Antecedent reactivation by surface and deep anaphora in Norwegian

Anaphora are expressions in language that depend on other linguistic entities for their full meaning. They can furthermore be divided into two types according to the level of representation where they find their antecedents: Surface anaphora, which resolve their reference at the sentence representation level, and deep anaphora, which resolve their reference at the non-grammatical level of discourse representation. The linguistic theory of these two anaphor types, and recent findings about processing differences at these two levels, combine to predict that surface anaphora should show fast and immediate reactivation of their antecedents, whereas deep anaphora should have a slower time course of antecedent re-access. These predictions were confirmed with two lexical decision task experiments with Norwegian stimuli.     

Working memory capacity predicts the beneficial effect of selective memory retrieval

Selective retrieval of some studied items can both impair and improve recall of the other items. This study examined the role of working memory capacity (WMC) for the two effects of memory retrieval. Participants studied an item list consisting of predefined target and nontarget items. After study of the list, half of the participants performed an imagination task supposed to induce a change in mental context, whereas the other half performed a counting task which does not induce such context change. Following presentation of a second list, memory for the original list's target items was tested, either with or without preceding retrieval of the list's nontarget items. Consistent with previous work, preceding nontarget retrieval impaired target recall in the absence of the context change, but improved target recall in its presence. In particular, there was a positive relationship between WMC and the beneficial, but not the detrimental effect of memory retrieval. On the basis of the view that the beneficial effect of memory retrieval reflects context-reactivation processes, the results indicate that individuals with higher WMC are better able to capitalise on retrieval-induced context reactivation than individuals with lower WMC.     

Brief wakeful resting can eliminate directed forgetting

When cued to intentionally forget previously encoded memories, participants typically show reduced recall of the memories on a later recall test. We examined how such directed forgetting is affected by a brief period of wakeful resting between encoding and test. Encoding was followed by a “passive” wakeful resting period in which subjects heard emotionally neutral music or perceived neutral pictures, or it was followed by an “active” distraction period in which subjects were engaged in counting or calculation tasks. Whereas typical directed forgetting was present after active distraction, the forgetting was absent after wakeful resting. The findings indicate that the degree to which people can intentionally forget memories is influenced by the cognitive activity that people engage in shortly after learning takes place. The results provide first evidence on the interplay between wakeful resting and intentional forgetting.     

Reactivation and Consolidation of Memory During Sleep

ABSTRACT— Recent research has shown compellingly that sleep supports the consolidation of declarative memories for events and facts. During consolidation, memories are stabilized against future interference and undergo qualitative changes with regard to their "explicitness" and underlying neural representation. In this article, we argue that declarative memory consolidation during sleep is based on covert reactivations of newly encoded memory traces in the hippocampus. During slow-wave sleep (SWS), the prominent slow oscillations act to synchronize the repeated reactivation of the newly encoded representations in hippocampal networks with the generation of spindle activity in the thalamus, supporting changes in neocortical networks that contribute to long-term memory storage. In this view, sleep plays an active role in the consolidation of memories, in which the neuronal reactivation of newly acquired memories is critical for the redistribution and integration of these memories into the network of pre-existing long-term memories.     

Searching for the Trace: The Influence of Age, Lexical Activation and Working Memory on Sentence Processing

To investigate the stability of trace reactivation in healthy older adults, 22 older volunteers with no significant neurological history participated in a cross-modal priming task. Whilst both object relative center embedded (ORC) and object relative right branching (ORR) sentences were employed, working memory load was reduced by limiting the number of words separating the antecedent from the gap for both sentence types. Analysis of the results did not reveal any significant trace reactivation for the ORC or ORR sentences. The results did reveal, however, a positive correlation between age and semantic priming at the pre-gap position and a negative correlation between age and semantic priming at the gap position for ORC sentences. In contrast, there was no correlation between age and priming effects for the ORR sentences. These results indicated that trace reactivation may be sensitive to a variety of age related factors, including lexical activation and working memory. The implications of these results for sentence processing in the older population are discussed.     

Memory retrieval as a self-propagating process

Retrieval of a subset of studied items and the presentation of those items as retrieval cues typically impair retrieval of the other items. Previous research on this self-limiting property of memory retrieval has relied heavily on short retention intervals and similar context between encoding and test. Here, we examined retrieval dynamics also after a prolonged retention interval with different spatial and social context between encoding and test, conditions that mimic people’s remembering in many situations of daily life. For both unrelated word lists and more integrated prose material, we found retrieval and cuing to impair recall of other studied items after a short retention interval, but to improve recall in the prolonged retention interval condition. The results demonstrate that retrieval dynamics depend critically on situation, indicating that quite often in daily life, retrieval may be a self-propagating, rather than a self-limiting process.     

Reactivated memory of an inhibitory avoidance response in mice is sensitive to a nitric oxide synthase inhibitor

It is accepted that once consolidation is completed memory becomes permanent. However, it has also been suggested that reactivation (retrieval) of the original memory, again, makes it sensitive to the same treatments that affect memory consolidation when given after training. Previous results demonstrated that the immediate post-training intraperitoneal administration of N^ω-nitro-l-arginine methyl ester (L-NAME), a non-specific inhibitor of nitric oxide synthase (NOS), impairs retention test performance of a one-trial step-through inhibitory avoidance response in adult mice. The effect of L-NAME on retention was attributed to an action on memory consolidation of the original learning. For the first time, we report that the administration of L-NAME after the first retention test (memory reactivation) of the inhibitory avoidance response impairs retention performance over six consecutive days. This impairment effect is dose-and-time dependent and could not be attributed to a retrieval deficit since a mild footshock did not reinstate the original avoidance response and no spontaneous recovery was observed at least 21 days after training. Further support for a storage deficit interpretation as opposed to a retrieval deficit was obtained from the fact that L-NAME’s effects after retrieval were not due to state-dependency. The impairment effect of L-NAME was dependent on the age of the original memory. That is, there was an inverse correlation between the susceptibility of the memory trace when reactivated and the time elapsed between training and the first retrieval session. We suggest an action of L-NAME on memory reactivation-induced processes that are different from memory extinction of the original learning extending the biological significance of nitric oxide on memory.     

Antecedent priming at trace positions in Japanese long-distance scrambling

We report the results from three cross-modal lexical decision experiments investigating antecedent priming effects in Japanese. In the first two experiments we examined antecedent reactivation at the preverbal trace position in long-distance scrambling sentences. We found an interaction between the participants' working memory (WM) span and antecedent priming. For the high span group, the magnitude of antecedent priming at the trace position was significantly larger than at the earlier control position; for the low span group, on the other hand, there was no such difference. In a third experiment, we examined whether similar reactivation effects could be observed for argument expressions that are not base-generated adjacent to the verb. Contrary to scrambled objects, subject noun phrases (NPs) in canonically ordered sentences were not reactivated at the preverbal test position in either of the two participant groups. We argue that the priming effect observed in the high span group supports a trace-based account of long-distance scrambling. The degree of complexity of the experimental sentences was such that they exceeded the memory span of the low span group. We conclude that argument traces access their antecedents irrespective of the position of their subcategorizers.     

Associative links between discrete memories in early infancy

The specificity and independence of two successively established memories were assessed in two studies with 6-month-olds. On different days, infants learned two paired-associate tasks, each involving a specific cue-response pair, in a common distinctive context. Retention of each pair was tested either 3 days later, when both memories were still highly accessible (Experiment 1), or 22 days later, when a reminder was necessary to reactivate them (Experiment 2). In both instances, infants produced only the response associated with the test cue; neither retroactive nor proactive interference occurred. Surprisingly, the cue from one task indirectly reactivated the forgotten memory of the other task, revealing that they were linked in an associative network.