Deficits in verbal long-term memory and learning in children with poor phonological short-term memory skills

Possible links between phonological short-term memory and both longer term memory and learning in 8-year-old children were investigated in this study. Performance on a range of tests of long-term memory and learning was compared for a group of 16 children with poor phonological short-term memory skills and a comparison group of children of the same age with matched nonverbal reasoning abilities but memory scores in the average range. The low-phonological-memory group were impaired on longer term memory and learning tasks that taxed memory for arbitrary verbal material such as names and nonwords. However, the two groups performed at comparable levels on tasks requiring the retention of visuo-spatial information and of meaningful material and at carrying out prospective memory tasks in which the children were asked to carry out actions at a future point in time. The results are consistent with the view that poor short-term memory function impairs the longer term retention and ease of learning of novel verbal material.     

Deficits in verbal long-term memory and learning in children with poor phonological short-term memory skills

Possible links between phonological short-term memory and both longer term memory and learning in 8-year-old children were investigated in this study. Performance on a range of tests of long-term memory and learning was compared for a group of 16 children with poor phonological short-term memory skills and a comparison group of children of the same age with matched nonverbal reasoning abilities but memory scores in the average range. The low-phonological-memory group were impaired on longer term memory and learning tasks that taxed memory for arbitrary verbal material such as names and nonwords. However, the two groups performed at comparable levels on tasks requiring the retention of visuo-spatial information and of meaningful material and at carrying out prospective memory tasks in which the children were asked to carry out actions at a future point in time. The results are consistent with the view that poor short-term memory function impairs the longer term retention and ease of learning of novel verbal material.     

Adult age differences in short-term memory and subsequent long-term memory for actions.

Short-term memory for actions was investigated for young adult and elderly adult subjects with the Brown-Peterson procedure at retention intervals of 0 and 15 s. The short-term memory trials were followed by the long-term recall of the prior to-be-remembered actions. The 15-s retention interval was filled either with no activity or with 1 of 3 different interfering activities. Verbal interference had little effect on short-term memory at either age level. Actions performed in the interval either by the subjects or by the experimenter produced significantly lower recall scores at each age level, with the decrement being more pronounced for the elderly than for the young subjects. The long-term memory results indicated that successful short-term recall enhanced later long-term recall, regardless of age level.     

Vasopressin/oxytocin-related peptides influence long-term memory of a passive avoidance task in the cuttlefish,Sepia officinalis

The vasopressin (VP)/oxytocin (OT)-related peptides constitute a large superfamily found in a wide range of both vertebrate and invertebrate species. While intensive literature reports that these neuropeptides influence behavior, especially learning and memory, in numerous species from diverse vertebrate groups, their roles in behavioral regulation have never been studied in invertebrates. Here, we investigated the role of two VP/OT superfamily peptides, octopressin (OP) and cephalotocin (CT), on long-term memory (LTM) formation of a passive avoidance task in a cephalopod mollusc, the cuttlefish, Sepia officinalis. Subadult cuttlefish were intravenously injected, in a dose range of 3–60 μg/kg, 1 h after the training phase (consolidation design); retention performance was tested 24 h post-training. We found that administration of OP at low dose (3 μg/kg) enhanced LTM, whereas a dose of 60 μg/kg attenuated it. No effect of OP on LTM was observed for the 15 μg/kg dose. Conversely, an enhancement of retention performance was observed at all doses of CT tested. This study is the first to demonstrate the behavioral effects of VP/OT superfamily peptides in an invertebrate species. The valuable role of VP/OT-like peptides on memory processes offers new evolutionary perspectives on peptidergic transmission and neuromodulation.     

Short-term memory for spatial configurations in the tactile modality: A comparison with vision

This study investigates the role of acquisition constraints on the short-term retention of spatial configurations in the tactile modality in comparison with vision. It tests whether the sequential processing of information inherent to the tactile modality could account for limitation in short-term memory span for tactual-spatial information. In addition, this study investigates developmental aspects of short-term memory for tactual- and visual-spatial configurations. A total of 144 child and adult participants were assessed for their memory span in three different conditions: tactual, visual, and visual with a limited field of view. The results showed lower tactual-spatial memory span than visual-spatial, regardless of age. However, differences in memory span observed between the tactile and visual modalities vanished when the visual processing of information occurred within a limited field. These results provide evidence for an impact of acquisition constraints on the retention of spatial information in the tactile modality in both childhood and adulthood.     

Absence of age-related proneness to short-term retroactive interference in the absence of rehearsal

Age differences in short-term retroactive interference, unconfounded with age differences in rehearsal in the retention interval of the Brown-Peterson Task, were not found in a cross-sectional study of adults 18-32 and 64-78 years of age. Degree of retroactive interference was manipulated conjointly with distractor interval length (0-15 s). Individual memory span was assessed and used as the list length in order to achieve stimulus equivalence of memory loads across individuals and age groups. An attention-demanding matching task that adjusted itself in difficulty to the individual's attentional capacity was used as the distractor activity. Covert rehearsal during the retention interval was inferred using several measures, including a comparison of distractor task performance in the presence and in the absence of a memory load, and rehearsers were excluded from the primary analyses. We conclude that there is no interference proneness with increasing age in the present study.     

Different importance of the volatile and non-volatile fractions of an olfactory signature for individual social recognition in rats versus mice and short-term versus long-term memory

When tested in the olfactory cued social recognition/discrimination test, rats and mice differ in their retention of a recognition memory for a previously encountered conspecific juvenile: Rats are able to recognize a given juvenile for approximately 45 min only whereas mice show not only short-term, but also long-term recognition memory (≥ 24 h). Here we modified the social recognition/social discrimination procedure to investigate the neurobiological mechanism(s) underlying the species differences. We presented a conspecific juvenile repeatedly to the experimental subjects and monitored the investigation duration as a measure for recognition. Presentation of only the volatile fraction of the juvenile olfactory signature was sufficient for both short- and long-term recognition in mice but not rats. Applying additional volatile, mono-molecular odours to the "to be recognized" juveniles failed to affect short-term memory in both species, but interfered with long-term recognition in mice. Finally immunocytochemical analysis of c-Fos as a marker for cellular activation, revealed that juvenile exposure stimulated areas involved in the processing of olfactory signals in both the main and the accessory olfactory bulb in mice. In rats, we measured an increased c-Fos synthesis almost exclusively in cells of the accessory olfactory bulb. Our data suggest that the species difference in the retention of social recognition memory is based on differences in the processing of the volatile versus non-volatile fraction of the individuals' olfactory signature. The non-volatile fraction is sufficient for retaining a short-term social memory only. Long-term social memory - as observed in mice - requires a processing of both the volatile and non-volatile fractions of the olfactory signature.     

Reactivated memory of an inhibitory avoidance response in mice is sensitive to a nitric oxide synthase inhibitor

It is accepted that once consolidation is completed memory becomes permanent. However, it has also been suggested that reactivation (retrieval) of the original memory, again, makes it sensitive to the same treatments that affect memory consolidation when given after training. Previous results demonstrated that the immediate post-training intraperitoneal administration of N^ω-nitro-l-arginine methyl ester (L-NAME), a non-specific inhibitor of nitric oxide synthase (NOS), impairs retention test performance of a one-trial step-through inhibitory avoidance response in adult mice. The effect of L-NAME on retention was attributed to an action on memory consolidation of the original learning. For the first time, we report that the administration of L-NAME after the first retention test (memory reactivation) of the inhibitory avoidance response impairs retention performance over six consecutive days. This impairment effect is dose-and-time dependent and could not be attributed to a retrieval deficit since a mild footshock did not reinstate the original avoidance response and no spontaneous recovery was observed at least 21 days after training. Further support for a storage deficit interpretation as opposed to a retrieval deficit was obtained from the fact that L-NAME’s effects after retrieval were not due to state-dependency. The impairment effect of L-NAME was dependent on the age of the original memory. That is, there was an inverse correlation between the susceptibility of the memory trace when reactivated and the time elapsed between training and the first retrieval session. We suggest an action of L-NAME on memory reactivation-induced processes that are different from memory extinction of the original learning extending the biological significance of nitric oxide on memory.     

Facilitation of retention by white noise.

Second and fifth grade subjects were given three verbal tasks: serial, free recall, or paired-associate learning. Retention tests were administered immediately after the acquisition phase or following a long delay. Half the subjects were exposed to a 2-min period of bursts of white noise (arousal) immediately prior to the retention test. The finding of primary interest was that white noise produced substantial improvement in performance relative to a control condition. This effect may be more pronounced for long-term memory than for short-term memory. Although older children exhibited better long-term memory than younger subjects, no interaction of age with arousal condition was observed.     

Do the mentally retarded have poor memory?

The hypothesis that mentally retarded persons have a short-term memory deficit whixh is due to inadequate rehearsal strategies is reexamined. A reevaluation of results of a number of experiments suggests that normal and retarded persons differ on short-term memory tasks, and the superiority of normals is present from the time of initial stimulus exposure. While some evidence for slope differences in retention curves is found in a few tasks, it is not strong support for memory differences. The hypothesis that “memory” differences are due to differential encoding as a result of more adequate rehearsal by the normal subjects is unacceptable. If this were the case, some differences in slope of retention curves could be expected unless rehearsal beyond the encoding stage was totally precluded. The review points to a need for an empirical reevaluation of the issue with a full recognition that deficits in particular processes may characterize some retarded persons and not others.     

Effects of retention intervals on receiver operating characteristics in artificial grammar learning

Current theories of memory suggest that recognition is composed of separate processes of familiarity and recollection (e.g. [Yonelinas, A. P. (2002). The nature of recollection and familiarity: a review of 30 years of research. Journal of Memory and Language, 46, 441-517]). A key feature of these two processes is that they decay, or are forgotten at different rates. The dual-process model has also been useful in understanding artificial grammar learning. We obtained evidence for recollection and familiarity in artificial grammar learning by analyses of receiver operating characteristics (ROC). Furthermore we found that these were dissociated by retention intervals of 14 days. The slope of the zROC curves deviated reliably from 1 immediately after study and increased towards 1 suggesting that recollection contributed to recognition decisions but declined over the 14-day period leaving familiarity as the only basis for recognition. These data show similar patterns to those observed in word-recognition [Gardiner, J. M., & Java, R. I. (1991). Forgetting in recognition memory with and without recollective experience. Memory &Cognition, 19, 617-623; Tunney, R. J. (submitted for publication). Changes in the subjective experience of recognition over time suggest independent processes] and confirm the view that recollection and familiarity are implicated in artificial grammar learning. Moreover, the data confirm the finding that recollection and familiarity-based memory show different patterns of forgetting.     

Conditions affecting retention test performance: A developmental study

Developmental studies of retention have yielded remarkably diverse results: however, it is widely assumed that retention ability increases with age. This study examined this assumption by investigating some of the conditions that might affect retention test performance in third graders and tenth graders. The most important results were the absence of age differences in proportionalized short-term retention, despite substantial differences in the number of items learned, and significant age differences in long-term retention only between groups that had received a different number of learning trials. These and other results suggest that age differences in retention test performance occur only when age is confounded with degree of learning. In short, there do not appear to be any age differences in retention per se.     

Gummed-up memory: Chewing gum impairs short-term recall

Several studies have suggested that short-term memory is generally improved by chewing gum. However, we report the first studies to show that chewing gum impairs short-term memory for both item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter lists. Experiment 2 indicated that chewing does not simply disrupt vocal–articulatory planning required for order retention: Chewing equally impairs a matched task that required retention of list item identity. Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of chewing gum. These results clearly qualify the assertion that chewing gum improves short-term memory. They also pose a problem for short-term memory theories asserting that forgetting is based on domain-specific interference given that chewing does not interfere with verbal memory any more than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.     

Two critical periods of protein and glycoprotein synthesis in memory consolidation for visual categorization learning in chicks

A protein synthesis inhibitor, anisomycin (ANI), and an inhibitor of glycoprotein synthesis, 2-deoxygalactose (2-D-gal), were used to investigate memory consolidation following visual categorization training in 2-day-old chicks. ANI (0.6 micromole/chick) and 2-D-gal (40 micromoles/chick) were injected intracerebrally at different time intervals from 1 hr before to 23 hr after the training. Retention was tested 24 hr post-training. Both ANI and 2-D-gal injections revealed two periods of memory sensitivity to pharmacological intervention. ANI impaired retention when injected from 5 min before to 30 min after the training or from 4 hr to 5 hr post-training, thus demonstrating that consolidation of long-term memory in this task requires two periods of protein synthesis. 2-D-Gal first produced an amnesia when it was injected in the interval from 5 min before to 5 min after the training. Injections made between 5 min and 5 hr post-training were without effect on the retention. The second period of memory impairment by 2-D-gal started at 5 hr post-training and lasted until 21 hr after the training. Administration of 2-D-gal made 23 hr after the training did not influence retention in the test at either 24 hr or 26 hr. These results are consistent with the hypothesis that two waves of protein and glycoprotein synthesis are necessary for the formation of long-term memory. The prolonged duration of performance impairment by 2-D-gal in the present task might reflect an extended memory consolidation period for a categorization form of learning.     

Depletion of serotonin selectively impairs short-term memory without affecting long-term memory in odor learning in the terrestrial slug Limax valentianus

The terrestrial slug Limax is able to acquire short-term and long-term memories during aversive odor-taste associative learning. We investigated the effect of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) on memory. Behavioral studies indicated that 5,7-DHT impaired short-term memory but not long-term memory. HPLC (high-performance liquid chromatography) analysis revealed that 5,7-DHT significantly reduced serotonin content in the central nervous system. The present study suggests that acquisition, retention, and/or retrieval of short-term memory involves serotonin, and neither acquisition nor retrieval of long-term memory requires serotonin at a level as high as that required for short-term memory.     

Gummed-up memory: chewing gum impairs short-term recall

Several studies have suggested that short-term memory is generally improved by chewing gum. However, we report the first studies to show that chewing gum impairs short-term memory for both item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter lists. Experiment 2 indicated that chewing does not simply disrupt vocal-articulatory planning required for order retention: Chewing equally impairs a matched task that required retention of list item identity. Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of chewing gum. These results clearly qualify the assertion that chewing gum improves short-term memory. They also pose a problem for short-term memory theories asserting that forgetting is based on domain-specific interference given that chewing does not interfere with verbal memory any more than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.     

Inhibitory avoidance deficit following short-term adrenalectomy in the rat: the role of adrenal catecholamines

Impaired retention of an inhibitory avoidance response was observed in rats subjected to adrenalectomy (ADX) up to 120 hr before the single learning trial. Corticosterone substitution failed to normalize this behavioral deficit. Rats ADX 240 hr prior to the learning trial showed a normalized behavior. Adrenomedullectomy (ADXM) 48 or 240 hr before learning caused a similar impairment as in short-term ADX rats. The 240-hr ADX rats subjected to corticosterone substitution showed the same behavioral deficit as short-term ADX rats or ADXM ones. Immediate postlearning subcutaneous injection of adrenaline in a dose range of 0.005-5.0 micrograms/kg or of noradrenaline (0.005-0.5 microgram/kg) to 48-hr ADX rats resulted in a dose-related improvement of later retention behavior. Higher doses of catecholamines were less or ineffective. Postlearning treatment of 48-hr ADXM rats with adrenaline (0.5-500 micrograms/kg) caused a similar pattern of behavioral changes. It is concluded that adrenal catecholamines play an important role in the modulation of consolidation of memory. In addition, the high circulating ACTH levels that follow long-term ADX may correct for the behaviorial deficit induced by the absence of adrenomedullary catecholamines.     

Facilitative effects of forgetting from short-term memory on growth of long-term memory in retardates

Competing explanations of the beneficial effect of spacing in retardate discrimination learning were tested. Three-trial multidimensional (“junk”) problems were presented concurrently to educable retardates with MAs over 8 years. The spacing interval spearating Trials 1 and 2 was filled with either zero, four, or eight interpolations, the interpolations being either trials on similar junk problems or repetitions of a single, well-learned dot-pattern discrimination. The principal findings were that: (1) while short-term retention of junk problems (as measured by Trial 2 performance) suffered greater interference from similar junk interpolations than from dot-pattern interpolations, long-term learning (as measured by a delayed Trial 3) was superior following the highly interfering junk problems; and (2) spacing facilitated learning only following highly interfering interpolations. These results are inconsistent with consolidation and rehearsal theories but support the prediction of the Sperber. Greenfield, and House (Journal of Experimental Psychology, 1973, 99) spacing model that forgetting from short-term memory facilitates retardate learning.     

Cognitive approaches to the development of short-term memory

The capacity to retain information for brief periods of time increases dramatically during the childhood years. The increases in temporary storage of speech-based material that take place in the period spanning the pre-school years and adolescence reflect complex changes in many of the different component processes, including perceptual analysis, construction and maintenance of a memory trace, retention of order information, rehearsal, retrieval and redintegration. Another crucial capacity that undergoes a similar striking development is complex working memory, the ability to manipulate and store material simultaneously. Possible sources of age-related changes in working memory include increases in processing efficiency and attentional capacity, and task-switching. These two short-term memory systems might play significant but distinct roles in supporting the acquisition of knowledge and skills during childhood. Whereas phonological short-term memory is linked specifically with the learning of the phonological structures of new words, complex working memory appears to support processing and learning in a wide range of contexts, in both childhood and adulthood.