Potentiation or diminution of discrete motor unconditioned responses (rabbit eyeblink) to an aversive Pavlovian unconditioned stimulus by two associative processes: Conditioned fear and a conditioned diminution of unconditioned stimulus processing.

1992 ◽  
Vol 106 (3) ◽  
pp. 498-508 ◽  
Author(s):  
Turhan Canli ◽  
Wayne M. Detmer ◽  
Nelson H. Donegan
Keyword(s):  
Unconditioned Stimulus ◽  
Conditioned Fear ◽  
Stimulus Processing ◽  
Associative Processes

Serotonin depletion reduces both acquisition and expression of context-conditioned fear

2021 ◽  
pp. 1-8
Author(s):  
S. Melker Hagsäter ◽  
Robert Pettersson ◽  
Axel Holmäng ◽  
Elias Eriksson
Keyword(s):  
Unconditioned Stimulus ◽  
Memory Consolidation ◽  
Clinical Studies ◽  
Conditioned Fear ◽  
Sprague Dawley ◽  
Serotonin Synthesis ◽  
Synthesis Inhibitor ◽  
Serotonin Depletion ◽  
Sprague Dawley Rats ◽  
The Impact

Abstract Objective: Whereas numerous experimental and clinical studies suggest a complex involvement of serotonin in the regulation of anxiety, it remains to be clarified if the dominating impact of this transmitter is best described as anxiety-reducing or anxiety-promoting. The aim of this study was to assess the impact of serotonin depletion on acquisition, consolidation, and expression of conditioned fear. Methods: Male Sprague–Dawley rats were exposed to foot shocks as unconditioned stimulus and assessed with respect to freezing behaviour when re-subjected to context. Serotonin depletion was achieved by administration of a serotonin synthesis inhibitor, para-chlorophenylalanine (PCPA) (300 mg/kg daily × 3), (i) throughout the period from (and including) acquisition to (and including) expression, (ii) during acquisition but not expression, (iii) after acquisition only, and (iv) during expression only. Results: The time spent freezing was significantly reduced in animals that were serotonin-depleted during the entire period from (and including) acquisition to (and including) expression, as well as in those being serotonin-depleted during either acquisition only or expression only. In contrast, PCPA administrated immediately after acquisition, that is during memory consolidation, did not impact the expression of conditioned fear. Conclusion: Intact serotonergic neurotransmission is important for both acquisition and expression of context-conditioned fear.

Selective serotonin reuptake inhibition increases noise burst-induced unconditioned and context-conditioned freezing

2018 ◽  
Vol 31 (1) ◽  
pp. 46-51
Author(s):  
S. Melker Hagsäter ◽  
Johan Thorén ◽  
Robert Pettersson ◽  
Elias Eriksson
Keyword(s):  
Unconditioned Stimulus ◽  
Serotonin Reuptake ◽  
Conditioned Response ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Conditioned Fear ◽  
Noise Burst ◽  
Selective Serotonin ◽  
Unconditioned Response ◽  
Acute Administration ◽  
Sprague Dawley

AbstractObjectiveWhereas long-term administration of selective serotonin reuptake inhibitors (SSRIs) is effective for the treatment of anxiety disorders, acute administration of these drugs may exert a paradoxical anxiogenic effect. The aim of the present study was to explore the possible effect of an SSRI in situations of unconditioned or limited conditioned fear.MethodsMale Sprague Dawley rats were administered a single dose of an SSRI, escitalopram, before acquisition or expression of context conditioned fear, where noise bursts were used as the unconditioned stimulus. Freezing was assessed as a measure of unconditioned fear (=the acute response to noise bursts) or conditioned fear (=the response to the context), respectively.ResultsNoise bursts elicited an acute increase in freezing but no robust conditioned response 7 days after exposure. Administration of escitalopram before testing exacerbated the freezing response during presentation of the unconditioned stimulus and also unmasked a conditioned response; in contrast, administration of escitalopram prior to acquisition did not influence the conditioned response.ConclusionThe data suggest that freezing in rats exposed to a stimulus inducing relatively mild fear may be enhanced by acute pretreatment with an SSRI regardless of whether the freezing displayed by the animals is an acute unconditioned response to the stimulus in question or a conditioned response to the same stimulus.

scholarly journals Renewal of conditioned fear responses using a film clip as the aversive unconditioned stimulus

2019 ◽  
Vol 65 ◽  
pp. 101493 ◽  
Author(s):  
Elze Landkroon ◽  
Gaëtan Mertens ◽  
Dieuwke Sevenster ◽  
Pauline Dibbets ◽  
Iris M. Engelhard
Keyword(s):  
Unconditioned Stimulus ◽  
Conditioned Fear ◽  
Film Clip

Effects of Fear on Exploratory Behaviour in Rats

1970 ◽  
Vol 22 (2) ◽  
pp. 205-214 ◽  
Author(s):  
R. Kumar
Keyword(s):  
Unconditioned Stimulus ◽  
Stimulus Control ◽  
Electric Shock ◽  
Conditioned Fear ◽  
Exploratory Behaviour ◽  
The Relationship

It has been suggested that mild fear may evoke rather than inhibit exploratory responses in rats. The relationship between conditioned fear and exploratory behaviour was analysed in three experiments and there was no evidence that mild fear increased exploration. Conditioned fear was found to be under relatively precise stimulus control and its magnitude was related to the intensities and durations of the unconditioned stimulus, inescapable electric shock.

Differential Acquisition, Extinction, and Reinstatement of Conditioned Suppression in Mice

2007 ◽  
Vol 60 (10) ◽  
pp. 1313-1320 ◽  
Author(s):  
Trinette Dirikx ◽  
Tom Beckers ◽  
Clara Muyls ◽  
Paul Eelen ◽  
Debora Vansteenwegen ◽  
...  
Keyword(s):  
Conditioned Stimulus ◽  
Unconditioned Stimulus ◽  
Conditioned Suppression ◽  
Conditioned Fear ◽  
The Other ◽  
Control Group ◽  
Selective Suppression ◽  
Differential Acquisition ◽  
Group A ◽  
Conditioned Responding

In animals, the reappearance of conditioned fear responses after extinction has been primarily investigated using single-cue conditioning paradigms. However, a differential paradigm can overcome several of the disadvantages associated with a single-cue procedure. In the present study, the reinstatement phenomenon was assessed in mice using a differential conditioned suppression paradigm. In a first phase, one conditioned stimulus (CS +) was consistently paired with an unconditioned stimulus (US; footshock) while another CS (CS–) was not, resulting in selective suppression of previously trained instrumental behaviour during the CS +. After the extinction phase, half of the animals (reinstatement group) were presented with unsignalled USs, while the other half were not (control group). A differential return of conditioned responding was observed in the reinstatement group, but not in the control group. The implications of these findings for future conditioning research are discussed.

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