Short-term Retention Of Information Research Articles

VERBAL SHORT-TERM IMPAIRMENT IN DYSLEXIA

Verbal short-term memory impairment is one of the most consistently associated deficits observed indevelopmental reading disorders such as dyslexia. The mechanisms involved in the short-term retention ofinformation for serial tasks may be shared across domains of short-term memory, such as verbal and visuospatialshort-term memory. Few studies have addressed the nature of verbal short-term impairment, particularly with regardto the possibility of temporary serial storage of information. A short-term memory serial order impairment appearsto occur for the retention of verbal and visuospatial sequence information. Impairment in the serial ordering of shorttermmemory is not a characteristic of every individual dyslexic subject and is not specific to dyslexia. Futurestudies should determine whether verbal short-term serial order memory impairment is a risk factor that, inassociation with a deficit in phonological processing, may lead to dyslexia or whether verbal short-term serial ordermemory impairment reflects related deficits unrelated to dyslexia. The purpose of this article is to consider theimplications for dyslexia of one aspect of short-term memory, memory for serialization

Shared Representational Formats for Information Maintained in Working Memory and Information Retrieved from Long-Term Memory.

Current theories propose that the short-term retention of information in working memory (WM) and the recall of information from long-term memory (LTM) are supported by overlapping neural mechanisms in occipital and parietal cortex. However, the extent of the shared representations between WM and LTM is unclear. We designed a spatial memory task that allowed us to directly compare the representations of remembered spatial information in WM and LTM with carefully matched behavioral response precision between tasks. Using multivariate pattern analyses on functional magnetic resonance imaging data, we show that visual memories were represented in a sensory-like code in both memory tasks across retinotopic regions in occipital and parietal cortex. Regions in lateral parietal cortex also encoded remembered locations in both tasks, but in a format that differed from sensory-evoked activity. These results suggest a striking correspondence in the format of representations maintained in WM and retrieved from LTM across occipital and parietal cortex. On the other hand, we also show that activity patterns in nearly all parietal regions, but not occipital regions, contained information that could discriminate between WM and LTM trials. Our data provide new evidence for theories of memory systems and the representation of mnemonic content.

The Effects of Formality of Documentation on Auditors’ Acquisition of Knowledge from Prior Year Workpapers

Auditors’ knowledge is critical for audit and financial reporting quality, as it facilitates task performance and information sharing. We examine whether auditors’ acquisition of knowledge from prior year workpapers, a primary means for learning on the job, is negatively affected by the commonly-used style of documentation in those workpapers, specifically a formal one that is regimented and rigid. We find that auditors completing a risk assessment task with more (versus less) formal prior year workpaper documentation acquire less knowledge about risk assessment. We posit, and provide empirical support for, this negative effect occurring due to more formal documentation reducing attention to learning-relevant information, as well as reducing effort devoted to self-explanation of that information. Robustness tests rule out alternative explanations, such as short-term retention of information and effects of other inferences from formality. Collectively, these findings highlight the critical need for an intervention, and also have implications outside of auditing.

Phone-based audience response system as an adjunct in orthodontic teaching of undergraduate dental students: a cross-over randomised controlled trial

BackgroundThe advent of electronic teaching facilities improves tutor-student communication. This study aims to explore the effectiveness of Phone-Based Audience Response System (PB-ARS), as an adjunctive pedagogy tool to enhance the retention of orthodontic information by dental students; and to explore the students’ perception of PB-ARS.MethodsThis cross-over clustered randomised control trial included 34 males who were in the final year of their undergraduate dental training. Participants were allocated to one of two event groups (G1 and G2) using computer-generated randomisation. Both groups simultaneously attended two different traditional lectures (L 1 and L2) a week apart. During L1, PB-ARS was used as an adjunct to conventional presentation to teach G1 participants, (PB-ARS group) while G2’s participants acted as a control group (CG), and were taught using a traditional presentation. In the second week (L2), the interventions were crossed-over. Participants from both groups completed pre- and post-lecture multiple-choice questionnaires (MCQ) to assess their short-term retention of information. Their performance in the final MCQ exam (10 weeks following L2) was tracked to assess the long-term retention of the information. Participants also completed post-lecture questionnaires to evaluate their perceptions.ResultsTwenty-nine and 31 participants from the CG and PB-ARS group completed this trial, respectively. Although 87.5% of students in the PB-ARS group showed an improvement in their immediate post-lecture scores compared with 79.3% for the CG, it was statistically insignificant (p = 0.465). Similarly, the intervention showed an insignificant effect on the long-term retention of the knowledge (p = 0.560).There was a mildly but favourable attitude of students towards the use of PB-ARS. However, the difference in the overall level of satisfaction between both groups was statistically insignificant (p = 0.183).ConclusionPB-ARS has a minimal and insignificant effect on the short- and long-term retention of orthodontic knowledge by male undergraduate dental students. PB-ARS was the preferred adjunct tool to conventional classroom teaching. Due to the limitations of this trial, a long-term randomised controlled trial with a larger sample size is recommended.

How Does the Brain Keep Information “in Mind”?

For decades, theoreticians and experimentalists have worked under the assumption that the short-term retention of information depends on elevated activity in the neural elements that represent this information. This was reinforced by the observation of elevated activity in the prefrontal cortex (PFC) during the performance of working memory tasks. Increasingly, however, researchers are realizing that the face-value interpretation of regional patterns of elevated activity, including in the PFC, is constrained, a priori, to the principle that brain functions (like working memory) are organized in a modular manner. This is at odds with our current understanding of the brain as a highly distributed, dynamical system capable of multiplexed processing. An alternative empirical approach, the application of multivariate pattern analysis to neural data sets, has led to two important developments in our conceptualization of working memory. First, it has shown that sustained delay-period activity in the PFC (and elsewhere) often does not correspond to the active retention, per se, of information. Second, it has provided strong empirical evidence for two mechanisms that may underlie our ability to keep in mind small amounts of information with which we can guide our behavior: sensorimotor recruitment, and the temporary activation of long-term memory representations.

An educational intervention on drug interactions and contraceptive options for epilepsy patients: a pilot randomized controlled trial

ObjectiveThis pilot study investigates whether an educational handout could increase short-term information retention about drug interactions between antiepileptic drugs (AEDs) and hormonal contraceptives among female epilepsy patients of reproductive age. Study designThis is a pilot randomized controlled trial of an educational intervention among reproductive-age women with epilepsy in an academic neurology clinic. Investigators measured knowledge before and after participants received either usual care or the educational handout. The 10-question test assessed increased knowledge of which AEDs affected efficacy of certain hormonal contraceptives and was assessed by calculating the improvement in score between the pretest and posttest. The educational handout included the names of AEDs that have drug interactions with certain contraceptives and the efficacy of the contraceptives. ResultsA total of 42 epilepsy patients participated in this study. Fourteen participants were taking AEDs that are enzyme p450 inducers and 13 participants were taking Lamotrigine. Twenty women were randomized to receive the educational handout and 22 women were randomized to usual care. We found no statistical difference in the groups with regard to age, ethnicity or level of education. We found a significantly higher improvement in quiz scores in the educational handout group (3.65 point increase) compared to the usual care group (0.68 point increase) as calculated by the Student's two-sample t test (p<.001). ConclusionsAn educational handout on drug interactions and contraceptives resulted in increased short-term information retention on this topic among reproductive-age female epilepsy patients. ImplicationsThis pilot study highlights the need for further larger studies to evaluate the impact of educational interventions on improving patient knowledge about the drug interaction of AEDs and hormonal contraceptives.

A robust in vivo-like persistent firing supported by a hybrid of intracellular and synaptic mechanisms.

Persistent firing is believed to support short-term information retention in the brain. Established hypotheses make use of the recurrent synaptic connectivity to support persistent firing. However, this mechanism is known to suffer from a lack of robustness. On the other hand, persistent firing can be supported by an intrinsic cellular mechanism in multiple brain areas. However, the consequences of having both the intrinsic and the synaptic mechanisms (a hybrid model) on persistent firing remain largely unknown. The goal of this study is to investigate whether a hybrid neural network model with these two mechanisms has advantages over a conventional recurrent network based model. Our computer simulations were based on in vitro recordings obtained from hippocampal CA3 pyramidal cells under cholinergic receptor activation. Calcium activated non-specific cationic (CAN) current supported persistent firing in the Hodgkin-Huxley style cellular models. Our results suggest that the hybrid model supports persistent firing within a physiological frequency range over a wide range of different parameters, eliminating parameter sensitivity issues generally recognized in network based persistent firing. In addition, persistent firing in the hybrid model is substantially more robust against distracting inputs, can coexist with theta frequency oscillations, and supports pattern completion.

The short- and long-term fates of memory items retained outside the focus of attention.

When a test of working memory (WM) requires the retention of multiple items, a subset of them can be prioritized. Recent studies have shown that, although prioritized (i.e., attended) items are associated with active neural representations, unprioritized (i.e., unattended) memory items can be retained in WM despite the absence of such active representations, and with no decrement in their recognition if they are cued later in the trial. These findings raise two intriguing questions about the nature of the short-term retention of information outside the focus of attention. First, when the focus of attention shifts from items in WM, is there a loss of fidelity for those unattended memory items? Second, could the retention of unattended memory items be accomplished by long-term memory mechanisms? We addressed the first question by comparing the precision of recall of attended versus unattended memory items, and found a significant decrease in precision for unattended memory items, reflecting a degradation in the quality of those representations. We addressed the second question by asking subjects to perform a WM task, followed by a surprise memory test for the items that they had seen in the WM task. Long-term memory for unattended memory items from the WM task was not better than memory for items that had remained selected by the focus of attention in the WM task. These results show that unattended WM representations are degraded in quality and are not preferentially represented in long-term memory, as compared to attended memory items.

Community health worker training for infant hearing health: Effectiveness of distance learning

Objective: The purpose of this study was to evaluate the effectiveness of a distance training program in infant hearing health to community health workers (CHWs). Design: Pre- and post- tests were administered to two groups of subjects following the use of an interactive CD-ROM for tele-educational training. Study sample: Two groups of subjects were used: Group I (GI) consisted of 43 CHWs who had previously participated in at least one training activity involving hearing health, and Group II (GII) were 47 CHWs who had received no prior training in hearing health. Results: CHWs retained a significant amount of training content. There was not significant correlation between the global post-training questionnaire score and performance on the simulation activity (GI: r = 0.11, p = 0.698 and GII: r = 0.29, p = 0.074), and the simulation activity performance was significantly better among GI CHWs (p = 0.05). Conclusion: The CHWs’ training in infant hearing health using an interactive tele-educational tool was effective, as the CHW demonstrated significant short-term information retention and applied such data in hypothetical situations representative of their daily activities.

Persistent firing supported by an intrinsic cellular mechanism in hippocampal CA3 pyramidal cells

Short-term information retention is crucial for information processing in the brain. It has long been suggested that the hippocampal CA3 region is able to support short-term information retention through persistent neural firing. Theoretical studies have shown that this persistent firing can be supported by abundant excitatory recurrent connections in CA3. However, it remains unclear whether individual cells can support persistent firing. In this study, using in vitro whole-cell patch-clamp recordings in a rat hippocampal slice preparation, we show that hippocampal CA3 pyramidal cells support persistent firing under perfusion of the cholinergic agonist carbachol (10 μm). Furthermore, in contrast to earlier theoretical studies, this persistent firing is independent of ionotropic glutamatergic synaptic transmission and is supported by the calcium-activated non-selective cationic current. Because cholinergic receptor activation is crucial for short-term memory tasks, persistent firing in individual cells may support short-term information retention in the hippocampal CA3 region.

Decoding Attended Information in Short-term Memory: An EEG Study

For decades it has been assumed that sustained, elevated neural activity--the so-called active trace--is the neural correlate of the short-term retention of information. However, a recent fMRI study has suggested that this activity may be more related to attention than to retention. Specifically, a multivariate pattern analysis failed to find evidence that information that was outside the focus of attention, but nonetheless in STM, was retained in an active state. Here, we replicate and extend this finding by querying the neural signatures of attended versus unattended information within STM with electroencephalograpy (EEG), a method sensitive to oscillatory neural activity to which the previous fMRI study was insensitive. We demonstrate that in the delay-period EEG activity, there is information only about memory items that are also in the focus of attention. Information about items outside the focus of attention is not detectable. This result converges with the fMRI findings to suggest that, contrary to conventional wisdom, an active memory trace may be unnecessary for the short-term retention of information.

The Relationship between Working Memory Storage and Elevated Activity as Measured with Functional Magnetic Resonance Imaging

Does the sustained, elevated neural activity observed during working memory tasks reflect the short-term retention of information? Functional magnetic resonance imaging (fMRI) data of delayed recognition of visual motion in human participants were analyzed with two methods: a general linear model (GLM) and multivoxel pattern analysis. Although the GLM identified sustained, elevated delay-period activity in superior and lateral frontal cortex and in intraparietal sulcus, pattern classifiers were unable to recover trial-specific stimulus information from these delay-active regions. The converse-no sustained, elevated delay-period activity but successful classification of trial-specific stimulus information-was true of posterior visual regions, including area MT+ (which contains both middle temporal area and medial superior temporal area) and calcarine and pericalcarine cortex. In contrast to stimulus information, pattern classifiers were able to extract trial-specific task instruction-related information from frontal and parietal areas showing elevated delay-period activity. Thus, the elevated delay-period activity that is measured with fMRI may reflect processes other than the storage, per se, of trial-specific stimulus information. It may be that the short-term storage of stimulus information is represented in patterns of (statistically) "subthreshold" activity distributed across regions of low-level sensory cortex that univariate methods cannot detect.

The Prefrontal Cortex and Oculomotor Delayed Response: A Reconsideration of the “Mnemonic Scotoma”

The concept of the "mnemonic scotoma," a spatially circumscribed region of working memory impairment produced by unilateral lesions of the PFC, is central to the view that PFC is critical for the short-term retention of information. Presented here, however, are previously unpublished data that offer an alternative, nonmnemonic interpretation of this pattern of deficit. In their study, Wajima and Sawaguchi [Wajima, K., & Sawaguchi, T. The role of GABAergic inhibiton in suppressing perseverative responses in the monkey prefrontal cortex. Neuroscience Research, 50(Suppl. 1), P3-P317, 2004] applied the GABA(A) antagonist bicuculline methiodide unilaterally to the PFC of two monkeys while they performed an oculomotor delayed-response task. Consistent with previous studies, errors for the initial memory-guided saccade were markedly higher when the cued location fell into the region of the visual field affected by the infusion. These erroneous saccades tended to select an alternative target location (out of a possible 16) that had not been cued on that trial. By extending the analysis window, however, it was observed that the second, "corrective" saccade often acquired the location that had been cued on that trial. Further analysis of the erroneous initial saccades indicated that they tended to be directed to a location that had been relevant on the previous trial. Thus, the deficit was not one of "forgetting" the cued location. Rather, it was one of selecting between currently and previously relevant locations. These findings suggest a need for a reconsideration of the concept of the mnemonic scotoma, which in turn invites a reconsideration of functional interpretations of sustained neuronal activity in PFC.

Neural Evidence for a Distinction between Short-term Memory and the Focus of Attention

It is widely assumed that the short-term retention of information is accomplished via maintenance of an active neural trace. However, we demonstrate that memory can be preserved across a brief delay despite the apparent loss of sustained representations. Delay period activity may, in fact, reflect the focus of attention, rather than STM. We unconfounded attention and memory by causing external and internal shifts of attention away from items that were being actively retained. Multivariate pattern analysis of fMRI indicated that only items within the focus of attention elicited an active neural trace. Activity corresponding to representations of items outside the focus quickly dropped to baseline. Nevertheless, this information was remembered after a brief delay. Our data also show that refocusing attention toward a previously unattended memory item can reactivate its neural signature. The loss of sustained activity has long been thought to indicate a disruption of STM, but our results suggest that, even for small memory loads not exceeding the capacity limits of STM, the active maintenance of a stimulus representation may not be necessary for its short-term retention.

Effects of 10 Hz rTMS on the Neural Efficiency of Working Memory

Working memory (WM) has been described as short-term retention of information that is no longer accessible in the environment, and the manipulation of this information for subsequent use in guiding behavior. WM is viewed as a cognitive process underlying higher-order cognitive functions. Evidence supports a critical role for PFC in mediating WM performance. Studies show psychomotor processing speed and accuracy account for considerable variance in neural efficiency (Ne). This study compared the relative effects of active and sham 10 Hz rTMS applied to dorsolateral prefrontal cortex (DLPFC) on indices of Ne in healthy participants performing a WM paradigm that models the association between WM load and task behavior [Sternberg, S. High-speed scanning in human memory. Science, 153, 652-654, 1966]. Previous studies identified a relationship between diminished Ne and impaired WM across a broad array of clinical disorders. In the present study, the authors predicted there would be a main effect of stimulation group (STM) on accuracy (SCR) and processing speed (RT), hence, Ne. We observed a main effect of STM for RT without an effect on SCR; even so, there was a robust effect of STM on Ne.

Central locomotor and cognitive effects of a NPFF receptor agonist in mouse

NPFF receptors are expressed in several brain regions directly or indirectly involved in cognition and behavior. However, the cognitive effects of the NPFF system have been poorly studied. Therefore, the aim of our study was to analyze the effects of i.c.v. injections of 1DMe, a stable agonist of NPFF receptors, on behavioral and cognitive performances in C57BL/6J mice. We measured locomotor activity, and an open field with objects was used to estimate the ability of mice to react to spatial changes and to measure short-term retention of information. The Morris navigation task was used to evaluate the acquisition, as well as long-term retention of a hippocampo-dependant spatial memory with a distributed training procedure. Finally, 1DMe was tested in a contextual fear conditioning paradigm to study its effect on long-term memory of contextual information acquired in a single training session. Altogether, our results demonstrate a small but complex influence of the NPFF system on mouse behavior. 1DMe injected i.c.v. induces a delayed hyperlocomotion and mildly impairs both short-term and long-term spatial memory processing without affecting contextual fear memory.

Task- and performance-related modulation of domain-specific auditory short-term memory representations in the gamma-band

The short-term retention of information has been related to oscillatory activity in the gamma-band. In recent auditory spatial short-term memory studies we have found stimulus-specific components of parieto-occipital gamma-band activity (GBA) which might reflect the activation of local networks tuned to task-relevant stimulus features. The present magnetoencephalography study (N=22) tested this interpretation by assessing whether the topography of stimulus-specific GBA depends on task demands. Sample sounds were characterized by both a variable interaural time delay and a variable central frequency. In separate task blocks, either the lateralization or the frequency of the same stimuli had to be maintained. Statistical probability mapping of differences in oscillatory responses to the retention of sample sounds replicated the contralateral posterior topography for GBA components distinguishing between medial and lateral sounds in the spatial memory task. In contrast, lower- and higher-frequency stimuli were accompanied by frontal GBA components in the frequency task. Memory for lateralization versus frequency selectively enhanced oscillatory activity for these posterior versus frontal components, directly demonstrating their modulation by task demands. Incorrect “non-match” responses were negatively correlated with delay-phase GBA to the relevant feature, whereas incorrect “match” responses correlated positively with GBA to the irrelevant feature. In summary, the topography of stimulus-specific GBA to identical stimuli reflected the selective representation of task-relevant features. Task performance was predicted by both enhanced stimulus-specific GBA for the task-relevant stimulus attribute and reduced gamma-band representations of the task-irrelevant stimulus feature. Stimulus-specific GBA may reflect the memory representation that is used in subsequent recognition.

Temporary Activation of Long-Term Memory Supports Working Memory

This study describes a functional magnetic resonance imaging study of humans engaged in long-term memory (LTM) and working memory tasks. A pattern classifier learned to identify patterns of brain activity associated with viewing and making judgments about three categories of pictures (famous people, famous locations, and common objects). The evaluation of these stimuli relied on perception and long-term semantic and/or episodic memories. We investigated whether this classifier could successfully decode brain activity from a subsequent delayed paired-associate recognition working memory task that required the short-term retention of the same stimuli. We reasoned that the LTM-trained classifier would be able to decode delay-period activity only if that activity reflected, to some extent, the temporary activation of LTM. Our results demonstrated successful decoding: delay-period activity from a distributed network of brain regions matched learned patterns of activity for task-relevant stimuli to a greater extent than for task-irrelevant stimuli. In varying degrees throughout the delay, activity reflected the target (a retrospective code) and its associate (a prospective code) with considerable variability among subjects. Although prefrontal cortex (PFC) demonstrated category-specific patterns of activity during the LTM task, these patterns were not reinstated in PFC during the working memory task. We conclude that the short-term retention of information can be supported by the temporary reactivation of LTM representations.

Evaluating frontal and parietal contributions to spatial working memory with repetitive transcranial magnetic stimulation

Functional neuroimaging studies have produced contradictory data about the extent to which specific regions of the frontal and the posterior parietal cortices contribute to the retention of information in spatial working memory. We used high frequency repetitive transcranial magnetic stimulation (rTMS) to assess the necessity for the short-term retention of spatial information of brain areas identified by previous functional imaging studies: dorsolateral prefrontal cortex (dlPFC), frontal eye fields (FEF), superior parietal lobule (SPL) and intraparietal sulcus (IPS). 10 Hz rTMS spanned the 3-s delay period of a spatial delayed-recognition task. The postcentral gyrus (PCG) was included to control for any regionally non-specific effects of rTMS. The only regionally-specific effect was a significant decrease in reaction time when rTMS was applied to SPL. Additionally, rTMS lowered accuracy to a greater extent when applied to left than to right hemisphere, and was more disruptive when applied contralaterally vs. ipsilaterally to the visual field in which the memory probe was presented. Although seemingly paradoxical, the finding of rTMS-induced improvement in task performance has a precedent, and is consistent with the idea that regions associated with spatial sensory-motor processing make necessary contributions to the short-term retention of this information. Possible factors underlying rTMS-induced behavioral facilitation are considered.

Role of the Lateral Prefrontal Cortex in Executive Behavioral Control

The lateral prefrontal cortex is critically involved in broad aspects of executive behavioral control. Early studies emphasized its role in the short-term retention of information retrieved from cortical association areas and in the inhibition of prepotent responses. Recent studies of subhuman primates and humans have revealed the role of this area in more general aspects of behavioral planning. Novel findings of neuronal activity have specified how neurons in this area take part in selective attention for action and in selecting an intended action. Furthermore, the involvement of the lateral prefrontal cortex in the implementation of behavioral rules and in setting multiple behavioral goals has been discovered. Recent studies have begun to reveal neuronal mechanisms for strategic behavioral planning and for the development of knowledge that enables the planning of macrostructures of event-action sequences at the conceptual level.