Using internal memory representations in associative learning to study hallucination-like phenomenon

Different theta frameworks coexist in the rat hippocampus and are coordinated during memory-guided and novelty tasks

eLife ◽

10.7554/elife.57313 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 2

Author(s):

Víctor J López-Madrona ◽

Elena Pérez-Montoyo ◽

Efrén Álvarez-Salvado ◽

David Moratal ◽

Oscar Herreras ◽

...

Keyword(s):

Sensory Information ◽

Gamma Oscillations ◽

Theta Activity ◽

Coherent Oscillation ◽

Phase Coupling ◽

Internal Memory ◽

Complex Interactions ◽

Theta Frequency ◽

Memory Representations ◽

Hippocampal Theta

Hippocampal firing is organized in theta sequences controlled by internal memory processes and by external sensory cues, but how these computations are coordinated is not fully understood. Although theta activity is commonly studied as a unique coherent oscillation, it is the result of complex interactions between different rhythm generators. Here, by separating hippocampal theta activity in three different current generators, we found epochs with variable theta frequency and phase coupling, suggesting flexible interactions between theta generators. We found that epochs of highly synchronized theta rhythmicity preferentially occurred during behavioral tasks requiring coordination between internal memory representations and incoming sensory information. In addition, we found that gamma oscillations were associated with specific theta generators and the strength of theta-gamma coupling predicted the synchronization between theta generators. We propose a mechanism for segregating or integrating hippocampal computations based on the flexible coordination of different theta frameworks to accommodate the cognitive needs.

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Blocking Is Sensitive to Causal Structure in 4-Year-Old and 8-Year-Old Children

Experimental Psychology (formerly Zeitschrift für Experimentelle Psychologie) ◽

10.1027/1618-3169.52.4.264 ◽

2005 ◽

Vol 52 (4) ◽

pp. 264-271 ◽

Cited By ~ 4

Author(s):

Tom Beckers ◽

Uschi Van den Broeck ◽

Marij Renne ◽

Stefaan Vandorpe ◽

Jan De Houwer ◽

...

Keyword(s):

Young Children ◽

Associative Learning ◽

Learning Theory ◽

Causal Structure ◽

Age Groups ◽

Learning Task ◽

Contingency Learning

Abstract. In a contingency learning task, 4-year-old and 8-year-old children had to predict the outcome displayed on the back of a card on the basis of cues presented on the front. The task was embedded in either a causal or a merely predictive scenario. Within this task, either a forward blocking or a backward blocking procedure was implemented. Blocking occurred in the causal but not in the predictive scenario. Moreover, blocking was affected by the scenario to the same extent in both age groups. The pattern of results was similar for forward and backward blocking. These results suggest that even young children are sensitive to the causal structure of a contingency learning task and that the occurrence of blocking in such a task defies an explanation in terms of associative learning theory.

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Learned Placebo Effects in the Immune System

Zeitschrift für Psychologie ◽

10.1027/2151-2604/a000184 ◽

2014 ◽

Vol 222 (3) ◽

pp. 148-153 ◽

Cited By ~ 2

Author(s):

Sabine Vits ◽

Manfred Schedlowski

Keyword(s):

Nervous System ◽

Immune System ◽

Associative Learning ◽

Placebo Response ◽

Immunosuppressive Drug ◽

Immune Functions ◽

Placebo Effects ◽

New Therapeutic Approaches ◽

Biological Variables ◽

Experimental Approaches

Associative learning processes are one of the major neuropsychological mechanisms steering the placebo response in different physiological systems and end organ functions. Learned placebo effects on immune functions are based on the bidirectional communication between the central nervous system (CNS) and the peripheral immune system. Based on this “hardware,” experimental evidence in animals and humans showed that humoral and cellular immune functions can be affected by behavioral conditioning processes. We will first highlight and summarize data documenting the variety of experimental approaches conditioning protocols employed, affecting different immunological functions by associative learning. Taking a well-established paradigm employing a conditioned taste aversion model in rats with the immunosuppressive drug cyclosporine A (CsA) as an unconditioned stimulus (US) as an example, we will then summarize the efferent and afferent communication pathways as well as central processes activated during a learned immunosuppression. In addition, the potential clinical relevance of learned placebo effects on the outcome of immune-related diseases has been demonstrated in a number of different clinical conditions in rodents. More importantly, the learned immunosuppression is not restricted to experimental animals but can be also induced in humans. These data so far show that (i) behavioral conditioned immunosuppression is not limited to a single event but can be reproduced over time, (ii) immunosuppression cannot be induced by mere expectation, (iii) psychological and biological variables can be identified as predictors for this learned immunosuppression. Together with experimental approaches employing a placebo-controlled dose reduction these data provide a basis for new therapeutic approaches to the treatment of diseases where a suppression of immune functions is required via modulation of nervous system-immune system communication by learned placebo effects.

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