mIPSCs in this group was reduced from 0.042 Hz in controls to 0.027 Hz in the kindled animals. The reduction in this group resulted in a highly significant difference in the amplitude distributions. A distinction was made between fast mIPSCs (rise time <2.8 ms) and slow mIPSCs. Fast mIPSCs, which could originate from synapses onto the soma and proximal dendrites, had significantly larger amplitudes than slow mIPSCs, which could originate from more distal synapses (35.4 ± 1.1 vs. 26.2 ± 0.4 pA in the kindled group; means ± SE). The difference in the value of the mean of all amplitudes and frequency of fast and slow mIPSCs did not reach significance when the kindled group was compared with controls. The mIPSC kinetics were not different after kindling, from which we conclude that the receptor properties had not changed. Nonstationary noise analysis of the largest mIPSCs suggested that the single-channel conductance and the number of postsynaptic receptors was similar in the kindled and control groups. Our results suggest a 40–50% reduction in a small fraction of (peri-) somatic synapses with large or complex postsynaptic structure after kindling. This functionally relevant reduction may be related to previously observed loss of a specific class of interneurons. Our findings are consistent with a reduction in inhibitory drive in the CA1 area. Such a reduction could underlie the enhanced seizure susceptibility after kindling epileptogenesis.
Effects of Acute and Chronic Midthoracic Spinal Cord Injury on Neural Circuits for Male Sexual Function. I. Ascending Pathways
Authors: Hubscher Charles H. , Johnson Richard D.
Published: December 2017

Normal male reproductive function, particularly ejaculation, requires the integrity of urogenital sensory input and its ascending spinal projections. After midthoracic chronic spinal cord injury, sexual dysfunction occurs in both rats and humans. Neurons in the medullary reticular formation (MRF) are involved in the processing of bilaterally convergent sensory inputs from multiple cutaneous, mucocutaneous, and visceral regions of the body, including the penis and male urogenital tract. A variety of acute and chronic lesions were used to determine the midthoracic location of ascending spinal pathways conveying sensory input from the penis and male urogenital tract to MRF. A total of 371 single neurons were recorded in the MRF of 34 urethan-anesthetized mature male rats. Twenty-seven rats received a chronic T8dorsal (DHx) or lateral (LHx) hemisection or contusion (Cx) injury 30 days before the terminal electrophysiological experiments. In addition, nine dorsal nerve of the penis (DNP)-responsive MRF neurons in seven intact control animals were tested completely both before and after various select acute spinal cord lesions. The chronic lesion data indicate that low and high threshold input from the penis (mucocutaneous) and male urogenital tract (visceral) ascend bilaterally within the dorsal quadrant at T8 as opposed to high threshold input from the hindpaws (cutaneous), which ascends unilaterally in the ventrolateral quadrant (VLQ). The acute lesion data indicate that the low-threshold information conveyed from the penis and male urogenital tract ascends in the dorsal columns, as opposed to the high-threshold nociceptive inputs that ascend bilaterally in the dorsolateral quadrant (DLQ). These results, as well as previous data on ascending projections from female reproductive organs within the dorsal columns and DLQ to other caudal brain stem nuclei, provide evidence for ascending pathways conveying nociceptive information centrally via the DLQ. This spinal gray-DLQ pathway(s) conveying information from mucocutaneous/pelvic/visceral territories therefore differs from the traditionally recognized spinal gray-VLQ pathway(s), which is known to convey nociceptive information from cutaneous regions of the body.
Oscillatory Membrane Potential Activity in the Soma of a Primary Afferent Neuron
Authors: Pedroarena Cristina M. , Pose Inés E. , Yamuy Jack , Chase Michael H. , Morales Francisco R.
Published: December 2017

In the present report, we provide evidence that mesencephalic trigeminal (Mes-V) sensory neurons, a peculiar type of primary afferent cell with its cell body located within the CNS, may operate in different functional modes depending on the degree of their membrane polarization. Using intracellular recording techniques in the slice preparation of the adult rat brain stem, we demonstrate that when these neurons are depolarized, they exhibit sustained, high-frequency, amplitude-modulated membrane potential oscillations. Under these conditions, the cells discharge high-frequency trains of spikes. Oscillations occur at membrane potential levels more depolarized than −53 ± 2.3 mV (mean ± SD). The amplitude of these oscillations increases with increasing levels of membrane depolarization. The peak-to-peak amplitude of these waves is ∼3 mV when the cells are depolarized to levels near threshold for repetitive firing. The frequency of oscillations is similar in different neurons (108.9 ± 15.5 Hz) and was not modified, in any individual neuron, by changes in the membrane potential level. These oscillations are abolished by hyperpolarization and by TTX, whereas blockers of voltage-dependent K+ currents slow the frequency of oscillations but do not abolish the activity. These data indicate that the oscillations are generated by the activation of inward Na+ current/s and shaped by voltage-dependent K+ outward currents. The oscillatory activity is not modified by perfusion with low-calcium, high-magnesium, or cobalt-containing solutions nor is it modified in the presence of cadmium or Apamin. These results indicate that a calcium-dependent K+ current does not play a significant role in this activity. We postulate that the membrane oscillatory activity in Mes-V neurons is synchronized in adjoining electrotonically coupled cells and that this activity may be modulated in the behaving animal by synaptic influences.
P2X Receptor–Mediated Ionic Currents in Dorsal Root Ganglion Neurons
Authors: Burgard Edward C. , Niforatos Wende , van Biesen Tim , Lynch Kevin J. , Touma Edward , Metzger Randy E. , Kowaluk Elizabeth A. , Jarvis Michael F.
Published: December 2017

Nociceptive neurons in the dorsal root ganglia (DRG) are activated by extracellular ATP, implicating P2X receptors as potential mediators of painful stimuli. However, the P2X receptor subtype(s) underlying this activity remain in question. Using electrophysiological techniques, the effects of P2X receptor agonists and antagonists were examined on acutely dissociated adult rat lumbar DRG neurons. Putative P2X-expressing nociceptors were identified by labeling neurons with the lectin IB4. These neurons could be grouped into three categories based on response kinetics to extracellularly applied ATP. Some DRG responses (slow DRG) were relatively slowly activating, nondesensitizing, and activated by the ATP analogue α,β-meATP. These responses resembled those recorded from 1321N1 cells expressing recombinant heteromultimeric rat P2X2/3 receptors. Other responses (fast DRG) were rapidly activating and desensitized almost completely during agonist application. These responses had properties similar to those recorded from 1321N1 cells expressing recombinant rat P2X3 receptors. A third group (mixed DRG) activated and desensitized rapidly (P2X3-like), but also had a slow, nondesensitizing component that functionally prolonged the current. Like the fast component, the slow component was activated by both ATP and α,β-meATP and was blocked by the P2X antagonist TNP-ATP. But unlike the fast component, the slow component could follow high-frequency activation by agonist, and its amplitude was potentiated under acidic conditions. These characteristics most closely resemble those of rat P2X2/3 receptors. These data suggest that there are at least two populations of P2X receptors present on adult DRG nociceptive neurons, P2X3 and P2X2/3. These receptors are expressed either separately or together on individual neurons and may play a role in the processing of nociceptive information from the periphery to the spinal cord.
Activation of the Right Inferior Frontal Cortex During Assessment of Facial Emotion
Authors: Nakamura Katsuki , Kawashima Ryuta , Ito Kengo , Sugiura Motoaki , Kato Takashi , Nakamura Akinori , Hatano Kentaro , Nagumo Sumiharu , Kubota Kisou , Fukuda Hiroshi , Kojima Shozo
Published: December 2017

We measured regional cerebral blood flow (rCBF) using positron emission tomography (PET) to determine which brain regions are involved in the assessment of facial emotion. We asked right-handed normal subjects to assess the signalers’ emotional state based on facial gestures and to assess the facial attractiveness, as well as to discriminate the background color of the facial stimuli, and compared the activity produced by each condition. The right inferior frontal cortex showed significant activation during the assessment of facial emotion in comparison with the other two tests. The activated area was located within a triangular area of the inferior frontal cortex in the right cerebral hemisphere. These results, together with those of previous imaging and clinical studies, suggest that the right inferior frontal cortex processes emotional communicative signals that could be visual or auditory and that there is a hemispheric asymmetry in the inferior frontal cortex in relation to the processing of emotional communicative signals.
TGFβ1 Regulates the Gating Properties of Intermediate-Conductance KCa Channels in Developing Parasympathetic Neurons
Authors: Lhuillier Loic , Dryer Stuart E.
Published: December 2017

The developmental expression of Ca2+-activated K+ channels (KCa) in chick ciliary ganglion (CG) neurons is regulated by a target-derived avian isoform of TGFβ1, which evokes a robust increase in the number of functional large-conductance (BK) KCa channels but which produces no change in their kinetics. However, CG neurons express multiple KCa channel subtypes. Here we show that TGFβ1 regulates the gating properties of intermediate-conductance (IK) KCachannels in developing CG neurons. IK channels in inside-out patches excised from control E9 CG neurons became active on exposure to 1–5 μM free Ca2+ but then remained active on return to Ca2+-free salines. In contrast, IK channels in TGFβ1-treated cells became active on exposure to 1–5 μM Ca2+, but became quiescent immediately on return to Ca2+-free salines. In contrast to its effects on BK channels, TGFβ1 had no effect on the mean number of IK channels detected in excised patches. IK channels were not activated in cell-attached patches on E9 neurons depolarized by bath application of 145 mM KCl in the presence of 5 mM external Ca2+. However, BK channels were activated immediately by this procedure and were detected at a higher density in TGFβ1-treated cells. In addition, analyses of macroscopic KCa fluctuations, and the voltage-dependence of KCa tail currents, suggest that IK channels do not contribute to voltage-evoked whole cell KCa. IK channels therefore may have some other function. These results indicate that the effects of TGFβ1 on CG neurons entail distinct actions on multiple KCa channel subtypes.
Residues in a JellyfishShaker-Like Channel Involved in Modulation by External Potassium
Authors: Grigoriev Nikita G. , Spafford J. David , Spencer Andrew N.
Published: December 2017

The jellyfish gene, jShak2, coded for a potassium channel that showed increased conductance and a decreased inactivation rate as [K+]outwas increased. The relative modulatory effectiveness of K+, Rb+, Cs+, and Na+indicated that a weak-field-strength site is present. Cysteine substituted mutants (L369C and F370C) of an N-terminal truncated construct, ( jShak2Δ2–38) which only showed C-type inactivation, were used to establish the position and nature of this site(s). In comparison with jShak2Δ2–38 and F370C, L369C showed a greater relative increase in peak current when [K+]outwas increased from 1 to 100 mM because the affinity of this site was reduced at low [K+]out. Increasing [K+]outhad little effect on the rate of inactivation of L369C; however, the appearance of a second, hyperbolic component to the inactivation curve for F370C indicated that this mutation had increased the affinity of the low-affinity site by bringing the backbone oxygens closer together. Methanethiosulphonate reagents were used to form positively (MTSET), negatively (MTSES), and neutrally (MTSM) charged side groups on the cysteine-substituted residues at the purported K+binding site(s) in the channel mouth and conductance and inactivation kinetic measurements made. The reduced affinity of the site produced by the mutation L369C was probably due to the increased hydrophobicity of cysteine, which changed the relative positions of carbonyl oxygens since MTSES modification did not form a high-field-strength site as might be expected if the cysteine residues project into the pore. Addition of the side chain -CH2-S-S-CH3, which is similar to the side chain of methionine, a conserved residue in many potassium channels, resulted in an increased peak current and reduced inactivation rate, hence a higher affinity binding site. Modification of cysteine substituted mutants occurred more readily from the inactivated state confirming that side chains probably rotate into the pore from a buried position when no K ions are in the pore. In conclusion we were able to show that, as for certain potassium channels in higher taxonomic groups, the site(s) responsible for modulation by [K+]outis situated just outside the selectivity filter and is represented by the residues L369and F370in the jellyfish Shaker channel, jShak2.
Differential Modulation of Motor Neurons That Innervate the Same Muscle but Use Different Excitatory Transmitters inAplysia
Authors: Keating Christopher , Lloyd Philip E.
Published: December 2017

The medial portion of intrinsic buccal muscle 3 (I3m) is innervated by two excitatory motor neurons, B3 and B9. B3 uses glutamate as its fast transmitter and expresses the neuropeptide FMRFamide, whereas B9 uses acetylcholine as its fast transmitter and expresses the neuropeptide SCP. This preparation was used to study peptidergic modulation of muscles innervated by neurons that use different fast excitatory transmitters. First, we determined the effects of the application of the neuropeptides expressed in these neurons on excitatory junction potentials (EJPs) and contractions. FMRFamide increased the amplitude of EJPs and contractions evoked by B3 while decreasing those evoked by B9. This is the first observation in buccal muscle of a substance that modulates two excitatory neurons innervating the same muscle in opposite directions. SCP increased EJPs contraction amplitude, and the rate of muscle relaxation for both motor neurons. We determined that SCP potently increased cAMP levels in I3m as it does in other buccal muscles. Stimulation of B9 also caused increased cAMP levels in I3m providing independent evidence for SCP release. Finally, stimulation of B9 increased both the contraction amplitude and relaxation rate of B3-evoked I3m contractions in a manner similar to that observed using exogenous SCP. By inhibiting B9’s cholinergic transmission with an antagonist, we were able to observe modulatory effects of B9 in the absence of fast excitatory effects. We found that the magnitude of the modulation was dependent on the firing frequency and did occur at frequencies and patterns of firing recorded previously for B9 during ingestive-like motor programs.
Cortical Columnar Processing in the Rat Whisker-to-Barrel System
Authors: Brumberg Joshua C. , Pinto David J , Simons Daniel J.
Published: December 2017

Controlled whisker stimulation and single-unit recordings were used to elucidate response transformations that occur during the processing of tactile information from ventral posterior medial thalamus (VPM) through cortical columns in the rat whisker/barrel cortex. Whiskers were either deflected alone, using punctate ramp-and-hold stimuli, or in combination with a random noise vibration applied simultaneously to two or more neighboring whiskers. Quantitative data were obtained from five anatomically defined groups of neurons based on their being located in: VPM, layer IV barrels, layer IV septa, supragranular laminae, and infragranular laminae. Neurons in each of these populations displayed characteristic properties related to their response latency and time course, relative magnitudes of responses evoked by stimulus onset versus offset, strength of excitatory responses evoked by the noise stimulus, and/or the degree to which the noise stimulus, when applied to neighboring whiskers, suppressed or facilitated responses evoked by the columnar whisker. Results indicate that within layer IV itself there are at least two anatomically distinct networks, barrel and septum, that independently process afferent information, transforming thalamic input in similar but quantitatively distinguishable ways. Transformed signals are passed on to circuits in supragranular and infragranular laminae. In the case of supragranular neurons, evidence suggests that circuits there function in a qualitatively different fashion from those in layer IV, diminishing response differentials between weak and strong inputs, rather than enhancing them. Compared to layer IV, the greater heterogeneity of receptive field properties in nongranular layers suggests the existence of multiple, operationally distinct local circuits in the output layers of the cortical column.
Convergent Mechanosensory Input Structures the Firing Phase of a Steering Motor Neuron in the Blowfly,Calliphora
Authors: Fayyazuddin Amir , Dickinson Michael H.
Published: December 2017

The first basalar muscle (B1) is 1 of 17 small steering muscles in flies that control changes in wing stroke kinematics during flight. The B1 is often tonically active, firing a single phase-locked action potential in each and every wingbeat cycle. Changes in activation phase alter the biomechanical properties of B1, which in turn cause aerodynamically relevant changes in wing motion. The phase-locked firing of the B1 motor neuron (MNB1), is thought to arise from an interaction of wingbeat-synchronous inputs from the wings and from specialized equilibrium organs called halteres that beat antiphase to the wings and function to detect angular rotation of the body during flight. We investigated how the wing and haltere inputs interact to determine the firing phase of MNB1. Our results indicate that both wing and haltere afferents make strong monosynaptic connections with MNB1, consisting of fast electrical and slow Ca2+-sensitive components. Although both the wing and haltere-evoked excitatory postsynaptic potentials (EPSPs) display the two components, their relative contribution is different for the two inputs. Whereas the haltere-evoked EPSP is dominated by the fast electrical component, the wing-evoked EPSP is dominated by a large chemically mediated component and displays an additional prolonged Ca2+-dependent component that is absent in the haltere-evoked EPSP. Both inputs display an activity-dependent fatigue affecting both electrical and Ca2+-sensitive components, from which the haltere synapse recovers more rapidly. The net result of these synaptic differences is that the two pathways differ significantly in their relative ability to evoke action potentials in MNB1. Although the haltere pathway displays greater temporal precision, the wing pathway is stronger, judged by its ability to entrain MNB1 within a background of haltere stimulation. We propose a model by which these physiological differences play a functional role in tuning the firing phase of MNB1 during flight. The wing input may serve primarily to set the background firing phase of MNB1, whereas the haltere input serves to transiently advance the firing phase during equilibrium reflexes.
Response Latency of Macaque Area MT/V5 Neurons and Its Relationship to Stimulus Parameters
Authors: Raiguel S. E. , Xiao D.-K. , Marcar V. L. , Orban G. A.
Published: December 2017

A total of 310 MT/V5 single cells were tested in anesthetized, paralyzed macaque monkeys with moving random-dot stimuli. At optimum stimulus parameters, latencies ranged from 35 to 325 ms with a mean of 87 ± 45 (SD) ms. By examining the relationship between latency and response levels, stimulus parameters, and stimulus selectivities, we attempted to isolate the contributions of these factors to latency and to identify delays representing intervening synapses (circuitry) and signal processing (flow of information through that circuitry). First, the relationship between stimulus parameters and latency was investigated by varying stimulus speed and direction for individual cells. Resulting changes in latencies were explainable in terms of response levels corresponding to how closely the actual stimulus matched the preferred stimulus of the cell. Second, the relationship between stimulus selectivity and latency across the population of cells was examined using the optimum speed and direction of each neuron. A weak tendency for cells tuned for slow speeds to have longer latencies was explainable by lower response rates among slower-tuned neurons. In contrast, sharper direction tuning was significantly associated with short latencies even after taking response rate into account, ( P = 0.002, ANCOVA). Accordingly, even the first 10 ms of the population response fully demonstrates direction tuning. A third study, which examined the relationship between antagonistic surrounds and latency, revealed a significant association between the strength of the surround and the latency that was independent of response levels ( P < 0.002, ANCOVA). Neurons having strong surrounds exhibited latencies averaging 20 ms longer than those with little or no surround influence, suggesting that neurons with surrounds represent a later stage in processing with one or more intervening synapses. The laminar distribution of latencies closely followed the average surround antagonism in each layer, increasing with distance from input layer IV but precisely mirroring response levels, which were highest near the input layer and gradually decreased with distance from input layer IV. Layer II proved the exception with unexpectedly shorter latencies ( P < 0.02, ANOVA) yet showing only modest response levels. The short latency and lack of strong direction tuning in layer II is consistent with input from the superior colliculus. Finally, experiments with static stimuli showed that latency does not vary with response rate for such stimuli, suggesting a fundamentally different mode of processing than that for a moving stimulus.
Robust Suppression of Afferent-Induced Excitation in the Rat Spinal Dorsal Horn After Conditioning Low-Frequency Stimulation
Authors: Ikeda Hiroshi , Asai Tatsuya , Randić Mirjana , Murase Kazuyuki
Published: December 2017

The neuronal plasticity in the spinal dorsal horn induced after conditioning low-frequency stimulation of afferent A fibers, and its relationship with spinal inhibitory networks, was investigated with an optical-imaging method that detects neuronal excitation. High-intensity single-pulse stimulation of the dorsal root activating both A and C fibers evoked an optical response in the dorsal horn in transverse slices of 12- to 25-day-old rat spinal cords stained with a voltage-sensitive dye, RH-482. The optical response, reflecting the net excitation of neuronal elements along the thickness of each slice, was suppressed after a conditioning low-frequency stimulation (0.2–1 Hz for 10 min) to A fibers in the dorsal root. The degree of suppression was largest in the lamina II of the dorsal horn (48% reduction), where the majority of C fibers terminate, and much less in the deeper dorsal horn (5% reduction in laminae III–IV). The onset of suppression was somewhat slow; after the low-frequency stimulation, the magnitude of excitation gradually decreased, reached the maximum effect 30 min after the conditioning, and remained at the suppressed level for >1 h. Suppression was not observed when the low-frequency stimulation was given during a 20-min perfusion with a solution containing an NMDA-receptor antagonist, dl-2-amino-5-phosphonovaleric acid (30 μM). A brief application of an opioid-receptor antagonist, naloxone (0.5 μM), inhibited the induction, but not the maintenance, of low-frequency stimulus-induced suppression. However, treatments with the GABAA receptor antagonist bicuculline (1 μM) and the glycine receptor antagonist strychnine (0.3 μM) did not affect suppression induction and maintenance. In conclusion, conditioning low-frequency stimulation to A fibers interferes with the afferent-induced excitation in the dorsal horn. The low-frequency stimulation-induced suppression is maintained by a reduction of glutamatergic excitatory transmissions in the dorsal horn, not by an enhanced inhibition. Activation of the spinal opioid-mediated system by low-frequency stimulation, but not the inhibitory amino acid–mediated system, is necessary to initiate robust suppression. The long-term depression of afferent synaptic efficacy onto excitatory interneurons likely takes the primary role in the robust suppression of neuronal excitation in the dorsal horn.
Epileptiform Activity Can Be Initiated in Various Neocortical Layers: An Optical Imaging Study
Authors: Tsau Yang , Guan Li , Wu Jian-Young
Published: December 2017

The initiation site for triggering epileptiform activity was investigated via optical imaging using voltage-sensitive dyes in the neocortical slice perfused with artificial cerebral spinal fluid containing nominally zero magnesium. The neocortical slices (400-μm thick) were harvested from Sprague-Dawley rats (P21–28). Optical imaging was made by using a high speed photodiode array. Spontaneous epileptiform activity emerged 20–40 min after the preparation was perfused with zero-magnesium solution. There was a good correspondence between electrical and optical signals ( n = 46), although the details of the two recordings were somewhat different. The initiation sites were measured optically in 11 preparations. Among them, four were found to be located in superficial layers, two were found in middle layers, and five were found in deep layers. Repeated recordings revealed that these initiation sites were relatively stable; shifting of the initiation site was not observed. Therefore spontaneous epileptiform activity could be initiated in various cortical layers, from layer I to layer VI. The activation started from a small area <0.04 mm3 and spread smoothly from the initiation site to adjacent cortical areas, suggesting that the initiation site is very confined to one of the cortical layers. The initiation sites were distributed randomly in various cortical areas, and no higher probability was found in a special cortical region. Electrical stimulation delivered via a glass microelectrode filled with 2 M NaCl (2–5 MΩ) could reliably trigger epileptiform activity that had the same characteristics as the spontaneous activity. The cortical neurons activated directly by the stimulation were around the electrode’s tip and estimated to be within a 50-μm area, suggesting that only a few neurons were needed to form an initiation site. Because the timing for stimulation was arbitrary and the evoked events were initiated independent of discharges of neurons in any other layers, it is likely that the initiation site for epileptiform activity in various cortical layers is independent of the control of layer V pyramidal neurons. Together these finding suggest that the epileptiform focus is confined and can be formed in several (probably all) neocortical layers and in many cortical areas. The initiating neurons may be of different types because neuronal types in various cortical layers are different.
Group I Metabotropic Glutamate Receptors Mediate an Inward Current in Rat Substantia Nigra Dopamine Neurons That Is Independent From Calcium Mobilization
Authors: Guatteo Ezia , Mercuri Nicola B. , Bernardi Giorgio , Knöpfel Thomas
Published: December 2017

Metabotropic glutamate receptors modulate neuronal excitability via a multitude of mechanisms, and they have been implicated in the pathogenesis of neurodegenerative processes. Here we investigated the responses mediated by group I metabotropic glutamate receptors (mGluRs) in dopamine neurons of the rat substantia nigra pars compacta, using whole cell patch-clamp recordings in combination with microfluorometric measurements of [Ca2+]iand [Na+]i. The selective group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (3,5-DHPG) was bath-applied (20 μM, 30 s to 2 min) or applied locally by means of short-lasting (2–4 s) pressure pulses, delivered through an agonist-containing pipette positioned close to the cell body of the neuron. 3,5-DHPG evoked an inward current characterized by a transient and a sustained component, the latter of which was uncovered only with long-lasting agonist applications. The fast component coincided with a transient elevation of [Ca2+]i, whereas the total current was associated with a rise in [Na+]i. These responses were not affected either by the superfusion of ionotropic excitatory amino acid antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and d-2-amino-5-phosphono-pentanoic acid (d-APV), nor by the sodium channel blocker tetrodotoxin (TTX). (S)-α-methyl-4-carboxyphenylglycine (S-MCPG) and the more selective mGluR1 antagonist 7(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate (CPCCOEt) depressed both 3,5-DHPG–induced inward current components and, although less effectively, the associated [Ca2+]ielevations. On repeated agonist applications the inward current and the calcium transients both desensitized. The time constant of recovery from desensitization differed significantly between these two responses, being 67.4 ± 4.4 s for the inward current and 28.6 ± 2.7 s for the calcium response. Bathing the tissue in a calcium-free/EGTA medium or adding thapsigargin (1 μM) to the extracellular medium prevented the generation of the [Ca2+]itransient, but did not prevent the activation of the inward current. These electrophysiological and fluorometric results show that the 3,5-DHPG–induced inward current and the [Ca2+]ielevations are mediated by independent pathways downstream the activation of mGluR1.
Maturation of Lobster Stomatogastric Ganglion Rhythmic Activity
Authors: Richards Kathryn S. , Miller William L. , Marder Eve
Published: December 2017

The stomatogastric ganglion of the adult lobster, Homarus americanus generates extremely regular pyloric rhythms with a characteristic period of 0.5–1.5 Hz. To study the changes in the pyloric rhythm during embryonic and larval development, we recorded excitatory junctional potentials evoked by lateral pyloric (LP) neuron activity. Early in development the motor discharge of the LP neuron was often irregular, preventing use of conventional analysis methods that rely on extracting burst times to calculate cycle frequency and its variability. Instead, cycle frequency was determined for the LP neuron from the peak of the power spectrum obtained from the occurrence times of excitatory junctional potentials in the p1 muscle. The ratio of the power in the peak to the power from 0 to 3 Hz was used as a relative measure of the regularity of the rhythm. Throughout embryonic and the first larval stage, LP neuron activity is slow, irregular, and only weakly periodic. The regularity of the rhythm increased during midlarval stages, and both the frequency and regularity increased considerably by the postlarval stage LIV.
Diseases Linked to Polypharmacy in Elderly Patients
Authors: Vrettos Ioannis , Voukelatou Panagiota , Katsoras Apostolos , Theotoka Despoina , Kalliakmanis Andreas
Published: December 2017

Introduction. Polypharmacy in several cases is deemed necessary and elderly patients are prone to this phenomenon. The objective of this study was to identify the prevalence and the predictors of polypharmacy among consecutively unplanned admissions of patients aged ≥65 years. Patients and Methods. In 310 patients (51% women), mean age 80.24 years (95% CI 79.35–81.10), demographic characteristics, medical history, medications, and cause of admission were recorded. Parametric tests and multiple logistic regression analysis were applied to identify the factors that have significant association with polypharmacy. Results. 53.5% of patients belonged to polypharmacy group. In multivariate analysis the independent predictors of polypharmacy were arterial hypertension (p=0.003, OR = 2.708, and 95% CI 1.400–5.238), coronary artery disease (p=0.001, OR = 8.274, and 95% CI 3.161–21.656), heart failure (p=0.030, OR = 4.042, and 95% CI 1.145–14.270), atrial fibrillation (p=0.031, OR = 2.477, and 95% CI 1.086–5.648), diabetes mellitus (p=0.010, OR = 2.390, and 95% CI 1.232–4.636), dementia (p=0.001, OR = 4.637, and 95% CI 1.876–11.464), and COPD (p=0.022, OR = 3.626, and 95% CI 1.208–10.891). Conclusions. Polypharmacy mainly was linked to cardiovascular diseases. If deprescribing is not feasible, physicians must oversee those patients in order to recognise early, possible drug reactions.
A Generalization of Linear and Nonlinear Retarded Integral Inequalities in Two Independent Variables
Authors: Jiang Ying , Xing Guojing , Zhang Chenghui
Published: December 2017

Integral inequalities, which provide explicit bounds on unknown functions, are used to serve as handy tools in the study of the qualitative properties of solutions to differential and integral equations. By utilizing some analysis techniques, such as amplification method, differential, and integration, several new types of linear and nonlinear retarded integral inequalities in two independent variables are provided. These results generalize and complement previous ones. An illustrative example is given to support the obtained results. The study of the numerical example shows that the new results presented in this paper work well in the analysis of retarded integral inequalities in two independent variables.
Completeness and Nonclassicality of Coherent States for Generalized Oscillator Algebras
Authors: Zelaya Kevin , Rosas-Ortiz Oscar , Blanco-Garcia Zurika , Cruz y Cruz Sara
Published: December 2017

The purposes of this work are (1) to show that the appropriate generalizations of the oscillator algebra permit the construction of a wide set of nonlinear coherent states in unified form and (2) to clarify the likely contradiction between the nonclassical properties of such nonlinear coherent states and the possibility of finding a classical analog for them since they are P-represented by a delta function. In (1) we prove that a class of nonlinear coherent states can be constructed to satisfy a closure relation that is expressed uniquely in terms of the Meijer G-function. This property automatically defines the delta distribution as the P-representation of such states. Then, in principle, there must be a classical analog for them. Among other examples, we construct a family of nonlinear coherent states for a representation of the su(1,1) Lie algebra that is realized as a deformation of the oscillator algebra. In (2), we use a beam splitter to show that the nonlinear coherent states exhibit properties like antibunching that prohibit a classical description for them. We also show that these states lack second-order coherence. That is, although the P-representation of the nonlinear coherent states is a delta function, they are not full coherent. Therefore, the systems associated with the generalized oscillator algebras cannot be considered “classical” in the context of the quantum theory of optical coherence.
Insulation Characteristics of Sisal Fibre/Epoxy Composites
Authors: Shalwan A. , Alajmi M. , Alajmi A.
Published: December 2017

Using natural fibres in civil engineering is the aim of many industrial and academics sectors to overcome the impact of synthetic fibres on environments. One of the potential applications of natural fibres composites is to be implemented in insulation components. Thermal behaviour of polymer composites based on natural fibres is recent ongoing research. In this article, thermal characteristics of sisal fibre reinforced epoxy composites are evaluated for treated and untreated fibres considering different volume fractions of 0–30%. The results revealed that the increase in the fibre volume fraction increased the insulation performance of the composites for both treated and untreated fibres. More than 200% insulation rate was achieved at the volume fraction of 20% of treated sisal fibres. Untreated fibres showed about 400% insulation rate; however, it is not recommended to use untreated fibres from mechanical point of view. The results indicated that there is potential of using the developed composites for insulation purposes.
Ka-Band Lightweight High-Efficiency Wideband 3D Printed Reflector Antenna
Authors: Zhai Yu , Xu Ding , Zhang Yan
Published: December 2017

This paper presents a lightweight, cost-efficient, wideband, and high-gain 3D printed parabolic reflector antenna in the Ka-band. A 10 λ reflector is printed with polylactic acid- (PLA-) based material that is a biodegradable type of plastic, preferred in 3D printing. The reflecting surface is made up of multiple stacked layers of copper tape, thick enough to function as a reflecting surface (which is found 4 mm). A conical horn is used for the incident field. A center-fed method has been used to converge the energy in the broadside direction. The proposed antenna results measured a gain of 27.8 dBi, a side lobe level (SLL) of −22 dB, and a maximum of 61.2% aperture efficiency (at 30 GHz). A near-field analysis in terms of amplitude and phase has also been presented which authenticates the accurate spherical to planar wavefront transformation in the scattered field.