Long-term working memory.

To account for the large demands on working memory during text comprehension and expert performance, the traditional models of working memory involving temporary storage must be extended to include working memory based on storage in long-term memory. In the proposed theoretical framework cognitive processes are viewed as a sequence of stable states representing end products of processing. In skilled activities, acquired memory skills allow these end products to be stored in long-term memory and kept directly accessible by means of retrieval cues in short-term memory, as proposed by skilled memory theory. These theoretical claims are supported by a review of evidence on memory in text comprehension and expert performance in such domains as mental calculation, medical diagnosis, and chess. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential ontogeny of working memory and reference memory in the rat.

Examined the ability of 15-, 21-, and 27-day-old rats to perform 2 spatial working memory problems (delayed alternation and discrete-trials delayed alternation) and a reference memory problem (position habit) in a T-maze. In the delayed alternation problem, each S was presented with a series of free-choice trials and was rewarded for regularly alternating responses to the left and right arms of the T-maze. In the discrete-trials delayed alternation problem, each S was forced to one maze arm and rewarded (forced run) and was then placed back into the start box and given a choice of arms (choice run). The direction of forced runs followed an irregular, counterbalanced series, and Ss were rewarded for choosing the alternate maze arm on choice runs. In the position habit problem, Ss were rewarded for consistently choosing 1 of the 2 arms of the T-maze. At all ages, rat pups learned to perform the delayed alternation and position habit problems. Only 21- and 27-day-old rats were able to learn the discrete-trials delayed alternation problem. Results of these experiments show that reference memory capacity is present by at least 15 days of age in the rat and does not develop further at later ages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short- and long-term components of working memory in the rat.

In Experiment 1 of this report, we examined the neuropharmacological nature of short-term working memory of rats trained to retrieve food from all arms of a 12-arm radial maze. Delay intervals of varying length were placed between Choices 6 and 7. Lanthanum (LaCl?) and glutamate (GLU) injected bilaterally into the hippocampus effectively impaired retention over short delay intervals, which suggests a possible role for calcium and/or potassium and for glutamate in working memory. However, another equally likely explanation for the amnesic effects of LaCl? and GLU is that these drugs impaired reference memory. To test more directly the hypothesis that LaCl?, GLU, or ANI might differentially affect working and reference memory, we tested the effects of these drugs on performance of rats trained to retrieve food from only 8 arms of the 12-arm maze in Experiment 2. The remaining 4 arms were never baited, in order to test reference memory function. We predicted that rats would make errors only in baited arms (i.e., errors of working memory). Instead, results of Experiment 2 showed that LaCl?, GLU, or ANI injection produced errors in unbaited arms even before a 120-min delay. If rats were injected with LaCl? or GLU, baited-arm errors were observed only after the delay period. No impairment of performance on baited arms were observed after injection of ANI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Central cholinergic involvement in working memory: Effects of scopolamine on continuous nonmatching and discrimination performance in the rat.

In 4 experiments, male Sprague-Dawley rats (N?=?37) were trained to stable baselines of leverpressing on a variable intertrial interval continuous nonmatching-to-sample schedule (CNM) or on an analogous discrimination schedule. Scopolamine HBr (0.125, 0.25, and 0.50 mg/kg) reduced the accuracy of CNM performance to a similar extent over the 3 intertrial (retention) intervals: 2.5, 5, and 10 sec, indicating that the drug did not affect the time-dependent process of retention in working memory. When baseline levels of performance accuracy were similar in the CNM and discrimination tasks (but stimulus discriminability was greater in the CNM task), scopolamine reduced accuracy equally in the 2 procedures. The effects of scopolamine on the accuracy of noncorrection trial CNM performance were simulated by reducing stimulus discriminability; however, scopolamine disrupted CNM correction trial performance much more than did reductions in stimulus discriminability. It is concluded that scopolamine's effects on working memory are not limited to the possible effects on stimulus discrimination—scopolamine may also affect the retrieval of response rules from reference memory. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term study of chronic oral aluminum exposure and spatial working memory in rats.

The authors report an effort to advance animal models that mimic the cognitive decline of Alzheimer's disease. Rats were trained and repeatedly tested in a spatial delayed matching-to-position paradigm in the water maze, with the location of the submerged platform changing between, but not within, days. After Trial 1 (random search) and intertrial intervals of 30 s or 1 hr, memory was tested in Trial 2. Young rats quickly acquired this task and were repeatedly tested after different intervals over 7 months, with a slight increase in performance toward the end of testing, but no difference in latencies between delays. Oral long-term treatment of 1 group with 0.1 % aluminum caused no delay-dependent working memory deficit. This testing protocol may enable between- and within-subject long-term assessment of spatial working memory before and after drug treatment and may prove useful in animal models of progressive cognitive decline. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Episodic long-term memory in the rat: Effects of hippocampal stimulation.

Seven male Long-Evans rats with electrodes implanted in the dorsal hippocampus were trained to perform a delayed spatial matching-to-sample task on a radial arm maze. Subseizure-level electrical stimulation of the dorsal hippocampus applied during the study phase disrupted retention of a specific arm when tested at a 20-min delay but had no effects at 1- and 12-min delays. Subseizure-level stimulation of the hippocampus immediately after the study phase resulted in normal retention. In contrast, seizure-level stimulation of the hippocampus applied either during or immediately after the study phase disrupted retention at 1-, 12-, and 20-min delays. Data support the interpretation that the hippocampus is involved in the encoding of critical information (spatiotemporal attributes) in long-term working memory, but not in short-term memory. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developments in the concept of working memory.

The authors summarize developments in the concept of working memory as a multicomponent system, beginning by contrasting this approach with alternative uses of the term working memory. According to a 3-component model, working memory comprises a phonological loop for manipulating and storing speech-based information and a visuospatial sketchpad that performs a similar function for visual and spatial information. Both are supervised by a central executive, which functions as an attentional control system. A simple trace-decay model of the phonological loop provides a coherent account of the effects of word length, phonemic similarity, irrelevant speech, and articulatory suppression in verbal short-term memory tasks. This model of the loop has also proved useful in the analysis of neuropsychological, developmental and, cross-cultural data. The notion of the sketchpad is supported by selective interference with imagery in normal adults and by specific neuropsychological impairment. Analysis of the central executive is illustrated by work on deficits in the ability to coordinate subproccesses in Alzheimer's disease (AD). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of ethanol on nonspatial working memory and attention in rats.

Investigation into the neural basis for ethanol-induced cognitive dysfunction requires the use of valid animal models. An operant signal detection procedure was developed to assess simultaneously the processes of sustained attention and working memory in rats, and to determine the effects of ethanol on these cognitive functions. Ethanol, at 0.75 g/kg intraperitoneal/ly (ip), produced delay- and stimulus length-dependent decreases in choice accuracy, effects that are consistent with deficits in both working memory and sustained attention. Local infusion of ethanol directly into the medial septal area resulted in a selective loss of choice accuracy at the long delay. The impairment by intraseptal ethanol did not interact with stimulus length. Thus, the working memory impairment, but not the decrement in sustained attention, was mimicked by intraseptal ethanol. The current model provides a foundation for studying the neural basis of ethanol's cognitive effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of increased processing demands on age differences in working memory.

Three studies investigated (a) the plausibility of the claim that increasing the processing demands in a memory task contributes to greater involvement of a central processor and (b) the effects of altering reliance on the central processor on the magnitude of age-related differences in working-memory tasks. In the first study, young adults performed versions of 2 tasks presumed to vary in the degree of reliance on the central processor. In the second and third studies, young and older adults performed versions of a computation-span task that were assumed to vary along a rough continuum of the amount of required processing. The results indicated that although a central processor appears to be involved when working-memory tasks require simultaneous storage and processing of information, age related differences in working memory seem to be determined at least as much by differences in the capacity of storage as by differences in the efficacy of processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reduced working memory span in Parkinson's disease: Evidence for the role of frontostriatal system in working and strategic memory.

Working and strategic memory were examined in unmedicated patients with Parkinson's disease who had neither depression nor dementia. The patients, relative to control participants, had reduced working memory spans for verbal and arithmetic materials. They also had impairment on strategic memory tests of fee recall, temporal ordering, and self-ordered pointing, but no impairment on tests of recognition memory and semantic memory. Impairments in working memory capacity correlated with impairments in strategic memory and with a measure of perceptual-motor speed, but not with motor speed. It is hypothesized that a frontostriatal memory system, in which dopamine plays a critical role, mediates perceptual-motor processing speed that contributes to working memory capacity, which in turn, contributes to strategic memory performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Speech recognition and working memory capacity in young-elderly listeners: Effects of hearing sensitivity.

Young normal-hearing listeners and young-elderly listeners between 55 and 65 years of age, ranging from near-normal hearing to moderate hearing loss, were compared using different speech recognition tasks (consonant recognition in quiet and in noise, and time-compressed sentences) and working memory tasks (serial word recall and digit ordering). The results showed that the group of young-elderly listeners performed worse on both the speech recognition and working memory tasks than the young listeners. However, when pure-tone audiometric thresholds were used as a covariate variable, the significant differences between groups disappeared. These results support the hypothesis that sensory decline in young-elderly listeners seems to be an important factor in explaining the decrease in speech processing and working memory capacity observed at these ages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychology and working memory: A review.

Reviews the relationship between neuropsychological approaches to human memory and the working memory theory introduced by A. D. Baddeley and G. J. Hitch (1974). It is argued that neuropsychological perspectives have made a number of different contributions to the development of the theory. On occasion, they have provided unique natural experiments that cannot be simulated in the laboratory and that represent a significant input to theoretical refinement. They also yield a rich source of information on a central tenet of working memory theory, which is that the components of working memory support everyday complex cognitive activities. Neuropsychological studies have played an important role in identifying the contributions of the phonological loop to the acquisition and processing of language and of the visuospatial sketchpad to learning to recognize new faces. More generally, neuropsychological investigations have substantially reinforced developments of theory based on work from the experimental laboratory, and they provide convincing evidence for the robustness and generality of the theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The aging of working memory.

Research concerned with relations between adult age and working memory is reviewed, especially that relevant to the A. D. Baddeley (e.g., see PA, Vol 79:26150; see also Baddeley & G. J. Hitch, 1974) model of working memory. The evidence suggests that although increased age is associated with lower scores on measures of working memory functioning, many of the age-related influences appear to be mediated by a slower speed of processing. Furthermore, recent studies indicate that slower processing primarily influences the time required to achieve a stable encoding of the information rather than the rate at which information is lost across time or subsequent processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term potentiation and long-term depression in the lateral septum in spatial working and reference memory

We report two experiments conducted on a radial arm maze in the mouse showing that training could either enhance or reduce the efficacy of the fimbria-lateral septal synapses. It is suggested that the direction of change is determined by the kind of situation the animal is faced with (ie trial-dependent, respectively).     

Effects of age on working memory: an event-related potential study

The effects of age on behavioural performance and event-related potentials recorded during a working memory task using digits presented either acoustically or visually, were studied in 37 healthy subjects with an age range from 19 to 71 years. With increasing age, psychological tests showed a progressive decline in visuo-spatial performance and both auditory and visual reaction times (RT) increased. There were multiple and varying effects of age on both early and late ERP components. For both auditory and visual responses, increasing age was associated with an increased amplitude of early positive waves (auditory P100 and visual P145) and, in the oldest subjects, significant delays of the major late positive waves. Other changes were modality-specific with a progressive shift of amplitude maxima in the early negative waves of the visual ERPs (from an N190 peak maximal at Pz in the young, to an N270 peak maximal at Cz in the older subjects) and an altered amplitude distribution of late potentials (after the P250 wave) in the auditory responses. The age at which ERP changes occurred varied-significant latency prolongations and increases in the amplitude of the major frontal positive waves occurred only in the oldest subjects, whereas a redistribution of late auditory ERPs also occurred in the intermediate age group. There was no interaction between age and increasing memory load, suggesting that there is no specific effect of age on memory scanning in this age range for these levels of task difficulty. Thus, although performance in working memory was apparently unaffected by age, as judged by behavioural parameters (apart from slowing of the reaction times), ERPs revealed significant changes in both early and late electrical brain processes associated with working memory as age increases. These changes which were not symptomatically manifest and only revealed by sensitive tests, may represent subtle dysfunction of working memory (or associated processes) which does not prevent the successful completion of our task, compensatory mechanisms (which are essential to successfully complete the task), or a combination of both age-induced dysfunction and compensatory mechanisms.     

Adult age differences in working memory.

Active and passive measures of short-term memory over a large segment of the adult life span were compared. Two hundred twenty-eight volunteers, aged 30 to 99 years, performed the digit span forward and backward task, the Peterson-Peterson task, and a new working memory task in which active manipulation of information is emphasized. Age differences were slight for passive tasks. For the working memory task, significant declines were found between the ages of 60 to 69 and 70+ years. It is suggested that the age differences may be due to a decrease in the flexibility with which processing changes are made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in visuospatial working memory.

In two visuospatial working memory (VSWM) span experiments, older and young participants were tested under conditions of either high or low interference, using two different displays: computerized versions of a 3 × 3 matrix or the standard (randomly arrayed) Corsi block task (P. M. Corsi, 1972). Older adults' VSWM estimates were increased in the low-interference, compared with the high-interference, condition, replicating findings with verbal memory span studies. Young adults showed the opposite pattern, and together the findings suggest that typical VSWM span tasks include opposing components (interference and practice) that differentially affect young and older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in working memory.

Two experiments were conducted to determine whether adult age differences in working memory should be attributed to less efficient processing, a smaller working memory storage capacity, or both. In Experiment 1, young, middle-age, and older adults solved 3 additional problems before giving the answers to any. Older adults added as well as young and middle-age adults but showed a more pronounced serial position curve across the 3 problem positions. In Experiment 2, young and older adults constructed linear orderings (e.g., ABCD) from pairwise information presented in sentences (e.g., BC). Manipulations involving processing (e.g., type of sentence) did not interact with age differences, but those involving storage capacity (e.g., ordering length) did. All main effects and interactions support the hypothesis of a smaller storage capacity but do not rule out some processing deficit in older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in working memory: Introduction to the special section.

This special section includes a set of 5 articles that examine the nature of inter- and intraindividual differences in working memory, using working memory span tasks as the main research tools. These span tasks are different from traditional short-term memory spans (e.g., digit or word span) in that they require participants to maintain some target memory items (e.g., words) while simultaneously performing some other tasks (e.g., reading sentences). In this introduction, a brief discussion of these working memory span tasks and their characteristics is provided first. This is followed by an overview of 2 major theoretic issues that are addressed by the subsequent articles—(a) the factors influencing the inter- and intraindividual differences in working memory performance and (b) the domain generality versus domain specificity of working memory—and also of some important issues that must be kept in mind when readers try to evaluate the claims regarding these 2 theoretical issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction of acoustic stimulation during acquisition and resistance to extinction in the normal and hippocampally damaged rat.

Conducted 3 experiments to determine whether exposure to acoustic stimulation in acquisition of a fixed response chain would increase persistence in the subsequent extinction of that response. Other factors manipulated in the experiments were (a) the manner of introduction of the tone stimulus (gradual increase in intensity of terminal intensity from the outset), (b) locus of introduction of tone in the response chain (at beginning or end), and (c) the interaction of tone-in-acquisition treatment with presence or absence of hippocampal lesions in the Ss. Findings show that introduction of the tone in acquisition increased resistance to extinction (a) more greatly under terminal than under gradual conditions, (b) both when it was introduced at the beginning and at the end of the response chain, and (c) in operated controls but not in Ss with lesions of the hippocampus. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)