Working Memory Elements Research Articles

Brain Connectivity in Ateles geoffroyi: Resting-State Functional Magnetic Resonance Imaging of Working Memory and Executive Control

The objective of this research was to describe the organization and connectivity of the working memory (WM) and executive control (EC) networks in Ateles geoffroyi in resting-state conditions. Recent studies have shown that resting-state activity may underlie rudimentary brain functioning, showing that several brain regions can be tonically active at rest, maximizing the efficiency of information transfer while preserving a low physical connection cost. Whole-brain resting-state images were acquired from three healthy adult Ateles monkeys (2 females, 1 male; mean age 10.5 ± SD 2.5 years). Data were analyzed with independent component analysis, and results were grouped together using the GIFT software. The present study compared the EC and WM networks obtained with human data and with results found in the literature in other primate species. Nine resting-state networks were found, which were similar to resting networks found in healthy human adults in the prefrontal basal portion and frontopolar area. Additionally, components of the WM network were found to be extending into the hypothalamus and the olfactory areas. A key finding was the discovery of connections in the WM and EC networks to the hypothalamus, the motor cortex, and the entorhinal cortex, suggesting that information is integrated from larger brain areas. The correlated areas suggest that many elements of WM and EC may be conserved across primate species. Characterization of these networks in resting-state conditions in nonhuman primate brains is a fundamental prerequisite for understanding of the neural bases underlying the evolution and function of this cognitive system.

The enhanced cognitive interview: could individual differences in visuo-spatial working memory explain differences in recalling an event?

ABSTRACTThe Enhanced Cognitive Interview (ECI) is one of the most useful witness interviews, consisting of 5 techniques (context reinstatement: CR; report everything: RE, mental imagery: MI, change order: CO and change of perspectives: CP) aimed at increasing both the quantity and the quality of elements recalled. All the techniques require mental imagery skills. The present study investigates the relationship between forward and backward visuo-spatial working memory (VSWM) and correct elements recalled through the ECI with respect to its techniques. 99 college students (48 males) watched a color videotape of a fictional crime and performed a visuo-spatial working memory task. The following day they were interviewed about what they had seen. Results showed that high forward VSWM capacity has a role in favoring the total amount of correct information recalled, specifically in the MI technique. This suggests that maintaining and processing mood-related contents in VSWM is easier for individuals with high working memory skills.

Interference Resolution in Emotional Working Memory as a Function of Alexithymia.

Although alexithymia is recognized as a set of traitlike deficits in emotion processing, research suggests there are concomitant cognitive issues as well, including what appears to be an unusual pattern of enhanced working memory (WM) despite broader executive dysfunction. It is unknown whether this enhancement includes the executive elements of WM and whether executive control of WM in alexithymia differs for emotional and neutral stimuli. This study examined how alexithymia moderates patterns of interference resolution in WM with valenced and nonvalenced stimuli. Participants (N = 93) completed the Toronto Alexithymia Scale and a recency probes WM task containing positive, negative, and neutral stimuli, with some trials containing proactive interference from previous trials. The reaction time difference between interference and noninterference trials indexed degree of interference resolution. Toronto Alexithymia Scale score moderated a within-subject effect such that, when valenced probes were used, there was less proactive interference in the positive relative to negative valence condition; this valence-based interference discrepancy was significant for a subset of highly alexithymic participants. Alexithymia did not moderate proactive interference to negative or neutral stimuli or accuracy of responses. These results suggest that, although alexithymia does not influence executive control in WM for nonemotional items, alexithymic people demonstrate an idiosyncratic response to positive stimuli that might indicate blunted reactivity.

Prefrontal electroencephalographic activity during the working memory processes involved in a sexually motivated task in male rats

The prefrontal cortex is involved in working memory functions, and several studies using food or drink as rewards have demonstrated that the rat is capable of performing tasks that involve working memory. Sexual activity is another highly-rewarding, motivated behaviour that has proven to be an efficient incentive in classical operant tasks. The objective of this study was to determine whether the functional activity of the medial prefrontal cortex (mPFC) changes in relation to the working memory processes involved in a sexually motivated task performed in male rats. Thus, male Wistar rats implanted in the mPFC were subjected to a nonmatching-to-sample task in a T-maze using sexual interaction as a reinforcer during a 4-day training period. On the basis of their performance during training, the rats were classified as 'good-learners' or 'bad-learners'. Only the good-learner rats showed an increase in the absolute power of the 8-13Hz band during both the sample and test runs; a finding that could be related to learning of the working memory elements entailed in the task. During the maintenance phase only (i.e., once the rule had been learned well), the good-learner rats also showed an increased correlation of the 8-13Hz band during the sample run, indicating that a high degree of coupling between the prefrontal cortices is necessary for the processing required to allow the rats to make correct decisions in the maintenance phase. Taken together, these data show that mPFC activity changes in relation to the working memory processes involved in a sexually motivated task in male rats.

N-Back auditory test performancein normal individuals.

The working memory construct refers to the capacity to maintain information for a limited time.ObjectivesTo devise stimuli and adapt the 5-back test and to verify the effect of age in normal Brazilian individuals.Methods31 healthy adults (15 young adults and 16 older adults) were evaluated by batteries of auditory stimuli to verify the inter-group differences (age effect) in working memory span, total correct answers and intrusions, and the intra-group effect of type of stimulus.Results There was no intra-group stimulus effect. Individuals from both groups processed di and tri-syllables similarly. No difference between groups (no age effect) was observed for any N-Back parameters: total score, span, number of intrusions, in either di or tri-syllable presentation.Conclusionthe processing capacity of 5 elements in phonological working memory was not affected by age.

Does advanced driver training improve situational awareness?

Over 70 years of experiential evidence suggests that a specific form of advanced driver training, one based on an explicit system of car control, improves driver situation awareness (SA). Five experimental hypotheses are developed. They propose that advanced driving should increase the number of information elements in the driver's working memory, increase the interconnection between those elements, increase the amount of ‘new’ information in memory as well as the prominence of existing information, and that finally, it should stimulate behaviours that help drivers evolve better situations to be aware of. An approach to SA based on Neisser's perceptual cycle theory is anchored to a network based methodology. This is applied within the context of a longitudinal on-road study involving three groups of 25 drivers, all of whom were measured pre- and post-intervention. One experimental group was subject to advanced driver training and two further groups provided control for time and for being accompanied whilst driving. Empirical support is found for all five hypotheses. Advanced driving does improve driver SA but not necessarily in the way that existing situation focused, closed loop models of the concept might predict.

Reading and writing of vortex circulation in pseudo-spin-valve ring devices

The authors present a simple method of reading the circulation direction of vortex states in pseudo-spin-valve ferromagnetic ring devices via magnetoresistance measurements. It is shown that by placing the current contacts asymmetrically onto the structure, the circulation of a vortex state in the hard layer may be read directly from the total resistance of the device. Furthermore, they show that by choosing the direction in which the ring is initially saturated prior to obtaining the vortex state, the vortex circulation may be selectively written to the structure, creating the basis of a working memory element.

HAL: a faster match algorithm

Existing match algorithms treat the matching process like the querying process of relational databases. Owing to the combinatorial nature of the matching process, the match time greatly varies in different recognize-act cycles. Current match algorithms utilize local matching support networks with redundant working memory elements shared among rules involving the same classes. Since the match time is a dominant factor in the total execution time of a production system, such large match time makes production systems with existing match algorithms unsuitable for many applications. To reduce match time, we introduce the Heuristically-Annotated-Linkage (HAL) match algorithm. HAL differs from traditional match algorithms in that HAL employs a fixed-traversal-distance pseudobipartite network approach of treating rules and classes as objects, or nodes, in only one global pseudobipartite-graph-like connection and communication scheme. In addition, HAL is more efficient than other existing match algorithms because it is capable of immediate characterization of any new datum upon arrival. This paper reviews existing match algorithms, presents HAL, and analyzes the performance of HAL in comparison with existing algorithms.

Interference with performance of a response selection task that has no working memory component: an rTMS comparison of the dorsolateral prefrontal and medial frontal cortex.

It has been suggested that the dorsolateral prefrontal cortex (DLPFC) is involved in free selection (FS), the process by which subjects themselves decide what action to perform. Evidence for this proposal has been provided by imaging studies showing activation of the DLPFC when subjects randomly generate responses. However, these response selection tasks have a hidden working memory element and it has been widely reported that the DLPFC is activated when subjects perform tasks which involve working memory. The primary aim of this experiment was to establish if the DLPFC is genuinely involved in response selection. We used repetitive transcranial magnetic stimulation (rTMS) to investigate whether temporary interference of the DLPFC could disrupt performance of a response selection task that had no working memory component. Subjects performed tasks in which they made bimanual sequences of eight nonrepeating finger movements. In the FS task, subjects chose their movements at random while a computer monitor displayed these moves. This visual feedback obviated the need for subjects to maintain their previous moves "on-line." No selection was required for the two control tasks as responses were cued by the visual display. The attentional demands of the control tasks varied. In the high load (HL) version, subjects had to maintain their attention throughout the sequence, but this requirement was absent in the low load (LL) task. rTMS over the DLPFC slowed response times on the FS task and at the end of the sequence on the HL task, but had no effect on the LL task. rTMS over the medial frontal cortex (MFC) slowed response times on the FS task but had no effect on the HL task. This suggests that a response selection task without a working memory load will depend on the DLPFC and the MFC. The difference appears to be that the DLPFC is important when selecting between competing responses or when concentrating if there is a high attentional demand, but that the MFC is only important during the response selection task.

164. Attenuated frontal activation during mental rotation in schizophrenia

Patients with schizophrenia are impaired on tasks of occulomotor and haptic delay as well as visuo-spatial working memory, suggestive of frontal cortex abnormalities. Mental rotation tasks combine elements of visuo-spatial processing and working memory which requires the involvement of the central executive, localized to the frontal cortex. We used fMRI to investigate a mental rotation task in 5 dextral schizophrenic patients and 7 controls matched on age, IQ and handedness. We hypothesised that patients would have a deficit in mental rotation which will manifest as abnormalities in the BOLD signal in the frontal cortex. Schizophrenic subjects have intact basic spatial processing, therefore we predicted that occipital areas will be equally active in both groups while frontal regions of activation will be reduced or absent in the schizophrenic group.

205. Distinct contribution of glutamate and dopamine receptors to the temporal range of rodent working memory using a task with elements of human working memory

205. Distinct contribution of glutamate and dopamine receptors to the temporal range of rodent working memory using a task with elements of human working memory

Detection of Relative Gaseous Indoor Air-pollution by Tin Oxide Gas Sensor using Production System

Gaseous indoor air-pollutants are detected by a tin oxide gas-sensor using the OPS5 system. The system is one of several production systems. The grade of pollution can be indicated more correctly by recognizing types of human behaviors, awaking and sleeping etc. The standard level for gaseous indoor air-pollution is computed by sensor outout data in last 3 weeks. The current input data is compared with the level and the grade of pollution displayed. There are 15 rules to help recognizing indooor air-pollution. Rete algorithm is adopted to match working memory elements and condition parts of rules in production memory quickly.

Direct match algorithm for production systems

AbstractA production system is a typical tool for constructing an expert system. The Rete algorithm has been used as the condition match in the production system. The Rete algorithm features in that the condition match can executed efficiently by retaining the intermediate result of matching using the data‐flow graph (called Rete network). Efficiency is deteriorated, however, when most of the intermediate results are updated by a single recognition‐action cycle. Moreover, execution time for the condition match increases rapidly with an increase in the working memory elements. From such a viewpoint, this paper proposes a condition match algorithm wherein the intermediate result of matching is not retained, and the number of working memory tuples to be examined is reduced by connecting the common variables among the condition element. The proposed algorithm directly tries the condition match without using the Rete algorithm. The execution time does not increase so rapidly as in the Rete algorithm, but increases only slowly with the increase of the working memory elements. Consequently, the efficiency of the Rete algorithm is better when there are fewer working memory elements, and the efficiency of the proposed method is better when both the number of working memory elements and the computation cost for the condition match are increased. In other words, the proposed algorithm can handle high‐cost rules.

High‐speed match algorithm of a production system

AbstractThe production system is suited to representing the miscellaneous pieces of human knowledge, and is used most widely in constructing the expert system. A problem is that a tremendous amount of time is required for the condition match, and an efficient condition match algorithm is desired.This paper considers the expert system which has been designed for the inference based on the semantic network, and aims at the realization of the high‐speed condition match in the expert system rewritten by OPS5. The working memory elements which are the objects of investigation are mostly the knowledge of two‐term relations, and the number of attributes usually is 2.This paper also proposes a data structure for the working memory, which can derive directly all working memory elements satisfying the condition, from the condition elements with 2 or less attributes. Using the proposed data structure, an algorithm is shown that can realize a high‐speed condition match. It is shown for the considered expert system that the proposed algorithm can realize a higher speed than the conventional condition match algorithm.

Object/rule integration in CLIPS

Abstract: This paper gives a brief overview of the C Language Integrated Production System (CLIPS) with a focus on the object‐oriented features. The advantages of an object data representation over the traditional working memory element (WME), i.e. facts, are discussed and the implementation of the Rete inference algorithm in CLIPS is presented in detail. A few methods for achieving pattern‐matching on objects with the current inference engine are given and, finally, the paper examines the modifications necessary to the Rete algorithm to allow direct object pattern‐matching.

A qualitative model for estimation of plant behaviour

A simulator which can qualitatively estimate the plant behaviour during abnormal situations is developed. The qualitative modeling illustrated by applying it to a fault diagnosis process system study. The system currently can perform fault diagnosis in a plant consisting of pumps, values, tanks, reactors and streams. No, limitation is placed on the number of equipment units or streams since it is a simple matter to create a new frame and working memory element. This paper describes the QSPE (Qualitative Simulator in Proceess Engineering) for system diagnosis. The simulated results show the applicability this simulator to the solution of problems related to chemical process qualitative dynamics.

Bounding the computation time of forward-chaining rule-based systems

For real-time applications of expert systems, success depends on the computational efficiency of the implementation. In this study, we propose an analytical method for evaluating the processing time of forward-chaining rule-based systems. An upper bound based on this system model is developed. If the upper bound stays within the time available for planning the operational or control task, the expert system would be able to complete the rule-processing in time. To compute the upper bound, the worst case working memory element sets are obtained for each functional step of the matching procedure. The worst case time for rule selection in the conflict resolution step is also derived. The maximal number of firings for each rule is considered in order to arrive at a bound for total processing time. Numerical examples are presented which point out the importance of rule and data structures in the efficient implementation of rule-based systems.