Differentiating Generalized Anxiety Disorder from Major Depressive Disorder by Examining Reward Sensitivity in a Laboratory Setting

Generalized anxiety disorder (GAD) and major depressive disorder (MDD) are frequently co-occurring disorders (e.g., Kessler et al., 2005). Based on the current diagnostic criteria (American Psychiatric Association, 2013), there is a large overlap in symptoms and thus the two disorders are closely associated. However, there is growing evidence that suggests the importance of separating GAD from MDD, given their different patterns of emotion regulation (e.g., Mennin & Fresco, 2014). This may be examined through differential responses to rewards and punishments; however, there has been no systematic examination of reactivity to reward and punishment in laboratory settings in relation to GAD and MDD. This study examines sensitivity to reward and sensitivity to punishment via self-report measures (subjective) and physiological reactivity. Participants were presented with a food stimulus (popcorn) and a series of four videos (two disgust, two craving) in a randomized order. They were instructed to either eat or save popcorn. The crave-eat (reward) block provided the highest reward, followed by crave-save (frustrative non-reward), disgust-save (relief), and finally, the disgust-eat block (punishment). Participants reported the extent to which they experienced anxiety, disgust and craving, and we recorded heart rate variability (HRV; which reflects physiological flexibility) and cardiac impedance (pre-ejection period, which reflects sensitivity to rewards) throughout each of the blocks. I found 1) high levels of GAD symptoms were associated with elevated anxiety in all contexts 2) high levels of MDD symptoms were associated with increased anxiety in all contexts. This study yielded no differences in craving or disgust based on GAD or MDD symptom levels and yielded no differences for HRV or PEP measures based on film clip or GAD or MDD symptom levels. Also, these findings did not lend support to context insensitivity theories for GAD or MDD. Future studies should examine these effects in a larger, clinical sample.2015 URO Summer Research FellowshipArts and Sciences Undergraduate Research ScholarshipA one-year embargo was granted for this item.Academic Major: Psycholog

Pain in farm animals

This review will address how we can measure pain in farm animals and discuss the major causes of acute pain and also chronically painful conditions, and finally make suggestions for future improvements. Pain is a relatively difficult concept to define since it comprises both a physiological sensory and a psychological or emotional component. Pain is the subjective interpretation of nerve impulses induced by a stimulus that is actually or potentially damaging to tissues. The sensation of pain is a response to a noxious stimulus and should elicit protective motor (e.g. withdrawal reflex, escape) and vegetative responses (e.g. cardiovascular responses, inflammation). Zimmerman (1986) also suggested that in animals a painful experience should result in learned avoidance and affect the animal’s behaviour including social behaviour. Therefore we can use behavioural and physiological criteria to determine whether an experience is painful to an animal. It is easier to assess pain in humans since we can tell each other how we are feeling. Many people are unwilling to accept that animals can feel pain since they believe that animals are not capable of having emotions that are similar to humans. The purpose of this review is not to debate this point but animal pain is possibly different to human pain, and can be defined as an “unpleasant sensory and emotional experience” (Bateson 1991). Pain is associated with suffering and distress and the treatment of animals in farm situations has been subject to increasing public concern. During production, farm animals are exposed to procedures which can lead to injury, disease and other noxious events and this will have negative consequences for the animal and on production (Table 1; Fraser and Duncan 1988; Bath 1998). Therefore it is vital for the animal’s wellbeing and for economic reasons that we measure and evaluate potentially painful situations in order to reduce suffering and financial losses. Esslemont (1990) estimated the impact of lameness caused by a sole ulcer to be between £227 and £297 per animal

Pain in farm animals

This review will address how we can measure pain in farm animals and discuss the major causes of acute pain and also chronically painful conditions, and finally make suggestions for future improvements. Pain is a relatively difficult concept to define since it comprises both a physiological sensory and a psychological or emotional component. Pain is the subjective interpretation of nerve impulses induced by a stimulus that is actually or potentially damaging to tissues. The sensation of pain is a response to a noxious stimulus and should elicit protective motor (e.g. withdrawal reflex, escape) and vegetative responses (e.g. cardiovascular responses, inflammation). Zimmerman (1986) also suggested that in animals a painful experience should result in learned avoidance and affect the animal’s behaviour including social behaviour. Therefore we can use behavioural and physiological criteria to determine whether an experience is painful to an animal. It is easier to assess pain in humans since we can tell each other how we are feeling. Many people are unwilling to accept that animals can feel pain since they believe that animals are not capable of having emotions that are similar to humans. The purpose of this review is not to debate this point but animal pain is possibly different to human pain, and can be defined as an “unpleasant sensory and emotional experience” (Bateson 1991). Pain is associated with suffering and distress and the treatment of animals in farm situations has been subject to increasing public concern. During production, farm animals are exposed to procedures which can lead to injury, disease and other noxious events and this will have negative consequences for the animal and on production (Table 1; Fraser and Duncan 1988; Bath 1998). Therefore it is vital for the animal’s wellbeing and for economic reasons that we measure and evaluate potentially painful situations in order to reduce suffering and financial losses. Esslemont (1990) estimated the impact of lameness caused by a sole ulcer to be between £227 and £297 per animal

Adaptation dynamics in densely clustered chemoreceptors

In many sensory systems, transmembrane receptors are spatially organized in large clusters. Such arrangement may facilitate signal amplification and the integration of multiple stimuli. However, this organization likely also affects the kinetics of signaling since the cytoplasmic enzymes that modulate the activity of the receptors must localize to the cluster prior to receptor modification. Here we examine how these spatial considerations shape signaling dynamics at rest and in response to stimuli. As a model, we use the chemotaxis pathway of Escherichia coli, a canonical system for the study of how organisms sense, respond, and adapt to environmental stimuli. In bacterial chemotaxis, adaptation is mediated by two enzymes that localize to the clustered receptors and modulate their activity through methylation-demethylation. Using a novel stochastic simulation, we show that distributive receptor methylation is necessary for successful adaptation to stimulus and also leads to large fluctuations in receptor activity in the steady state. These fluctuations arise from noise in the number of localized enzymes combined with saturated modification kinetics between localized enzymes and receptor substrate. An analytical model explains how saturated enzyme kinetics and large fluctuations can coexist with an adapted state robust to variation in the expression level of the pathway constituents, a key requirement to ensure the functionality of individual cells within a population. This contrasts with the well-mixed covalent modification system studied by Goldbeter and Koshland in which mean activity becomes ultrasensitive to protein abundances when the enzymes operate at saturation. Large fluctuations in receptor activity have been quantified experimentally. Here we clarify their mechanistic relationship with well-studied aspects of the chemotaxis system, precise adaptation and functional robustness.Comment: Pontius W, Sneddon MW, Emonet T (2013) Adaptation Dynamics in Densely Clustered Chemoreceptors. PLoS Comput Biol 9(9): e1003230. doi:10.1371/journal.pcbi.100323

Novel Object Test: Examining Nociception and Fear in the Rainbow Trout

This study aimed to assess fear responses to a novel object while experiencing a noxious event to determine whether nociception or fear will dominate attention in a fish in novel object testing paradigm. This experimentally tractable animal model was used to investigate (1) the degree of neophobia to a novel object while experiencing noxious stimulation, (2) the response of the fish after removing the fear-causing event by using a familiar object, and (3) the effects of removing the nociceptive response by morphine administration and examining the response to a novel object. Control animals displayed a classic fear response to the novel objects and spent most of their time moving away from this stimulus, as well as showing an increase in respiration rate when the novel object was presented. In contrast, noxiously stimulated animals spent most of their time in close proximity to the novel object and showed no additional increase in respiration rate to novel object presentation. There was evidence of a slight hypoalgesia in noxiously stimulated animals. The responses to familiar objects demonstrated that by familiarizing the animal with the object, fear was removed from the experiment. Both control and noxiously treated animals responded in similar ways to a novel object by spending the majority of their time in close proximity. Treatment with morphine reduced effects of noxious stimulation and appears to be an effective analgesic. After morphine administration, the acid-injected animals showed a neophobic response to a novel object and this was similar to the response of the control fish, with a similar amount of time spent moving away from the object and an increase in ventilation in response to the novel object. Morphine affected the fear response because both groups approached the novel object more quickly than the non-morphine controls. These results suggest that nociception captures the animal’s attention with only a relatively small amount of attention directed at responding to the fear of the novel object

Inducing cold-sensitivity in the frigophilic fly Drosophila montana by RNAi

The work was supported by CNPq (Fellowship to FMV) and a NERC Studentship to DJP.Cold acclimation is a critical physiological adaptation for coping with seasonal cold. By increasing their cold tolerance individuals can remain active for longer at the onset of winter and can recover more quickly from a cold shock. In insects, despite many physiological studies, little is known about the genetic basis of cold acclimation. Recently, transcriptomic analyses in Drosophila virilis and D.montana revealed candidate genes for cold acclimation by identifying genes upregulated during exposure to cold. Here, we test the role of myo-inositol-1-phosphate synthase (Inos), in cold tolerance in D. montana using an RNAi approach. D. montana has a circumpolar distribution and overwinters as an adult in northern latitudes with extreme cold. We assessed cold tolerance of dsRNA knock-down flies using two metrics: chill-coma recovery time (CCRT) and mortality rate after cold acclimation. Injection of dsRNAInos did not alter CCRT,either overall or in interaction with the cold treatment, however it did induced cold specific mortality, with high levels of mortality observed in injected flies acclimated at 5°C but not at 19°C. Overall, injection with dsRNAInos induced a temperature sensitive mortality rate of over 60% in this normally cold-tolerant species. qPCRanalysis confirmed that dsRNA injection successfully reduced gene expression of Inos. Thus, our results demonstrate the involvement of Inos in increasing cold tolerance in D. montana. The potential mechanisms involved by which Inos increases cold tolerance are also discussed.Publisher PDFPeer reviewe