An appetitive conditioned stimulus enhances fear acquisition and impairs fear extinction

Abstract

Four experiments used between-and within-subject designs to examine appetitive -aversive interactions in rats. Experiments 1 and 2 examined the effect of an excitatory appetitive conditioned stimulus (CS) on acquisition and extinction of conditioned fear. In Experiment 1, a CS shocked in a compound with an appetitive excitor (i.e., a stimulus previously paired with sucrose) underwent greater fear conditioning than a CS shocked in a compound with a neutral stimulus. Conversely, in Experiment 2, a CS extinguished in a compound with an appetitive excitor underwent less extinction than a CS extinguished in a compound with a neutral stimulus. Experiments 3 and 4 compared the amount of fear conditioning to an appetitive excitor and a familiar but neutral target CS when the compound of these stimuli was paired with shock. In each experiment, more fear accrued to the appetitive excitor than to the neutral CS. These results show that an appetitive excitor influences acquisition and extinction of conditioned fear to a neutral CS and itself undergoes a greater associative change than the neutral CS across compound conditioning. They are discussed with respect to the role of motivational information in regulating an associative change in appetitive -aversive interactions.Pavlovian conditioned fear in laboratory rodents is widely used to study the substrates of learning and memory in the mammalian brain. One reason for the use of this model is that conditioned fear is thought to contribute to anxiety disorders, such as panic, posttraumatic stress, social, and specific phobias (Rosen and Schulkin 1998). A second reason is that extinction of this fear is a goal of exposure-based treatments of these disorders (VanElzakker et al. 2014). A standard protocol to produce conditioned fear in rodents consists in pairings of a relatively innocuous stimulus, such as a noise, with an innate source of danger, typically brief but aversive foot shock. One or a few such pairings produces an excitatory association between the noise [conditioned stimulus (CS)] and the aversive foot shock [unconditioned stimulus (US)]. The consequence of this association is that subsequent presentations of the CS elicit defensive responses (immobility or freezing, potentiated startle, analgesia, changes in heart rate and blood pressure) indicative of fear in people. Extinction consists in repeated presentations of the CS in the absence of the US. Fear responses decline across these presentations and eventually cease. This decline and cessation of fear responses to the CS is not due to the progressive erasure of its association with the US. Fear restoration phenomena such as renewal, reinstatement, and spontaneous recovery show that at least some of the original CS-US association survives extinction despite the fact that the CS failed to elicit fear responses. These phenomena imply that extinction involves new learning that inhibits retrieval of the CS-US association and/or its expression in fear responses (Delamater and Westbrook 2014).A question of both theore...

Warm hands, warm hearts: An investigation of physical warmth as a prepared safety stimulus.

“…Specifically, social support figures are the first demonstrated prepared safety stimuli , stimuli that have historically enhanced survival and have therefore come to be less easily associated with threat and able to inhibit fear responding (Hornstein & Eisenberger, 2017; Hornstein et al, 2016, 2018). This combination of effects is unique in the Pavlovian fear conditioning literature, in which inhibitors typically require learning (Rescorla, 1969) and have detrimental effects on long-term fear occurrence and recurrence, leading to enhanced fear acquisition (Dickinson, 1976; Rescorla, 1971) and impaired fear extinction (Leung et al, 2016; Lovibond et al, 2000; Rescorla, 1969). Yet, thus far, social support figures are the only identified members of the prepared safety category, leaving questions as to whether there are other cues endowed with this novel ability to inhibit fear responding without specific training and in both the short- and long-term.…”

Social support and fear-inhibition: an examination of underlying neural mechanisms

“…, 2021 ). While other fear inhibitors reduce fear-responding while present, they have harmful effects in the long-term: augmenting fear-acquisition ( Rescorla, 1971 ; Dickinson, 1976 ; Leung et al. , 2016 ) and preventing fear-extinction ( Rescorla, 1969 ; Lovibond et al.…”

Reclassifying the Unique Inhibitory Properties of Social Support Figures: A Roadmap for Exploring Prepared Fear Suppression

“…Interestingly, safety-signals are not the only cues that are able to pass the retardation-ofacquisition and summation tests. Appetitive-cues, cues that signal the occurrence of a reward (e.g., a light paired with food), are also able to resist becoming associated with fear and inhibit the fear-response (9,10). Appetitive and aversive systems are thought to work in opposition to one-another (11)(12)(13)(14), enabling cues that signal expected-reward to compete with, and reduce, aversive-expectations, reducing aversive processes whilst they are present.…”

“…Specifically, the very source of their inhibitory properties-the ability to lessen expectation that an aversive-event will occur-results in changes to the calculations that drive fear-associations and prevents the reduction of long-term-fear in two ways (8,23). First, if these known inhibitors are present during fear extinction, when an already-feared-cue is presented in the absence of an aversive-outcome, lowered aversive-expectation prevents new learning, such that no new association between the feared-cue and absence of shock is formed-a process known as protection-from-extinction (7,10,28). Second, if these known inhibitors are present during fear acquisition, when a separate conditional-cue is being paired with an aversiveoutcome (i.e., shock), lowered aversive-expectation results in more 'surprise' when the shock does occur leading it to become even more robustly associated with the conditional-cue-a process known as superconditioning (9,10,29,30).…”

“…First, if these known inhibitors are present during fear extinction, when an already-feared-cue is presented in the absence of an aversive-outcome, lowered aversive-expectation prevents new learning, such that no new association between the feared-cue and absence of shock is formed-a process known as protection-from-extinction (7,10,28). Second, if these known inhibitors are present during fear acquisition, when a separate conditional-cue is being paired with an aversiveoutcome (i.e., shock), lowered aversive-expectation results in more 'surprise' when the shock does occur leading it to become even more robustly associated with the conditional-cue-a process known as superconditioning (9,10,29,30). Thus, known inhibitors not only reduce fear extinction, but they enhance fear acquisition.…”