Respiratory responses during affective picture viewing

Previous research has demonstrated covariation of physiological responding with judgments of valence and arousal. However, until now links between these affective dimensions and respiratory measures have not been extensively investigated. In this study, eight picture series of different affective valence and arousal level were shown to 30 subjects, while respiration, skin conductance level (SCL), heart rate (HR) and affective judgments were measured. With increasing pleasantness, inspiratory time lengthened, mean inspiratory flow decreased and thoracic breathing increased. With increasing arousal, inspiratory time and total breath duration shortened and mean inspiratory flow, minute ventilation, thoracic breathing and electrodermal activity increased. These findings confirm the importance of arousal in respiratory responding, but also indicate a modulatory role of affective valence.We propose that the arousal effects reflect energy mobilization in preparation to act, and thatthe valence effects might be a manifestation of an attention bias toward negative stimuli. [Authors]

Responsiveness to a physiological regimen of GnRH therapy and relation to genotype in women with isolated hypogonadotropic hypogonadism.

CONTEXT: Isolated hypogonadotropic hypogonadism (IHH) is caused by defective GnRH secretion or action resulting in absent or incomplete pubertal development and infertility. Most women with IHH ovulate with physiological GnRH replacement, implicating GnRH deficiency as the etiology. However, a subset does not respond normally, suggesting the presence of defects at the pituitary or ovary. OBJECTIVES: The objective of the study was to unmask pituitary or ovarian defects in IHH women using a physiological regimen of GnRH replacement, relating these responses to genes known to cause IHH. DESIGN, SETTING, AND SUBJECTS: This study is a retrospective analysis of 37 IHH women treated with iv pulsatile GnRH (75 ng/kg per bolus). MAIN OUTCOME MEASURES: Serum gonadotropin and sex steroid levels were measured, and 14 genes implicated in IHH were sequenced. RESULTS: During their first cycle of GnRH replacement, normal cycles were recreated in 60% (22 of 37) of IHH women. Thirty percent of women (12 of 37) demonstrated an attenuated gonadotropin response, indicating pituitary resistance, and 10% (3 of 37) exhibited an exaggerated FSH response, consistent with ovarian resistance. Mutations in CHD7, FGFR1, KAL1, TAC3, and TACR3 were documented in IHH women with normal cycles, whereas mutations were identified in GNRHR, PROKR2, and FGFR1 in those with pituitary resistance. Women with ovarian resistance were mutation negative. CONCLUSIONS: Although physiological replacement with GnRH recreates normal menstrual cycle dynamics in most IHH women, hypogonadotropic responses in the first week of treatment identify a subset of women with pituitary dysfunction, only some of whom have mutations in GNRHR. IHH women with hypergonadotropic responses to GnRH replacement, consistent with an additional ovarian defect, did not have mutations in genes known to cause IHH, similar to our findings in a subset of IHH men with evidence of an additional testicular defect.

Distinct neuronal circuits underlying the bahavioral and physiological components of the fear response

Abstract : Expression of fear involves changes in a number of behavioral and physiological parameters that are triggered by the central amygdala (CeA). The fear circuit also includes a series of brain stem nuclei that are the final effectors of the changes induced by the fear reaction. The CeA expresses many different neuropeptide receptors that can modulate fear responses. Today, the precise organization and the modulation of projections from the amygdala to the brain stem are still poorly understood. The aim of this project was to better understand the organization and the modulation of the fear circuit. To investigate this we first determined whether the CeA is composed of separate neuronal populations, where each one projects to specific brain stem nuclei, or whether single CeA neurons project to several nuclei. For this purpose, we first selected two brain stem nuclei implicated in the modulation of different components of the fear reactions, the periaqueductal gray (implicated in freezing) and the nucleus of solitary tract (implicated in heart rate modulation). We then performed double injections of two different retrograde tracers in these two nuclei and we quantified the subsequent presence of co-labelling in the CeA. We found that neurons projecting to the PAG and to the NTS are organized in separate populations. Subsequent electrophysiological recordings of the two populations revealed that PAG and NTS projecting neurons also have different electrophysiological characteristics. We then verified in vitro whether the neurons projecting to different brain stem nuclei express specific combinations of neuropeptide receptors, and whether a neuropeptide acting pre-synaptically (oxytocin) specifically modulates one of these two projections. We did not find differences at the level of expression of neurópeptide receptors, but we observed that oxytocin, a neuropeptide with anxiolytic properties, modulates PAG projecting neurons without affecting NTS projecting neurons. As oxytocin appeared to specifically modulate projections to the PAG, involved in the modulation of the freezing reaction, but did not affect the projections to the NTS, implicated in the modulation of cardiovascular parameters, we verified how this modulation translates in living animals. We investigated the effects of infra-amygdala injection of oxytocin on cardiovascular and behavioral changes induced by contextual fear conditioning. We found that oxytocin decreased the freezing response without affecting the cardiovascular system. Finally, as neuropeptides are considered potential future anxiolytics, we investigated whether diazepam and oxytocin, acting on the same circuit, had additive effects. This question was addressed exclusively with an in vitro electrophysiological approach. We obtained that oxytocin and diazepam, when co-applied, had an additive effect on both synaptic transmission and neuronal activity. These results open new perspectives for the possible clinical applications of oxytocin. Résumé : L'expression de la peur est accompagnée par de nombreux changements physiologiques et comportementaux qui sont déclenchés par l'amygdale centrale (CeA). Le circuit inclue aussi une série de noyaux du tronc cérébrale qui sont les effecteurs des différentes composantes de la réaction de peur. On sait que CeA envoie des projections aux noyaux du tronc cérébral et que ces neurones expriment une grande variété de récepteurs aux neuropeptides. Par contre, l'organisation des projections, ainsi que la modulation de ces projections par les neuropeptides reste encore peu connue. Avec ce projet, on premièrement voulu déterminer si CeA est composée de populations neuronales séparées qui projettent vers un noyau spécifique, ou bien si chaque neurones envoie des projections vers plusieurs noyaux. A ce propos, on a effectué des doubles injections de deux traceurs rétrogrades différentes dans deux noyaux du tronc cérébral impliqués dans des différentes composantes des réactions de peur. On a injecté la substance grise périaqueducale (PAG), qui est impliquée dans la réponse d'immobilisation, ainsi que le noyau du tractus solitaire (NTS) qui est responsable des changements cardiovasculaires. On a ensuite quantifié la présence de neurones contenant les deux traceurs dans CeA. On a trouvé que la plupart des neurones de l'amygdale centrale projettent vers un noyau spécifique, et on peut donc dire que l'amygdale semble être composée de populations neuronales séparées. On a ensuite mesuré les caractéristiques électrophysiologiques de ces deux projections et on a trouvé des différences substantielles concernant la résistance membranaire, la capacitance, le potentiel membranaire de repos ainsi que la fréquence des potentiels d'action spontanés. Puis, comme beaucoup de neuropéptides dans l'amygdale exercent un effet modulatoire sûr les réactions de peur et sur l'anxiété, on a étudié les effets directs et indirects d'une série de neuropeptides sur les différentes projections pour évaluer s'il y a des neuropeptides qui agissent spécifiquement sur une. On n'a pas trouvé de différences entre neurones qui projettent vers le PAG et neurones qui projettent vers le NTS concernant les effets de neuropeptides qui agissent directement sur ces cellules. Par contre, on a trouvé que l'ocytocine, un neuropeptide qui se lie à des récepteurs dans la partie latérale de l'amygdale centrale et inhibe de façon indirecte les neurones de l'amygdala centrale médiale, module les projections vers le PAG sans affecter celles qui vont vers le NTS. Comme le PAG est impliqué dans la réponse d'immobilisation, alors que le NTS est impliqué dans la modulation cardiovasculaire, on a ensuite étudié les effets de l'ocytocine injectée dans l'amygdale de rat vivants sur les réactions de peur conditionnées. On a trouvé que l'ocytocine diminue la réponse d'immobilisation sans par contre affecter la réponse cardiovasculaire. Pour terminer, on a vérifié si l'ocytocine potentialise les effets d'un médicament anxiolytique, le diazeparn. Avec une étude in vitro on a trouvé qu'une co-application d'ocytocine et diazeparn résulte en un effet additionnel à la fois sur la transmission synaptique ainsi que sur l'activité neuronale des neurones de l'amygdale centrale médiale. Ces résultats ouvrent des nouvelles perspectives pour une potentielle utilisation clinique de l'ocytocine.

Physiological differences between cycling and running

This review compares the differences in systemic responses (VO2max, anaerobic threshold, heart rate and economy) and in underlying mechanisms of adaptation (ventilatory and hemodynamic and neuromuscular responses) between cycling and running. VO2max is specific to the exercise modality. Overall, there is more physiological training transfer from running to cycling than vice-versa. Several other physiological differences between cycling and running are discussed: HR is different between the two activities both for maximal and sub-maximal intensities. The delta efficiency is higher in running. Ventilation is more impaired in cycling than running due to mechanical constraints. Central fatigue and decrease in maximal strength are more important after prolonged exercise in running than in cycling.

Morphological and physiological species-dependent characteristics of the rodent Grueneberg ganglion.

In the mouse, the Grueneberg ganglion (GG) is an olfactory subsystem implicated both in chemo- and thermo-sensing. It is specifically involved in the recognition of volatile danger cues such as alarm pheromones and structurally-related predator scents. No evidence for these GG sensory functions has been reported yet in other rodent species. In this study, we used a combination of histological and physiological techniques to verify the presence of a GG and investigate its function in the rat, hamster, and gerbil comparing with the mouse. By scanning electron microscopy (SEM) and transmitted electron microscopy (TEM), we found isolated or groups of large GG cells of different shapes that in spite of their gross anatomical similarities, display important structural differences between species. We performed a comparative and morphological study focusing on the conserved olfactory features of these cells. We found fine ciliary processes, mostly wrapped in ensheating glial cells, in variable number of clusters deeply invaginated in the neuronal soma. Interestingly, the glial wrapping, the amount of microtubules and their distribution in the ciliary processes were different between rodents. Using immunohistochemistry, we were able to detect the expression of known GG proteins, such as the membrane guanylyl cyclase G and the cyclic nucleotide-gated channel A3. Both the expression and the subcellular localization of these signaling proteins were found to be species-dependent. Calcium imaging experiments on acute tissue slice preparations from rodent GG demonstrated that the chemo- and thermo-evoked neuronal responses were different between species. Thus, GG neurons from mice and rats displayed both chemo- and thermo-sensing, while hamsters and gerbils showed profound differences in their sensitivities. We suggest that the integrative comparison between the structural morphologies, the sensory properties, and the ethological contexts supports species-dependent GG features prompted by the environmental pressure.

Oxytocin selectively gates fear responses through distinct outputs from the central amygdala.

Central amygdala (CeA) projections to hypothalamic and brain stem nuclei regulate the behavioral and physiological expression of fear, but it is unknown whether these different aspects of the fear response can be separately regulated by the CeA. We combined fluorescent retrograde tracing of CeA projections to nuclei that modulate fear-related freezing or cardiovascular responses with in vitro electrophysiological recordings and with in vivo monitoring of related behavioral and physiological parameters. CeA projections emerged from separate neuronal populations with different electrophysiological characteristics and different response properties to oxytocin. In vivo, oxytocin decreased freezing responses in fear-conditioned rats without affecting the cardiovascular response. Thus, neuropeptidergic signaling can modulate the CeA outputs through separate neuronal circuits and thereby individually steer the various aspects of the fear response.

Neuroticism modifies psychophysiological responses to fearful films

Background: Neuroticism is a personality component frequently found in anxious and depressive psychiatric disorders. The influence of neuroticism on negative emotions could be due to its action on stimuli related to fear and sadness, but this remains debated. Our goal was thus to better understand the impact of neuroticism through verbal and physiological assessment in response to stimuli inducing fear and sadness as compared to another negative emotion (disgust).¦Methods: Fifteen low neurotic and 18 high neurotic subjects were assessed on an emotional attending task by using film excerpts inducing fear, disgust, and sadness. We recorded skin conductance response (SCR) and corrugator muscle activity (frowning) as indices of emotional expression.¦Results: SCR was larger in high neurotic subjects than in low neurotics for fear relative to sadness and disgust. Moreover, corrugator activity and SCR were larger in high than in low neurotic subjects when fear was induced.¦Conclusion: After decades of evidence that individuals higher in neuroticism experience more intense emotional reactions to even minor stressors, our results indicate that they show greater SCR and expressive reactivity specifically to stimuli evoking fear rather than to those inducing sadness or disgust. Fear processing seems mainly under the influence of neuroticism. This modulation of autonomic activity by neurotics in response to threat/fear may explain their increased vulnerability to anxious psychopathologies such as PTSD (post traumatic stress disorder).

Evénements traumatiques et réponses de stress: le rôle de l'ocytocine et de l'attachement [Traumatic events and stress responses: the role of oxytocin and attachement].

Being repeatedly confronted to very difficult situations since childhood influences the way indivuals will later respond to even mildly stressful events. The hypothalamic-pituitary-adrenal axis (HPA) is a complex system implicated in regulating neuroendocrine responses to stress. Its activation produces among others the <stress hormonea, cortisol. However, the regulation of the physiological response to stress depends on psychological factors linked with the representations that individuals develop regarding their close relationships i.e. attachment. Furthermore, attachment representations seem to be associated with oxytocin, a hormone involved both in cortisol reduction and in positive social behaviours.

Trunk neuromuscular responses to a single whole-body vibration session in patients with chronic low back pain: a cross-sectional study.

OBJECTIVE: Whole-body vibration (WBV) exercise is progressively adopted as an alternative therapeutic modality for enhancing muscle force and muscle activity via neurogenic potentiation. So far, possible changes in the recruitment patterns of the trunk musculature after WBV remain undetermined. The main objective of this study was to evaluate the short-term effects of a single WBV session on trunk neuromuscular responses in patients with chronic low back pain (cLBP) and healthy participants. METHODS: Twenty patients with cLBP and 21 healthy participants performed 10 trunk flexion-extensions before and after a single WBV session consisting of five 1-minute vibration sets. Surface electromyography (EMG) of erector spinae at L2-L3 and L4-L5 and lumbopelvic kinematic variables were collected during the trials. Data were analyzed using 2-way mixed analysis of variance models. RESULTS: The WBV session led to increased lumbar EMG activity during the flexion and extension phases but yielded no change in the quiet standing and fully flexed phases. Kinematic data showed a decreased contribution to the movement of the lumbar region in the second extension quartile. These effects were not different between patients with cLBP and healthy participants. CONCLUSIONS: Increased lumbar EMG activity after a single WBV session most probably results from potentiation effects of WBV on lumbar muscles reflex responses. Decreased EMG activity in full trunk flexion, usually observed in healthy individuals, was still present after WBV, suggesting that the ability of the spine stabilizing mechanisms to transfer the extension torque from muscles to passive structures was not affected.

Psychophysiological responses to affective pictures in younger and older adults

Despite the central role that emotional reactivity plays in adaptation, few studies have examined age differences in this capacity under well-controlled laboratory conditions, on the basis of standardized emotion-evoking stimuli and assessing experiential, expressive, and physiological measures. 212 adults ranging in age from 20 to 81 years were exposed to 14 picture series, each lasting 60 s and of a different valence and arousal. We assessed valence and arousal ratings, cardiovascular, respiratory and electrodermalmeasures, facial muscle activity and gaze activity. Here, we present findings for 22 younger (mean age=24.0) and 22 older (mean age=72.1) adults for valence and arousal ratings, systolic bloodpressure (SBP) andheart rate (HR).Compared to younger adults, older adults rated unpleasant seriesmore negatively and showed a smaller range in arousal for pleasant series. SBP linearly increased with increasing appetitive activation. HR showed the expected deceleration from the pleasant to the unpleasant series.However, this effect was clearer for the younger adults than the older adults. For older adults, if something is pleasant, it is also judged to be generally lower in arousal, whereas, if something is unpleasant, it is also judged to be generally higher in arousal. The results for SBP indicate that the association between arousal and sympathetic outflow to the cardiovascular system might be similar in younger and older adults. The results for HR suggest that the parasympathetic activation might be attenuated in older adults as compared to younger adults.

Physiological and morphological responces of Brachiaria spp. to flooding

The physiological and morphological responses of the forage grasses Brachiaria brizantha cv. Marandu, B. decumbens and B. humidicola were compared for plants grown in pots under flooding and well-drained conditions for 14 days. Flooding reduced specific leaf area and biomass allocation to roots in all species and enhanced leaf senescence in B. brizantha and B. decumbens. Relative growth rate was reduced by flooding in B. brizantha and B. decumbens, but not in B. humidicola.Leaf elongation rate was unaffected by flooding in B. decumbens and B. humidicola, but declined in B. brizantha since the first day of flooding. Net photosynthesis and leaf chlorophyll content were reduced by flooding in B. brizantha; however, no flooding effect could be detected in the other two species. For all species, there was a close relationship between net photosynthesis and stomatal conductance under flooding. These results show that the studied species have distinct degrees of tolerance to flood, B. brizantha is intolerant, B. decumbens is moderately tolerant and B. humidicola is tolerant. Because leaf elongation rate was immediately depressed by flooding only in B. brizantha, this measurement could be appropriate as an early detection mechanism for relative flood tolerance in Brachiaria spp.

Responses and adaptations of collembolan communities (Hexapoda: Collembola) to flooding and hypoxic conditions

Standard ecological methods (pitfall traps, trunk eclectors and soil cores) were used to evaluate collembolan community responses to different flooding intensities. Three sites of a floodplain habitat near Mainz, Germany, with different flooding regimes were investigated. The structures of collembolan communities are markedly different depending on flooding intensity. Sites more affected by flooding are dominated by hygrophilic and hygrotolerant species, whereas the hardwood floodplain is dominated by mesophilic species. The survival strategies of the hygrophilic and hygrotolerant species include egg diapause and passive drifting. The physiological adaptations to hypoxic conditions of several collembolan species were analyzed using a microcalorimeter. The activities were tested under normoxic and hypoxic/anoxic conditions as well as during post-hypoxic recovery. Lactate was increased after hypoxic intervals in the species studied, suggesting that, in addition to a massive decrease in metabolic rate, a modest glycolytic activity may be involved in the tolerance to hypoxia.

Dissection of local and systemic transcriptional responses to phosphate starvation in Arabidopsis.

Phosphate is a crucial and often limiting nutrient for plant growth. To obtain inorganic phosphate (P(i) ), which is very insoluble, and is heterogeneously distributed in the soil, plants have evolved a complex network of morphological and biochemical processes. These processes are controlled by a regulatory system triggered by P(i) concentration, not only present in the medium (external P(i) ), but also inside plant cells (internal P(i) ). A 'split-root' assay was performed to mimic a heterogeneous environment, after which a transcriptomic analysis identified groups of genes either locally or systemically regulated by P(i) starvation at the transcriptional level. These groups revealed coordinated regulations for various functions associated with P(i) starvation (including P(i) uptake, P(i) recovery, lipid metabolism, and metal uptake), and distinct roles for members in gene families. Genetic tools and physiological analyses revealed that genes that are locally regulated appear to be modulated mostly by root development independently of the internal P(i) content. By contrast, internal P(i) was essential to promote the activation of systemic regulation. Reducing the flow of P(i) had no effect on the systemic response, suggesting that a secondary signal, independent of P(i) , could be involved in the response. Furthermore, our results display a direct role for the transcription factor PHR1, as genes systemically controlled by low P(i) have promoters enriched with P1BS motif (PHR1-binding sequences). These data detail various regulatory systems regarding P(i) starvation responses (systemic versus local, and internal versus external P(i) ), and provide tools to analyze and classify the effects of P(i) starvation on plant physiology.

Importance of abiotic stress as a range-limit determinant for European plants: insights from species' responses to climatic gradients

Aim We examined whether species occurrences are primarily limited by physiological tolerance in the abiotically more stressful end of climatic gradients (the asymmetric abiotic stress limitation (AASL) hypothesis) and the geographical predictions of this hypothesis: abiotic stress mainly determines upper-latitudinal and upper-altitudinal species range limits, and the importance of abiotic stress for these range limits increases the further northwards and upwards a species occurs. Location Europe and the Swiss Alps. Methods The AASL hypothesis predicts that species have skewed responses to climatic gradients, with a steep decline towards the more stressful conditions. Based on presence-absence data we examined the shape of plant species responses (measured as probability of occurrence) along three climatic gradients across latitudes in Europe (1577 species) and altitudes in the Swiss Alps (284 species) using Huisman-Olff-Fresco, generalized linear and generalized additive models. Results We found that almost half of the species from Europe and one-third from the Swiss Alps showed responses consistent with the predictions of the AASL hypothesis. Cold temperatures and a short growing season seemed to determine the upper-latitudinal and upper-altitudinal range limits of up to one-third of the species, while drought provided an important constraint at lower-latitudinal range limits for up to one-fifth of the species. We found a biome-dependent influence of abiotic stress and no clear support for abiotic stress as a stronger upper range-limit determinant for species with higher latitudinal and altitudinal distributions. However, the overall influence of climate as a range-limit determinant increased with latitude. Main conclusions Our results support the AASL hypothesis for almost half of the studied species, and suggest that temperature-related stress controls the upper-latitudinal and upper-altitudinal range limits of a large proportion of these species, while other factors including drought stress may be important at the lower range limits.

Identifying quantitative operation principles in metabolic pathways: a systematic method for searching feasible enzyme activity patterns leading to cellular adaptive responses

Background: Optimization methods allow designing changes in a system so that specific goals are attained. These techniques are fundamental for metabolic engineering. However, they are not directly applicable for investigating the evolution of metabolic adaptation to environmental changes. Although biological systems have evolved by natural selection and result in well-adapted systems, we can hardly expect that actual metabolic processes are at the theoretical optimum that could result from an optimization analysis. More likely, natural systems are to be found in a feasible region compatible with global physiological requirements. Results: We first present a new method for globally optimizing nonlinear models of metabolic pathways that are based on the Generalized Mass Action (GMA) representation. The optimization task is posed as a nonconvex nonlinear programming (NLP) problem that is solved by an outer- approximation algorithm. This method relies on solving iteratively reduced NLP slave subproblems and mixed-integer linear programming (MILP) master problems that provide valid upper and lower bounds, respectively, on the global solution to the original NLP. The capabilities of this method are illustrated through its application to the anaerobic fermentation pathway in Saccharomyces cerevisiae. We next introduce a method to identify the feasibility parametric regions that allow a system to meet a set of physiological constraints that can be represented in mathematical terms through algebraic equations. This technique is based on applying the outer-approximation based algorithm iteratively over a reduced search space in order to identify regions that contain feasible solutions to the problem and discard others in which no feasible solution exists. As an example, we characterize the feasible enzyme activity changes that are compatible with an appropriate adaptive response of yeast Saccharomyces cerevisiae to heat shock Conclusion: Our results show the utility of the suggested approach for investigating the evolution of adaptive responses to environmental changes. The proposed method can be used in other important applications such as the evaluation of parameter changes that are compatible with health and disease states.