Placeboeffekten; att få klinisk effekt av inaktiv behandling är ett fenomen som tilldrar sig allt större intresse. Trots att mekanismerna bakom effekten ännu är långt ifrån helt klarlagda så finns en stor mängd forskning som visar att placebobehandling på olika vis kan vara av klinisk relevans. Bland de mest imponerande demonstrationerna av placeboeffekten är de experiment som visar att s.k. klassisk betingning kan påverka immunförsvaret. Experiment har visat att detta är möjligt både hos gnagare och människor: en medicin administreras samtidigt som ett neutralt gustatoriskt stimulus i vad som kallas betingningsfasen. När denna genomförts kan associationen mellan smak och farmakologisk effekt vara så stark att samma smak, på egen hand, kan framkalla nämnd effekt. I detta arbete sammanfattas kort begrepp och forskning kring placebo i allmänhet och betingad placebo i synnerhet. Vetenskapliga belägg för betingad placebos förmåga till immunpåverkan granskas, och det mesta tyder på att sådan är möjlig i praktiken. Därefter diskuteras möjliga kliniska tillämpningar av betingad placebo i form av medicinsk dosreduktion. Avslutningsvis följer en kort genomgång av det stora kunskapsgapet mellan beläggen för denna dosreduktions kliniska relevans, och dess lämplighet inom konventionell vård.

Previous research has indicated two distinctive characteristics of flavour-aversion learning in rats: (1) rats very readily associate flavors with an internal malaise (toxicosis) , as evidenced by their subsequent aversion to the flavor, but they do not readily associate flafors with peripherally-applied electric shock. In contrast, rats readily associate auditory and visual stimuli with shock but not with toxicosis; (2) rats associate flavors with a subsequent toxicosis even when the gustatory stimulus is removed hours prior to onset of toxicosis. However, associations are formed between audio/visual cues and shock only if the offset of the signal does not precede onset of shock by more than one or two minutes. It has been suggested that the unique features of flavour-aversionn learning result from the fact that toxicosis is primarily a visceral experience while shock is applied to somesthetic receptors. However, toxicosis differs from shock along a number of dimensions in addition to receptor site. Most notably, toxicosis typically rises to a peak intensity over a period of many minutes and lasts for hours while shock is usually applied with a rapid onset (milliseconds) and short duration (seconds or milliseconds). Inasmuch as aversion learning experiments have confounded the receptor site of the aversive stimulus with its distinctive temporal features, it is not clear whether receptor site or temporal features is the functionally important characteristic of toxicosis as an aversive stimulus in the taste-aversion learning preparation. To determine the role played by the temporal features of the aversive stimulus in taste-aversion learning, rats were prepared with a stomach balloon and stomach balloon inflation was paired with ingestion of a flavored solution. In contrast to toxicosis, the onset/offset rate and duration of balloon inflation may be directly manipulated thus permitting application of a relatively discrete internal stimulus (in comparison to toxicosis) to visceral receptors. Experiments presented here found: (a) rats associated a flavor with a stomach balloon inflation as indicated by an aversion to the flavor during a two-solution preference test. In contrast to toxicosis, the stomach balloon inflation had a rapid onset (seconds) and short duration (minutes). Control groups demonstrated that the rapid onset, short duration balloon inflation did not produce the long lasting malaise characteristic of toxicosis. (b) Rats associated a flavor with a rapid onset, short duration balloon inflation even when exposure to the flavor was terminated many minutes prior to onset of balloon inflation. (c) Rats readily associated a flavor with balloon inflation but not with shock, and an auditory stimulus with shock but not with balloon inflation, even though balloon inflation and shock were equated in terms of their temporal parameters. These findings clearly indicate that the very slow onset and long duration characteristics of toxicosis are not the functionally important features of toxicosis as the aversive stimulus in the taste-aversion learning preparation. Furthermore, the unique temporal features of toxicosis and shock do not appear responsible for the distinctive characteristics of flavor-aversion learning in rats. / Thesis / Doctor of Philosophy (PhD)

Thesis (M.A.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 27, 2007) Includes bibliographical references.

Le système de l’immunité innée cérébrale module le fonctionnement du cerveau et les processus comportementaux tout au long de la vie d'un individu. Parmi les différents protagonistes de ce système de l'immunité innée cérébrale, les cellules gliales jouent un rôle majeur notamment en régulant la synthèse de facteurs inflammatoires tels que les cytokines. Ces dernières, outre leur rôle dans la coordination de l'action des différents partenaires cellulaires de ce système, modifient l'activité neuronale. Lors d'un épisode inflammatoire, le système de l'immunité innée s'active et l'ensemble des signaux mis en place par les processus immunitaires est regroupé sous le terme de neuroinflammation. Plus particulièrement, les cytokines proinflammatoires et l’ATP libérés dans ce cadre ont été décrits comme étant capables de moduler la plasticité synaptique d'une part et les capacités d’apprentissages et de mémorisation d'autre part. Cependant, la compréhension de l’impact d’un épisode inflammatoire sur le système nerveux central et les capacités d’apprentissage n’est pas totale. Une cible potentielle de ces facteurs est le système de neurotransmission glutamatergique. En effet, les facteurs proinflammatoires peuvent augmenter ou diminuer l’expression ou l’activité de certaines sous-unités des récepteurs glutamatergiques. Mon objectif a été de déterminer dans quelle mesure la transmission glutamatergique est altérée en condition neuroinflammatoire et comment cela pouvait induire des altérations des capacités d’apprentissage chez le rongeur. Pour cela nous avons choisi comme tâche comportementale l’aversion gustative conditionnée, dont les mécanismes moléculaires nécessaire à sa mise en place sont connus et reposent sur la transmission glutamatergique dans une structure corticale particulière chez les rongeurs: le cortex insulaire. Notre étude visait à déterminer les mécanismes cellulaires et moléculaires par lesquels une inflammation localisée à ce cortex peut induire des modifications comportementales et biochimiques. Nous avons pu montrer que l’infusion de lipopolysaccharide, un puissant agent inflammatoire, dans le cortex insulaire induisait une augmentation de l'aversion conditionnée. Ceci était corrélé à une augmentation d’expression des récepteurs AMPA au glutamate dans cette structure, plus particulièrement dans le compartiment synaptique. Nous avons également pu montrer que l’infusion de LPS dans le cortex insulaire induisait la synthèse et la libération de cytokines proinflammatoires localement, sans stimuler le système de l’immunité périphérique. Même si ces cytokines sont connues comme étant des agents modulateurs de la neurotransmission glutamatergique, leur infusion dans le cortex insulaire n’a pas reproduit dans notre cas les effets de l’infusion du LPS. Par contre, nous avons montré que l’ATP était impliqué dans les effets du LPS sur l’apprentissage aversif, puisque le blocage des récepteurs purinergiques dans le cortex insulaire a permis de reverser les effets du LPS sur l’acquisition de l’aversion gustative. En conclusion, nos résultats suggèrent qu'une inflammation localisée dans le cortex insulaire conduit à la libération et à l'action d’ATP sur les cellules gliales et/ou neuronales, aboutissant à une hausse de l’acquisition de l’aversion gustative conditionnée. / The cerebral innate immune system is activated under pathophysiological conditions and can consequently modulate brain functioning and cognitive processes. This modulation is exerted by signals produced by immune-like processes grouped under the term of neuroinflammation and involving neuro-glial communication within the brain. In particular, proinflammatory cytokines and ATP, all produced during this immune system activation have been directly linked to modulation of synaptic plasticity and/or learning and memory functions in animals models. However, the cellular mechanisms by which neuroinflammation modulates neural plasticity and cognitive processes are still unclear. One candidate is the glutamatergic system. Indeed, pro-inflammatory factors can increase or decrease glutamatergic receptors expression and/or activity. Our study was dedicated at deciphering to what extent glutamatergic transmission is altered under neuroinflammation and how this may lead to learning and memory alteration. To this aim, we used the conditioned taste aversion, a task highly dependent on glutamatergic transmission into the insular cortex. Indeed, blockade of NMDA or AMPA receptors in this cortical area before acquisition greatly impairs conditioned taste aversion. The aim of our study was thus to investigate the behavioral and cellular impact of an inflammation restricted to the insular cortex on glutamatergic receptors expression and CTA memory formation. Here we show that a cortical inflammation, induced by LPS infusion into the insular cortex, prior to CTA acquisition enhances the aversion strength presumably through LPS-induced increase of glutamatergic AMPA, but not NMDA, receptor expression/trafficking at the insular synapses. Moreover, we show that ATP release, but not pro-inflammatory cytokines, is responsible for LPS-induced CTA enhancement. In conclusion we propose that inflammation restricted to the insular cortex enhances CTA acquisition through an ATP-dependent mechanism presumably involving an increase of glutamatergic AMPA receptor expression at the neuronal synapses.

Conflicts between humans and black bears (Ursus americanus) jeopardize the safety of both humans and bears, especially when bears become food-conditioned to anthropogenic food sources in areas such as campgrounds. Interest in using non-lethal techniques, such as aversive conditioning, to manage such conflicts is growing. I conducted a captive experiment at The Wildlife Science Center in Minnesota and two field experiments in the La Sal Mountains, Utah, to investigate the effects of taste aversion conditioning using thiabendazole (TBZ) with a novel flavor cue and food removal on black bear food consumption and visitation to human food sources. In 2007, I conducted food trials with 6 captive black bears (3 control, 3 treatment). Controls received 1 kg baked goods scented with a peppermint-canola oil mixture and treatments received 1 kg baked goods also scented with a peppermint-canola oil mixture but mixed with 10-20 g TBZ. In the 2007 field experiment, I baited 24 field sites with 300 g of baked goods during a baseline phase for approximately 3 weeks. Half of these sites were then treated with 10 g of TBZ and camphor during a treatment phase for 4 weeks. In 2008, I baited 22 sites with 300 g of baked goods during a baseline phase for approximately 4 weeks. I then removed food and discontinued baiting at half of the sites for 4 weeks. Infrared cameras and barbed-wire hair snags were established at field sites to document bear visitation. I did not establish taste aversion in treated bears in captivity and bears fully consumed food in the majority of trials. Treating food supplies with 10 g TBZ and camphor flavor did not significantly reduce bear visitation (P = 0.615) or food consumption at field sites (P = 0.58). However, I observed a significant reduction in bear activity at sites where food was removed (P = 0.006). Potential reasons for my failure to reduce bear visitation using thiabendazole include insufficient conditioning, reluctance of bears to desist in investigating sites that previously contained untreated food, and masking of a treatment effect due to continued encounters of sites by new individuals.

Three experiments were conducted with five species of tropical fish to investigate the phenomena of taste aversion and food neophobia. In addition, an experiment determined specifically if position in the tank could acquire conditioned aversive properties. In Experiment 1 , four habituated fish were fed novel meat-flavored pellets on the treatment day. Six were made ill within 30, 60, or 90 minutes (2 subjects each) by intragastric administration of syrup or Epicac. The following day all were fed familiar commercial pellets. On the second day after treatment, all were offered the meat-flavored pellets. Results showed longer latencies, more tasting, and decreased consumption of novel pellets. All measures differed significantly for the treatment subjects compared to their own baseline and controls. Experiment II demonstrated food neophobia in four in experienced fish. After habituation they were fed novel meat-flavored pellets but not made ill (day 0). On day 1 and 2 they received familiar diet and were made ill after the feeding on day 2. On day 3 they received familiar food again and no change in approach latency, testing response, or quantity consumed occurred. On day 4, they were offered the novel meat-flavored pellets which they refused. These results indicate that the fish associated the illness with the more "novel" food even though their familiar diet was temporally closer to the illness. In Experiment III five species of naive fish were habituated to 20-gallon tanks and made ill after eating in one end and not in the other. The same food was us ed in both ends. The "illness end" could have taken on discriminitive properties and food consumption there should have decreased, as opposed to the other "safe end". The results indicated that "place" did not acquire aversive discriminitive properties. Food consumption decreased in quantity, food approach latencies increased and length of tasting bouts increased in both ends. These experiments were the first to use these species of fish in this type of research. The results extend the phenomena of taste aversion and food neophobia. In addition, Experiment III systematically replicated the hypothesis of relevant relations between stimuli and showed that it is easier to learn certain consequences with certain cues than with others. In this case illness was quickly associated with taste but "place" was treated as irrelevant.

No description available.

Long-term memories turn labile with reactivation and undergo a re-stabilization process, termed reconsolidation, involving molecular changes that allow updating of an existing memory trace. Such molecular changes may involve the activation of kinases and expression of proteins related to the increase of synaptic plasticity and memory formation. A kinase reported to have a role in a variety of memory tasks is the extracellular signal-regulated kinase 1/2 (ERK1/2). The downstream activation of ERK targets other regulatory enzymes, transcription factors and cytoskeletal proteins, which allow structural changes in the neuron due to protein synthesis up-regulation. Among the proteins up-regulated by ERK activity is the activity-regulated cytoskeleton-associated protein (ARC), an immediate early gene related to synaptic plasticity. The phase-dependent roles of ERK and ARC have not been examined as part of the molecular mechanisms triggered after a learning experience. In this study I used conditioned taste aversion (CTA) as the learning paradigm and investigated the expression of pERK and ARC in brain regions critical for taste information processing such as the insular cortex and the amygdala. A differential pattern of protein expression was observed in the insular cortex (IC) two hours after taste memory acquisition: pERK activity increased in the aversively conditioned group while ARC increased in the group that received only the novel taste. The central amygdala (CeA) showed a significant increase in pERK, but not ARC activity after CTA training. Immunoblotting experiments performed after memory retrieval in the appetitive group show that pERK continues to signal aversive taste to the IC with ARC exhibiting heightened expression an hour later. An increase in ARC expression 30 minutes after reactivation of the aversive taste was seen in the basolateral amygdala and the CeA exhibited a similar increase at 60 and 90 minutes. Local infusion of ARC antisense oligonucleotides within the IC interfered with the consolidation of safe taste memories, but not with their acquisition. Trace update experiments showed that ARC influences the memory switch from aversive to safe, but not the reverse. Our results indicate that ARC plays a critical role in consolidation and updating of safe taste memories, and the ARC signaling could possibly elicit ERK activation.

I tested the efficacy of aversive conditioning (AC) and conditioned taste aversion (CTA) on American black bears (Ursus americanus) in Whistler, British Columbia. Black bears subjected to 3-5 day AC programs responded by increasing their wariness toward humans, while control bears habituated. Bears were located closer to human developments during daylight hours after AC treatments. However, there was no difference in the proportion of utilization distribution that overlapped with developed areas in control or AC-treated bears. CTA may be effective for managing specific attractants that are difficult to secure from bears. Bears appeared to distinguish between baits treated with thiabendazole and baits that were not treated, but by using a protocol that caused severe illness and left the source of illness in doubt, I induced taste aversions to apples in 4 bears. Using both AC and CTA may help wildlife managers mitigate human-wildlife conflicts non-lethally more effectively. / Ecology

Research Doctorate - Doctor of Philosophy (PhD) / This thesis investigates mechanisms of brain maturation by utilising the special advantages offered by the protracted maturation of neural circuits in chicken forebrain. Biochemical, behavioural and electrophysiological techniques are used in behaving animals to investigate the functional consequences of maturation changes at the molecular, behavioural and physiological levels. Two issues are addressed: (1) do immature (2 week) and mature (8 week) chickens employ different molecular mechanisms to produce changes in neuronal function after learning a behavioural task; and (2) can quantitative non-invasive measures of neuronal function be used to monitor maturation changes in chicken forebrain? Biochemical investigation of subcellular fractions using antibodies and western blots of chicken forebrain and intermediate medial mesopallium (IMM) revealed regional differences in expression levels of a number of components of the glutamatergic neurotransmitter system. The discriminative taste aversion learning (DTAL) task was used to assess whether an animal learns the same task at different ages using different intracellular signalling pathways. The patterns of biochemical change seen in the IMM after DTAL training was very different at 2 weeks and 8 weeks. Two major differences were observed. Firstly, the same type of training induced changes occurred at both ages in GluR1 and CaMKII but they occurred faster at 8 weeks. Secondly the difference in ERK and CREB responses is consistent with a change in the relative contribution made by the ERK signalling pathway and CREB requirement to learning at these two ages. These results imply that the molecular changes induced by learning a behavioural task are faster in mature than immature brain and may involve a different balance of intracellular signalling pathways. In order to be able to investigate biological mechanisms controlling maturation and to use the chicken as an animal model in which pharmacological and/or environmental agents can be screened for potentially harmful effects on brain maturation two non-invasive measures of neuronal function were investigated. One was behavioural (prepulse inhibition: PPI) and the other was electrophysiological (auditory evoked related potentials: AERP). PPI in the chicken was examined electromyographically and via whole body movement with a stabilimeter apparatus. In two strains of chicken (a meat breed and a laying breed) PPI was identified but shown to be small and variable compared to that in the rat. The results indicate that the phenomenon of PPI in the chicken is too small and variable to be used as a quantitative measure of neural circuit maturation. Quantitative analysis of the chicken AERP revealed a significant decrease in amplitude of the positive AERP component and a decrease in latency of the negative AERP component with maturation. These maturation changes were comparable to developmental changes seen in human and other mammal AERPs. Such changes may reflect changes in the intracortical synaptic organisation of the auditory cortex. This technique allowed for repeated measures to be undertaken on the same animal over a number of weeks and enabled developmental changes to be monitored. This technique was extended to investigate perturbed maturation via the induction of chemically induced hypothyroidism. Results from this study showed that the induction of late onset hypothyroidism produces measurable effects on the chicken AERP consistent with perturbation in maturation of neuronal circuits and synapses. This suggests that AERPs may be useful non-invasive functional measures of brain maturation that can be used to study the effects of endogenous or exogenous factors on brain maturation in the chicken. Since human brain also exhibits a protracted maturation period the availability of a well characterised animal model for protracted brain maturation provides an opportunity to identify molecules, genes and environmental factors that are important in the regulation of maturation. Such a model may provide the basis for developing rational therapies or prevention strategies for some neurodevelopmental disorders. The protracted maturation of neuronal circuits observed in chicken forebrain offers such a model.