Abstract: The present investigation had two aims: (1) to study responses of dopamine neurons to stimuli with attentional and motivational significance during several steps of learning a behavioral task, and (2) to study the activity of dopamine neurons during the performance of cognitive tasks known to be impaired after lesions of these neurons Monkeys that had previously learned a simple reaction time task were trained to perform a spatial delayed response task via two intermediate tasks During the learning of each new task, a total of 25% of 76 dopamine neurons showed phasic responses to the delivery of primary liquid reward, whereas only 9% of 163 neurons responded to this event once task performance was established This produced an average population response during but not after learning of each task Reward responses during learning were significantly more numerous and pronounced in area A10, as compared to areas A8 and A9 Dopamine neurons also showed phasic responses to the two conditioned stimuli These were the instruction cue, which was the first stimulus in each trial and indicated the target of the upcoming arm movement (58% of 76 neurons during and 44% of 163 neurons after learning), and the trigger stimulus, which was a conditioned incentive stimulus predicting reward and eliciting a saccadic eye movement and an arm reaching movement (38% of neurons during and 40% after learning) None of the dopamine neurons showed sustained activity in the delay between the instruction and trigger stimuli that would resemble the activity of neurons in dopamine terminal areas, such as the striatum and frontal cortex Thus, dopamine neurons respond phasically to alerting external stimuli with behavioral significance whose detection is crucial for learning and performing delayed response tasks The lack of sustained activity suggests that dopamine neurons do not encode representational processes, such as working memory, expectation of external stimuli or reward, or preparation of movement Rather, dopamine neurons are involved with transient changes of impulse activity in basic attentional and motivational processes underlying learning and cognitive behavior

Abstract: Introduction to Working Memory. The Development of Working Memory. Vocabulary Acquisition. Speech Production. Introduction to Reading Development. Phonological Processing and Reading Development. Visual Word Recognition. Language Comprehension. Theoretical and Practical Issues.

Abstract: The concept of working memory is central to theories of human cognition because working memory is essential to such human skills as language comprehension and deductive reasoning. Working memory is thought to be composed of two parts, a set of buffers that temporarily store information in either a phonological or visuospatial form, and a central executive responsible for various computations such as mental arithmetic. Although most data on working memory come from behavioural studies of normal and brain-injured humans, there is evidence about its physiological basis from invasive studies of monkeys. Here we report positron emission tomography (PET) studies of regional cerebral blood flow in normal humans that reveal activation in right-hemisphere prefrontal, occipital, parietal and premotor cortices accompanying spatial working memory processes. These results begin to uncover the circuitry of a working memory system in humans.

Abstract: Regional cerebral blood flow was measured with positron emission tomography during the performance of verbal working memory tasks. The same type of verbal response (i.e., reciting numbers) was required in the control and the two experimental tasks. In the control task, the subjects were required to count aloud. In the two experimental tasks, the subjects were required to maintain within working memory the numbers they generated (self-ordered task) or the numbers generated by the experimenter (externally ordered task). Examination of the difference in activation between these conditions revealed strong bilateral activation within the mid-dorsolateral frontal cortex during both experimental tasks. There was, however, no evidence of additional activation within the mid-dorsolateral frontal cortex when monitoring self-generated responses as compared with the monitoring of externally generated responses. These results provide evidence regarding the role of the mid-dorsolateral frontal cortex in mnemonic processing that are in agreement with recent findings from work with non-human primates.

Abstract: Patients with damage to the dorsolateral prefrontal cortex are impaired on cognitive tasks such as the Wisconsin Card Sort Test, the Stroop Test and an anti-saccade paradigm, in which sensory-guided habitual responses must be suppressed in favour of conceptually or memory-guided responses. We report here recordings from prefrontal neurons in rhesus monkeys trained to perform a delayed anti-saccade task based on tests that have been used with humans. Activity in the same prefrontal neurons was recorded across conditions when saccades were made toward a remembered target, and also when this prepotent response was suppressed and a saccade in the opposite direction required. Our findings show that most prefrontal neurons code the location of the visual stimulus in working memory, and that this memory can be engaged to suppress as well as prescribe a response. These results establish, in a subset of prefrontal neurons, the iconic nature of the memory code, and suggest a role for visual memory in response suppression.

Abstract: We compared procedural learning, translation of procedural knowledge into declarative knowledge, and use of declarative knowledge in age-matched normal volunteers (n = 30), patients with Parkinson's disease (n = 20), and patients with cerebellar degeneration (n = 15) by using a serial reaction time task. Patients with Parkinson's disease achieved procedural knowledge and used declarative knowledge of the task to improve performance, but they required a larger number of repetitions of the task to translate procedural knowledge into declarative knowledge. Patients with cerebellar degeneration did not show performance improvement due to procedural learning, failed to achieve declarative knowledge, and showed limited use of declarative knowledge of the task to improve their performance. Both basal ganglia and cerebellum are involved in procedural learning, but their roles are different. The normal influence of the basal ganglia on the prefrontal cortex may be required for timely access of information to and from the working memory buffer, while the cerebellum may index and order events in the time domain and be therefore essential for any cognitive functions involving sequences.

Abstract: A series of studies addresses the possibility that tones disrupt serial recall of visually presented material in the same way as speech. A stream of changing tones is as disruptive of visual serial recall as 4 syllables (Experiments 1 and 2). Similar effects were also shown with a repeated syllable that changed only in pitch (Experiment 3). Just as for speech, the effect of tones is not at encoding but during storage of the serial lists (Experiments 4 and 5). The results suggest that speech and tones are equipotent in their capacity to disrupt short-term memory. A «blackboard» model of working memory to account for the effects is outlined

Abstract: Recordings of the activity of 2705 single neurones were made in entorhinal and perirhinal cortex, area TG of the temporal lobe, and the inferior temporal cortex both during monkeys' performance of a serial recognition memory task using complex pictures and when monkeys were shown objects. Responses of 120 (9.7%) of the visually responsive neurones recorded were significantly smaller to the second than to the first presentations of unfamiliar stimuli. The incidence of such responses was highest in perirhinal cortex plus areas TE1 and TE2 of the temporal lobe, intermediate in lateral entorhinal cortex and areas TE3 and TG, and lowest in other parts of entorhinal and inferior temporal cortex. Response decrements were maintained across 20 or more intervening presentations of other stimuli for the majority of the neurones tested. Responses of 43 (14.4%) of the visually responsive neurones tested were significantly greater to unfamiliar than to highly familiar stimuli. Such differential responses were found only in lateral entorhinal and perirhinal cortex plus areas TG, TE1, TE2 and TE3. For 6 neurones the response difference was significant even when the familiar stimuli had not been seen for more than 24 h: such neurones demonstrate access to information stored in long-term memory for more than 24 h. Seven familiarity neurones signalled information concerning the relative familiarity of stimuli but not information concerning how recently they were last seen; 58 recency neurones signalled information concerning the recency of presentation of stimuli, but not their relative familiarity. Thus certain neurones demonstrate the separable encoding of recency and familiarity information. Neurones signalling information of use for recognition memory are found in cortex close to the rhinal sulcus where lesions result in major deficits in the performance of recognition memory tasks. The conjunction of these findings provides strong evidence for the importance of these neurones and this cortex for processes (recency and familiarity discrimination) necessary for recognition and working memory. The possible relation of the neuronal responses to priming memory is also discussed.

Abstract: By Gathercole, Susan E.; Adams, Anne-Marie Developmental Psychology. Vol 29(4), Jul 1993, 770-778. Abstract This study was designed to establish whether phonological working memory skills could be assessed in children below 4 yrs of age. A group of 2- and 3-yr-old children were tested on 3 phonological memory measures (digit span, nonword repetition, and word repetition) and were also given tasks that tapped other cognitive skills. Scores on the 3 phonological memory tasks were closely related. In addition, repetition performance was linked with both vocabulary knowledge and articulation rate. Results indicate that phonological memory skills can be reliably assessed in very young children by using conventional serial span and repetition procedures. (PsycINFO Database Record (c) 2008 APA, all rights reserved)

Abstract: It has often been asserted that working-memory limitations are a major factor contributing to problem difficulty; for example, Johnson-Laird’s (1983) mental-models theory appeals to working memory limitations to explain the difficulty of syllogistic reasoning. However, few studies have directly explored working memory in problem solving in general or syllogistic reasoning in particular. This paper reports two studies. In the first, working-memory load was varied by presenting syllogistic tasks either verbally or visually (so that the premises were continuous1y avai1ab1e for inspection). A significant effect of memory load was obtained. In the second study, premises were presented visually for a subject-determined time. Dual-task methods were used to assess the role of working-memory components, as identified in Baddeley’s (1986) model. Syllogistic performance was disrupted by concurrent random-number generation but not by concurrent articulatory suppression or by concurrent tapping in a preset pattern. Furthermore, the concurrent syllogism task interfered with random generation and to a lesser extent with articulatory suppression, but not with tapping. We conclude that while the central-executive component of working memory played a major role in the syllogistic-task performance reported here, the articulatory loop had a lesser role, and the visuospatial scratch pad was not involved.

Abstract: Using the theoretical frameworks proposed by Cummins (1981a) and Bialystok and Ryan (1985), this research was designed to shed light on the relationship between cognitive correlates and linguistic skills in first (L1) and second (L2) language, and the extent to which performance on academic tasks in L2 can be predicted by these factors. The study was conducted with 73 Grade 5–7 children attending a bilingual English-Hebrew day school. The test battery included a measure of intelligence, measures of linguistic knowledge in L1, measures of reading comprehension in L1 and L2 and static and working memory measures in L1 and L2. Evidence was found for the theoretical notion that with increased speed of basic processing in L2, higher level cognitive processes involved in linguistic and oral communication in academic settings are facilitated. Additionally, results suggest that children who can more systematically employ analytic functions in their L1 are more likely to do so in their L2 as well, and that performance on linguistically demanding tasks such as reading in L2 can be more accurately predicted with the aid of information on memory storage and executive control functions, in combination with underlying intelligence and L2 oral proficiency. Results highlight the important role that memory plays in performing linguistic tasks in L2 and help to explain underlying ability factors related to Cummins' interdependence hypothesis.

Abstract: This study examined the influence of individual difference and contextual variables on the magnitude of age differences in memory for spatial location. Younger adults and 2 samples of older adults that differed in educational attainment, verbal intelligence, and working memory ability were compared. Ss studied and later recreated an arrangement of small objects that were placed on a plain map or a visually distinctive model. The objects were either unrelated or categorically related items. The results indicated that distinctive context enhanced spatial memory, and the magnitude of the benefit was generally comparable across age groups and stimulus sets. Hierarchical regression analyses confirmed that working memory resources accounted for a sizable proportion of age-related variance in memory for spatial location. The implications of these results for current views on age-related differences in memory for spatial location are discussed.

Abstract: The neurobiology of cingulate cortex is like a dog. Each of the four areas of study— anatomy, physiology, chemistry, and behavior—forms one of the dog’s legs. No one notices it when we are simply sitting still, but if we get together and try to get up and run, it is clearly a three-legged dog. An understanding of the contributions of area 29 neurons to the control of behavior is only now beginning to emerge, and it is becoming clear to us that this circuitry makes a unique contribution to memory processes; one that includes, but is not limited to, the spatial domain. Our experiments over the past 10 years have shown that circuitry in area 29 exerts a powerful influence in the spatial guidance of behavior. Its contribution bears family resemblances both to posterior parietal cortex and to the hippocampal formation.

Abstract: When not engaged in demanding tasks, we commonly experience streams of thoughts and images quite unrelated to immediate sensory input. Such stimulus-independent (SI) thoughts may be troublesome, as in worry, insomnia and depression. Previous research within a working memory paradigm suggested that SI thought production depended on central executive control resources. To explore this hypothesis further, we examined the interference with SI thought production resulting from shadowing auditorily presented digits compared to remembering them. Effects of stimulus presentation rate and size of memory load were also examined. At slow presentation rates, remembering produced more interference than shadowing. For shadowing, faster presentation produced greater interference than slow presentation. In remembering, interference was not substantially affected by size of memory load, was greater when subjects reported greater awareness of task stimuli, and was restricted to thoughts forming parts of connected ...

Abstract: This chapter suggests that the existence of an episodic memory of that experience allows the organism to reflect on the experience, and act accordingly; The understanding of consciousness is clearly a fascinating and difficult question, and the proposal that it is somehow linked to working memory goes back at least to the modal model of Atkinson and Shiffrin The increase in flexibility granted by such a memory mechanism gives it considerable potential advantages over a simpler learning mechanism that produces a more automatic response The classic amnesic syndrome is typically associated with damage to the temporal lobes and/or hippocampus and limbic system A system such as working memory could be extremely useful in such an enterprise, and it seems likely that laboratory-based tasks like mental rotation are ways of measuring the manipulative capacities of working memory, in this case the visuo-spatial sketchpad

Abstract: This chapter discusses thinking about the nature of short-term memory, and put forward some of our own speculations about children’s rehearsal. The use of rehearsal to help maintain verbal material has long been considered to be one of the most important features in the adult short-term memory system. The working memory model of short-term memory introduced by A. Baddeley and Graham J. Hitch has proved to be a useful theoretical tool, both for accommodating memory phenomena such as the phonological similarity and word length effects, and for characterising the developmental changes in short-term memory function. In order to construct a more complete account of short-term memory development than either hypothesis provides alone, the phonological readout process can readily be considered to be part of the primitive rehearsal mechanism. The phonological representations have to be sequentially read and translated into abstract articulatory commands, which are then used to guide the movements of speech musculature necessary to produce the target phonological form.

Abstract: Rats with conventional lesions of the hippocampus or fornix were compared postoperatively with controls on nonspatial memory tasks. Neither lesion impaired delayed matching-to-sample (DMS) performance in a discrete-trial task involving "pseudo-trial-unique" complex stimuli. An impairment emerged if a single pair of complex stimuli was used throughout each day's session, and the greatest impairment was obtained with the use of a single pair of less complex stimuli throughout each day's test. Transfer to a continuous DMS task with no explicit intertrial interval produced a different pattern because both lesion and control levels of performance were depressed when two complex stimuli were used repeatedly. A final, separate discrimination learning experiment showed that hippocampectomized rats readily discriminated between the stimuli associated with the greatest lesion-induced DMS deficit. Hippocampal dysfunction thus produces clear deficits on non-spatial memory tasks under appropriate test conditions.

Abstract: In a three-panel runway task, intrahippocampal injection of the nicotinic receptor antagonist, mecamylamine (10 and 18 μg/side), significantly increased the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points) in a test of working memory. This increase in errors also occurred after rats were given IP mecamylamine (10 mg/kg). Mecamylamine did not affect the number of errors in a test of reference memory whether it was given at doses up to 18 μg/side intrahippocampally or up to 10 mg/kg IP. These results suggest that mechanisms mediated by hippocampal nicotinic receptors play a role in working memory but not in reference memory.

Abstract: Older adults may be disadvantaged in the performance of procedural assembly tasks because of age-related declines in working memory operations. It was hypothesized that adding illustrations to instructional text may lessen age-related performance differences by minimizing processing demands on working memory in the elderly. In the present study, younger and older adults constructed a series of 3-dimensional objects from 3 types of instructions (text only, illustration only, or text and illustrations). Results indicated that instructions consisting of text and illustrations reduced errors in construction for both age groups compared with the other formats. Younger adults, however, outperformed older adults under all instructional format conditions. Measures of spatial and verbal working memory and text comprehension ability accounted for substantial age-related variance across the different format conditions but did not fully account for the age differences observed.

Abstract: Little is known about the role of working memory in conditional reasoning. This paper reports three experiments that examine the contributions of the visuo-spatial scratch pad (VSSP), the articulatory loop, and the central executive components of Baddeley and Hitch's (1974) model of working memory to conditional reasoning. The first experiment employs a spatial memory task that is presented concurrently with two putative spatial interference tasks (tapping and tracking), articulatory suppression, and a verbal memory load. Only the tracking and memory load impaired performance, suggesting that these tap the VSSP and central executive, respectively. Having established the potency of these interference tasks two further experiments examined the effects of tapping and tracking (Experiment 2) and articulation and memory load (Experiment 3) on a conditional reasoning task. Neither tracking nor tapping affected the number of inferences accepted or response latency. Articulation also failed to affect conditional ...

Abstract: We examined short-term memory (STM) among a group of 23 definite, chronic progressive multiple sclerosis (MS) patients, all of whom had experienced recent significant disease activity, and a control group matched closely on age and education. MS patients were impaired, relative to controls, on the majority of the measures used. Although there were no significant differences between groups on the Mini Mental State Examination, patients performed more poorly on digits forward and backward, the Brown-Peterson test, and the logical memory scale of the Revised Wechsler Memory Scale (both immediate and delayed). Performance on tests sensitive to central processing capacity was significantly correlated with measures of STM. Working memory was significantly impaired in this sample of chronic progressive MS patients. In conjunction with previous research showing deficient information processing and prefrontal dysfunction among this population, the findings suggest that an impairment of central information processing may be a fundamental aspect of the mnestic and cognitive decline observed in many chronic progressive MS patients.

Abstract: QU, an eight-year-old boy, was identified from a large scale normative study on the basis of his greatly reduced digit span, combined with normal long-term memory and non-verbal intelligence. Further investigation indicated that his visual STM was normal, but that he was clearly impaired on two verbal STM tests, nonword repetition, and memory span for words. His span showed clear effects of phonological similarity and word-length, suggesting qualitatively normal functioning of the phonological loop component of working memory, despite a quantitative impairment in level of performance. This pattern resembles that found in an earlier study of children with a specific language disorder. We tested QU on measures of vocabulary, syntax, and reading, and found him to be substantially below the age norms on all three. The implications of these findings are discussed for the role of the phonological loop in language development.