bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction Between Visual and Vestibular Signals for the Control of Rapid Eye Movements
Authors: Van Beuzekom A. D. , Van Gisbergen J.A.M.
Published: December 2017

To investigate interactions between voluntary and reflexive eye movements, five subjects were asked to make pro- or anti-saccades to various oblique locations cued by a head-fixed flash while being rotated sinusoidally in yaw (0.17 Hz; 73°/s peak velocity) in complete darkness. Eye movements were recorded with the coil technique. In the pro-saccade task, targeting responses showed clear compensation for the intervening nystagmus, but there was a marked increase in horizontal scatter. Most quick phases directed into the hemifield opposite to the flash (away trials) were suppressed from ∼100 ms onward. By contrast, quick phases directed into the hemifield of the flash (toward trials) continued virtually unabated until visually triggered saccades began to appear. From 80 ms onward, these vestibularly triggered movements showed signs of metrical modification by the visual signal. In the anti-saccade experiments, suppression of quick phases away from the flash was just as strong as in the pro-saccade experiments, and error rates in these trials were almost as low as in stationary control conditions. Suppression of quick phases directed toward the flash was a new phenomenon that emerged only in anti-saccade experiments. Since this inhibition had a late onset and was only partial, error rates in anti-saccade toward trials were very high. At short latencies, both components of most rapid eye movements were wrongly directed toward the flash. This was followed by a stage with frequent incongruent responses in which unsuppressed quick phases provoked an incorrect horizontal movement, whereas the vertical component showed a correct anti-saccade response. At still longer latencies, most responses were correct in both components. The visual modification of short-latency responses in both tasks showed that rapid eye movements could not simply be classified as either voluntary or reflexive, but suggested that signals underlying each class could merge into a compromise response. That vestibular rotation during the anti-saccade task may cause a wrongly directed horizontal component resembling a quick phase, combined with a vertical component expressing a correct anti-saccade signal, reveals a remarkable independence at the component level. These observations suggest that voluntary and involuntary movements can be programmed in parallel. This behavior is explained most parsimoniously by assuming that the two signals converge at a component-coding stage of the system, rather than at a vectorial coding stage.
Optical Approaches to Functional Organization of Glossopharyngeal and Vagal Motor Nuclei in the Embryonic Chick Hindbrain
Authors: Sato Katsushige , Mochida Hiraku , Yazawa Itaru , Sasaki Shinichi , Momose-Sato Yoko
Published: December 2017

We investigated the functional organization of the glossopharyngeal and vagal motor nuclei during embryogenesis using multiple-site optical recording with a fast voltage-sensitive dye. Intact brain stem preparations with glossopharyngeal and vagus nerves were dissected from 4- to 8-day-old chick embryos. Electrical responses evoked by glossopharyngeal/vagus nerve stimulation were optically recorded from many loci of the stained preparations. In 4- to 6-day-old preparations, action potential-related fast spikelike signals were detected from the nucleus of the glossopharyngeal nerve and the dorsal motor nucleus of the vagus nerve. Contour line maps of the signal amplitude showed multiple-peak patterns, suggesting that the neurons and/or their activity were not uniformly distributed within the nuclei at early developmental stages. As development proceeded from 4 to 6 days, the peaks fused with each other and the number of peaks decreased gradually. In most 7- and 8-day-old preparations, only a single peak was identified in the nuclei, and the distribution of the signal amplitude formed a layered pattern surrounding the peak-signal area. These results suggest that functional organization of the motor nuclei in the embryonic hindbrain changes dynamically with development, resulting in a rearrangement of functional nuclear cores from multiple-peaks to a single peak.
Differential Subcellular Localization of the Two Alternatively Spliced Isoforms of the Kv3.1 Potassium Channel Subunit in Brain
Authors: Ozaita A. , Martone M. E. , Ellisman M. H. , Rudy B.
Published: December 2017

Voltage-gated K+channels containing pore-forming subunits of the Kv3 subfamily have specific roles in the fast repolarization of action potentials and enable neurons to fire repetitively at high frequencies. Each of the four known Kv3 genes encode multiple products by alternative splicing of 3′ ends resulting in the expression of K+channel subunits differing only in their C-terminal sequence. The alternative splicing does not affect the electrophysiological properties of the channels, and its physiological role is unknown. It has been proposed that one of the functions of the alternative splicing of Kv3 genes is to produce subunit isoforms with differential subcellular membrane localizations in neurons and differential modulation by signaling pathways. We investigated the role of the alternative splicing of Kv3 subunits in subcellular localization by examining the brain distribution of the two alternatively spliced versions of the Kv3.1 gene (Kv3.1a and Kv3.1b) with antibodies specific for the alternative spliced C-termini. Kv3.1b proteins were prominently expressed in the somatic and proximal dendritic membrane of specific neuronal populations in the mouse brain. The axons of most of these neurons also expressed Kv3.1b protein. In contrast, Kv3.1a proteins were prominently expressed in the axons of some of the same neuronal populations, but there was little to no Kv3.1a protein expression in somatodendritic membrane. Exceptions to this pattern were seen in two neuronal populations with unusual targeting of axonal proteins, mitral cells of the olfactory bulb, and mesencephalic trigeminal neurons, which expressed Kv3.1a protein in dendritic and somatic membrane, respectively. The results support the hypothesis that the alternative spliced C-termini of Kv3 subunits regulate their subcellular targeting in neurons.
NRSF Causes cAMP-Sensitive Suppression of Sodium Current in Cultured Hippocampal Neurons
Authors: Nadeau H. , Lester H. A.
Published: December 2017

The neuron restrictive silencer factor (NRSF/REST) has been shown to bind to the promoters of many neuron-specific genes and is able to suppress transcription of Na+channels in PC12 cells, although its functional effect in terminally differentiated neurons is unknown. We constructed lentiviral vectors to express NRSF as a bicistronic message with green fluorescent protein (GFP) and followed infected hippocampal neurons in culture over a period of 1–2 wk. NRSF-expressing neurons showed a time-dependent suppression of Na+channel function as measured by whole cell electrophysiology. Suppression was reversed or prevented by the addition of membrane-permeable cAMP analogues and enhanced by cAMP antagonists but not affected by increasing protein expression with a viral enhancer. Secondary effects, including altered sensitivity to glutamate and GABA and reduced outward K+currents, were duplicated by culturing GFP-infected control neurons in TTX. The striking similarity of the phenotypes makes NRSF potentially useful as a genetic “silencer” and also suggests avenues of further exploration that may elucidate the transcription factor's in vivo role in neuronal plasticity.
Glutamate Mediates an Excitatory Influence of the Paraventricular Hypothalamic Nucleus on the Dorsal Motor Nucleus of the Vagus
Authors: Zhang Xueguo , Fogel Ronald
Published: December 2017

Data have shown that the paraventricular nucleus of the hypothalamus (PVN) and the dorsal motor nucleus of the vagus (DMNV) play important roles in the regulation of gastrointestinal function and eating behavior. Anatomical studies have demonstrated direct projections from the PVN to the DMNV and physiological studies showed that the DMNV mediates many of the effects of PVN stimulation and electrical current stimulation of the PVN excites a subset of DMNV neurons. The aim of this study was to characterize the role of glutamate receptors in the excitatory influence of the PVN on gut-related DMNV neurons. Using single-cell recording techniques, we determined the effects of kynurenic acid, 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX), anddl-2-amino-5-phosphonopentanoic acid (dl-AP5) on the increase in firing rate due to electrical current stimulation of the PVN. In initial experiments, we studied 24 DMNV neurons excited by electrical current stimulation of the PVN. Kynurenic acid, a broad-spectrum glutamate receptor antagonist, prevented the PVN effect in 22 neurons and significantly attenuated the effect in the other cells. Nine of these neurons demonstrated an inhibition in firing rate with PVN stimulation after pretreatment with kynurenic acid. In a separate group of 12 neurons, we determined the effects of CNQX (1.2 nmol) injected into the DMNV. This AMPA receptor antagonist completely blocked the excitatory response to PVN stimulation of six DMNV neurons and significantly attenuated the response of the other six DMNV neurons. The addition of 1.2 nmol dl-AP5, a N-methyl-d-aspartate (NMDA) receptor antagonist, further attenuated the response to PVN stimulation in four of the five DMNV neurons that were still excited after CNQX treatment. The fifth neuron demonstrated PVN- induced inhibition of firing rate after treatment with CNQX and dl-AP5. In a separate group of 11 DMNV neurons excited by electrical stimulation of the PVN,dl-AP5 partially attenuated the excitatory responses of only four DMNV neurons and did not block the excitation of any cells. The mean latency (14 neurons tested) from the PVN to the DMNV was 37.71 ± 2.40 (SE) ms. Monosynaptic action potentials and excitatory postsynaptic potentials were demonstrated in three DMNV neurons by intracellular recording. Our results indicate that glutamate released from PVN neurons projecting to the DMNV excite the gut-related vagal motor neurons by acting predominantly on the AMPA receptor. The NMDA receptor plays only a minor role in the excitatory effect.
Nitric Oxide as an Anterograde Neurotransmitter in the Trigeminal Motor Pool
Authors: Abudara Verónica , Alvarez Adriana Fernández , Chase Michael H. , Morales Francisco R.
Published: December 2017

We demonstrate the presence of nitric oxide synthase containing fibers within the guinea pig trigeminal motor nucleus and describe the effects of nitric oxide (NO) on trigeminal motoneurons. Using immunohistochemical techniques, we observed nitrergic fibers displaying varicosities and giving rise to bouton-like structures in apposition to retrogradely labeled motoneuron processes, most of which were dendrites. NO-donors evoked a membrane depolarization (mean 7.5 mV) and a decrease in rheobase (mean 38%). These substances also evoked an apparent increase in an hyperpolarization-activated cationic current ( I H). These changes were not accompanied by any modification of the motoneurons' input resistance or time constant. The effects were suppressed by blocking the cytosolic guanlyate cyclase. A membrane-permeant cyclic guanosine 3,5′-monophosphate (cGMP) analogue mimicked the effects of NO. There was a considerable increase in synaptic activity following NO-donors or db-cGMP application. Tetrodotoxin supressed the increase in synaptic activity evoked by NO-donors. The histological and electrophysiological evidence, taken together, indicates the existence of a nitrergic system able to modulate trigeminal motoneurons under yet unknown physiological conditions.
Auditory-Somatosensory Multisensory Processing in Auditory Association Cortex: An fMRI Study
Authors: Foxe John J. , Wylie Glenn R. , Martinez Antigona , Schroeder Charles E. , Javitt Daniel C. , Guilfoyle David , Ritter Walter , Murray Micah M.
Published: December 2017

Using high-field (3 Tesla) functional magnetic resonance imaging (fMRI), we demonstrate that auditory and somatosensory inputs converge in a subregion of human auditory cortex along the superior temporal gyrus. Further, simultaneous stimulation in both sensory modalities resulted in activity exceeding that predicted by summing the responses to the unisensory inputs, thereby showing multisensory integration in this convergence region. Recently, intracranial recordings in macaque monkeys have shown similar auditory-somatosensory convergence in a subregion of auditory cortex directly caudomedial to primary auditory cortex (area CM). The multisensory region identified in the present investigation may be the human homologue of CM. Our finding of auditory-somatosensory convergence in early auditory cortices contributes to mounting evidence for multisensory integration early in the cortical processing hierarchy, in brain regions that were previously assumed to be unisensory.
Age-Related Alterations in the Neural Coding of Envelope Periodicities
Authors: Walton Joseph P. , Simon Henry , Frisina Robert D.
Published: December 2017

This research was guided by the working hypothesis that the aging auditory system progressively loses its ability to process rapid acoustic transients efficiently, and in elderly listeners, this results in difficulties in speech perception. Neural correlates of age-related deficits in temporal processing were investigated by recording from inferior colliculus (IC) neurons from young adult and old CBA mice. Single-unit responses were recorded to sinusoidally amplitude-modulated (SAM) noise carriers, presented at 65–80 dB SPL, having modulation frequencies (MFs) that ranged from 10 to 800 Hz. Because phasic-type temporal response patterns dominate responses to tone and noise in mammalian IC, we limited our analyses to only phasic units. Modulation transfer functions (MTF) for both rate (rMTF) and synchronization (sMTF) measures were used to derive respective best modulation frequencies (rBMF and sBMF). The main age-related finding was that there was an overall increase in response rate to SAM noise carriers and a decrease in the median upper cutoff frequency in units from old mice. At rBMF, the median spike count from units from old animals was 1.63 times greater, and at the sBMF, the median spike count was 2.29 times greater than the young adult sample. We explored whether the increase in driven activity was due to a change in the transient (first cycle response) or periodic (remaining response) component of the response to SAM noise. Median spike counts of the transient component decreased with increasing MF for both young adult and old units, with median counts consistently greater in the old sample as compared with young. Median spike counts for the periodic response remained relatively constant as a function of MF; however, there was a significantly greater (3 times) response for older units in a restricted range of MFs. The greater median spike counts found for the transient and periodic response was also evident when we analyzed the cycle-by-cycle response. The magnitude of the differences between the young adult and the old spike median responses was greatest at low MFs and then declined as MF increased. Finally, the young adult distribution of rBMFs extends to higher MFs than the old, with 36.0% of units having rBMFs >100 Hz as compared with only 12.5% of the old unit sample. We postulate that this age-related difference in rate coding of SAM noise carriers is consistent with a loss, or imbalance, of excitatory and inhibitory neural mechanisms known to shape encoding of envelope periodicities in the IC.
Processing of Interaural Temporal Disparities in the Medial Division of the Ventral Nucleus of the Lateral Lemniscus
Authors: Batra Ranjan , Fitzpatrick Douglas C.
Published: December 2017

The medial division of the ventral nucleus of the lateral lemniscus (VNLLm) contains a specialized population of neurons that is sensitive to interaural temporal disparities (ITDs), a potent cue for sound localization along the azimuth. Unlike many ITD-sensitive neurons elsewhere in the auditory system, neurons in the VNLLm respond only at the onset of tones. An onset response may be significant for behavior because, under echoic conditions, tones require sharp onsets for accurate localization. In contrast, noise can generally be localized even with gradual onsets, presumably because transients occur at random intervals in noise. We recorded responses of neurons in the VNLLm to tones and noise in unanesthetized rabbits. We found that although tones elicited a transient response, noise elicited a sustained response as if it was a sequence of transients. The responses to tones indicate that these neurons represent a secondary stage in the processing of ITDs. The onset response to tones was only weakly synchronized to the phase of the tone, indicating that neurons in the VNLLm inherit their sensitivity to ITDs from their inputs. The latencies were short (∼8 ms), implying that the ITD sensitivity is derived from ascending inputs. Most neurons in the VNLLm discharged maximally at the same ITD at all frequencies, a characteristic shared with neurons of the medial superior olive. However, the latency of neurons in the VNLLm to interaurally delayed stimuli is linked strongly to the timing of the contralateral stimulus. This suggests that these neurons receive a suprathreshold, contralateral input that is modulated by a subthreshold input conveying information about ITDs. Other stations in the auditory pathway contain a subset of neurons that respond transiently to tones and are sensitive to ITDs. These neurons may represent a novel pathway that assists in localizing sounds in the presence of reflections.
Spatial Orientation of Caloric Nystagmus in Semicircular Canal-Plugged Monkeys
Authors: Arai Yasuko , Yakushin Sergei B. , Cohen Bernard , Suzuki Jun-Ichi , Raphan Theodore
Published: December 2017

We studied caloric nystagmus before and after plugging all six semicircular canals to determine whether velocity storage contributed to the spatial orientation of caloric nystagmus. Monkeys were stimulated unilaterally with cold (≈20°C) water while upright, supine, prone, right-side down, and left-side down. The decline in the slow phase velocity vector was determined over the last 37% of the nystagmus, at a time when the response was largely due to activation of velocity storage. Before plugging, yaw components varied with the convective flow of endolymph in the lateral canals in all head orientations. Plugging blocked endolymph flow, eliminating convection currents. Despite this, caloric nystagmus was readily elicited, but the horizontal component was always toward the stimulated (ipsilateral) side, regardless of head position relative to gravity. When upright, the slow phase velocity vector was close to the yaw and spatial vertical axes. Roll components became stronger in supine and prone positions, and vertical components were enhanced in side down positions. In each case, this brought the velocity vectors toward alignment with the spatial vertical. Consistent with principles governing the orientation of velocity storage, when the yaw component of the velocity vector was positive, the cross-coupled pitch or roll components brought the vector upward in space. Conversely, when yaw eye velocity vector was downward in the head coordinate frame, i.e., negative, pitch and roll were downward in space. The data could not be modeled simply by a reduction in activity in the ipsilateral vestibular nerve, which would direct the velocity vector along the roll direction. Since there is no cross coupling from roll to yaw, velocity storage alone could not rotate the vector to fit the data. We postulated, therefore, that cooling had caused contraction of the endolymph in the plugged canals. This contraction would deflect the cupula toward the plug, simulating ampullofugal flow of endolymph. Inhibition and excitation induced by such cupula deflection fit the data well in the upright position but not in lateral or prone/supine conditions. Data fits in these positions required the addition of a spatially orientated, velocity storage component. We conclude, therefore, that three factors produce cold caloric nystagmus after canal plugging: inhibition of activity in ampullary nerves, contraction of endolymph in the stimulated canals, and orientation of eye velocity to gravity through velocity storage. Although the response to convection currents dominates the normal response to caloric stimulation, velocity storage probably also contributes to the orientation of eye velocity.
Visual Categorization and the Primate Prefrontal Cortex: Neurophysiology and Behavior
Authors: Freedman David J. , Riesenhuber Maximilian , Poggio Tomaso , Miller Earl K.
Published: December 2017

The ability to group stimuli into meaningful categories is a fundamental cognitive process. To explore its neuronal basis, we trained monkeys to categorize computer-generated stimuli as “cats” and “dogs.” A morphing system was used to systematically vary stimulus shape and precisely define a category boundary. Psychophysical testing and analysis of eye movements suggest that the monkeys categorized the stimuli by attending to multiple stimulus features. Neuronal activity in the lateral prefrontal cortex reflected the category of visual stimuli and changed with learning when a monkey was retrained with the same stimuli assigned to new categories. Further, many neurons showed activity that appeared to reflect the monkey's decision about whether two stimuli were from the same category or not. These results suggest that the lateral prefrontal cortex is an important part of the neuronal circuitry underlying category learning and category-based behaviors.
Spontaneous Miniature Hyperpolarizations Affect Threshold for Action Potential Generation in Mudpuppy Cardiac Neurons
Authors: Parsons Rodney L. , Barstow Karen L. , Scornik Fabiana S.
Published: December 2017

Mudpuppy parasympathetic neurons exhibit spontaneous miniature hyperpolarizations (SMHs) that are generated by potassium currents, which are spontaneous miniature outward currents (SMOCs), flowing through clusters of large conductance voltage- and calcium (Ca2+)-activated potassium (BK) channels. The underlying SMOCs are initiated by a Ca2+-induced Ca2+release (CICR) mechanism. Perforated-patch whole cell voltage recordings were used to determine whether activation of SMHs contributed to action potential (AP) repolarization or affected the latency to AP generation. Blockade of BK channels by iberiotoxin (IBX, 100 nM) slowed AP repolarization and increased AP duration. Treatment with ω-conotoxin GVIA (3 μM) or nifedipine (10 μM) to inhibit Ca2+influx through N- or L-type voltage-dependent calcium channels (VDCCs), respectively, also decreased the rate of AP repolarization and increased AP duration. Elimination of CICR by treatment with either thapsigargin (1 μM) or ryanodine (10 μM) produced no significant change in AP repolarization or duration. Blockade of BK channels with IBX and inhibition of N-type VDCCs with ω-conotoxin GVIA, but not inhibition of L-type VDCCs with nifedipine, decreased the latency of AP generation. A decrease in latency to AP generation occurred with elimination of SMHs by inhibition of CICR following treatment with thapsigargin. Ryanodine treatment decreased AP latency in three of six cells. Apamin (100 nM) had no affect on AP repolarization, duration, or latency to AP generation, but did decrease the hyperpolarizing afterpotential (HAP). Inhibition of L-type VDCCs by nifedipine also decreased HAP amplitude. Inhibition of CICR by either thapsigargin or ryanodine treatment increased the number of APs generated with long depolarizing current pulses, whereas exposure to IBX or ω-conotoxin GVIA depressed excitability. We conclude that CICR, the process responsible for SMH generation, represents a unique mechanism to modulate the response to subthreshold depolarizing currents that drive the membrane potential toward the threshold for AP initiation but does not contribute to AP repolarization. Subthreshold depolarizations would not activate sufficient numbers of VDCCs to allow Ca2+influx to elevate [Ca2+]ito the extent needed to directly activate nearby BK channels. However, the elevation in [Ca2+]iis sufficient to trigger CICR from ryanodine-sensitive Ca2+stores. Thus CICR acts as an amplification mechanism to trigger a local elevation of [Ca2+]inear a cluster of BK channels to activate these channels at negative levels of membrane potential.
Effect of Tactile Inputs on Thalamic Responses to Noxious Colorectal Distension in Rat
Authors: Zhang Hong-Qi , Al-Chaer Elie D. , Willis William D.
Published: December 2017

Recent discoveries of visceral nociceptive inputs sharing the classical tactile pathway in the dorsal-column medial lemniscus system have opened a new venue for the investigation of somatovisceral interactions. The current study was designed to determine whether somatic innocuous inputs modulate visceral nociceptive transmission at the thalamic level. The investigation was carried out by means of extracellular single-unit recordings in the ventroposterior lateral nucleus of the thalamus in rats anesthetized with pentobarbital. Noxious visceral stimulation was achieved by reproducible colorectal distension (CRD, 20–80 mmHg) with a balloon catheter. Tactile stimulation was delivered by means of a feedback-controlled mechanical stimulator. The response of the neurons to CRD was compared before and after the conditioning procedure by giving tactile stimulation either immediately before CRD or overlapping it. Twenty-five ventroposterior lateral (VPL) thalamic neurons were found among numerous tactile-only neurons to have convergent inputs from both tactile and visceral sources. Their responses to CRD were excitatory (19), inhibitory (4), or bimodal. When cutaneous tactile stimuli were delivered before CRD, the responses were reduced in 18 cases. The reduction, however, was usually short-lasting, immediately following tactile stimulation and could not be enhanced by a prolonged conditioning procedure. It was unlikely to be attributable to neuronal habituation as the inverted procedure, CRD stimulation before tactile, often produced the opposite effect, that is, an enhanced response to skin stimulation. Repeated CRD could bring about sensitization of the responses of thalamic neurons as manifested by increased spontaneous discharge, lowered response threshold, and increased response level. Under such circumstances, the original effect of tactile stimulation on CRD responses could be weakened. In conclusion, tactile stimulation may in most circumstances inhibit thalamic neuronal responses to visceral nociceptive input produced by CRD. However, the effect appears to be mild and short-lasting at the individual neuronal level in the VPL thalamus.
Differential Involvement of Ca2+Channels in Survival and Neurite Outgrowth of Cultured Embryonic Cockroach Brain Neurons
Authors: Benquet Pascal , Le Guen Janine , Pichon Yves , Tiaho François
Published: December 2017

The contribution of voltage-gated calcium channels (VGCC) to the development of cultured embryonic cockroach brain neurons was assessed using pharmacological agents. VGCC currents were recorded using the patch-clamp technique and were found to be blocked dose-dependently by micromolar concentrations of mibefradil. The activation and inactivation properties of the calcium channels enable a sizeable calcium current to flow at rest (about −30 and −20 mV in high-potassium culture media). As expected, the cytoplasmic-free calcium concentration was found to rise when the extracellular potassium concentration was raised from 3 to 15 and 30 mM. The effects of VGCC blockers and calcium chelators were different in fresh and in mature cultures in which the neurons were connected to each other to form a defined network. In fresh cultures, the two non-selective VGCC blockers (verapamil and mibefradil) induced a dose-dependent cell death that was proportional to their blocking effect on IBa. This effect could not be prevented by addition of fetal calf serum to the culture medium. A similar effect was obtained using intra- or extracellular calcium chelating agents (10 μM BAPTA-AM or 10 mM EGTA). Quite unexpectedly, blockade of the P/Q-like (ω-Aga WA-sensitive) component of the calcium current by 500 nM of ω-AgaTx IVA had no lethal effect, suggesting that the corresponding channels are not involved in the survival mechanism. As expected from their lack of effect on IBa, isradipine, nifedipine, and ω-CgTx GVIA did not induce cell death. When the neurons started growing neurites, their sensitivity to calcium channel blockade by mibefradil decreased, indicating a correlation between neurite outgrowth and resistance to calcium depletion. In mature cultures, the neurons became resistant to mibefradil, verapamil, and BAPTA-AM. However, these agents, as well as ω-AgaTx IVA, had a significant inhibitory effect on the increase in diameter of the connectives that linked adjacent clusters of neurons. This effect has been shown to result, in the case of mibefradil, from an inhibition of neurite outgrowth characterized by a significant reduction of the number of primary neurites and secondary branchings but not to a significant modification of the diameter of individual neurites. These results support the view that, as in vertebrates, calcium influx through VGCC plays an important role in survival and neurite outgrowth of cultured embryonic insect neurons. The differential contribution of the P/Q-like and R-like (ω-Aga WA-sensitive) calcium channels in these processes is discussed.
The Soma of RPeD1 Must Be Present for Long-Term Memory Formation of Associative Learning inLymnaea
Authors: Scheibenstock Andi , Krygier Darin , Haque Zara , Syed Naweed , Lukowiak Ken
Published: December 2017

The cellular basis of long-term memory (LTM) storage is not completely known. We have developed a preparation where we are able to specify that a single identified neuron, Right Pedal Dorsal 1 (RPeD1), is a site of LTM formation of associative learning in the pond snail, Lymnaea stagnalis. We demonstrated this by ablating the soma of the neuron but leaving behind its functional primary neurite, as evidenced by electrophysiological and behavioral analyses. The soma-less RPeD1 neurite continues to be a necessary participant in the mediation of aerial respiratory behavior, associative learning, and intermediate-term memory (ITM); however, LTM cannot be formed. However, if RPeD1's soma is ablated after LTM consolidation has occurred, LTM can still be accessed. Thus the soma of RPeD1 is a site of LTM formation.
Engagement of Gaze in Capturing Targets for Future Sequential Manual Actions
Authors: Terao Yasuo , Andersson N. E. Micael , Flanagan J. Randall , Johansson Roland S.
Published: December 2017

We investigated the role of saccadic gaze fixations in encoding target locations for planning a future manual task consisting of a sequence of discrete target-oriented actions. We hypothesized that fixations of the individual targets are necessary for accurate encoding of target locations and that there is a transfer of sequence information from visual encoding to manual recall. Subjects viewed four targets presented at random positions on a screen. After various delays following target extinction, the subjects marked the remembered target locations on the screen with the tip of a hand-held stick. When the targets were presented simultaneously among distracting elements, the overall accuracy of marking increased with presentation time and total number of targets fixated because the subjects had to serially fixate the individual targets to locate them. Without distractors, the marking accuracy was similarly high regardless of duration of target presentation (0.25–8 s) and number of targets fixated; it was comparable to that with distractors when all four targets had been fixated. This indicates parallel encoding of target locations largely based on peripheral vision. Location memory was stable in these tasks over the delay periods investigated (0.5–8 s). With parallel encoding there was a “shrinkage” in the visuomotor transformation, i.e., the distances between the markings were systematically smaller than the corresponding inter-target distances. When the targets were presented sequentially without distractors, marking accuracy improved with the total number of targets fixated and shrinkage in the visuomotor transformation occurred only with parallel encoding, i.e., when subjects did not fixate the targets. In all experimental conditions for trials in which targets were fixated during encoding, there was little correspondence between the marking sequence and the sequence in which the targets were fixated. We conclude that subjects benefit from fixating targets for subsequent target-oriented manual actions when the targets are presented among distractors and when presented sequentially; when distinct targets are presented simultaneously against a blank background, they are efficiently encoded in parallel largely by peripheral vision.
Pharmacology of Nicotinic Receptors in PreBötzinger Complex That Mediate Modulation of Respiratory Pattern
Authors: Shao Xuesi M. , Feldman Jack L.
Published: December 2017

Nicotine regulates respiratory pattern by modulating excitatory neurotransmission affecting inspiratory neurons within the preBötzinger Complex (preBötC). The nicotinic acetylcholine receptor (nAChR) subtypes mediating these effects are unknown. Using a medullary slice preparation from neonatal rat, we recorded spontaneous respiratory-related rhythm from the hypoglossal nerve (XIIn) and patch-clamped inspiratory neurons in the preBötC simultaneously. The α7 nAChR antagonists α-bungarotoxin or methyllycaconitine (MLA) had little effect on the actions of low concentrations of nicotine (0.5 μM), which included an increase in respiratory frequency; a decrease in amplitude of XIIn inspiratory bursts; a tonic inward current associated with an increase in membrane noise; an increase in the frequency and amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), and; a decrease in the amplitude of inspiratory drive current in voltage-clamped preBötC inspiratory neurons. These nicotinic actions were completely reversed by dihydro-β-erythroidine (DH-β-E) or hexamethonium and reduced by d-tubocurarine. Comparable concentrations of RJR-2403 (0.5–1 μM), an agonist selective for α4β2 nAChRs, increased respiratory frequency to 186% and decreased the amplitude of XIIn inspiratory bursts to 83% of baseline. In voltage-clamped preBötC inspiratory (including pacemaker) neurons, RJR-2403 induced a tonic inward current of −15.2 pA associated with an increase in membrane noise, increased the frequency to 157% and amplitude to 106% of spontaneous EPSCs, and decreased the amplitude of inspiratory drive current to 80% of baseline. MLA had little effect on RJR-2403 actions, while DH-β-E completely reversed them. These results suggest that the predominant subtype of nAChRs in preBötC in neonatal rats that mediates the modulation of respiratory pattern by low concentrations of nicotine is an α4β2 combination and not an α7 subunit homomer. We do not exclude the possibility that co-assembly of α4β2 with other subunits or other nAChR subtypes are also expressed in preBötC neurons. The parallel changes in the cellular and systems level responses induced by different nicotinic agonists and antagonists support the idea that modulation of excitatory neurotransmission affecting preBötC inspiratory neurons is a mechanism underlying the cholinergic regulation of respiratory pattern ( Shao and Feldman 2001 ). This study provides a useful model system for evaluating potential therapeutic cholinergic agents for their respiratory effects and side effects.
Firing Rate Modulation of Motoneurons Activated by Cutaneous and Muscle Receptor Afferents in the Decerebrate Cat
Authors: Prather J. F. , Clark B. D. , Cope T. C.
Published: December 2017

The aim of this study was to investigate whether activation of spinal motoneurons by sensory afferents of the caudal cutaneous sural (CCS) nerve evokes an atypical motor control scheme. In this scheme, motor units that contract fast and forcefully are driven by CCS afferents to fire faster than motor units that contract more slowly and weakly. This is the opposite of the scheme described by the size principle. Earlier studies from this lab do not support the atypical scheme and instead demonstrate that both CCS and muscle stretch recruit motor units according to the size principle. The latter finding may indicate that CCS and muscle-stretch inputs have similar functional organizations or that comparison of recruitment sequence was simply unable to resolve a difference. In the present experiments, we examine this issue using rate modulation as a more sensitive index of motoneuron activation than recruitment. Quantification of the firing output generated by these two inputs in the same pairs of motoneurons enabled direct comparison of the functional arrangements of CCS versus muscle-stretch inputs across the pool of medial gastrocnemius (MG) motoneurons. No systematic difference was observed in the rate modulation produced by CCS versus muscle-stretch inputs for 35 pairs of MG motoneurons. For the subset of 24 motoneuron pairs exhibiting linear co-modulation of firing rate ( r > 0.5) in response to both CCS and muscle inputs, the slopes of the regression lines were statistically indistinguishable between the two inputs. For individual motoneuron pairs, small differences in slope between inputs were not related to differences in conduction velocity (CV), recruitment order, or, for a small sample, differences in motor unit force. We conclude that an atypical motor control scheme involving selective activation of typically less excitable motoneurons, if it does occur during normal movement, is not an obligatory consequence of activation by sural nerve afferents. On average and for both muscle-stretch and skin-pinch inputs, the motoneuron with the faster CV in the pair tended to be driven to fire at slightly but significantly faster firing rates. Computer simulations based in part on frequency-current relations measured directly from motoneurons revealed that properties intrinsic to motoneurons are sufficient to account for the higher firing rates of the faster CV motoneuron in a pair.
Asymmetric Integration Recorded From Vestibular-Only Cells in Response to Position Transients
Authors: Musallam Sam , Tomlinson R. D.
Published: December 2017

Angular and translational accelerations excite the semicircular canals and otolith organs, respectively. While canal afferents approximately encode head angular velocity due to the biomechanical integration performed by the canals, otolith signals have been found to approximate head translational acceleration. Because central vestibular pathways require velocity and position signals for their operation, the question has been raised as to how the integration of the otolith signals is accomplished. We recorded responses from 62 vestibular-only neurons in the vestibular nucleus of two monkeys to position transients in the naso-occipital and interaural orientations and varying directions in between. Responses to the transients were directionally asymmetric; one direction elicited a response that approximated the integral of the acceleration of the stimulus. In the opposite direction, the cells simply encoded the acceleration of the motion. We present a model that suggests that a neural integrator is not needed. Instead a neuron with a long membrane time constant and an excitatory postsynaptic potential duration that increases with the firing rate of the presynaptic cell can emulate the observed behavior.
Polymorphisms in theSP110andTNF-αGene and Susceptibility to Pulmonary and Spinal Tuberculosis among Southern Chinese Population
Authors: Zhou Ying , Tan Chun-yan , Mo Zhi-jiang , Gao Qi-le , He Dan , Li Jiong , Huang Rong-fu , Li Yan-bing , Guo Chao-feng , Guo Qiang , Wang Long-jie , Yang Guan-teng , Zhang Hong-qi
Published: December 2017

Objective.To investigate the association of single-nucleotide polymorphisms (SNPs) inSP110gene andTNF-αgene among pulmonary TB (PTB) and spinal TB (STB) patients.Methods. In a total of 190 PTB patients, 183 STB patients were enrolled as the case group and 362 healthy individuals at the same geographical region as the control group. TheSP110SNPs (rs722555 and rs1135791) and the promoter -308G>A (rs1800629) and -238G>A (rs361525) polymorphisms inTNF-αwere genotyped.Results. TNF-α-238G>A polymorphism was involved in susceptibility to STB, but not to PTB. TheTNF-α-238 A allele was a protective factor against STB (A versus G: OR [95% CI] = 0.331 [0.113–0.972],P=0.044). Furthermore, the presence of the -238 A allele was considered a trend to decrease the risk of STB (AG versus GG:P=0.062, OR [95% CI] = 0.352 [0.118–1.053]; AA + AG versus GG:P=0.050, OR [95CI%] = 0.335 [0.113–0.999]). However,SP110SNPs (rs722555 and rs1135791) andTNF-α-308G>A (rs1800629) showed no association with PTB and STB in all genetic models.Conclusion.TheTNF-α-238 A allele appeared a protective effect against STB, whereas theSP110SNPs (rs722555 and rs1135791) andTNF-α-308G>A (rs1800629) showed no association with susceptibility to PTB and STB patients in southern China.
Estimating Profit Efficiency of Artisanal Fishing in the Pru District of the Brong-Ahafo Region, Ghana
Authors: Setsoafia Edinam Dope , Owusu Phoebe , Danso-Abbeam Gideon
Published: December 2017

This study evaluated the profit efficiency of artisanal fishing in the Pru District of Ghana by explicitly computing profit efficiency level, identifying the sources of profit inefficiency, and examining the constraints of artisanal fisheries. Cross-sectional data was obtained from 120 small-scale fishing households using semistructured questionnaire. The stochastic profit frontier model was used to compute profit efficiency level and identify the determinants of profit inefficiency while Garrett ranking technique was used to rank the constraints. The average profit efficiency level was 81.66% which implies that about 82% of the prospective maximum profit was gained due to production efficiency. That is, only 18% of the potential profit was lost due to the fishers’ inefficiency. Also, the age of the household head and household size increase the inefficiency level while experience in artisanal fishing tends to decrease the inefficiency level. From the Garrett ranking, access to credit facility to fully operate the small-scale fishing business was ranked as the most pressing issue followed by unstable prices while perishability was ranked last among the constraints. The study, therefore, recommends that group formation should be encouraged to enable easy access to loans and contract sales to boost profitability.
Mesoscale Modelling of Bond Behavior at FRP-Concrete under Mode II Loading: Effect of Rayleigh Damping
Authors: An Feng-chen , Xiao Qiong-guan , Li Shuai , Li Hong-jun
Published: December 2017

The paper mainly focuses on the study of the effects of Rayleigh damping in the simulations of FRP-concrete bonded joints, thereby proposing an approach to determine the value of its appropriate Rayleigh damping. Specifically, the element tests under Mode I and Mode II fracture modes were first carried out to investigate the effects of the mass proportional Rayleigh damping and the stiffness proportional Rayleigh damping. An FRP-concrete bonded joint is then employed to further investigate the effects of Rayleigh damping on the simulation results under Mode II fracture mode. It is shown that low-frequency vibrations are produced in the simulations of the specimens loaded by Mode I loading and could be damped by the mass proportional Rayleigh damping, while high-frequency vibrations are produced in the simulations of the specimens loaded by Mode II loading and could only be damped by the stiffness proportional Rayleigh damping. It also shows that the stiffness proportional damping is essential to damp out the oscillations in such simulations, thereby improving the convergence. In addition, the procedure proposed in this paper can lead to a proper interval for the value of the stiffness proportional Rayleigh damping, beyond which an unreasonable simulation result may be obtained.
Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort
Authors: Oktay Tugrul , Sal Firat
Published: December 2017

In this study, the effect of simultaneous variation in blade root chord length and blade taper on the control effort of helicopter flight control system (i.e., FCS) of a helicopter is investigated. Therefore, helicopter models (i.e., complex, control-oriented, and physics-based models) including the main physics and essential dynamics are used. The effect of simultaneous variation in the blade root chord length and blade taper (i.e., in both chordwise and lengthwise directions dependently) on the control effort of an FCS of a helicopter and also on the closed-loop responses is studied. Comparisons in terms of the control effort and peak values with and without variations in the blade root chord and blade taper changes are carried out. For helicopter FCS variance-constrained controllers, specific output variance-constrained controllers are beneficial.
A Computable Measure of Algorithmic Probability by Finite Approximations with an Application to Integer Sequences
Authors: Soler-Toscano Fernando , Zenil Hector
Published: December 2017

Given the widespread use of lossless compression algorithms to approximate algorithmic (Kolmogorov-Chaitin) complexity and that, usually, generic lossless compression algorithms fall short at characterizing features other than statistical ones not different from entropy evaluations, here we explore an alternative and complementary approach. We study formal properties of a Levin-inspired measure m calculated from the output distribution of small Turing machines. We introduce and justify finite approximations mk that have been used in some applications as an alternative to lossless compression algorithms for approximating algorithmic (Kolmogorov-Chaitin) complexity. We provide proofs of the relevant properties of both m and mk and compare them to Levin’s Universal Distribution. We provide error estimations of mk with respect to m. Finally, we present an application to integer sequences from the On-Line Encyclopedia of Integer Sequences, which suggests that our AP-based measures may characterize nonstatistical patterns, and we report interesting correlations with textual, function, and program description lengths of the said sequences.
Tumor Side as Model of Integrative Molecular Classification of Colorectal Cancer
Authors: Dienstmann Rodrigo
Published: December 2017

It has long since been recognized that colorectal cancer is molecularly heterogeneous and its clinical behavior differs if the primary tumor was located in the right or left side of the colon. Recent studies have shown that part of this heterogeneity is captured by the anatomic location of the tumor. Clin Cancer Res; 24(5); 989–90. ©2017 AACR.

See related article by Loree et al., p. 1062