Stronger renewal in human fear conditioning when tested with an acquisition retrieval cue than with an extinction retrieval cue

It was previously demonstrated in our laboratory that conditioned fear in humans can renew after extinction, when this procedure took place in a different context (ABA-renewal [Vansteenwegen et al. (2005). Return of fear in a human differential conditioning paradigm caused by a return to the original acquisition context. Behaviour Research and Therapy, 43(3), 323–336]). Using the same experimental design, we now tested the power of retrieval cues to interact with this contextual renewal phenomenon. Two groups went through acquisition and extinction (in a different context). They were then tested in the original acquisition context and in the presence of a retrieval cue. In the acquisition-cue group, this cue previously featured during the acquisition procedure; in the extinction-cue group, the cue previously featured during the extinction procedure. As expected, renewal of conditioned electro-dermal responding and retrospective expectancy ratings was strongest in the acquisition-cue group. Theoretical and clinical implications of this finding are discussed.     

Both exposure to a novel context and associative learning induce an upregulation of AKAP150 protein in mouse hippocampus

A-kinase anchoring protein 150 (AKAP150) is a multi-enzyme signaling complex that coordinates the action of PKA, PKC, and PP2B at neuronal membranes and synapses. We measured levels of AKAP150 protein in the hippocampus 6h after training mice in a contextual fear conditioning paradigm. In contextual fear conditioning mice learn to associate a context with a footshock presentation. Mice were divided in four experimental groups with different training protocols: naive, no footshock exposure, immediate footshock exposure, and footshock 3min after exposure to the context. We found that AKAP150 protein levels were increased upon exposing mice to the novel context independent of the training protocol. However, when the animals were habituated to the experimental context, only mice that learned to associate the context with the footshock showed an upregulation of AKAP150. We suggest that upregulated levels of AKAP150 contribute to processing the exposure to a novel context and associative learning.     

Stimulus characteristics that can enhance or decrease aggression: Associations with prior positive or negative reinforcements for aggression

To establish an analogue of the “weapons effect,” male university subjects were required to use a distinctive apparatus in delivering noxious sounds to a peer in an adjoining room, and then were either (a) positively reinforced, or (b) negatively reinforced, or (c) not given any reaction by the experimenter, for what they had done. Immediately after this, each person had to administer other noise blasts to someone else in a different manner, but with the previous noise machines (the fist “weapon”) being either present or not present. The initial “weapon's” presence augmented the effects of the prior reinforcement; the second victim was attacked most strongly after the men had been positively reinforced and the earlier “weapon” was nearby, whereas he received the fewest blasts if the subjects had been negatively reinforced and the earlier noise machine was present. Other evidence indicates (1) that the aggressive cue, the “weapon,” had not affected the subjects' aggressive intentions, (2) the results are not due simply to differences in moods or general arousal, and (3) the subjects were not aware of the hypothesis regarding the interaction of reinforcement and cue presence.     

Does attitude acquisition in evaluative conditioning without explicit CS-US memory reflect implicit misattribution of affect?

Research that dissociates different types of processes within a given task using a processing tree approach suggests that attitudes may be acquired through evaluative conditioning in the absence of explicit encoding of CS-US pairings in memory. This research distinguishes explicit memory for the CS-US pairings from CS-liking acquired without encoding of CS-US pairs in explicit memory. It has been suggested that the latter effect may be due to an implicit misattribution process that is assumed to operate when US evocativeness is low. In the present research, the latter assumption was supported neither by two high-powered experiments nor by complementary meta-analytic evidence, whereas evocativeness exerted an influence on explicit memory. This pattern of findings is inconsistent with the view that CS-liking acquired without encoding of CS-US pairs in explicit memory reflects an implicit misattribution process at learning. Hence, the underlying learning process is awaiting further empirical scrutiny.