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.     

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.     

Why pigeons say what they do: reinforcer magnitude and response requirement effects on say responding in say-do correspondence

The effects of reinforcer magnitude and response requirement on pigeons' say choices in an experimental homologue of human say-do correspondence were assessed in two experiments. The procedure was similar to a conditional discrimination procedure except the pigeons chose both a sample stimulus (the say component) and a comparison stimulus that corresponded to it (the do component). Correspondence was trained on red, green, and white key colors before the duration of food presentations following correspondence on each key color (Experiment 1) and the number of key pecks required as the say response on each key color (Experiment 2) were manipulated in an attempt to influence the initial say response. The frequency of say responses on each key color coincided with programmed changes in the duration of food presentations and the key-peck requirements assigned to each key color. Correspondence accuracy remained stable in all conditions, even those in which the say responding occurred primarily on two of the three key colors. Implications for human behavior are discussed.     

Fragments of a Case of Psychosis: From Institutional Sheltering to Psychoanalytical Experience

This article describes a psychoanalytical experience that took place in an institution for mental health, located in Rio de Janeiro, Brazil. There, an art workshop was created in an attempt to welcome and shelter psychotic patients. This work space later proportioned a ''setting'' for the practice of psychoanalysis with psychotic patients. In the clinical case, herein examined, the author dedicates special attention to the relation that exists between certain psychotic aspects and the process described by Jacques Lacan as: the ''foreclosure of the name of the father''.     

The uninheritable state and the post-public sphere

In The Politics of Postsecular Religion (2008), Ananda Abeysekara contends that justice has to be predicated on the forgetting of systems of commensuration and calculation for an im-possibility – i.e., an ethical excess – that cannot be circumscribed by repeatable and calculable law. This ethical excess defines a space of politics that would similarly abandon the legacies of codified public memory. However, many of the elements that he identifies with uninheriting and active forgetting coincide with the ‘post-public’ sphere of Sri Lankan political culture, which undermines Habermasian assumptions of a rational and transparent public sphere. The structural forgetfulness that Abeysekara identifies with justice can be discerned in the artifacts and artifices of the Sri Lankan securitized state that is an unjust apparatus of extra-legal violence, moral indifference and orchestrated deniability.     

Negative causation in causal and mechanistic explanation

Instances of negative causation—preventions, omissions, and the like—have long created philosophical worries. In this paper, I argue that concerns about negative causation can be addressed in the context of causal explanation generally, and mechanistic explanation specifically. The gravest concern about negative causation is that it exacerbates the problem of causal promiscuity—that is, the problem that arises when a particular account of causation identifies too many causes for a particular effect. In the explanatory context, the problem of promiscuity can be solved by characterizing the phenomenon to be explained as a contrast between two or more events or non-events. This contrastive strategy also can solve other problems that negative causation presents for the leading accounts of mechanistic explanation. Along the way, I argue that to be effective, accounts of causal explanation must incorporate negative causation. I also develop a taxonomy of negative causation and incorporate each variety of negative causation into the leading accounts of mechanistic explanation.