Short-term Sensitivity Research Articles

A Neurodynamic Account of Musical Tonality

Science since antiquity has asked whether mathematical relationships among acoustic frequencies govern musical relationships. Psychophysics rejected frequency ratio theories, focusing on sensory phenomena predicted by linear analysis of sound. Cognitive psychologists have since focused on long-term exposure to the music of one’s culture and short-term sensitivity to statistical regularities. Today evidence is rapidly mounting that oscillatory neurodynamics is an important source of nonlinear auditory responses. This leads us to reevaluate the significance of frequency relationships in the perception of music. Here, we present a dynamical systems analysis of mode-locked neural oscillation that predicts cross-cultural invariances in music perception and cognition. We show that this theoretical framework combines with short- and long-term learning to explain the perception of Hindustani rāgas, not only by encultured Indian listeners but also by Western listeners unfamiliar with the style. These findings demonstrate that intrinsic neurodynamics contribute significantly to the perception of musical structure.

Short-Term Retinal Sensitivity and Metamorphopsia Changes following Half-Fluence Photodynamic Therapy in Central Serous Chorioretinopathy

Purpose: The aim of this study was to investigate the short-term retinal sensitivity and metamorphopsia changes after half-fluence photodynamic therapy (PDT) in patients with central serous chorioretinopathy (CSC). Methods: Patients with acute CSC and evidence of angiographic leakage and subretinal fluid on optical coherence tomography (OCT) were enrolled. Before, and 1 week (W-1) and 2 months (M-2) after PDT, all patients underwent best-corrected visual acuity, enhanced depth imaging OCT, microperimetry (MP) and preferential hyperacuity perimetry (PHP). We considered ‘affected' the Early Treatment of Diabetic Retinopathy Study (ETDRS) sectors showing a mean retinal thickness greater than 350 μm on the baseline OCT thickness map. MP retinal sensitivity, PHP ‘score' and retinal thickness were measured in each ETDRS ‘affected sector'. Functional correlation between MP and PHP was also investigated. Results: Twelve eyes of 12 patients were included. MP and PHP correlated with each other at baseline (p = 0.04) but not at W-1 (p = 0.12) and M-2 (p = 0.05). Mean MP retinal sensitivity slightly improved from 12.9 ± 5.0 dB at baseline to 14.5 ± 4.7 dB at M-2 (p = 0.2). The PHP score changed from 0.33 at baseline to 0.32 at M-2 (p = 0.3). In the ETDRS ‘affected sectors', MP retinal sensitivity improved significantly from 12.9 ± 5.0 dB at baseline to 14.5 ± 4.7 dB at M-2 (p = 0.03), whereas the PHP score did not show significant changes over time. Conclusion: Half-fluence PDT achieved short-term improvement in the sensitivity of the retinal ‘affected sectors' but did not influence metamorphopsia as measured on PHP in patients with acute CSC.

Air warming trends linked to permafrost warming in the sub-Arctic catchment of Tarfala, Sweden

Recent ground temperature records from the 100-m-deep borehole near the Tarfala Research Station in northern Sweden reveal that permafrost is warming at a pace consistent with the rate of measured air temperature increase at the site. Here we investigate whether air temperature increase is the main driver of the observed change in the permafrost thermal regime using a non-isothermal hydrogeological numerical model for partially frozen ground. The local site is investigated with different ground surface temperature scenarios representing different integrated effects of surficial heat attenuation processes. Results indicate that despite a short-term sensitivity to heat attenuation processes including snow conditions, the main driver of change in the permafrost thermal regime during the past decade is warming air temperatures. Additionally, the approach used here is shown to be particularly pertinent for modelling warming trends, despite limited prior knowledge of site-specific conditions and geological properties. Understanding the main driving mechanisms of changing permafrost is useful for assessing the suitability of borehole temperature records as proxies for past environmental conditions as well as for modelling possible future climatic impacts. Keywords: Permafrost; warming ground; PACE borehole; numerical modelling; climate change. (Published: 29 September 2016) To access the supplementary material for this article, please see the supplementary files in the column to the right (under Article Tools). Citation: Polar Research 2016, 35 , 28978, http://dx.doi.org/10.3402/polar.v35.28978

Blue-light filtering intraocular lenses (IOLs) for protecting macular health

Blue-light filtering intraocular lenses (IOLs) for protecting macular health

Proliferation of East Antarctic Adélie penguins in response to historical deglaciation.

BackgroundMajor, long-term environmental changes are projected in the Southern Ocean and these are likely to have impacts for marine predators such as the Adélie penguin (Pygoscelis adeliae). Decadal monitoring studies have provided insight into the short-term environmental sensitivities of Adélie penguin populations, particularly to sea ice changes. However, given the long-term nature of projected climate change, it is also prudent to consider the responses of populations to environmental change over longer time scales. We investigated the population trajectory of Adélie penguins during the last glacial-interglacial transition to determine how the species was affected by climate warming over millennia. We focussed our study on East Antarctica, which is home to 30 % of the global population of Adélie penguins.MethodsUsing mitochondrial DNA from extant colonies, we reconstructed the population trend of Adélie penguins in East Antarctica over the past 22,000 years using an extended Bayesian skyline plot method. To determine the relationship of East Antarctic Adélie penguins with populations elsewhere in Antarctica we constructed a phylogeny using mitochondrial DNA sequences.ResultsWe found that the Adélie penguin population expanded 135-fold from approximately 14,000 years ago. The population growth was coincident with deglaciation in East Antarctica and, therefore, an increase in ice-free ground suitable for Adélie penguin nesting. Our phylogenetic analysis indicated that East Antarctic Adélie penguins share a common ancestor with Adélie penguins from the Antarctic Peninsula and Scotia Arc, with an estimated age of 29,000 years ago, in the midst of the last glacial period. This finding suggests that extant colonies in East Antarctica, the Scotia Arc and the Antarctic Peninsula were founded from a single glacial refuge.ConclusionsWhile changes in sea ice conditions are a critical driver of Adélie penguin population success over decadal and yearly timescales, deglaciation appears to have been the key driver of population change over millennia. This suggests that environmental drivers of population trends over thousands of years may differ to drivers over years or decades, highlighting the need to consider millennial-scale trends alongside contemporary data for the forecasting of species’ abundance and distribution changes under future climate change scenarios.

Memory Formation in Tritonia via Recruitment of Variably Committed Neurons

Prior studies have found that functional networks can rapidly add neurons as they build short-term memories, yet little is known about the principles underlying this process. Using voltage-sensitive dye imaging, we found that short-term sensitization of Tritonia's swim motor program involves rapid expansion of the number of participating neurons. Tracking neurons across trials revealed that this involves the conversion of recently discovered variably participating neurons to reliable status. Further, we identify a candidate serotonergic cellular mechanism mediating this process. Our findings reveal a new mechanism for memory formation, involving recruitment of pre-positioned, variably committed neurons into memory networks. This represents a shift from the field's long-term focus on synaptic plasticity, toward a view that certain neurons have characteristics that predispose them to join networks with learning.

Characterization of a simultaneous dual-species atom interferometer for a quantum test of the weak equivalence principle

We present here the performance of a simultaneous dual-species matter-wave accelerometer for measuring the differential acceleration between two different atomic species ($^{87}$Rb and $^{85}$Rb). We study the expression and the extraction of the differential phase from the interferometer output. The differential accelerometer reaches a short-term sensitivity of $1.23\times10^{-7}g/\sqrt{Hz}$ limited by the detection noise and a resolution of $2\times10^{-9}g$ after 11000 s, the highest reported thus far with a dual-species atom interferometer to our knowledge. Thanks to the simultaneous measurement, such resolution levels can still be achieved even with vibration levels up to $3\times10^{-3}g$, corresponding to a common-mode vibration noise rejection ratio of 94 dB (rejection factor of 50 000). These results prove the ability of such atom sensors for realizing a quantum based test of the weak equivalence principle (WEP) at a level of $\eta\sim10^{-9}$ even with high vibration levels and a compact sensor.

Effects of Different Anesthetics on Pain Processing in an Experimental Human Pain Model.

After surgical procedures, anesthesia itself may affect pain perception. Particularly, there is increasing evidence that opioids not only have analgesic effects but also provoke pronociceptive changes, that is, opioid-induced hyperalgesia. We investigated the effect of different anesthetic regimens on pain processing in volunteers using a transdermal electrical pain model. In this model, stimulation of epidermal nerve fibers representing mainly peptidergic C-nociceptors leads to secondary hyperalgesia and habituation to the stimulus. Forty-eight healthy volunteers underwent conditioning noxious stimulation (CS) over 5days. On day 2, the volunteers were randomized into 4 groups: control group (no anesthesia) and 3 groups receiving anesthesia before CS in anesthetic doses: propofol (P), propofol/remifentanil (PR), and propofol/remifentanil/S-ketamine (PRK). Quantitative sensory testing was performed on days 1 through 5 and on day 22. In every group, CS was associated with short- and long-term habituation to the electrical stimulus. Repetitive CS resulted in unmodified short-term sensitization with stable areas of hyperalgesia. Although the PR group showed a trend toward increased areas of hyperalgesia on day 2, no significant differences were detectable between the groups. In contrast, anesthesia resulted in decreased intensity of the electrically evoked pain on day 2. Finally, the mechanical pain threshold before CS on day 5 was increased in all groups and remained elevated 3weeks after the first CS, consistent with a long-term antinociceptive effect after CS. The results suggest a short-term analgesic effect of general anesthesia. Furthermore, the conditioning stimulation over several days induced differential modulation of pro- and antinociceptive systems.

Brain mechanisms of short-term habituation and sensitization toward dyspnea.

Dyspnea is a prevalent and threatening cardinal symptom in many diseases including asthma. Whether patients suffering from dyspnea show habituation or sensitization toward repeated experiences of dyspnea is relevant for both quality of life and treatment success. Understanding the mechanisms, including the underlying brain activation patterns, that determine the dynamics of dyspnea perception seems crucial for the improvement of treatment and rehabilitation. Toward this aim, we investigated the interplay between short-term changes of dyspnea perception and changes of related brain activation. Healthy individuals underwent repeated blocks of resistive load induced dyspnea with parallel acquisition of functional magnetic resonance imaging data. Late vs. early ratings on dyspnea intensity and unpleasantness were correlated with late vs. early brain activation for both, dyspnea anticipation and dyspnea perception. Individual trait and state anxiety were determined using questionnaire data. Our results indicate an involvement of the orbitofrontal cortex (OFC), midbrain/periaqueductal gray (PAG) and anterior insular cortex in habituation/sensitization toward dyspnea. Changes in the anterior insular cortex were particularly linked to changes in dyspnea unpleasantness. Changes of both dyspnea intensity and unpleasantness were positively correlated with state and trait anxiety. Our findings are in line with the suggested relationship between the anterior insular cortex and dyspnea unpleasantness. They further support the notion that habituation/sensitization toward dyspnea is influenced by anxiety. Our study extends the known role of the midbrain/PAG in anti-nociception to an additional involvement in habituation/sensitization toward dyspnea and suggests an interplay with the OFC.

Enhanced Short-Term Sensitization of Facial Compared With Limb Heat Pain

Habituation and sensitization are important features of individual sensitivity to repetitive noxious stimulation and have been investigated in numerous studies. However, it is unclear whether these phenomena vary depending on the site of stimulation. Here we compared short-term and long-term effects of painful heat stimulation on the forehead and limb using an established longitudinal heat pain paradigm performed over 8 consecutive days in 36 healthy volunteers. Participants were randomized into 2 groups; participants received repetitive heat pain stimulation either on the left volar forearm or on the left side of the forehead. Our data show a comparable degree of habituation over the course of 8 days in both groups. However, participants in the trigeminal stimulation group exhibited stronger within-session sensitization (indexed by a higher within-session increase in pain intensity ratings) than those who received the forearm stimulation. Furthermore, over the course of the experiment we found a correlation between habituation and anxiety, showing less habituation in participants with higher trait anxiety scores. Our findings are in line with somatotopic differences in response to painful stimulation and a higher proneness of trigeminal pain to sensitization processes, which might be explained by the biological relevance of the head and facial area for vital functions. The contribution of this sensitivity to the development and maintenance of clinical facial pain and headache disorders warrants further investigation. PerspectiveThis study uses psychophysical methods to evaluate the differences in long-term habituation and short-term sensitization to heat pain between the trigeminal and spinal systems. We found stronger sensitization for trigeminal compared with nociceptive stimuli on the forearm. The contribution of this sensitivity to clinical pain states warrants further investigation.

Contrast decay in a trapped-atom interferometer

A Ramsey-Raman interferometer is used to realize a compact force sensor using cold $^{87}\mathrm{Rb}$ atoms trapped in a vertical optical lattice. The sensitivity and accuracy of the force measurements are discussed and the limits in short-term sensitivity evaluated. We reach a relative sensitivity on the Bloch frequency and thus on the gravity acceleration of $3.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ at 1 s. We perform an experimental study of the influence of the transverse confinement onto the decay of the interferometer contrast and compare the measurements with a simple semiclassical model. It is shown that vertical gradients of the trapping potential can contribute significantly to the loss of contrast.

Aging in Sensory and Motor Neurons Results in Learning Failure in Aplysia californica.

The physiological and molecular mechanisms of age-related memory loss are complicated by the complexity of vertebrate nervous systems. This study takes advantage of a simple neural model to investigate nervous system aging, focusing on changes in learning and memory in the form of behavioral sensitization in vivo and synaptic facilitation in vitro. The effect of aging on the tail withdrawal reflex (TWR) was studied in Aplysia californica at maturity and late in the annual lifecycle. We found that short-term sensitization in TWR was absent in aged Aplysia. This implied that the neuronal machinery governing nonassociative learning was compromised during aging. Synaptic plasticity in the form of short-term facilitation between tail sensory and motor neurons decreased during aging whether the sensitizing stimulus was tail shock or the heterosynaptic modulator serotonin (5-HT). Together, these results suggest that the cellular mechanisms governing behavioral sensitization are compromised during aging, thereby nearly eliminating sensitization in aged Aplysia.

MiR-218 targets survivin and regulates resistance to chemotherapeutics in breast cancer

Multidrug resistance (MDR) remains one of the most significant obstacles in breast cancer treatment, and this process often involves dysregulation of a great number of microRNAs (miRNAs). Some miRNAs are indicators of drug resistance and confer resistance to chemotherapeutic drugs, although our understanding of this complex process is still incomplete. We have used a combination of miRNA profiling and real-time PCR in two drug-resistant derivatives of MCF-7 and Cal51 cells. Experimental modulation of miR expression has been obtained by retroviral transfection. Taxol and doxorubicin IC50 values were obtained by short-term drug sensitivity assays. Apoptosis was determined by flow cytometry after annexin V staining, by caspase 3/7 and caspase 9 activity assays and the levels of apoptosis-related proteins bcl-2 and bax by real-time PCR and Western blot. miR target was studied using transient transfection of luciferase constructs with the 3' untranslated regions (UTR) of target mRNAs. Small interfering RNA-mediated genetic knock-down was performed in MDR cells and its modulatory effect on apoptosis examined. The effect of miRNA on tumorigenicity and tumor drug response was studied in mouse xenografts. miRNA profiling of two drug-resistant breast cancer cell models indicated that miR-218 was down-regulated in both MCF-7/A02 and CALDOX cells. Ectopic expression of miR-218 resensitized both drug-resistant cell lines to doxorubicin and taxol due to an increase in apoptosis. miR-218 binds survivin (BIRC5) mRNA 3'-UTR and down-regulated reporter luciferase activity. Experimental down-regulation of survivin by RNA interference in drug-resistant cells did mimic the sensitization observed when miRNA-218 was up-regulated. In addition, resensitization to taxol was also observed in mouse tumor xenografts from cells over-expressing miR-218. miR-218 is involved in the development of MDR in breast cancer cells via targeting survivin and leading to evasion of apoptosis. Targeting miR-218 and survivin may thus provide a potential strategy for reversing drug resistance in breast cancer.

EFFECT OF SHORT-TERM SENSITIVITY LOSS IN LiF:Mg,Cu,P THERMOLUMINESCENT DOSEMETER AND ITS IMPLICATIONS ON PERSONNEL DOSIMETRY OPERATIONS

A short-term sensitivity loss in LiF:Mg,Cu,P thermoluminescent dosemeters (TLDs) was observed and is described. Its observation occurred during a pre-irradiation anneal with a slightly elevated maximum temperature (5-15°C), which causes notable under-response (5-10 %) of the subsequent read at the recommended time-temperature profile (TTP), which has a peak temperature of 260°C. A subsequent irradiation and reading using the recommended TTP showed partial or complete recovery of the TLD's sensitivity. To the best of our knowledge, there were no publications on possible implications of a one-time 5-15°C overheat of LiF:Mg,Cu,P TLDs during anneal. This is not unusual when several readers with some variations in their heating cycles are used to calibrate and process the same population of dosemeters. A special test to identify if a small uncontrolled overheating of a dosemeter element has occurred was developed and tested. Two practical implications of the effect of a short-term sensitivity loss in LiF:Mg,Cu,P, e.g. inconsistency in results of metrological traceability verification and reporting of false neutron doses, are described in detail. Simple indicators of a small uncontrolled overheating are provided.

Herbicide impact on the growth and reproduction of characteristic and rare arable weeds of winter cereal fields.

The decline of arable species characteristic of winter cereal fields has often been attributed to different factors related to agricultural intensification but most importantly to herbicide use. Herbicide phytotoxicity is most frequently assessed using short-term endpoints, primarily aboveground biomass. However, short-term sensitivity is usually not sufficient to detect actual effects because plants may or may not recover over time following sublethal herbicide exposures. Therefore, it is important to assess the long-term effects of herbicide applications. Annual species rely on renewable seed production to ensure their persistence; hence, assessment of herbicide sensitivity is more accurately estimated through effects on reproduction. Here we aim to assess the phytotoxicity of two commonly used herbicides: tribenuron and 2,4-D on eight plant species belonging to four families, each with one rare and one more common species. Specifically we examined the pattern of sensitivity using short-term and long-term endpoints (total aboveground biomass, total seed biomass and number of seeds) of these species; we determined the levels of and time to recovery in terms of stem length and fruit number, and assessed whether their rarity relates to their sensitivity to herbicide application. Our results suggest that although differences in herbicide sensitivity are not a direct cause of rarity for all species, it may be an important driver of declining arable plants.

The influence of wind-wave energy spreading on the riser system response of a spread-moored FPSO

Floating unit, mooring lines and risers comprise an integrated dynamic system that responds to environmental loading due to wind, waves and currents in a complex way. The riser system response of a spread-moored FPSO in deepwaters is greatly influenced by first-order wave motions, where the consideration of wind-wave energy spreading may have an important impact on the integrity assessment. A 5-year database generated by a numerical wave model (available from NOAA) provides a proper representation of the wind-wave spreading factor distribution for Santos Basin, offshore Brazil. Based on these data and considering a cos $$^\mathrm{2s}$$ formulation for the spreading function, a short-term sensitivity study is performed to evaluate the spreading parameter $$s$$ influence on the top tension response when the system is subjected to beam seas. The numerical simulations are carried out employing a simultaneous dynamic analysis of the vessel and slender structure system. Second-order loads, which may also be important by inducing mean and slow drift motions, are taken into account with a modification of Newman’s method, where the drift force coefficients are averaged with the squared surface elevation. The results show a significant influence of $$s$$ on the riser response statistics.

Underground operation at best sensitivity of the mobile LNE-SYRTE cold atom gravimeter

Low noise underground environments offer conditions allowing assessment of ultimate performance of high sensitivity sensors such as accelerometers, gyrometers, seismometers⋯ Such facilities are for instance ideal for observing the tiny signals of interest for geophysical studies. Laboratoire Souterrain a Bas Bruit (LSBB) in which we have installed our cold atom gravimeter provides such an environment. We report here the best short term sensitivity ever obtained without any ground vibration isolation system with such an instrument: 10−8 m s−2 in 100 s measurement time.

Operating an atom-interferometry-based gravity gradiometer by the dual-fringe-locking method

We report a gravity gradiometer composed of two atom interferometers which are simultaneously locked to the respective fringe center by feedback control of the Raman laser phase and magnetic field gradient. Compared with the conventional full-fringe recording method, this dual-fringe-locking strategy is capable of increasing the sampling rate and improving the sensitivity for gravity gradient measurements. Meanwhile, it retains the intrinsic advantage of rejecting common mode noises for gravity gradiometers. A short-term sensitivity of $670 \mathrm{E}/{Hz}^{1/2}$ with a 0.25 Hz sampling rate is achieved in our gravity gradiometer. This approach may also find possible applications in other atom-interferometry-based experiments utilizing dual atomic clouds.

Connecting model species to nature: predator-induced long-term sensitization in Aplysia californica.

Previous research on sensitization in Aplysia was based entirely on unnatural noxious stimuli, usually electric shock, until our laboratory found that a natural noxious stimulus, a single sublethal lobster attack, causes short-term sensitization. We here extend that finding by demonstrating that multiple lobster attacks induce long-term sensitization (≥24 h) as well as similar, although not identical, neuronal correlates as observed after electric shock. Together these findings establish long- and short-term sensitization caused by sublethal predator attack as a natural equivalent to sensitization caused by artificial stimuli.

Thermal acclimation of shoot respiration in an Arctic woody plant species subjected to 22 years of warming and altered nutrient supply

Despite concern about the status of carbon (C) in the Arctic tundra, there is currently little information on how plant respiration varies in response to environmental change in this region. We quantified the impact of long-term nitrogen (N) and phosphorus (P) treatments and greenhouse warming on the short-term temperature (T) response and sensitivity of leaf respiration (R), the high-T threshold of R, and associated traits in shoots of the Arctic shrub Betula nana in experimental plots at Toolik Lake, Alaska. Respiration only acclimated to greenhouse warming in plots provided with both N and P (resulting in a ~30% reduction in carbon efflux in shoots measured at 10 and 20 °C), suggesting a nutrient dependence of metabolic adjustment. Neither greenhouse nor N+P treatments impacted on the respiratory sensitivity to T (Q10 ); overall, Q10 values decreased with increasing measuring T, from ~3.0 at 5 °C to ~1.5 at 35 °C. New high-resolution measurements of R across a range of measuring Ts (25-70 °C) yielded insights into the T at which maximal rates of R occurred (Tmax ). Although growth temperature did not affect Tmax , N+P fertilization increased Tmax values ~5 °C, from 53 to 58 °C. N+P fertilized shoots exhibited greater rates of R than nonfertilized shoots, with this effect diminishing under greenhouse warming. Collectively, our results highlight the nutrient dependence of thermal acclimation of leaf R in B. nana, suggesting that the metabolic efficiency allowed via thermal acclimation may be impaired at current levels of soil nutrient availability. This finding has important implications for predicting carbon fluxes in Arctic ecosystems, particularly if soil N and P become more abundant in the future as the tundra warms.