Altered top-down and bottom-up processing of fear conditioning in panic disorder with agoraphobia.

BACKGROUND: Although several neurophysiological models have been proposed for panic disorder with agoraphobia (PD/AG), there is limited evidence from functional magnetic resonance imaging (fMRI) studies on key neural networks in PD/AG. Fear conditioning has been proposed to represent a central pathway for the development and maintenance of this disorder; however, its neural substrates remain elusive. The present study aimed to investigate the neural correlates of fear conditioning in PD/AG patients. METHOD: The blood oxygen level-dependent (BOLD) response was measured using fMRI during a fear conditioning task. Indicators of differential conditioning, simple conditioning and safety signal processing were investigated in 60 PD/AG patients and 60 matched healthy controls. RESULTS: Differential conditioning was associated with enhanced activation of the bilateral dorsal inferior frontal gyrus (IFG) whereas simple conditioning and safety signal processing were related to increased midbrain activation in PD/AG patients versus controls. Anxiety sensitivity was associated positively with the magnitude of midbrain activation. CONCLUSIONS: The results suggest changes in top-down and bottom-up processes during fear conditioning in PD/AG that can be interpreted within a neural framework of defensive reactions mediating threat through distal (forebrain) versus proximal (midbrain) brain structures. Evidence is accumulating that this network plays a key role in the aetiopathogenesis of panic disorder.

Optimization of a contextual conditioning protocol for rats using combined measurements of startle amplitude and freezing: the effects of shock intensity and different types of conditioning.

Contextual conditioning in rats is typically quantified using startle amplitude or freezing time. Our goal was to create a robust contextual conditioning protocol combining both startle amplitude and freezing time as measures of contextual anxiety. Comparison of 0.8 mA - 250 ms shocks with an established shock configuration (0.3 mA - 1 s) favoured the first parameters. Subsequently, we systematically investigated the effect of shock intensity (0.6 mA, 0.8 mA or 1.0 mA) and concurrently compared two different contextual conditioning procedures (shocks alone versus unpaired shock-tone presentations). In future experiments, this second type of contextual conditioning may form the optimal contrasting condition for a cued fear conditioning group, trained with explicit cue-shock pairings. The 0.8 mA shocks produced significant contextual freezing and startle potentiation, whereas the 0.6 mA and 1.0 mA shocks only led to a significant increase of freezing time. We found no major differences between the two types of conditioning, implying that these procedures might be equivalent. In conclusion, training with ten 0.8 mA - 250 ms shocks produced reliable contextual conditioning as measured with both startle amplitude and freezing time.

Effect of a retention interval between pre-exposure and conditioning on latent inhibition in humans using a blink conditioning procedure

El fenómeno de la inhibición latente se refi ere al retraso que se observa cuando se presenta repetidamente sin consecuencias un estímulo que va a ser posteriormente condicionado. En este trabajo empleamos un procedimiento de condicionamiento palpebral para analizar la inhibición latente en participantes humanos. El Experimento 1 reveló que el procedimiento empleado era adecuado para reproducir el efecto de inhibición latente. En el Experimento 2, la introducción de un intervalo de tres minutos entre las fases de preexposición y condicionamiento dio lugar a la atenuación de la inhibición latente. Estos resultados contribuyen a la identifi cación de los mecanismos que participan en la preexposición y posterior condicionamiento de un estímulo, aspectos particularmente importantes si tenemos en cuenta que el fenómeno de la inhibición latente ha sido utilizado repetidamente como un instrumento para analizar el curso del proceso atencional tanto en poblaciones normales como con determinadas psicopatologías(AU)

Latent inhibition, retarded learning after pre-exposure to the to-be-conditioned stimulus, was examined using a blink conditioned procedure in humans. Experiment 1 showed that the procedure is suited to inducing the latent inhibition effect. In Experiment 2, the introduction of a 3-minute interval between pre-exposure and conditioning phases attenuated latent inhibition. These results contribute to identify the mechanisms involved in pre-exposure and subsequent conditioning of a stimulus, which is particularly important if we bear in mind that latent inhibition has been used repeatedly as an instrument to analyze the course of attentional processes in normal and pathological populations(AU)

Efectos de la duración del condicionamiento clásico en una situación de interacción clásico-operante / Effect of the duration of the classic conditioning in the an interaction situation classic-operant

En este experimento se examinó el efecto de la duración del condicionamiento clásico sobre la respuesta operante en situación de interacción en 9 sujetos experimentales (divididos en 3 grupos), y sometidos a varias condiciones experimentales, para evaluar las diferencias en la respuesta operante entre los tres grupos, uno de control, en el que los condicionamientos demoran el tiempo necesario para el aprendizaje, un segundo grupo que tuvo un entrenamiento operante de larga duración y un entrenamiento clásico de corta duración y un tercer grupo que se caracterizó por un entrenamiento operante de corta duración y un clásico de larga duración. En el grupo control seobservó una mayor reducción del tiempo de ejecución de la respuesta, portanto no hubo supresión de la respuesta, lo que indica que a mayor entrenamientoclásico, más fuerte es el efecto de éste sobre la tasa de la respuestaoperante.

Modelos animales de ansiedad condicionada (II) / Animal models of conditioned anxiety (part II)

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Acquisition and severity of driving-related fears.

Rachman's theory of fear acquisition proposes that directly-conditioned fears will differ from indirectly-conditioned fears in magnitude and anxiety response patterns, however the theory has received inconsistent empirical support. The aim of the present study was to describe the fear acquisition pathways for a community sample who reported driving-related fears, and to test Rachman's theory of fear acquisition. One hundred and ninety participants completed a questionnaire which assessed a variety of driving-related situations, reactions to motor vehicle accidents (MVAs), and anxiety response patterns. Professional psychological helpseeking and perceived need for treatment for driving-related fears were also assessed. Results failed to support Rachman's predictions. However, it was confirmed that respondents who had been involved in an MVA were more likely to ascribe their fears to a directly-conditioned pathway. The theoretical and methodological implications of the findings are discussed, along with suggestions for assessment of those with driving-related fears.

Importancia do condicionamento para o tratamento odontologico / The importance of conditioning in dental treatment

Procurou-se no presente estudo, ressaltar os varios trabalhos sobre metodos de condicionamento da crianca para o tratamento odontologico. Atraves dele foi possivel chegar a algumas conclusoes com respeito ao assunto, visando a educacao e a sua familiarizacao com a odontologia. Sao elementos importantes para o condicionamento infantil a amizade, a sugestao verbal, a confianca, as experiencias anteriores, o apoio dos familiares e o ambiente do consultorio.