Post-training infusion of glutamate into the bed nucleus of the stria terminalis enhanced inhibitory avoidance memory: An effect involving norepinephrine

This study examined an interaction between glutamate and norepinephrine in the bed nucleus of the stria terminalis (BNST) in modulating affective memory formation. Male Wistar rats with indwelling cannulae in the BNST were trained on a one-trial step-through inhibitory avoidance task and received pre- or post-training intra-BNST infusion of glutamate, norepinephrine or their antagonists. Results of the 1-day test indicated that post-training intra-BNST infusion of dl-2-amino-5-phosphonovaleric acid (APV) impaired retention in a dose- and time-dependent manner, while infusion of glutamate had an opposite effect. Co-infusion of 0.2 μg glutamate and 0.02 μg norepinephrine resulted in marked retention enhancement by summating non-apparent effects of the two drugs given at a sub-enhancing dose. The amnesic effect of 5.0 μg APV was ameliorated by 0.02 μg norepinephrine, while the memory enhancing effect of 1.0 μg glutamate was attenuated by 5.0 μg propranolol. These findings suggest that training on an inhibitory avoidance task may alter glutamate neurotransmission, which by activating NMDA receptors releases norepinephrine to modulate memory formation via β adrenoceptors in the BNST.     

A one-trial inhibitory avoidance task to zebrafish: Rapid acquisition of an NMDA-dependent long-term memory

The behavioral tasks aiming to evaluate learning and memory mechanisms currently available to zebrafish (Danio rerio) involve long training sessions frequently along multiple days and are based on shuttle box or active-avoidance protocols, preventing a detailed analysis of cellular and molecular time-dependent processes involved in memory acquisition and consolidation. In order to explore zebrafish’s potential contribution to the characterization of the molecular machinery underlying learning and memory rapidly acquired and reliable paradigms are necessary. In this study we present a rapid and effective learning protocol in a single-trial inhibitory avoidance in zebrafish. In a simple apparatus, adult animals learned to refrain from swimming from a white into a dark compartment in order to avoid an electric shock during a single-trial training session that lasted less than 2 min. The resulting memory is robust, long-lasting and sensitive to NMDA-receptor antagonist MK-801 given in the tank water immediately after training. Experiments aiming to further characterize the events underlying memory formation, retrieval or extinction or those looking for cognitive profiling of mutants, neurotoxicological studies and disease models may benefit from this task, and together with complementary strategies available for zebrafish may significantly improve our current knowledge on learning and memory mechanisms.     

Language proficiency and executive control in proactive interference: evidence from monolingual and bilingual children and adults

Two studies are reported in which monolingual and bilingual children (Study 1) and adults (Study 2) completed a memory task involving proactive interference. In both cases, the bilinguals attained lower scores on a vocabulary test than monolinguals but performed the same on the proactive interference task. For the children, bilinguals made fewer intrusions from previous lists even though they recalled the same number of words. For the adults, bilinguals recalled more words than monolinguals when the scores were corrected for differences in vocabulary. In addition, there was a strong effect of vocabulary in which higher vocabulary participants recalled more words irrespective of language group. These results point to the important role of vocabulary in verbal performance and memory. They also suggest that bilinguals may compensate for weaker language proficiency with their greater executive control to achieve the same or better levels of performance as monolinguals.     

Vocabulary teaching strategies and conceptual representations of words in L2 in children: Evidence with novice learners

A controversial issue in bilingual research is whether in the early stages of L2 learning, access to the conceptual system involves mediation of L1 lexical representations [Kroll, J. F., & Stewart, E. (1994). Category interference in translation and picture naming: Evidence for asymmetric connections between bilingual memory representations. Journal of Memory and Language, 33, 149-174] or a direct route from the L2 word [Altarriba, J., & Mathis, K. M. (1997). Conceptual and lexical development in second language acquisition. Journal of Memory and Language, 36, 550-568; Finkbeiner, M., & Nicol, J. (2003). Semantic category effects in second language word learning. Applied Psycholinguistics, 24, 369-383]. The main goal of this paper is to study, in a child population, whether the creation of conceptual representations for L2 words is possible, even after only one session of learning of the L2 vocabulary. Furthermore, we do so by examining the efficacy of two different L2 learning methods: L2-L1 association learning vs. L2-picture association learning. A translation recognition task was employed to test whether there was a difference between a semantically related pair and an unrelated pair across conditions (i.e., a semantic interference effect). Results showed a significant semantic interference effect—a conceptual effect—in children after just one vocabulary learning session. Importantly, the L2-picture method produced a greater semantic interference effect than the L2-L1 method. The implications of these findings for models of bilingual memory are examined.     

Contexts and control operations used in accessing list-specific, generalized, and semantic memories

The human ability to focus memory retrieval operations on a particular list, episode or memory structure has not been fully appreciated or documented. In Experiment 1-3, we make it increasingly difficult for participants to switch between a less recent list (multiple study opportunities), and a more recent list (single study opportunity). Task performance was good, although there was a cost associated with switching. In Experiment 4, list-specific learning experiences were used to create a generalized memory as a step towards semantic memory. List-specific memories intruded during attempts to retrieve the generalized memory and the generalized memory enhanced list-specific performance. The generalized memory also intruded in a free-association task. We propose that a hierarchy of contexts and control operations underlie the human ability to access different memory structures and that there is no sharp discontinuity in the control operations needed to access list-specific, generalized, and semantic memories.     

Are errors differentiable from deceptive responses when feigning memory impairment? An fMRI study

Previous neuroimaging studies have suggested that the neural activity associated with truthful recall, with false memory, and with feigned memory impairment are different from one another. Here, we report a functional magnetic resonance imaging (fMRI) study that addressed an important but yet unanswered question: Is the neural activity associated with intentional faked responses and with errors differentiable? Using a word list learning recognition paradigm, the findings of this mixed event-related fMRI study clearly indicated that the brain activity associated with intentional faked responses was different to the activity associated with errors committed unintentionally. For intentional faked responses, significant activation was found in the ventrolateral prefrontal cortex, the posterior cingulate region, and the precuneus. However, no significant activation was observed for unintentional errors. The results suggest that deception, in terms of feigning memory impairment, is not only more cognitively demanding than making unintentional errors but also utilizes different cognitive processes.     

Plasma BDNF is reduced among middle-aged and elderly women with impaired insulin function: Evidence of a compensatory mechanism

Brain-derived neurotrophic factor (BDNF) plays a regulatory role in neuronal differentiation and synaptic plasticity and has been linked to glucose regulation and cognition. Associations among plasma BDNF, cognition, and insulin function were explored. Forty-one participants with impaired insulin function (IIF), ranging from insulin resistance to type 2 diabetes mellitus (T2DM), were matched with 41 healthy controls on gender, age, education, and IQ. Participants received complete medical, neurological, psychiatric, and neuropsychological evaluations. IIF individuals had significantly lower plasma BDNF levels than controls, particularly females, and higher BDNF levels were associated with poorer explicit memory in IIF females, suggesting that higher levels within this group may reflect the body’s efforts to respond to damage. After accounting for age, education, and HbA1c, BDNF significantly predicted 13.1–23.5% of the variance in explicit memory in IIF women. These findings suggest that BDNF elevations within diseased groups may not always be a marker of health.     

Thinking about the self influences thinking in general: cognitive consequences of salient self-concept

Two studies support our hypothesis that connected and interdependent self-focus evokes a generally context-dependent cognitive mode (focused on object-context relations) and provide some evidence that separate and independent self-focus evokes a generally context-independent cognitive mode (focused on objects, independent of contexts). Consistent with our predictions, experimental manipulation of interdependent self-focus influences cognitive speed/accuracy (Experiment 1) and memory (Experiment 2). When primed self-focus is congruent with the perceptual task at hand, perceptual speed increases (as shown by a significant task by prime interaction effect) and when primed, interdependent self-focus improves memory for incidentally encoded contextual information. Further research to link primed and chronic self-focus effects is called for.     

Does action make you faster? A retrieval‐based approach to investigating the origins of the enactment effect

The enactment effect, the stable finding that memory for action phrases is enhanced in a subject-performed compared to a verbal task (SPT; VT), has repeatedly been demonstrated. The question remains whether the enactment effect has to do with specific characteristics of the SPT-retrieval process. Experiment 1 tested younger and older adults in a within-subjects design with two direct free recall tests. Thorough analyses of the recall process showed that the benefit from self-performing the items becomes apparent early into the retrieval phase for both age groups. Experiment 2 tested the same age groups with a retention phase of 30 minutes. The same general results pattern emerged. The acceleration of the recall process in SPTs is indicative of a heightened accessibility of the actively encoded material, making it less susceptible to forgetting. This property of SPTs must be taken into account when trying to determine the origins of the enactment effect.     

The associations between Self-Criticism and Dependency and incidental learning of interpersonal and achievement words

Personality trait-congruent implicit content processing was studied experimentally. In Experiment-1 (N = 132), individual differences in Self-Criticism were most strongly associated with incidental learning of negative achievement words, whereas individual differences in Dependency were most strongly associated with incidental learning of negative interpersonal words. In Experiment-2 (N = 172), individual differences interacted with processing tendencies in predicting negative affect. Highly dependent and highly self-critical individuals experienced higher negative affect if they were low in incidental learning of positive interpersonal words. Overall, these findings indicate that Self-Criticism and Dependency have significantly differential impacts on implicit cognitive processes.