Catálogo de publicaciones - revistas

<jats:title>Remembering Stressful Events</jats:title> <jats:p> Situations surrounding emotional events are better remembered than others that accompany neutral events. However, in severe pathological states such as posttraumatic stress disorder (PTSD), exposure to threatening situations can also result in memory impairment. In this case, a hypermnesia for a salient trauma-related cue is associated with loss of memory for important aspects of the traumatic event. The memory for the core traumatic event is enhanced, but the capacity to place it in the right place and in response to the right cues is reduced. <jats:bold> Kaouane <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1510" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1207615">1510</jats:related-article> , published online 23 February) associated a high-intensity threat with the infusion of corticosterone in the hippocampus to induce PTSD-like memory impairments in mice. The animals became unable to identify the threat context as the right predictor of the threat, and they showed a fear response for discrete salient cues normally identified as safe. The neural activation patterns in the amygdala and hippocampal regions of these mice were similar to those observed in human PTSD. </jats:p>

<jats:title>Adding Artificial Associations</jats:title> <jats:p> In the mammalian cortex, there is significant spontaneous neural activity that is internally generated, rather than arising from sensory inputs, and this activity influences the processing of natural sensory stimuli. What role does this internally generated activity play in forming and accessing new memory representations? Using transgenic mice combined with controlled artificial activation of widely distributed neuronal ensembles associated with specific contexts, <jats:bold> Garner <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="1513" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1214985">1513</jats:related-article> ; see the Perspective by <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6075" page="1455" related-article-type="in-this-issue" vol="335" xlink:href="10.1126/science.1220824"> <jats:bold>Morris and Takeuchi</jats:bold> </jats:related-article> ) investigated how spontaneous neuronal activity is integrated into a given context representation. Animals underwent fear conditioning in two distinct contexts. When a circuit in one context was artificially activated during fear conditioning in a separate context, a so-called “hybrid” memory was formed. This artificially stimulated network became a necessary component of the memory trace. These results are consistent with the emerging view that internally generated brain activity is not noise, but a coherent representation that can be incorporated into new associations and memories. </jats:p>

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