Le conditionnement classique de la réponse sexuelle humaine masculine

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Comparación del efecto de mera exposición y el condicionamiento clásico en la formación de preferencias

El objetivo de este estudio fue comparar la eficacia del condicionamiento clásico (CC) y el efecto de mera exposición (ME), en condiciones supraliminales (2000 milisegundos –ms-), sobre la formación de preferencias hacia marcas publicitarias. Se realizó un experimento con diseño intrasujeto, donde se manipuló la variable tratamiento afectivo representada por los dos procedimientos a comparar y se midió la variable dependiente –preferencia hacia las marcas- a través de una tarea de elección forzosa y un diferencial semántico. En el experimento participaron 70 hombres, estudiantes de medicina de la Universidad del Rosario con edades entre 18 y 22 años. El CC se realizó a través de un procedimiento simultáneo y en ambas condiciones la variable independiente se expuso el estímulo 8 veces con una duración de 2000 ms. Los resultados mostraron que los dos procedimientos generaron preferencias en los sujetos, pero no diferencias significativas entre la efectividad de los procedimientos.

Attempts to control pain prioritize attention to signals of pain: an experimental study

Clinical evidence suggests that a persistent search for solutions for chronic pain may bring along costs at the cognitive, affective, and behavioral level. Specifically, attempts to control pain may fuel hypervigilance and prioritize attention towards pain-related information. This hypothesis was investigated in an experiment with 41 healthy volunteers. Prioritization of attention towards a signal for pain was measured using an adaptation of a visual search paradigm in which participants had to search for a target presented in a varying number of colored circles. One of these colors (Conditioned Stimulus) became a signal for pain (Unconditioned Stimulus: electrocutaneous stimulus at tolerance level) using a classical conditioning procedure. Intermixed with the visual search task, participants also performed another task. In the pain-control group, participants were informed that correct and fast responses on trials of this second task would result in an avoidance of the Unconditioned Stimulus. In the comparison group, performance on the second task was not instrumental in controlling pain. Results showed that in the pain-control group, attention was more prioritized towards the Conditioned Stimulus than in the comparison group. The theoretical and clinical implications of these results are discussed.

Contribution to the chemoreception capacity of juvenile Loggerhead sea turtles (Caretta caretta, L.)

Loggerhead sea turtle juveniles (Caretta caretta), pelagic stage, are found in waters of Madeira archipelago. Pelagic turtles are in the main growth phase of their life cycle and consequently higher energy needs. However, knowledge about the ecology of pelagic loggerhead sea turtles is still quite rudimentary, mainly about the mechanisms that lead them to find food in the vast ocean. Studies with other pelagic species, such as procellariiform birds, revealed that the olfactory system play an important role for the detection of feeding areas, through the detection of concentration peaks of DMS (dimethylsulfide), a scent compound that naturally exists in the marine environment and it is related to areas of high productivity. Based on the assumption that loggerhead sea turtles use a similar mechanism, behavioural experiments were conducted in order to analyze the chemoreception capacity to DMS (airborne chemoreception - theoretically responsible for the long distance detection of areas with food patches; and aquatic chemoreception - theoretically responsible for the short distance detection of preys). The first step was to observe if pelagic loggerheads demonstrate sensitivity to DMS and the second was to verify if they really use the DMS, in natural conditions, as an airborne cue to find areas where food patches might be available. Four juveniles of loggerhead sea turtles were tested in captivity and three wild turtles in the open ocean. The results of airborne chemoreception experiments in captivity revealed that one turtle clearly demonstrated sensitivity to DMS and the sea experiments confirmed this result. However, the experiments were not conclusive on the question whether the pelagic turtles actually use the DMS as an airborne cue to detect long distance food patches. In aquatic chemoreception experiments was not observed sensitivity to DMS by the three sea turtles tested. In the classical conditioning experiment, where DMS and food were given nearly at the same time revealed that after a certain period of time, the sea turtle tested did not associated the DMS stimulus with a possible food reward. The main cause of mortality of loggerhead sea turtles in Madeira waters is due to the accidental capture (bycatch) by deep pelagic longlines fishery which the target species is the black-scabbard (Aphanopus carbo) fish. Chub mackerel (Scomber japonicus) is one of the baits used in this fishery. Aquatic chemoreception experiments were conducted in order to evaluate the attractiveness of the chub mackerel for sea turtles. For the three sea turtles tested, the results showed that in 90% of the cases the sea turtles were extremely attracted by the underwater smell of this fish.

Repeated unrewarded scent exposure influences the food choice of stingless bee foragers, Melipona scutellaris

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Repeated measurements of learned irrelevance by a novel within-subject paradigm in humans

Learned irrelevance (LIrr) refers to the retardation of classical conditioning following preexposure of the to-be-associated stimuli. Healthy volunteers have been tested on three occasions with a new LIrr paradigm avoiding methodological problems which afflict traditional paradigms. A significant LIrr effect was demonstrated on each occasion. Thus, the new paradigm enables repeated measurements of LIrr and might be useful in evaluating long-term effects of medication in psychiatric disorders exhibiting aberrant LIrr.

Stress effects on working memory, explicit memory, and implicit memory for neutral and emotional stimuli in healthy men

Stress is a strong modulator of memory function. However, memory is not a unitary process and stress seems to exert different effects depending on the memory type under study. Here, we explored the impact of social stress on different aspects of human memory, including tests for explicit memory and working memory (for neutral materials), as well as implicit memory (perceptual priming, contextual priming and classical conditioning for emotional stimuli). A total of 35 young adult male students were randomly assigned to either the stress or the control group, with stress being induced by the Trier Social Stress Test (TSST). Salivary cortisol levels were assessed repeatedly throughout the experiment to validate stress effects. The results support previous evidence indicating complex effects of stress on different types of memory: A pronounced working memory deficit was associated with exposure to stress. No performance differences between groups of stressed and unstressed subjects were observed in verbal explicit memory (but note that learning and recall took place within 1 h and immediately following stress) or in implicit memory for neutral stimuli. Stress enhanced classical conditioning for negative but not positive stimuli. In addition, stress improved spatial explicit memory. These results reinforce the view that acute stress can be highly disruptive for working memory processing. They provide new evidence for the facilitating effects of stress on implicit memory for negative emotional materials. Our findings are discussed with respect to their potential relevance for psychiatric disorders, such as post traumatic stress disorder.

Neural analogs of associative learning in {\it Aplysia\/}: Experimental and theoretical approaches

A change in synaptic strength arising from the activation of two neuronal pathways at approximately the same time is a form of associative plasticity and may underlie classical conditioning. Previously, a cellular analog of a classical conditioning protocol has been demonstrated to produce short-term associative plasticity at the connections between sensory and motor neurons in Aplysia. A similar training protocol produced long-term (24 hour) enhancement of excitatory postsynaptic potentials (EPSPs). EPSPs produced by sensory neurons in which activity was paired with a reinforcing stimulus were significantly larger than unpaired controls 24 hours after training. To examined whether the associative plasticity observed at these synapses may be involved in higher-order forms of classical conditioning, a neural analog of contingency was developed. In addition, computer simulations were used to analyze whether the associative plasticity observed in Aplysia could, in theory, account for second-order conditioning and blocking. ^

Responses of Atlantic Salmon Parr to Output of Pulsed Ultrasonic Transmitters

The output from some pulsed ultrasonic transmitters commonly used in fish movement studies is faintly audible to humans. This study was undertaken to determine if the output from these and some other transmitters is detectable by Atlantic salmon (Salmo salar) parr. Classical conditioning of cardiac deceleration was attempted using the transmitter's output as the conditioned stimulus. The results from 29 experimental and 14 control fish suggest that the parr were unable to detect the output from these transmitters.

Memory systems in the brain and localization of a memory

It is now clear that there are a number of different forms or aspects of learning and memory that involve different brain systems. Broadly, memory phenomena have been categorized as explicit or implicit. Thus, explicit memories for experience involve the hippocampus–medial temporal lobe system and implicit basic associative learning and memory involves the cerebellum, amygdala, and other systems. Under normal conditions, however, many of these brain–memory systems are engaged to some degree in learning situations. But each of these brain systems is learning something different about the situation. The cerebellum is necessary for classical conditioning of discrete behavioral responses (eyeblink, limb flexion) under all conditions; however, in the “trace” procedure where a period of no stimuli intervenes between the conditioned stimulus and the unconditioned stimulus the hippocampus plays a critical role. Trace conditioning appears to provide a simple model of explicit memory where analysis of brain substrates is feasible. Analysis of the role of the cerebellum in basic delay conditioning (stimuli overlap) indicates that the memories are formed and stored in the cerebellum. The phenomenon of cerebellar long-term depression is considered as a putative mechanism of memory storage.

Rapidly induced auditory plasticity: The ventriloquism aftereffect

Cortical representational plasticity has been well documented after peripheral and central injuries or improvements in perceptual and motor abilities. This has led to inferences that the changes in cortical representations parallel and account for the improvement in performance during the period of skill acquisition. There have also been several examples of rapidly induced changes in cortical neuronal response properties, for example, by intracortical microstimulation or by classical conditioning paradigms. This report describes similar rapidly induced changes in a cortically mediated perception in human subjects, the ventriloquism aftereffect, which presumably reflects a corresponding change in the cortical representation of acoustic space. The ventriloquism aftereffect describes an enduring shift in the perception of the spatial location of acoustic stimuli after a period of exposure of spatially disparate and simultaneously presented acoustic and visual stimuli. Exposure of a mismatch of 8° for 20–30 min is sufficient to shift the perception of acoustic space by approximately the same amount across subjects and acoustic frequencies. Given that the cerebral cortex is necessary for the perception of acoustic space, it is likely that the ventriloquism aftereffect reflects a change in the cortical representation of acoustic space. Comparisons between the responses of single cortical neurons in the behaving macaque monkey and the stimulus parameters that give rise to the ventriloquism aftereffect suggest that the changes in the cortical representation of acoustic space may begin as early as the primary auditory cortex.

Experience as a moderator of involvement and satisfaction on brand loyalty in a business-to-business setting 02-314R

This paper examines the relative influence of two key antecedents of brand loyalty-satisfaction and involvement and the moderating role of experience, using a sample of business buyers. The central argument of this paper is that the strength of the effect of these variables on attitudinal brand loyalty will vary with the level of customer experience with purchasing the service. Building on previous research which examined low-risk, customer product settings [Kim, J., Lim, J.S., & Bhargava, M. (1998). The role of affect in attitude formation: A classical conditioning approach. Journal of the Academy of Marketing Science 26 (2): pp. 143-152; Shiv, B., & Fedorikhin, A. (1999). Heart and mind in conflict: The interplay of affect and cognition in consumer decision-making. Journal of Consumer Research 26: 278], this study shows that for a high-risk setting, involvement with the service category will be more dominant in its influence on brand loyalty than satisfaction with the preferred brand. Furthermore, it was found that experience moderated the influence of involvement and satisfaction on attitudinal brand loyalty for a high-risk business-to-business service. This study provides new insights into the theory and practice of buyer behavior and business-to-business brands. Crown Copyright (C) 2004 Published by Elsevier Inc. All rights reserved.

Consumers' responses to sponsorship by foreign companies

Purpose: The study aims to explore the novel issue of how consumers perceive sponsorship initiatives by foreign companies and how the sponsors' country-of-origin (COO) cue may influence sponsorship outcomes. Design/methodology/approach: The measurement model and proposed relationships were tested based on a sample of 811 Chinese consumers using confirmatory factor analysis and structural path analysis. Findings: The results reveal that attitudes toward the sponsor completely mediate the effect of event involvement on willingness to buy from the sponsor (WBS). Attitudes toward the sponsor also partially mediate the relationship between economic animosity towards a specific sponsor's COO and WBS. Additionally, the level of a country's economic competitiveness found to moderate the negative relationship between economic animosity, attitudes toward the sponsor and WBS. Research limitations/implications: The nature of the product type and the desire of the consumer to own such a product may have influenced the measurement of willingness to buy. Practical implications: The research adds to the existing knowledge by identifying the opportunities and potential biases that a foreign company may encounter when considering sponsoring a mega sport event in a different cultural context. The study helps managers to understand how sports sponsorship could be used effectively in emerging markets. Originality/value: The proposed conceptual model advances the application of classical conditioning theory, the consumer animosity model of foreign product purchase and the belief-attitude-intention hierarchy in the sponsorship arena. It is the first investigation of the role of event involvement and economic animosity in understanding sponsorship responses. © Emerald Group Publishing Limited.

An automated method for the determination of electroreception thresholds in weakly electric fish

Weakly electric fish produce a dual function electric signal that makes them ideal models for the study of sensory computation and signal evolution. This signal, the electric organ discharge (EOD), is used for communication and navigation. In some families of gymnotiform electric fish, the EOD is a dynamic signal that increases in amplitude during social interactions. Amplitude increase could facilitate communication by increasing the likelihood of being sensed by others or by impressing prospective mates or rivals. Conversely, by increasing its signal amplitude a fish might increase its sensitivity to objects by lowering its electrolocation detection threshold. To determine how EOD modulations elicited in the social context affect electrolocation, I developed an automated and fast method for measuring electroreception thresholds using a classical conditioning paradigm. This method employs a moving shelter tube, which these fish occupy at rest during the day, paired with an electrical stimulus. A custom built and programmed robotic system presents the electrical stimulus to the fish, slides the shelter tube requiring them to follow, and records video of their movements. I trained the electric fish of the genus Sternopygus was trained to respond to a resistive stimulus on this apparatus in 2 days. The motion detection algorithm correctly identifies the responses 91% of the time, with a false positive rate of only 4%. This system allows for a large number of trials, decreasing the amount of time needed to determine behavioral electroreception thresholds. This novel method enables the evaluation the evolutionary interplay between two conflicting sensory forces, social communication and navigation.

Molecular mechanisms of classical fear conditioning : GABAergic factors and their role in fear-related network activities

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010