Sum Of Responses Research Articles

Multisensory integration of speech and gestures in a naturalistic paradigm.

Speech comprehension is crucial for human social interaction, relying on the integration of auditory and visual cues across various levels of representation. While research has extensively studied multisensory integration (MSI) using idealised, well-controlled stimuli, there is a need to understand this process in response to complex, naturalistic stimuli encountered in everyday life. This study investigated behavioural and neural MSI in neurotypical adults experiencing audio-visual speech within a naturalistic, social context. Our novel paradigm incorporated a broader social situational context, complete words, and speech-supporting iconic gestures, allowing for context-based pragmatics and semantic priors. We investigated MSI in the presence of unimodal (auditory or visual) or complementary, bimodal speech signals. During audio-visual speech trials, compared to unimodal trials, participants more accurately recognised spoken words and showed a more pronounced suppression of alpha power-an indicator of heightened integration load. Importantly, on the neural level, these effects surpassed mere summation of unimodal responses, suggesting non-linear MSI mechanisms. Overall, our findings demonstrate that typically developing adults integrate audio-visual speech and gesture information to facilitate speech comprehension in noisy environments, highlighting the importance of studying MSI in ecologically valid contexts.

Morphological and Functional Alterations in the CA1 Pyramidal Neurons of the Rat Hippocampus in the Chronic Phase of the Lithium-Pilocarpine Model of Epilepsy.

Epilepsy is known to cause alterations in neural networks. However, many details of these changes remain poorly understood. The objective of this study was to investigate changes in the properties of hippocampal CA1 pyramidal neurons and their synaptic inputs in a rat lithium-pilocarpine model of epilepsy. In the chronic phase of the model, we found a marked loss of pyramidal neurons in the CA1 area. However, the membrane properties of the neurons remained essentially unaltered. The results of the electrophysiological and morphological studies indicate that the direct pathway from the entorhinal cortex to CA1 neurons is reinforced in epileptic animals, whereas the inputs to them from CA3 are either unaltered or even diminished. In particular, the dendritic spine density in the str. lacunosum moleculare, where the direct pathway from the entorhinal cortex terminates, was found to be 2.5 times higher in epileptic rats than in control rats. Furthermore, the summation of responses upon stimulation of the temporoammonic pathway was enhanced by approximately twofold in epileptic rats. This enhancement is believed to be a significant contributing factor to the heightened epileptic activity observed in the entorhinal cortex of epileptic rats using an ex vivo 4-aminopyridine model.

Prediction of isometric forces from combined epidural spinal cord and neuromuscular electrical stimulation in the rat lower limb

Although epidural spinal cord and muscle stimulation have each been separately used for restoration of movement after spinal cord injury, their combined use has not been widely explored. Using both approaches in combination could provide more flexible control compared to using either approach alone, but whether responses evoked from such combined stimulation can be easily predicted is unknown. We evaluate whether responses evoked by combined spinal and muscle stimulation can be predicted simply, as the linear summation of responses produced by each type of stimulation individually. Should this be true, it would simplify the prediction of co-stimulation responses and the development of control schemes for spinal cord injury rehabilitation. In healthy anesthetized rats, we measured hindlimb isometric forces in response to spinal and muscle stimulation. Force prediction errors were calculated as the difference between predicted and observed co-stimulation forces. We found that spinal and muscle co-stimulation could be closely predicted as the linear summation of the individual spinal and muscle responses and that the errors were relatively low. We discuss the implications of these results to the use of combined muscle and spinal stimulation for the restoration of movement following spinal cord injury.

Effects of temperament during handling and social rank on the blood biochemical parameters of common eland (Taurotragus oryx)

Large herbivores are subject to handling and social stress in captivity. These may affect blood biochemical values, which motivated this research. Twelve healthy common eland (Taurotragus oryx) were monitored for 12 months. The animals were handled monthly, and blood samples were collected. Samples from every second month were analysed for 14 blood biochemical parameters. Temperament throughout the handling, as the summation of various behavioural responses, was calculated as a proxy of the stress generated during handling. Social behaviour was recorded each month, and the agonistic interactions were used to calculate the social rank, which was considered a proxy of social stress. Generalised Linear Mixed Models were designed to test the effects of temperament and social rank on the blood biochemical parameters while keeping sex, age, body condition, and body weight as covariates. The results show that the temperament during handling influences blood levels of albumin, alkaline phosphate, blood urea nitrogen, glucose, total bilirubin, and total protein; however, social rank has little influence, affecting just albumin. The ranges observed in the values of these biochemical parameters were still within their reference intervals, implying the absence of pathology or physiological problems during the study. The results suggest that blood biochemical values of physically restrained common eland should be carefully interpreted, even in animals already habituated to routine handling. On the contrary, social rank has low effects on the blood biochemical parameters.

Influence of Heat Stress on Body Temperatures Measured by Infrared Thermography, Blood Metabolic Parameters and Its Correlation in Sheep.

The aim of this research is to examine the influence of heat stress (HS) on body temperature (BT) measured rectally (RT) or by infrared thermography (IRT) of the nose (NT), eye (ET), leg (LT) and abdominal (AT) regions in intensively and extensively breed sheep and to detect a correlation between body temperature and metabolic response in sheep. A total of 33 Wurttemberg × Sjenica Pramenka sheep breeds were examined, 17 ewes were from outdoors and 16 were from indoor housing systems during three experimental periods (thermoneutral period, severe HS and moderate HS). Sheep under HS have a higher BT, and the magnitude of BT measured by infrared thermography (IRT) was higher than RT. LT and AT showed positive linear correlations with the temperature-humidity index (THI), while other ways of measuring BT did not give statistically significant correlations. Sheep under HS showed higher cortisol, insulin, total protein, albumin, urea, creatinine, bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase and index of insulin resistance, with lower values of triiodothyronine (T3), thyroxine (T4), non-esterified fatty acids, beta-hydroxybutyrate (BHB), glucose, calcium, inorganic phosphates, magnesium and cholesterol. BT and metabolic response were different in the function of the housing method of sheep. LT and AT showed a significant correlation with almost all blood parameters, and the strongest connections were made with T3, T4, BHB and the revised quantitative insulin sensitivity check index of insulin resistance. The abdomen and legs are good thermal windows because LT and AT are good summative responses to external ambient THI and internal metabolic changes in sheep under heat stress.

A complete SRSS format for the response spectrum method of high-cycle fatigue life assessment considering modal truncation error correction

In this paper, a more accurate and efficient format of the fatigue response spectrum method is further proposed considering modal truncation error. Firstly, the quasi-static response of higher-order modes is taken into account to modify the modal truncation error. Then, an analytical description of the cross-correlation between the modal responses as well as quasi-static response is developed by two coefficients associated with the natural frequency and modal damping ratio. Finally, the expected damage rate is transformed into a summation of modal damage responses strictly, resulting in a dual improvement in accuracy and efficiency. In numerical examples, the correctness and efficiency are verified and the influences of load spectrum and material fatigue properties on the modal truncation error are further investigated.

CERVICAL VESTIBULAR EVOKED MYOGENIC POTENTIALS IN PATIENTS WITHTYPE IIDIABETES MELLITUS

Introduction:Vestibular impairment has been demonstrated in patients with diabetes mellitus. Vestibular evoked myogenic potential (VEMP) is a short latency electromyographic response to sound or vibration stimuli that may reflect otolith organ or related reflex functions. cVEMPs are summation responses recorded from the contracted sternocleidomastoid inresponse to synchronized acoustic stimulation of the ipsilateral ear/saccule.In diabetic patients. Objective: Here, we asses prevalence of vestibular dysfunction by measuring cVEMP findings in patients with diabetes mellitus typeII. Methods: This study was carried out on two groups of subjects including 20 adult subjects with diabetes mellitustypeIIand 20 adult subjectsnon-diabetics, both group their aged ranged from 20-60 years. Results:showed statistically significant difference in cVEMP between diabetes mellitus type 2 control group with increase in latencies of P1 and N1 and decrease in amplitude. Conclusion: In diabetic individuals who are asymptomatic and never complained of vestibular dysfunction, cVEMPsis able to identify these patients.

Responders and nonresponders to topical capsaicin display distinct temporal summation of pain profiles.

Topical application of capsaicin can produce an ongoing pain state in healthy participants. However, approximately one-third report no pain response (ie, nonresponders), and the reasons for this are poorly understood. In this study, we investigated temporal summation of pain (TSP) profiles, pain ratings and secondary hyperalgesia responses in responders and nonresponders to 1% topical capsaicin cream. Assessments were made at baseline and then during an early (ie, 15 minutes) and late (ie, 45 minutes) time points post-capsaicin in 37 healthy participants. Participants reporting a visual analogue scale (VAS) rating of >50 were defined as responders (n = 24) and those with <50 VAS rating were defined as nonresponders (n = 13). There was a facilitation of TSP during the transition from an early to the late time point post-capsaicin (P<0.001) and the development of secondary hyperalgesia (P<0.05) in the responder group. Nonresponders showed no changes in TSP or secondary hyperalgesia during the early and late time points. There was an association between baseline TSP scores and the later development of a responder or nonresponder phenotype (r = 0.36; P = 0.03). Receiver operating characteristic analysis revealed that baseline TSP works as a good response predictor at an individual level (area under the curve = 0.75). These data suggest that responders and nonresponders have different facilitatory pain mechanisms. The assessment of TSP may help to identify participants with stronger endogenous pain facilitation who may be more likely to respond to topical capsaicin.

Assessment of the uniform field electroretinogram for mouse retinal ganglion cell functional analysis.

The uniform field electroretinogram (UF-ERG) has been suggested as an alternative to the pattern electroretinogram (PERG) for non-invasive assessment of retinal ganglion cell (RGC) function in primates. We evaluated the validity of the UF-ERG to assess mouse RGC activity in vivo. Unilateral optic nerve crush (ONC) was performed on adult C57BL/6J mice. Contralateral eyes with uncrushed optic nerves and eyes from surgically naive mice served as experimental controls. Electrophysiological visual assessment was performed at 12weeks post-ONC. Flash-mediated visual-evoked cortical potentials (VEPs) were measured to confirm the robustness of the ONC procedure. Full-field flash ERGs were used to interrogate photoreceptor and retinal bipolar cell function. RGC function was assessed with pattern ERGs. Summed onset and offset UF-ERG responses to alternating dark and light uniform field flash stimuli of different intensities and wavelengths were recorded from ONC and control eyes, and relative differences were compared to the PERG results. Following electrophysiological analysis, RGC loss was monitored by immunohistochemical staining of the RGC marker protein, RBPMS, in post-mortem retinal tissues. ONC dramatically impacts RGC integrity and optic nerve function, demonstrated by reduced RGC counts and near complete elimination of VEPs. ONC did not affect scotopic ERG a-wave and b-wave amplitudes, while PERG amplitudes of eyes subjected to ONC were reduced by approximately 50% compared to controls. Summation of ON and OFF UF-ERG responses did not reveal statistically significant differences between ONC and control eyes, regardless of visual stimulus. PERG responses are markedly impaired upon ONC, while UF-ERG responses are not significantly affected by surgical trauma to RGC axons in mice. The more closely related pattern and uniform field ERGs recorded in primates suggests species-specific differences in RGC features or subpopulations corresponding to PERG and UF-ERG response generators, limiting the utility of the UF-ERG for mouse RGC functional analysis.

Syngap1 Disruption Induced by Recombination between Inverted loxP Sites Is Associated with Hippocampal Interneuron Dysfunction.

SYNGAP1 haploinsufficiency in humans causes intellectual disability (ID). SYNGAP1 is highly expressed in cortical excitatory neurons and, reducing its expression in mice accelerates the maturation of excitatory synapses during sensitive developmental periods, restricts the critical period window for plasticity, and impairs cognition. However, its specific role in interneurons remains largely undetermined. In this study, we investigated the effects of conditional Syngap1 disruption in medial ganglionic eminence (MGE)-derived interneurons on hippocampal interneuron firing properties and excitatory synaptic inputs, as well as on pyramidal cell synaptic inhibition and synaptic integration. We show that conditional Syngap1 disruption in MGE-derived interneurons results in cell-specific impairment of firing properties of hippocampal Nkx2.1 fast-spiking interneurons, with enhancement of their AMPA receptor (AMPAR)-mediated excitatory synaptic inputs but compromised short-term plasticity. In contrast, regular-spiking Nkx2.1 interneurons are largely unaffected. These changes are associated with impaired pyramidal cell synaptic inhibition and enhanced summation of excitatory responses. Unexpectedly, we found that the Syngap1flox allele used in this study contains inverted loxP sites and that its targeted recombination in MGE-derived interneurons induces some cell loss during embryonic development and the reversible inversion of the sequence flanked by the loxP sites in postmitotic cells. Together, these results suggest that Syngap1 plays a role in cell-specific regulation of hippocampal interneuron function and inhibition of pyramidal cells in mice. However, because of our finding that the Syngap1flox allele used in this study contains inverted loxP sites, it will be important to further investigate interneuron function using a different Syngap1 conditional allele.

Spatiotemporal summation of perimetric stimuli in healthy observers.

Spatial summation of perimetric stimuli has been used to derive conclusions about the spatial extent of retinal-cortical convergence, mostly from the size of the critical area of summation (Ricco's area, RA) and critical number of retinal ganglion cells (RGCs). However, spatial summation is known to change dynamically with stimulus duration. Conversely, temporal summation and critical duration also vary with stimulus size. Such an important and often neglected spatiotemporal interaction has important implications for modeling perimetric sensitivity in healthy observers and for formulating hypotheses for changes measured in disease. In this work, we performed experiments on visually heathy observers confirming the interaction of stimulus size and duration in determining summation responses in photopic conditions. We then propose a simplified computational model that captures these aspects of perimetric sensitivity by modelling the total retinal input, the combined effect of stimulus size, duration, and retinal cones-to-RGC ratio. We additionally show that, in the macula, the enlargement of RA with eccentricity might not correspond to a constant critical number of RGCs, as often reported, but to a constant critical total retinal input. We finally compare our results with previous literature and show possible implications for modeling disease, especially glaucoma.

Cultures of support and resilience are associated with certified pharmacy technicians embracing new roles.

Various technological, economic, and regulatory factors are creating opportunities for pharmacy technicians to take on additional responsibilities. Technicians in the broader sense have indicated a preference for expanded scope of duties; however, it is not known what drives technicians' greater inclinations to accept these new roles. The purpose of this study was to determine the association of various work-related factors, such as co-worker support, pharmacist-leadership style, future uncertainty, their own organizational commitment, and personal characteristics of technicians, including their resilience, on pharmacy technicians' willingness to take on emerging responsibilities in pharmacy. A self-administered questionnaire survey was disseminated through email to a national, randomized sample of 3000 technicians certified through the National Healthcareer Association (NHA). The questionnaire solicited data on willingness to participate in either of 13 emerging responsibilities as well as resilience, perceived transformative leadership behaviors of supervising pharmacists, future uncertainty, coworker support, organizational commitment, and various personal and practice-related variables. Following the use of principal component analyses for item purification and summation of various scale responses, inferential analyses were conducted via independent sample t-tests, one way analyses of variance, and Pearson's product moment correlation, as appropriate. From 2906 surveys delivered, 878 were returned, with 745 of them providing completed responses on willingness to participate in emerging responsibilities. Willingness on most items/responsibilities was highly rated, with many means being at least 4 on a 5-point scale, though some were lower and perhaps a reflection of less exposure to these by way of their personal experience orpractice setting. Technicians' resilience, their coworker support, organizational commitment, and perceived transformative behaviors undertaken by their supervising pharmacists were all highly associated with willingness to engage. Pharmacists, pharmacy technician peers, and organizations can contribute to a culture that is supportive for pharmacy technicians and may serve to encourage commitment, resilience, and willingness to embrace new, or emerging responsibilities.

Construction and Standardization of Knowledge Test for Broiler Farmers Regarding Scientific Broiler Farming Practices

An appropriate knowledge test is required to evaluate the knowledge level of poultry farmers over the period as no scientifi cally tested and validated standard instrument is available to measure the knowledge of poultry farmers practicing broiler farming. Therefore, to study the knowledge level of broiler farmers on broiler farming, a test was constructed. Items for the knowledge test were collected from diff erent sources, such as literature, scientists, professional colleagues, fi eld extension personnel, experienced farmers, the private veterinary professional who works in the poultry industry, and the researcher’s own experience in scientifi c broiler farming. Initially 108 items on various aspects of broiler farming “i.e.” brooding, feeding, housing, health &amp; bio-security, and market management” were selected. Questions were subjected to concerned scientists and extension personnel for screening out unrelated items. After screening and editing based on the view of the scientists and extension personnel 86 items were retained. These 86 items were administered to the 60 broiler farmers from non-sampling areas for item analysis to screen out non-relevant and weak items. Item analysis was carried out using the diffi culty and discrimination index. A total of 42 items were selected for the last format of the knowledge test. Further, all the items were subjected to check out reliability and validity. The knowledge level of farmers was determined by the summation of correct responses to the items. This knowledge test is highly reliable, stable, very simple, and easy to use.

On the haemodynamic consequence of the chemoreflex and muscle mechanoreflex interaction in women and men: two tales, one story.

The cardiovascular response resulting from the individual activation of the muscle mechanoreflex (MMR) or the chemoreflex (CR) is different between men and women. Whether the haemodynamic consequence resulting from the interaction of these sympathoexcitatory reflexes is also sex-dependent remains unknown. MMR and CR were activated by passive leg movement (LM) and exposure to hypoxia (O2 -CR) or hypercapnia (CO2 -CR), respectively. Twelve young men and 12 young women completed two experimental protocols: (1) resting in normoxia (PET O2 : ∼83mmHg, PET CO2 : ∼34mmHg), normocapnic hypoxia (PET O2 : ∼48mmHg, PET CO2 : ∼34mmHg) and hyperoxic hypercapnia (PET O2 : ∼524mmHg, PET CO2 : ∼44mmHg); (2) LM under the same gas conditions. During the MMR:O2 -CR coactivation, in men, the observed mean arterial pressure (MAP) and cardiac output (CO) were not different (additive effect), while the observed leg blood flow (LBF) and vascular conductance (LVC) were significantly lower (hypo-additive), compared with the sum of the responses elicited by each reflex alone. In women, the observed MAP was not different (additive) while the observed CO, LBF and LVC were significantly greater (hyper-additive), compared with the summated responses. During the MMR:CO2 -CR coactivation, in men, the observed MAP, CO and LBF were not different (additive), while the observed LVC was significantly lower (hypo-additive), compared with the summated responses. In women, the observed MAP was significantly higher (hyper-additive), while the observed CO, LBF and LVC were not different (additive), compared with the summated responses. The interaction of the MMR and CR has a pronounced influence on the autonomic cardiovascular control, with the haemodynamic consequences differing between men and women. KEY POINTS: The cardiovascular response resulting from the activation of the muscle mechanoreflex (MMR) or the chemoreflex (CR) was previously shown to be different between women and men; this study focused on the haemodynamic consequence of the interaction of these two sympathoexcitatory reflexes. MMR and CR were activated by passive leg movement and exposure to hypoxia (O2 -CR) or hypercapnia (CO2 -CR), respectively. Individual and interactive reflex effects on central and peripheral haemodynamics were quantified in healthy young women and men. In men, the MMR:O2 -CR and MMR:CO2 -CR interactions restricted peripheral haemodynamics, likely by potentiating sympathetic vasoconstriction. In women, the MMR:O2 -CR interaction facilitated central and peripheral haemodynamics, likely by potentiating sympathetic vasodilatation; however, the MMR:CO2 -CR interaction was simply additive for the central and peripheral haemodynamics. The interaction between the MMR and the CR exerts a profound influence on the autonomic control of cardiovascular function in humans, with the haemodynamic consequences differing between women and men.

Reducing Behavioral Detection Thresholds per Electrode via Synchronous, Spatially-Dependent Intracortical Microstimulation.

Intracortical microstimulation (ICMS) has shown promise in restoring quality of life to patients suffering from paralysis, specifically when used in the primary somatosensory cortex (S1). However, these benefits can be hampered by long-term degradation of electrode performance due to the brain’s foreign body response. Advances in microfabrication techniques have allowed for the development of neuroprostheses with subcellular electrodes, which are characterized by greater versatility and a less detrimental immune response during chronic use. These probes are hypothesized to enable more selective, higher-resolution stimulation of cortical tissue with long-term implants. However, microstimulation using physiologically relevant charges with these smaller-scale devices can damage electrode sites and reduce the efficacy of the overall device. Studies have shown promise in bypassing this limitation by spreading the stimulation charge between multiple channels in an implanted electrode array, but to our knowledge the usefulness of this strategy in laminar arrays with electrode sites spanning each layer of the cortex remains unexplored. To investigate the efficacy of simultaneous multi-channel ICMS in electrode arrays with stimulation sites spanning cortical depth, we implanted laminar electrode arrays in the primary somatosensory cortex of rats trained in a behavioral avoidance paradigm. By measuring detection thresholds, we were able to quantify improvements in ICMS performance using a simultaneous multi-channel stimulation paradigm. The charge required per site to elicit detection thresholds was halved when stimulating from two adjacent electrode sites, although the overall charge used by the implant was increased. This reduction in threshold charge was more pronounced when stimulating with more than two channels and lessened with greater distance between stimulating channels. Our findings suggest that these improvements are based on the synchronicity and polarity of each stimulus, leading us to conclude that these improvements in stimulation efficiency per electrode are due to charge summation as opposed to a summation of neural responses to stimulation. Additionally, the per-site charge reductions are seen regardless of the cortical depth of each utilized channel. This evocation of physiological detection thresholds with lower stimulation currents per electrode site has implications for the feasibility of stimulation regimes in future advanced neuroprosthetic devices, which could benefit from reducing the charge output per site.

On the Regulation of Regional Cerebral Blood Flow during Hypoxic and Hypercapnic Exercise in Humans

BackgroundIt has been previously documented that the circulatory interaction resulting from the co‐activation of the arterial chemoreflex and the exercise pressor reflex is different when the chemoreflex is evoked by hypoxia vs. hypercapnia. While the interaction effect on sympathoexcitation is simply additive during hypercapnic exercise, it is hyper‐additive during hypoxic exercise. We hypothesize that a relative hypoperfusion and compromised O2 delivery (DO2) to O2‐sensitive brainstem areas/cardiovascular control centers may trigger the Cushing’s mechanism and thereby account, in part, for this potentiated sympathetic activation during exercise in hypoxia. However, although hypoxia, hypercapnia, and exercise are recognized for their strong influence on the cerebrovascular control, the interaction between these stressors and the resulting impact upon regional brain perfusion remains unknown.PurposeTo evaluate the cerebrovascular consequence of the interaction of hypoxia, or hypercapnia, with exercise in humans.MethodOn separate occasions, six healthy volunteers rested and performed rhythmic handgrip exercise (1 Hz, 50% MVC, 3 min) in normoxia (NormRest or NormExercise: SpO2 ~97%, PETO2 ~83 mmHg, PETCO2 ~36 mmHg), normocapnic hypoxia (HypoRestor HypoExercise: SpO2 ~84%, PETO2 ~49 mmHg, PETCO2 ~36 mmHg), and normoxic hypercapnia (HyperRest or HyperExercise: SpO2 ~98%, PETO2 ~111 mmHg, PETCO2 ~46 mmHg). Doppler ultrasound was used to quantify blood flow in the contralateral internal carotid artery (ICA‐BF) and ipsilateral vertebral artery (VA‐BF), and DO2 to the anterior (via ICA‐BF) and posterior (via VA‐BF) brain regions.ResultsExercise alone (i.e., ΔNormExercise‐NormRest) significantly increased ICA‐BF (+52 ± 24 mL· min‐1), VA‐BF (+27 ± 13 mL ·min‐1), and anterior (+11 ± 5 mL ·min‐1) and posterior DO2 (+6 ± 3 mL· min‐1). Hypoxia alone (i.e., ΔHypoRest‐NormRest) significantly increased ICA‐BF (+54 ± 17 mL· min‐1) and VA‐BF (+15 ± 5 mL ·min‐1), but did not affect anterior and posterior DO2 (p ≥ 0.23). Hypercapnia alone (i.e., ΔHyperRest‐NormRest) significantly increased ICA‐BF (+135 ± 27 mL· min‐1), VA‐BF (+54 ± 11 mL· min‐1), and anterior (+28 ± 5 mL ·min‐1) and posterior DO2 (+11 ± 2 mL ·min‐1). During hypoxic exercise (i.e., ΔHypoExercise‐NormRest), the responses of ICA‐BF, VA‐BF, and regional DO2 were significantly lower compared to the sum of the responses elicited by each stressor alone (ICA‐BF: 48 ± 20 vs. 106 ± 37 mL ·min‐1; VA‐BF: 24 ± 8 vs. 41 ± 10 mL ·min‐1; anterior DO2: 0 ± 4 vs. 12 ± 7 mL· min‐1; posterior DO2: 1 ± 1 vs. 5 ± 2 mL· min‐1). During hypercapnic exercise (i.e., ΔHyperExercise‐NormRest), the observed cerebrovascular responses did not differ from the summated responses (p ≥ 0.12).ConclusionWhile the interaction between hypercapnia and exercise is additive in terms of regional cerebral blood flow and DO2, the interaction between hypoxia and exercise is hypo‐additive. The resulting hypoperfusion and compromised DO2 to the brainstem (i.e., VA‐BF and posterior DO2), via the Cushing’s mechanism, might therefore contribute to the potentiated sympathoexcitation previously observed during hypoxic exercise.

Characterization of bilateral, pudendal nerve-evoked, urethral rhabdosphincter contractions in anesthetized cats

Pudendal (PUD) efferent activity contracts urethral rhabdosphincters to resist urine leakage. This study evaluates the potential for PUD nerve stimulation to provide benefit for urinary incontinence. Acute responses of the urethral rhabdosphincter to modulation of current amplitude, pulse duration (PD), and frequency of stimulation were examined. Urethral pressure was measured using a microtip catheter in chloralose-anesthetized, male cats with or without acute spinalization at T10. Stimulation was applied from an external pulse generator coupled to cuff electrodes placed around left and right PUD nerves in the ischiorectal fossa, central to its branching. Bladder pressure clamp techniques were used for testing effects of stimulation on time and rate of leakage during PUD stimulation. Single pulses (0.1 ms) produced single transient increases in urethral pressure that peaked at 50 ms and diminished to 50% of peak at 90 ms. Threshold current was 88 ± 30μA with maximal responses occurring with 50% increases in current. Peak pressures increased with increasing PDs between 40–180μs. Summation, tetany, peak pressures, and fatigue of responses to increasing stimulation frequencies during 2 min periods of stimulation are described. Stimulation under pressures that are typical during bladder filling or during bladder contractions (30–40 cm H2O) prevented leakage up to an hour in some animals, increased the median time to leak from 0.3 min to 56.0 min, and decreased the median rate of leakage from 1.44 ml/min to 0.04 ml/min when leakage did occur in less than hour. During rapid elevations in bladder pressure to simulate a Valsalva-like bladder pressure (120 cm H2O), PUD stimulation increased the median time to leak from 9 s to 93 s and decreased the median rate of leakage from 5.5 ml/min to 3.4 ml/min. These results support future studies of bilateral PUD stimulation in a clinically-relevant, animal model of urinary incontinence.

Simultaneous determination of ergotamine, caffeine and dipyrone in their ternary mixture by applying double divisor and first derivative ratio spectra methods

Two validated methods namely, double divisor ratio spectra derivative spectroscopy and derivative ratio spectroscopy with zero crossing point were applied to assay a ternary mixture of ergotamine tartrate (EGT), caffeine (CAF) and dipyrone sodium (DIP) without any additional separation steps. The linearity ranges using both methods were (1.0μg/mL-70.0μg/mL), (60.0μg/mL-100.0μg/mL) and (100.0μg/mL-300.0μg/mL) for EGT, CAF and DIP respectively. Double divisor ratio spectroscopy (method A) depends on dividing the different peak responses of EGT on (summation of peaks responses of CAF and DIP each of 10.0μg/mL concentration) at λ max=342nm, 310nm and 315nm for EGT, CAF and DIP respectively. Derivative ratio spectroscopy with zero crossing point (method B) depends on dividing the peak responses of two drugs (EGT and CAF) on (10.0μg/mL of DIP) and dividing the peak response of DIP on peak response of (10.0μg/mL of EGT). The detection limits of the studied drugs applying method A were (3.54, 12.96 and 8.748μg/mL), with quantitation limits of (10.73, 39.28 and 26.51μg/mL) for EGT, CAF and DIP respectively. Regarding method B, the limits of detection and quantitation for EGT were 0.604μg/mL and 1.829μg/mL respectively: with corresponding values of 19.44μg/mL and 58.92μg/mL for CAF and 20.44μg/mL and 61.9μg/mL for DIP. The obtained results were compared to those obtained by published methods and were found to be in accordance.

Linear and non-linear summation of responses to visual and olfactory cues in male Drosophila melanogaster

The decision-making and navigating abilities of animals assist them in surviving in an environment with multimodal stimuli, but how the nervous system integrates multisensory information remains unknown. Thus, we chose to study summation, a main mode of integration in Drosophila melanogaster. We investigated whether summation of the responses to visual and olfactory cues was linear or non-linear and explored the significance of both patterns. By a population assay, we quantitatively characterized male Drosophila’s spatial steering behavior in response to visual and olfactory cues. Based on a pioneer study from previous research, we hypothesized that the response to concurrent presentation of visual and olfactory cues would be a simple linear summation of cues presented separately. The visual stimulus in our study was 250 lux white light, and the five attractive odorants were 1-hexanol, acetoin, ethyl acetate, 2,3-butanedione, and isopentyl acetate. The results showed that the performance of 1-hexanol, ethyl acetate, and isopentyl acetate supported the hypothesis. These phenomena indicate that visual and olfactory information are relayed to descending neurons in the ventral nerve cord to direct behavior separately, suggesting independent sensorimotor pathways between these odorants and light. However, acetoin demonstrated inhibition, and 2,3-butanedione demonstrated synergy with light. These phenomena indicate that information first be relayed to some higher site in brain for multisensory integration and computation then be relayed to descending neurons in the ventral nerve cord to direct behavior. Therefore, the results indicate that the integration pattern of phototaxis and odortaxis may depend on the specific odorant. In addition, our data suggest that the integration pattern may not depend on odorant representation by glomeruli in the antennal lobes. Instead, integration pattern may depend on some higher order of odorant processing center, where information could be more efficiently and accurately processed. Our experiment contributes to understanding neural circuits and information processing in insects and more complex species.

Predicting pain after Cesarean delivery: pressure algometry, temporal summation, three-item questionnaire

Approximately one in five women will experience severe postoperative pain after Cesarean delivery (CD). Previously, a bedside three-item questionnaire (3-IQ) has shown to predict women experiencing higher evoked pain intensity after CD, with an area under the receiver operator characteristics (ROC) curve of 0.72. We hypothesized that the addition of psychophysical pain tests to the existing 3-IQ would improve the ability to predict severe pain in women undergoing elective CD under spinal anesthesia METHODS: This was a prospective cohort study on women undergoing elective CD under spinal anesthesia. Women were assessed preoperatively using the 3-IQ, pressure algometry (PA) and mechanical temporal summation (TS) response. All women received standard perioperative care, including a multimodal analgesia regimen that included intrathecal fentanyl and morphine. A 0-100 mm visual analogue scale (VAS) was used to assess the severity of pain at rest (VASr) and on movement (VASm) at 24 and 48 hr after surgery. Patient satisfaction and opioid consumption were also recorded. We performed ROC curve analyses to assess whether we could improve the ability to predict our primary outcome of severe pain on movement at 24 hr (VASm24 ≥ 70). We studied 195 women. Median [interquartile range] VASm24 was 53 [32-72] and 28% of patients experienced a VASm24 ≥ 70. The ability to predict a VASm24 ≥ 70 assessed by the area under the ROC curve was 0.64 using the 3-IQ and 0.67 using the 3-IQ combined with TS and PA. The addition of PA and TS to the 3-IQ model resulted in a predictive model that performed similarly to the 3-IQ model alone. Further research is warranted in this area to better predict women at risk of severe pain post CD.