Pavlov’s procedure for demonstrating conditioned Inhibition was applied to the case of a discriminated operant to see whether a parallel exists in the operant case. A stimulus (tone) that had become a signal for not responding when paired with one excitatory stimulus (key-color used in conjunction with a go/no-go auditory discrimination) also served as a signal for not responding when it was combined with another excitatory stimulus (key-color used for transfer test) that was clearly discriminated from the one employed in the original training. Skinner’s injections to Pavlov’s demonstration of conditioned inhibition were shown not to apply to the present experiment. A second experiment showed that training of a kind that led to a conditioned inhibitory function for a stimulus paired with nonreinforcement can also lead to a conditioned excitatory function for a stimulus paired with reinforcement. Appropriate controls made it evident that these results were not due to unconditioned effects of tone. When training and testing procedures which parallel those used in classical conditioning are applied to the discriminated operant, the functions of stimuli in the two types of conditioning prove to be more similar than was previously thought. / Thesis / Master of Arts (MA)

<p>In the present study, we examined the predictions of an attentional-associative model (Schmajuk, Lam, & Gray Journal of Experimental Psychology: Animal Behavior Processes, 22, 321-349, 1996) regarding the effect of attentional manipulations on both discrete and contextual conditioned inhibitors.</p><p>The SLG model assumes that non-reinforced presentations of an inhibitory conditioned stimulus (CS) do not decrease its inhibitory associations. However, the model predicts that extended presentations will decrease attention to the inhibitor, thereby, decreasing both the expression of its inhibitory power in a summation test and the rate of acquisition in a retardation test. The model also predicts that subsequent presentations of the inhibitory CS with a novel CS will increase both its inhibitory power in a summation test and the rate of acquisition in a retardation test. Using a predictive learning design in humans, Experiment 1 examined the predictions involving the summation tests, whereas Experiments 2 and 3 examined the predictions involving the retardation tests. Experimental results were in agreement with the predictions of the model. </p><p>The SLG model also predicts that a salient extinction context (CX) becomes inhibitory and prevents extinction of the excitatory CS-unconditioned stimulus (US) association. Although some data seem to contradict that prediction (e.g., Bouton and King, 1983, Bouton and Swartzentruber, 1986, 1989), Larrauri and Schmajuk (2008) indicated that the CX might not appear inhibitory in a summation test because attention to the CX decreases with many but not few extinction trials. In a human predictive learning experiment, we confirmed the model's predictions that the inhibitory power of the extinction CX can be detected after a few extinction trials when attention to the CX is still high, but not after many extinction trials once attention to the CX has decreased (Experiment 4), and even after many extinction trials by presenting novel CSs to increase attention to the unattended CX (Experiment 5). Furthermore, using an eye-tracker, we confirmed the model's explanation of Experiment 4 results by showing decreased overt attention to the CX after many but not after few extinction trials (Experiment 6).</p><p> Importantly, the view that the extinction CX becomes inhibitory allows the model to explain spontaneous recovery (because attention to the excitatory CS increases before attention to the inhibitory CX), renewal (because the inhibition provided by the extinction CX disappears), and reinstatement (the inhibitory CX becomes neutral or excitatory), as well as a very large number of other experimental results related to extinction. Based on the prediction of the SLG, model the implications of our results for the treatments of anxiety disorders were discussed.</p> / Dissertation

Organisms can form safety associations with cues that predict the absence of an aversive event. This cognitive process, learned safety, is important for modulating emotional processing, as safety cues can decrease fear in the presence of previously learned danger cues. Further, there are clinical implications in understanding learned safety, as individuals with PTSD present with deficits in learned safety. Additionally, there is a well established relationship between smoking and PTSD. The link between smoking and PTSD is unclear, however one possibility is that nicotine-associated changes in cognition could facilitate PTSD symptoms, particularly by disrupting are altering learned safety. Considering that nicotine has been shown to modulate associative learning, including hippocampus-dependent forms of fear learning, we hypothesized that nicotine administration could cause maladaptive associative learning to occur, leading to altered safety learning. In the present study, mice were administered acute nicotine and trained and tested in two forms of cued safety learning, explicitly unpaired and backwards trace conditioning. To test for conditioned inhibition of fear by safety cues we performed summation testing. Summation testing indicated that acute nicotine did not impact unpaired learned safety, but did disrupt backwards trace conditioned safety. Additionally, chronic nicotine was found to have no effect on backwards trace conditioned safety, suggesting the development of tolerance. Importantly, on a separate test in which the backwards trace conditioned stimulus was presented alone in a novel context, acute nicotine administration was found to facilitate a fear association with the backwards trace conditioned stimulus. Therefore, acute nicotine prevented backwards trace conditioned safety, by facilitating the formation of a maladaptive fear association. Finally, we found that infusion of nicotine into the dorsal hippocampus and medial prefrontal cortex resulted in similar maladaptive behavioral patterns in summation testing. These findings are discussed with respect to how nicotine can alter cognition and the role alterations in cognition may play PTSD. / Psychology