Post-retrieval effects of icv infusions of hemicholinium in mice are dependent on the age of the original memory

CF-1 male mice were trained in an inhibitory avoidance task using a high footshock (1,2 mA, 50 Hz, 1 sec) in order to reduce the influence of extinction on retention performance. At 2, 7, 14, or 30 d after training, the first retention test was performed and hemicholinium (HC-3, 1.0 microg/mice), a specific inhibitor of high-affinity choline uptake in brain cholinergic neurons, was given intracerebroventricularly immediately after. Twenty four hours after treatment, mice were tested in an inhibitory avoidance task during five consecutive days, each 24 h apart. Retention performance was impaired by HC-3 when the first re-exposure took place at 2, 7, or 14 d, but the effect was no longer seen when re-exposure occurred 30 d after training. We did not find spontaneous recovery 21 d after training, when memory was retrieved 2 d after training and HC-3 was given immediately after. Although we cannot definitively discard a retrieval deficit, this lack of spontaneous recovery is in accordance with the storage-deficit interpretation. These results confirm and extend previous ones, suggesting that central cholinergic mechanisms are involved in the hypothetical reconsolidation memory processes of an inhibitory avoidance task in mice and also suggest that this participation depends on the "age" of the original memory trace. This implies that the vulnerability of a reactivated memory to a specific treatment, as the one used in this study, inversely correlates with the age of the original memory, and it is likely to determine memory reconsolidation processes.     

Stability of recent and remote contextual fear memory

Following initial encoding, memories undergo a prolonged period of reorganization. While such reorganization may occur in many different memory systems, its purpose is not clear. Previously, we have shown that recall of recent contextual fear memories engages the dorsal hippocampus (dHPC). In contrast, recall of remote contextual fear memories engages a number of different cortical regions, including the anterior cingulate cortex (ACC). To examine whether this reorganization leads to greater memory stability, we examined reconsolidation of 1 d-old (recent) and 36 d-old (remote) contextual fear memory in mice. We infused the protein synthesis inhibitor, anisomycin (ANI), into either the dHPC or ACC immediately following retrieval of either a recent or remote contextual fear memory. In the dHPC, ANI infusions disrupted subsequent expression of recent, but not remote, contextual fear memory. Similar infusions into the ACC had no effect on either recent or remote contextual fear memories, whereas systemically applied ANI blocked subsequent remote memory expression when long re-exposure durations were used. Together, these data suggest that as memories mature they become increasingly stable. Furthermore, the dissociation between the effects of systemically and centrally administered ANI on remote memory suggests that stability is due, in part, to the distributed nature of remote contextual fear memories.     

Humans’ folk physics is not enough to explain variations in their tool-using behavior

Two experiments examined adult humans’ folk physics (i.e., their naturally occurring and spontaneous understanding of the physical world) using variations of trap-table problems used to study chimpanzees’ folk physics. When presented with these problems, people unnecessarily avoided retrieving a reward by pulling a rake on the side of a table with a trapping hole—even though it was highly unlikely that the hole would trap the reward. However, when the distance between the reward and the trap was sufficiently large and the distance that the reward had to travel to be retrieved was sufficiently short, people preferred to retrieve a reward by pulling the rake on the side of the table with the trap. These results underscore that behavior during tool-use tasks has many possible causes, only one of which might be a subject’s folk physics.     

Histamine enhances inhibitory avoidance memory consolidation through a H2 receptor-dependent mechanism

Several evidences suggest that brain histamine is involved in memory consolidation but the actual contribution of the hippocampal histaminergic system to this process remains controversial. Here, we show that when infused into the CA1 region of the dorsal hippocampus immediately after training in an inhibitory avoidance task, but not later, histamine induced a dose-dependent promnesic effect without altering locomotor activity, exploratory behavior, anxiety state or retrieval of the avoidance response. The facilitatory effect of intra-CA1 histamine was mimicked by the histamine N-methyltransferase inhibitor SKF-91844 as well as by the H2 receptor agonist dimaprit and it was blocked completely by the H2 receptor antagonist ranitidine. Conversely, the promnesic action of histamine was unaffected by the H1 receptor antagonist pyrilamine, the H3 receptor antagonist, thioperamide, and the NMDAr polyamine-binding site antagonist ifenprodil. By themselves, ranitidine, pyrilamine, thioperamide, and ifenprodil did not affect IA memory consolidation. Our data indicate that, when given into CA1, histamine enhances memory consolidation through a mechanism that involves activation of H2 receptors; however, endogenous CA1 histamine does not seem to participate in the consolidation of IA memory at least at the post-training times analyzed.     

Hidden covariation detection produces faster, not slower, social judgments

In P. Lewicki's (1986b) demonstration of hidden covariation detection (HCD), responses of participants were slower to faces that corresponded with a covariation encountered previously than to faces with novel covariations. This slowing contrasts with the typical finding that priming leads to faster responding and suggests that HCD is a unique type of implicit process. The authors extended Lewicki's methodology and showed that participants exposed to nonsalient covariations between hair length and personality were subsequently faster to respond to faces with those covariations than to faces without, despite lack of awareness of the critical covariations. This result confirms that people can detect subtle relationships between features of stimuli and that, as with other types of implicit cognition, this detection facilitates responding.     

Visuospatial tasks suppress craving for cigarettes

The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task.We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit.     

Cognitive and Psychosocial Consequences of Hurricanes Katrina and Rita Among Middle-Aged, Older, and Oldest-Old Adults in the Louisiana Healthy Aging Study (LHAS)

This study examined the impact of Hurricanes Katrina and Rita on cognitive and psychosocial functioning among middle-aged (45-64 years), older (65-89 years) and oldest-old adults (90 years and over) in the Louisiana Healthy Aging Study (LHAS). Analyses of pre- and post-disaster cognitive data showed storm-related decrements in working memory for the middle-aged and older adults, but not for the oldest-old adults. Regression analyses confirmed that measures of social engagement and storm-related disruption significantly predicted pre- to post-disaster differences in short-term and working memory performance for the middle-aged and older adults only. These results are consistent with a burden perspective on post-disaster psychological reactions. Implications for current views of disaster reactions are discussed.