A systematic study of the necessary and sufficient ingredients of a successful model of classical conditioning is presented. Models are constructed along the lines proposed by Gelperin, Hopfield, and Tank, who showed that many conditioning phenomena could be reproduced in a model using non-trivial distributed representations of the sensory stimuli. The additional phenomena of extinction and blocking are found to be obtainable by generalizing the Hebbian learning algorithm, rather than by additional complications in the hardware. The most successful algorithms have a minimal number of adjustable parameters, and require only local-time information about the level of postsynaptic activity. The proper behavior of these algorithms is verified by both simple analytic arguments and by direct numerical simulation. Certain detailed assumptions concerning the distributed sensory representations are also found to have a surprising degree of importance.
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Psychophysiology
January 2025
Department of Psychology, University of Bonn, Bonn, Germany.
Imaginal exposure is a standard procedure of cognitive behavioral therapy for the treatment of anxiety and panic disorders. It is often used when in vivo exposure is not possible, too stressful for patients, or would be too expensive. The Bio-Informational Theory implies that imaginal exposure is effective because of the perceptual proximity of mental imagery to real events, whereas empirical findings suggest that propositional thought of fear stimuli (i.
View Article and Find Full Text PDFFront Public Health
January 2025
Dipartimento di Scienze Cognitive, Psicologiche, Pedagogiche e Degli Studi Culturali, Università di Messina, Messina, Italy.
Religious beliefs can shape how people process fear. Yet the psychophysiological mechanisms underlying this phenomenon remain poorly understood. We investigated fear learning and extinction processes in a group of individuals who professed a belief in God, compared to non-believers.
View Article and Find Full Text PDFBehav Brain Res
March 2025
Department of Psychological and Brain Sciences, Indiana University, USA. Electronic address:
Exposure to extreme stress can negatively impact behavior and lead to prolonged fear sensitization. These processes can be studied in the lab using stress-enhanced fear learning (SEFL), where prior exposure to inescapable stress exacerbates later contextual fear conditioning. A common method to reduce conditional fear is through extinction, where a conditional stimulus once paired with an unconditional (US; e.
View Article and Find Full Text PDFLearn Mem
January 2025
Department of Psychology, Arizona State University, Tempe, Arizona 85287, USA
Chronic stress typically leads to deficits in fear extinction. However, when a delay occurs from the end of chronic stress and the start of fear conditioning (a "recovery"), rats show improved context-cue discrimination, compared to recently stressed rats or nonstressed rats. The infralimbic cortex (IL) is important for fear extinction and undergoes neuronal remodeling after chronic stress ends, which could drive improved context-cue discrimination.
View Article and Find Full Text PDFJ Pain
January 2025
Innovative Clinical Training, Trials & Healthcare Initiative, Zermatt CH-3920, Switzerland.
In order to disentangle the effects of drugs from placebo responses, several approaches have been used, such as a placebo run-in phase in which only placebo nonresponders, or poor responders, are considered for further randomization to either placebo or active treatment. This study is aimed at investigating the variability of placebo nonresponders obtained through the classical placebo run-in paradigm (group RUN) and through mismatch conditioning (group MIS), as done in our previous study. To do this, we simulated a real clinical trial in the laboratory, in which the placebo responders of both groups were discarded and the remaining nonresponders of both groups RUN and MIS were randomized to either continuing on placebo (groups RUN-P and MIS-P, respectively) or receiving topical 0.
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