Sequential Memory Task Research Articles

Broad Alpha-rhythm Enhancement and Its Convergence during Sequential Memory Task

Broad Alpha-rhythm Enhancement and Its Convergence during Sequential Memory Task

Processing time affects sequential memory performance beginning at the level of visual encoding.

Electrophysiological studies have demonstrated that theta-band activity is useful for investigating neural mechanisms of memory. However, mechanisms specifically driving memory performance remain poorly understood. In sequential memory, performance can be artificially attenuated by shortening the inter-stimulus interval (ISI) between memory item presentations. Therefore, we sought to clarify the mechanisms of sequential memory performance by analyzing theta-band (4–8 Hz) activity recorded via magnetoencephalogram in 33 participants during performance of a sequential memory task where memory items were presented at either slow or fast rates in accordance with longer or shorter ISIs, respectively. Particularly in the slow task, theta activity clearly modulated in accordance with the presentation of memory items. Common cortical target regions in the occipital and frontal cortex were identified in both tasks and related to visual encoding and memory maintenance, respectively. Compared to the slow task, occipital-theta activity was significantly lower in the fast task from the midterm until the ending of encoding, in correspondence with significantly lower recall for memory items in this same period. Meanwhile, despite a loss of clarity in responsiveness to individual memory items in the fast task, frontal-theta activity was not different between tasks and exhibited particularly strong responses in both tasks during the holding period prior to recall. Our results indicate that shorter processing time erodes sequential memory performance beginning at the level of visual encoding.

Polymorphisms in SLC44A1 are associated with cognitive improvement in children diagnosed with fetal alcohol spectrum disorder: an exploratory study of oral choline supplementation

The essential nutrient choline provides one-carbon units for metabolite synthesis and epigenetic regulation in tissues including brain. Dietary choline intake is often inadequate, and higher intakes are associated with improved cognitive function. Choline supplements confer cognitive improvement for those diagnosed with fetal alcohol spectrum disorder (FASD), a common set of neurodevelopmental impairments; however, the effect sizes have been modest. In this retrospective analysis, we report that genetic polymorphisms affecting choline utilization are associated with cognitive improvement following choline intervention. Fifty-two children from the upper midwestern United States and diagnosed with FASD, ages 2-5 y, were randomly assigned to receive choline (500 mg/d; n=26) or placebo (n=26) for 9 mo, and were genotyped for 384 choline-related single nucleotide polymorphisms (SNPs). Memory and cognition were assessed at enrollment, study terminus, and at 4-y follow-up for a subset. When stratified by intervention (choline vs. placebo), 14-16 SNPs within the cellular choline transporter gene solute carrier family 44 member 1 (SLC44A1) were significantly associated with performance in an elicited imitation sequential memory task, wherein the effect alleles were associated with the greatest pre-/postintervention improvement. Of these, rs3199966 is a structural variant (S644A) and rs2771040 is a single-nucleotide variant within the 3' untranslated region of the plasma membrane isoform. An additive genetic model best explained the genotype associations. Lesser associations were observed for cognitive outcome and polymorphisms in flavin monooxygenase-3 (FMO3), methylenetetrahydrofolate dehydrogenase-1 (MTHFD1), fatty acid desaturase-2 (FADS2), and adiponectin receptor 1 (ADIPOR1). These SLC44A1 variants were previously associated with greater vulnerability to choline deficiency. Our data potentially support the use of choline supplements to improve cognitive function in individuals diagnosed with FASD who carry these effect alleles. Although these findings require replication in both retrospective and prospective confirmatory trials, they emphasize the need to incorporate similar genetic analyses of choline-related polymorphisms in other FASD-choline trials, and to test for similar associations within the general FASD population. This trial was registered at www.clinicaltrials.gov as NCT01149538.

Functional decline of the precuneus associated with mild cognitive impairment: Magnetoencephalographic observations.

Mild Cognitive Impairment (MCI) is a border or precursor state of dementia. To optimize implemented interventions for MCI, it is essential to clarify the underlying neural mechanisms. However, knowledge regarding the brain regions responsible for MCI is still limited. Here, we implemented the Montreal Cognitive Assessment (MoCA) test, a screening tool for MCI, in 20 healthy elderly participants (mean age, 67.5 years), and then recorded magnetoencephalograms (MEG) while they performed a visual sequential memory task. In the task, each participant memorized the four possible directions of seven sequentially presented arrow images. Recall accuracy for beginning items of the memory sequence was significantly positively related with MoCA score. Meanwhile, MEG revealed stronger alpha-band (8-13 Hz) rhythm desynchronization bilaterally in the precuneus (PCu) for higher MoCA (normal) participants. Most importantly, this PCu desynchronization response weakened in correspondence with lower MoCA score during the beginning of sequential memory encoding, a time period that should rely on working memory and be affected by declined cognitive function. Our results suggest that deactivation of the PCu is associated with early MCI, and corroborate pathophysiological findings based on post-mortem tissue which have implicated hypoperfusion of the PCu in early stages of Alzheimer disease. Our results indicate the possibility that cognitive decline can be detected early and non-invasively by monitoring PCu activity with electrophysiological methods.

Cognitive Functions in Childhood Apraxia of Speech.

Childhood apraxia of speech (CAS) is diagnosed on the basis of specific speech characteristics, in the absence of problems in hearing, intelligence, and language comprehension. This does not preclude the possibility that children with this speech disorder might demonstrate additional problems. Cognitive functions were investigated in 3 domains: complex sensorimotor and sequential memory functions, simple sensorimotor functions, and nonrelated control functions. Seventeen children with CAS were compared with 17 children with normal speech development at 2 occasions within 15 months. The children with CAS showed overall lower scores but similar improvement at Occasion 2 compared with the typically developing controls, indicating an overall delay in the development of cognitive functions. However, a specific deviant development in sequential abilities was found as well, indicated by significantly lower scores at Occasion 2 as compared with younger control children at Occasion 1. Furthermore, the scores on the complex sensorimotor and sequential memory tasks were significantly correlated with the severity of the speech impairment. These results suggest that CAS involves a symptom complex that not only comprises errors of sequencing speech movements but implicates comorbidity in nonverbal sequential functioning in most children with CAS.

The statistical analysis of partially confounded covariates important to neural spiking

A method is presented capable of disambiguating the relative influence of statistical covariates upon neural spiking activity. The method, an extension of the generalized linear model (GLM) methodology introduced in Truccolo et al. (2005) to analyze neural spiking data, exploits projection operations motivated by a geometry present in the Fisher information of the GLM maximum likelihood parameter estimator. By exploiting these projections, neural activity can be divided into three categories. These three categories, neural activity due solely to a set of covariates of interest, neural activity due solely to a set of uninteresting, or nuisance, covariates, and neural activity that cannot be unequivocally assigned to either set of covariates, can be associated with physical variables such as time, position, head-direction and velocity. This association allows the analysis of neural activity that can, for example, be due solely to temporal influence, irrespective of other, identified, influences. The method is applied in simulation to a rat exploring a temporally modulated place field. A portion of the analysis reported in MacDonald et al. (2011), using the methodology described herein, is reproduced. This analysis demonstrates the temporal bridging of a delay period in a sequential memory task by firing activity of cells present in the rodent hippocampus that cannot be explained by rodent position, head direction or velocity.

Generation of short-term memory for items and order by unsupervised learning

Event Abstract Back to Event Generation of short-term memory for items and order by unsupervised learning In a multiple-item sequential memory task, animals can remember the identity of successive items and their order of appearance [1]. Such ability puts demands on standard models of short-term memory arising from persistent activity of neurons, which typically encode either the first stimulus or the most recent stimulus. In this presentation we show how repeated presentations of stimulus sequences to a network, with an initially limited, transient response to stimuli, can generate the necessary connectivity pattern to solve a two-item sequential memory task. We find that essential plasticity mechanisms within the network are: 1) Hebbian plasticity, which we implement through a well-characterized triplet form of spike-timing dependent plasticity (STDP) [2]. STDP in a sparse network generates an increase in recurrent excitation that is essential to produce persistent activity and memory. 2) Long-term potentiation of inhibition [3] (LTPi), which increases inhibition from active interneurons to inactive pyramidal cells. LTPi produces the cross-inhibition necessary to prevent memory activity from spreading, thus maintaining the specificity of memory. 3) Homeostasis by multiplicative scaling of synaptic strengths [4] prevents a single attractor state from dominating the network, allowing for multiple, approximately equally visited states to be maintained in the network. We produce a simplified, intuitive example of sequential memory as a bump of activity, which requires local excitation to persist following a transient stimulus and which moves toward neurons tuned to subsequent stimuli, provided some longer-range connections exist. Thus we suggest that such a small-world architecture in the pattern of connections between neurons is essential to generate multiple-item sequential memory.

Relation between methamphetamine-induced monoamine depletions in the striatum and sequential motor learning

Methamphetamine (METH) use results in depletion of monoamines in the striatum. The purpose of this study was to evaluate the relation between the degree of METH-induced monoamine depletion in the striatum and impairment on a striatally-dependent learning task in rats. Male Sprague–Dawley rats received four injections of METH (10 mg/kg) or saline at 2-h intervals. METH treatment produced a 38.5% (± 5.6) and 46.7% (± 6.7) dopamine (DA) depletion in the medial and lateral striatum, respectively. Serotonin (5-HT) was depleted 15.6% (± 10.4) and 21.1% (± 8.2) in the medial and lateral striatum, respectively. One month after treatment, rats were trained on a sequential-memory task on an 8-arm radial maze. METH-treated rats made significantly fewer direct movements between arms in the maze sequence across days of trials. The learning impairment was significantly correlated with the degree of DA depletion in the medial striatum, as well as serotonin tissue content in striatum. Only rats with a greater than 40% DA depletion in medial striatum showed significant impairments. These results provide additional evidence for METH-induced learning impairments and suggest that this impairment is dependent on the striatal monoamine loss, in general, and the degree of DA loss in medial striatum, in particular.

Dissociation related to subjective memory fragmentation and intrusions but not to objective memory disturbances

The present study was a replication of Kindt and Van den Hout (Behaviour Research and Therapy 41 (2003) 167) with several methodological adaptations. Two experiments were designed to test whether state dissociation is related to objective memory disturbances, or whether dissociation is confined to the realm of subjective experience. High trait dissociative participants ( N exp . 1 = 25 ; N exp . 2 = 25 ) and low trait dissociative participants ( N exp . 1 = 25 ; N exp . 2 = 25 ) were selected from normal samples ( N exp . 1 = 372 ; N exp . 2 = 341 ) on basis of scores on the Dissociative Experience Scale (DES). Participants watched an extremely aversive film, after which state dissociation was measured by the Peri-traumatic Dissociative Experience Questionnaire (PDEQ). Memory disturbances were assessed 4 h later (Exp. 1) or 1 week later (Exp. 2). Objective memory disturbances were assessed by a sequential memory task, items tapping perceptual representations (Exp. 1), or an open question with respect to the remembrance of the film (Exp. 2). Subjective memory disturbances were measured by means of visual analogue scales assessing fragmentation and intrusions. The two experiments provided a fairly exact replication of an earlier experiment (Behaviour Research and Therapy 41 (2003) 167–178), indicating a relation between dissociation and memory disturbances that appeared to be confined to the subjective experience of memory.

Dissociation and memory fragmentation: experimental effects on meta-memory but not on actual memory performance

The relation between state dissociation and fragmentary memory was investigated by assessing both actual memory performance and meta-memory. From a sample of 330 normal subjects, two subsamples were selected on basis of trait dissociation, as measured by the Dissociative Experience Scale. Twenty subjects scoring above 30 and 20 subjects scoring below 10 were selected. Subjects watched an extremely aversive film, after which state dissociation was measured by the Peri-traumatic Dissociative Experience Scale. Four hours later memory fragmentation was assessed in two ways. Actual fragmentation was measured by a sequential memory task, and perceived fragmentation (meta-memory) was measured using a visual analogue scale. Subjects who tended to dissociate during the film judged their recollections of the film as more fragmentary. Although this finding is in line with clinical reports given by trauma victims, it was not sustained by objective evidence. That is, no effect was observed of state dissociation on the sequential memory task. The present findings suggest that the claim that dissociation induces memory fragmentation may have to be confined to meta-memory. Implications of this divergence between actual memory and meta-memory are discussed.

The nature of the cognitive deficit in specific language impairment

Fifteen language-impaired children between 3 and 5 years and 15 non-impaired children matched on sex, age, and non-verbal IQ were compared on classification, symbolic play, spatial memory and verbal memory tasks. The two groups differed only on the verbal memory tasks, and it was particularly the verbal sequential memory task that predicted language production, both Reynell expressive scores and MLU from spontaneous speech samples. These findings suggest that sequential processing/memory of verbal items is a critical factor in language impairment, while classi fication, symbolic play and spatial memory are not problematic.

Performance of inattentive-overactive children on selected measures of prefrontal-type function.

Several theorists have suggested that childhood inattention-overactivity ("attention deficit disorder," "hyperactivity") may arise from a deficit in the inhibitory mechanisms of the prefrontal cortex. Accordingly, it was hypothesized that inattentive-overactive children would exhibit prefrontal-type deficits on several relevant neuropsychological measures. Subjects were 21 elementary school pupils who had been referred for disruptive behavior problems and who had been rated as high in inattention-overactivity. Controls were 26 age-matched normal children from the same school. It was found that the Inattentive-Overactive group, relative to the Control group, performed in the direction of prefrontal-type deficit on three measures that have an empirical history of discriminating patients with prefrontal lesions from controls: Perseverative errors on the Wisconsin Card Sorting Test, errors on the sequential Matching Memory Task, and Necker Cube reversals. On three theoretical indices of prefrontal-type deficit--Trailmaking, the Stroop Color-Word Test, and a sequential memory task for children--the Inattentive-Overactive group also exhibited predicted deficits. There were no differences between groups on the WISC-R Vocabulary subtest. The results of the study are generally compatible with a prefrontal-deficit theory of inattention-overactivity. However, the presence of other deficits cannot be ruled out nor can an organic cause be inferred from these findings alone.

Vocalisation et mémoire séquentielle des dessins et des mots

Summary : Vocalization and the sequential memory of pictures and words. Pictures and words were compared in two sequential memory tasks with two vocalization conditions, with loud voice and with suppression of subvocalization. The verbal recall of order and the reconstruction of order were better for the pictures than for the words ; this confirms previous research (Lieury & Calvez, 1986) with lists of 3 to 8 items. Thus the image code can integrale, like the verbal code, some sequential information and the hypothesis of a non sequential processing system for pictures (Paivio & Csapo, 1969, 1971) seems to be invalidated. When the pictures and the words are compared, the lexical code (increased by vocalization aloud) seemed to get a special status. Lexical eues seemed to be necessary for the words in verbal recall and for the reconstruction of order, but optional or not used for the pictures because the suppression of subvocalization decrease the recall of words more and had no effect on the reconstruction of order of the pictures. Key words : sequential memory, pictures-words, vocalization.

Cognitive strategies of children with reading disability and normal readers in visual sequential memory.

Primary school boys with reading disability were divided into two groups (dysphonetics and dyseidetics) on the basis of learning style defined by an analysis of spelling errors. Dysphonetics and dyseidetics clearly differed in their cognitive strategies in visual sequential memory tasks, yet were able to remember items presented sequentially provided that the nature of the stimulus was congruent with learning style. In memory for order tasks incorporating both spatial and serial formats, dysphonetics chose spatial order in preference to serial order whereas preferences of dyseidetics were in the opposite direction. When they were required to recognise both spatial order and serial order, dysphonetics made more correct spatial order responses than dyseidetics. The converse was the case for correct serial order responses. As a composite group, children with reading disability were shown to be no less competent in these tasks than normal readers who also revealed strong strategy preferences and little flexibility in switching strategies.

The relevance of visual sequential memory to reading.

Summary. One feature of the Barking Reading Project has been the development of a range of assesment techniques for classroom use. The assessment of visual sequential memory is discussed in relation to an assessment procedure included in the final revision of the test battery. A series of reliability and validity measures are presented. One study in particular related to this test development is described. This was concerned with the effects of labelling strategies on visual sequential memory tasks. Two alternatives are compared with the Barking Reading Project test. Nineteen junior school children were given the three visual sequential memory assessments individually and were also given a group reading test. Results are discussed in terms of two approaches to the description of reading difficulties: a task analysis approach and a structuralist approach. The relationship of visual sequential memory to other reading subskills is considered in the light of current research. Implications for the channel/process theory of deficits are drawn.

Identifying Causal Elements in the Thematic-Fantasy Play Paradigm

The intent of the study was to examine the effectiveness of elements of the thematic-fantasy play training paradigm in facilitating children’s immediate and maintained story recall. One-hundred and ninety-two children in kindergarten and first grade (balanced for sex) were randomly assigned to one of four groups: adult-directed play, peer-directed play, accommodation questions, or control. Children were read different books on three occasions and exposed to their appropriate treatments after each reading. After the third session, story recall was measured by a 10-item CRT, a story recall task, and a sequential memory task. Maintenance effects were measured 1 week later on the first two measures. Results generally indicated that adult tuition was not an important element for players. In terms of immediate recall, fantasy reenactment was generally more effective than were accommodation questions. For maintained recall, accommodation questions were generally as effective as the play conditions.

Task instructions and strategy transfer in the directed forgetting performance of mentally retarded adolescents

The influence of task explanation on strategy transfer was studied in educable mentally retarded adolescents (13 to 15 years old). A directed forgetting task was used in which the person was required to recall short sequences of picture names. In some sequences there was a cue to forget the first few pictures (irrelevant information) and to remember only the subsequent pictures (relevant information). During the first session the amount of explanation given the directed forgetting task was varied, and during the second, some of the subjects were trained to rehearse in a simple sequential memory task. Transfer of training was then examined on a retest of the directed forgetting task. The majority of subjects trained to rehearse and given a minimal explanation of the directed forgetting task maintained the strategy on trials which were identical to those used during rehearsal training, but failed to generalize the strategy on other trials. The results indicate that providing a full explanation of the task requirements does not assure strategy generalization, but providing only a minimal explanation makes strategy generalization unlikely.

Developmental Changes in the Effects of Instructions on Production-deficient Children

BRAY, NORMAN W.; JUSTICE, ELAINE M.; FERGUSON, ROBERT P.; and SIMON, DEBORAH L. Developmental Changes in the Effects of Instructions on Production-deficient Children. Cmum DEVELOPMENT, 1977, 48, 1019-1026. Firstand third-grade children were tested under 6 different instruction conditions which varied in how explicitly they cued a rehearsal strategy in a self-paced sequential-memory task. The type of strategy adopted was monitored with study time and overt verbalization measures. Instructions to either look, remember, label, or say the picture names over and over did not prime the use of cumulative rehearsal. Modeling of cumulative rehearsal was necessary for the younger children, whereas cumulative-rehearsal instructions were sufficient for the older children. Since both age groups were production deficient on this task, the results illustrate that production deficiencies are not all-or-none phenomena and that they are dependent on particular task conditions.

Component processes of an overt rehearsal strategy in young children

The locus of facilitation due to rehearsal was investigated in three experiments with first-grade children. Several different overt acquisition strategies in a four-item sequential memory task were compared, including ordered repetition, item repetition, item labeling, and free strategy conditions. Experiment 1 showed that ordered repetition yields most of the facilitation due to rehearsal, and Experiment 2 demonstrated that the facilitation cannot be attributed to spaced practice. Experiment 3 showed that retrieval practice during study may improve memory performance but that the facilitation due to ordered repetition and retrieval practice is relatively short term. Mere repetition and labeling were not found to be significant component processes of rehearsal in any of the experiments. These results were discussed in terms of their relevance to rehearsal training studies and a differentiation between maintenance and elaborative rehearsal.

Development of strategies for recall and recognition.

Kindergartners, third graders, and fifth graders viewed 30 pictures of familiar objects, and then their free recall of the object names and their recognition of the original pictures were tested. The recognition test included pairing each picture with another similar picture of the same object. Half the subjects in each age-group were prepared for recall with a strategy known to improve it in adults, and half were prepared for recognition with a strategy known to improve recognition in adults. Children encoded the stimuli differentially in accordance with the expected memory task and retrieved different stored information for each task. Both free recall and picture recognition memory improved with age. The recall strategy improved free recall performance at all ages, but the recognition strategy improved recognition performance only at the oldest age tested. Investigators of both children's and adults' memory have found different strategies beneficial for different memory tasks (e.g., Flavell, 1970; Paivio, 1971). Strategies are ways of encoding or representing material to facilitate later retrieval. For instance, Paivio and Csapo (1969) found that whereas verbal codes are particularly effective in sequential memory tasks, imaginal or pictorial codes are effective in free recall and paired-associate learning.