Abstract: In human long-term memory, ideas and concepts become associated in the learning process. No neuronal correlate for this cognitive function has so far been described, except that memory traces are thought to be localized in the cerebral cortex; the temporal lobe has been assigned as the site for visual experience because electric stimulation of this area results in imagery recall and lesions produce deficits in visual recognition of objects. We previously reported that in the anterior ventral temporal cortex of monkeys, individual neurons have a sustained activity that is highly selective for a few of the 100 coloured fractal patterns used in a visual working-memory task. Here I report the development of this selectivity through repeated trials involving the working memory. The few patterns for which a neuron was conjointly selective were frequently related to each other through stimulus-stimulus association imposed during training. The results indicate that the selectivity acquired by these cells represents a neuronal correlate of the associative long-term memory of pictures.

Abstract: Five experiments investigated immediate memory for drawings of familiar objects in children of different ages. The aims were to demonstrate younger children’s greater dependence on visual working memory and to explore the nature of this memory system. Experiment 1 showed that visual similarity of drawings impaired recall in young (5-year-old) children but not in older (10-year-old) children. Experiment 2 showed that younger and older children were affected in contrasting ways when the temporal order of recall was manipulated. Experiment 3 explored a recency effect found in backward recall and investigated its sensitivity to the presentation modality of materials used to produce retroactive interference (RI). For younger children, recency was reduced by visual but not by auditory-verbal RI; for older children, recency was more sensitive to auditoryverbal RI. Experiment 4 confirmed the effect of visual RI on visual recency in young children and showed that the same RI had little effect on their recall of spoken words. These results confirm younger children’s dependence on visual working memory. A final experiment showed that the effects of visual similarity and visual RI are additive, suggesting that they reflect different modes of accessing stored visuospatial information. Implications of these findings for developmental issues and for the nature of visual working memory are discussed.

Abstract: The existence of automatic negative self-referential thought in depression was examined by using the concurrent memory load paradigm. Depressed and nondepressed subjects judged each of a series of depressed- and nondepressed-content adjectives as to its descriptiveness of the self or of the average other person. While making each judgment, some subjects held six digits in working memory, whereas the remaining subjects had no concurrent memory load. We found that the memory load manipulation resulted in a reliably smaller increase in depressed subjects' self-referential judgment latencies for depressed content than for nondepressed content, with the reverse being true of nondepressed subjects. For all subjects, however, the load effect on other-referential judgment latencies was smaller for nondepressed-content adjectives than for depressed-content adjectives. The results suggest an automatic, unintentional component in the depressed person's use of negative social constructs in self-perception but not in other-perception, indicating a context-dependent form of automatic processing.

Abstract: Five experiments are reported in which subjects were asked to remember short, visually presented sequences of whole body movement patterns, words, and spatial positions. The items were recalled in order in a memory span paradigm. During presentation of the items to be remembered subjects simply watched, or they carried out a concurrent activity involving articulatory suppression, movement to external spatial targets, or body-related movement. When the movement patterns to be remembered were familiar to subjects, movement span was not disrupted by articulatory suppression or movement to spatial targets but was disrupted by body-related movement. This movement suppression task, however, did not interfere with performance on a spatial span task or on verbal span. It is concluded that the memory for patterns of limb movement differs from memory for movement to spatial targets and that accounts of visuo-spatial processes in working memory involve the latter type of movement.

Abstract: The 2-deoxyglucose method was used to examine metabolic activity in the hippocampus, dentate gyrus, and amygdala of rhesus monkeys performing working-memory and control tasks. A working-memory group was tested on 1 of 3 tasks requiring trial-by-trial updating of information: delayed spatial response, delayed spatial alternation, or delayed object alternation. A control group was tested either on an associative memory problem, visual pattern discrimination, or a sensory-motor task that did not have an explicit mnemonic component. Local cerebral glucose utilization (LCGU) in specific layers of the dentate gyrus and the CA1 and CA3 sectors of the hippocampus, as well as in 7 distinct nuclei of the amygdala, was measured and compared across groups. Metabolic rate in specific layers of the dentate gyrus and the CA3 and CA1 fields of the hippocampus was enhanced in the working-memory compared with the control group: LCGU was between 18 and 24% higher in the granule cell and molecular layers of the dentate gyrus and in the molecular and radiatum layers of CA1 and CA3 in the hippocampus. In contrast, no significant group differences in LCGU were found for any of the 7 amygdaloid nuclei examined: the lateral, lateral basal, medial basal, accessory basal, cortical, central, and medial nuclei. These results are consistent with previous evidence showing that lesions of the hippocampus affect memory selectively, producing deficits on some memory problems while sparing others. Our findings further suggest that working-memory may be a common denominator among those tasks that are sensitive to hippocampal damage in monkeys. The contribution of the amygdala to performance on memory tasks, on the other hand, appears to be independent of the specific type of memory process that is engaged.

Abstract: • Some patients with multiple sclerosis (MS) demonstrate impaired memory. A group of 16 patients with MS who were mildly to moderately affected (Kurtzke Expanded Disability Status Scale Score = 3.8) were studied, and they were compared with a matched control group on tests of "working memory." The working memory system was explored by evaluating the amount of information that can temporarily be held in a buffer system during encoding. Results indicated that patients with MS have difficulty in processing information at the level of a hypothesized articulatory loop in working memory. This deficit was correlated with their retrieval of verbal information from long-term memory, as well as how accurately they processed verbal information presented at a rapid rate. There was no significant relationship between ratings of MS severity or number of plaques visualized on magnetic resonance imaging scans and the degree of working memory deficit.

Abstract: Dynamic Interactions in Neural Networks: An Introductory Perspective.- I. Development and Learning in Adaptive Networks.- Dynamical Stability of Formation of Cortical Maps.- Visual Plasticity in the Auditory Pathway: Visual Inputs Induced into Auditory Thalamus and Cortex Illustrate Principles of Adaptive Organization in Sensory Systems.- The Hippocampus and the Control of Information Storage in the Brain.- A Memory with Cognitive Ability.- Feature Handling in Learning Algorithms.- Self-Organizing Neural Networks with the Mechanism of Feedback Information Processing.- II. Visual Function.- Interacting Subsystems for Depth Perception and Detour Behavior.- Role of Basal Ganglia in Initiation of Voluntary Movements.- Neural Mechanisms of Attention in Extrastriate Cortex of Monkeys.- Neuronal Representation of Pictorial Working Memory in the Primate Temporal Cortex.- III. Motor Control and the Cerebellum.- Hierarchical Learning of Voluntary Movement by Cerebellum and Sensory Association Cortex.- A Model for Oblique Saccade Generation and Adaptation.- Cerebellar Mechanisms in the Adaptation of Vestibuloocular Reflex.- A Kalman Filter Theory of the Cerebellum.- Conditioning and the Cerebellum.

Abstract: The memory performance of patients suffering from senile dementia of the Alzheimer type (SDAT) (N = 29), normal subjects of equivalent age and education (N = 58), and young normal controls (N = 42) was tested using free recall and verbal and nonverbal span. Three measures were derived from the free recall task: primacy based on the first item, secondary memory based on the middle serial positions, and primary memory based on recency and the Waugh-Norman correction factor. The SDAT patients differed from the normal elderly on all free recall and span measures except for primary memory. The elderly were clearly inferior to the young on secondary memory, and were marginally poorer on primary memory and the two span measures. Three possible explanations of this pattern of results are considered, based on the dichotomous modal model of memory, levels of processing, and working memory. It is suggested that the assumption that SDAT patients suffer from a deficit in the central executive component of wor...

Abstract: The memory loss associated with Alzheimer's Disease (AD) may have multiple cognitive components. Working Memory appears to be impaired due to failures of a Central Executive System. Secondary Memory, on the other hand, is affected due to poor encoding or mediational processes. An analysis of the performance of 71 AD patients on tests related to these neuropsychological constructs revealed that they could indeed be dissociated. In fact, individual patients were identified with significantly different, and unique, patterns of impairment which were consistent with the two-component model. These data, therefore, lend preliminary support for the notion of multiple cognitive impairments being responsible for the memory loss in AD.

Abstract: The effect of scopolamine on remembering was examined in a delayed conditional discrimination procedure with rats. Remembering was quantified by a negative exponential function fitted to estimates of discriminability derived from a signal detection type of analysis. This function had two parameters: a measure of initial discriminability of the sample stimuli in the absence of a memory requirement (at zero delay) and a measure of rate of forgetting. Eight rats were trained on an auditory delayed conditional discrimination task until they were showing stable performance. Each rat then received doses of 0, 0.005, 0.014, 0.042, 0.125 and 0.375 mg/kg scopolamine IP in a saline vehicle. There was a highly significant, largely linear, decrease in initial discriminability. This was obvious even at the lowest dose of scopolamine. Poorer memory, as demonstrated by an increase in b, was only apparent at the highest dose. Significant changes in per cent of correct responses were also only obtained at higher doses. These results show that initial discriminability and rate of forgetting are pharmacologically as well as theoretically independent. They suggest that the measure of initial discriminability used here is a particularly sensitive measure of at least some types of cholinergic dysfunction; and they also suggest that effects of scopolamine in other working memory tasks could be more a result of changed stimulus processing than of impairment of memorial processes.

Abstract: Twenty healthy young adults completed a series of nonverbal and problem solving tasks in a repeated measures design involving placebo and 0.6 mg scopolamine, administered by subcutaneous injection. Subjects completed the test battery under standard presentation conditions and with concurrent articulation, which precludes verbal recoding of test material. Under standard presentation conditions, scopolamine significantly impaired performance on the problem solving task and on tasks of visuo-spatial and spatial memory; memory for abstract shapes was not impaired. Concurrent articulation impaired performance on the shape recognition and interacted with drug treatment on the problem solving task. The results suggest that scopolamine impairs working memory, and that the decrement is at the level of the central executive mechanism rather than the subsystems which it controls.

Abstract: There has been a recent debate about the utilization of phonological information by poor readers in both working memory and reading tasks. The purpose of the first experiment in this study was to examine whether the absence of phonological similarity effects in working memory reported in previous studies was due to inappropriate levels of task difficulty. Poor readers and their reading age controls were found to show a normal effect when the memory task was at an appropriate level of difficulty, but no effect when a large number of items had to be recalled. However, in a recognition memory task, the poor readers chose orthographically similar pairs, whereas the reading-age and chronological age controls chose phonologically similar pairs. The purpose of a final experiment was to determine whether or not the good and poor readers could be differentiated in terms of their reading strategies; both groups showed regularity effects in a naming task and pseudohomophone effects in a lexical decision task. However, although poor readers could read three-letter nonwords as well as their controls, they were significantly impaired in reading more complex one-syllable nonwords. It was concluded that poor readers may have a phonological dysfunction in some aspects of reading that is unrelated to whether or not they show phonological similarity effects in working memory. Impaired segmentation skills may underly their difficulties in both reading and nonreading tasks.

Abstract: Three levels of working memory load of a visual search (Memory and Search) task were tested in a 72-hour sleep deprivation paradigm. General performance and accuracy decrease over time with monoton...

Abstract: The effects of isolating the hippocampus from its neocortical inputs and outputs by damaging the deep layers of entorhinal cortex and subiculum were compared with direct removal of the hippocampus using acquisition of a complex radial maze task. A series of eight problems (four out of eight arms being correct) were learned under either massed (45 s) or distributed (10 min) practice conditions, thus varying contextual information. Performance of rats with subiculum/entorhinal cortex lesions was similar to that of controls in all aspects of the radial maze task; whereas animals with hippocampal lesions were impaired on nearly all dependent measures. Although the effects of varying the intertrial interval were generally small, distributed practice did serve to facilitate the performance of hippocampal rats in terms of working memory. These findings are discussed as they related to recent theorizing in the area.

Abstract: The effects of the long-acting acetylcholinesterase (AChE) inhibitor, galanthamine, on spatial memory were investigated in mice. Mice received ibotenic acid or sham lesions to the nucleus basalis magnocellularis (nBM). Groups of nBM-lesioned and control mice were then trained on a modified Morris swim maze task. Each mouse was first placed on a platform and then into quadrants of the swim tank in a random order. Time required to find the hidden platform was measured. In different phases of testing, the animal had to find a platform that either remained in the same quadrant (reference memory component) or was moved daily (working memory component). The nBM-lesioned mice took significantly longer to find the platform as compared to controls on the working, but not on the reference, memory component of the task. Galanthamine (5.0 mg/kg, IP), given 3.5 hours before testing, improved performance on the working memory task in nBM-lesioned mice by 70% and strikingly impaired performance in controls. Galanthamine's ability to reverse cognitive deficits induced by nBM lesions and its comparatively long half-life suggest that it may be effective in treating the central cholinergic deficits in Alzheimer's disease patients.

Abstract: This paper reports three experiments using the secondary task methodology of working memory, in the task analysis of a complex computer game, ‘SPACE FORTRESS’. Unlike traditional studies of working memory, the primary task relies on perceptual-motor skills and accurate timing of responses as well as short- and long-term strategic decisions. In experiment 1, highly trained game performance was affected by the requirement to generate concurrent, paced responses and by concurrent loads on working memory, but not by the requirement to produce a vocal or a tapping response to a secondary stimulus. In experiment 2, expert performance was substantially affected by secondary tasks which had high visuo-spatial or verbal cognitive processing loads, but was not contingent upon the nature (verbal or visuo-spatial) of the processing requirement. In experiment 3, subjects were tested on dual-task performance after only 3 hours practice on Space Fortress, and again after a further five hours practice on the game. Early in training, paced generation of responses had very little effect on game performance. Game performance was affected by general working memory load, but an analysis of component measures showed that a wider range and rather different aspects of performance were disrupted by a visuo-spatial memory load than were affected by a secondary verbal load. With further training this pattern changed such that the differential nature of the disruption by a secondary visuo-spatial task was much reduced. Also, paced generation of responses had a small effect on game performance. However the disruption was not as dramatic as that shown for expert players. Subjective ratings of task difficulty were poor predictors of performance in all of the three experiments. These results suggested that general working memory load was an important aspect of performance at all levels

Abstract: Eighty-three (83) high school chemistry students were administered tests of cognitive reasoning level, cognitive restructuring ability, disembedding ability, working memory capacity, and prior knowledge before a learning segment on balancing chemical equations by inspection. After a four-day instructional segment utilizing direct teaching methodology, participants were given a posttest on balancing equations. Initial regression analysis indicated that a multicollinearity problem existed. Factor analysis and correlational data indicated that the reasoning, restructuring, and disembedding variables could be collapsed and redefined as a single restructuring variable. A hierarchial regression analysis was then performed, and the following conclusions were derived: (1) when prior knowledge alone is considered, students' understanding of chemical formulas significantly (p < 0.05) influences overall equation balancing performance; (2) when prior knowledge, restructuring, and working memory are considered, only restructuring ability significantly (p < 0.05) influences overall performance; (3) working memory capacity does not significantly (p < 0.05) influence overall performance but does on certain posttest items; (4) prior knowledge and restructuring ability also significantly (p < 0.05) influence performance on certain posttest items. Discussion includes the rationale for identifying the collapsed variable as restructuring and the absence of working memory capacity as a significant influence on overall performance.

Abstract: It is suggested that the concept of working memory offers a useful framework for discussing the phenomenon of imagery. The framework assumes a Central Executive aided by two slave systems, the Articulatory Loop and the Visuo-spatial Sketchpad. The Sketchpad is assumed to be responsible for the setting up and manipulating of temporary visuo-spatial representations, and as such to be an important component in the utilisation of imagery. Experiments are described that demonstrate the separability of visuo-spatial and verbal coding effects. Furthermore, the system is shown to be important for tasks that involve manipulating visual images, such as that of using a visual imagery mnemonic, but is not responsible for the advantage enjoyed by highly imageable words in verbal memory. The paper concludes by speculating on unsolved problems and future developments.

Abstract: We report two experiments concerned with a reconstructive processing model of reasoning/remembering dependencies in cognitive development. According to this model, such dependencies occur because problem-solving tasks often permit children to answer short-term memory probes by activating the same information-processing operations that they use to solve problems, not because reasoning and remembering compete for the same supply for scarce resources. This claim was examined in the context of mental arithmetic problems that were accompanied by memory probes for problem-relevant information. The data were generally consistent with the view that preschoolers and elementary schoolers can respond to memory probes by applying arithmetical processing to running gist from recently solved problems. The findings are discussed with reference to two competing interpretations of the development of working memory, fuzzy-trace theory and the generic-resources hypothesis.

Abstract: Although pigeons seem to require special training before they will display accurate spatial working memory in radial-arm mazes, they readily show accurate working memory for recently visited feeder locations in an open-field analog of the radial maze. In this task, pigeons forage among sites located on the floor of an open room, with no constraints on the path they take between sites. Experiment 1 suggested that pigeons’ working memory for recently visited sites is facilitated if they are permitted to develop a stable reference memory “map” of the location of the sites with respect to landmarks in the room: Pigeons for which the landmarks remained constant from day to day displayed more accurate working memory than did pigeons for which the landmarks were rearranged between daily trials. The second experiment investigated the durability of pigeons’ working memory, using a forced-choice procedure. Accuracy remained high for retention intervals of up to 32 min, but dropped significantly with a 2-h delay.