Decay Of Memory Trace Research Articles

The decay and consolidation of effector-independent motor memories

Learning a motor adaptation task produces intrinsically unstable or transient motor memories. Despite the presence of effector-independent motor memories following the learning of novel environmental dynamics, it remains largely unknown how those memory traces decay in different contexts and whether an “offline” consolidation period protects memories against decay. Here, we exploit inter-effector transfer to address these questions. We found that newly acquired motor memories formed with one effector could be partially retrieved by the untrained effector to enhance its performance when the decay occurred with the passage of time or “washout” trials on which error feedback was provided. The decay of motor memories was slower following “error-free” trials, on which errors were artificially clamped to zero or removed, compared with “washout” trials. However, effector-independent memory components were abolished following movements made in the absence of task errors, resulting in no transfer gains. The brain can stabilize motor memories during daytime wakefulness. We found that 6 h of wakeful resting increased the resistance of effector-independent memories to decay. Collectively, our results suggest that the decay of effector-independent motor memories is context-dependent, and offline processing preserves those memories against decay, leading to improvements of the subsequent inter-effector transfer.

Interference-adjusted power learning curve model with forgetting

Researchers in production and operations management have studied the effect of worker learning and forgetting on system performance for decades. It remains an active research topic. Those studies have assumed that production interruptions (or production breaks) cause forgetting, which deteriorates performance. Research on human working memory provides enough evidence that continuous forgetting, precisely cognitive interference, results from overloading the memory with information. Despite the evidence, few studies have incorporated it into learning curve models. This paper presents an enhanced version of the power learning curve that accounts for a variable degree of interference when moving from a production cycle to the next. It adopts the concept of memory trace decay to measure the residual (interference-adjusted), not the nominal (maximum) cumulative experience. We test the developed model against learning data from manual assembly and inspection tasks, with varying numbers of repetitions and breaks. We also test three alternative power-form learning and forgetting curve models from the literature. The results show that the interference-adjusted model fits the data very well. The proposed learning and forgetting model and its individualized cumulative metrics can help identify struggling workers early and release precocious learners earlier than expected. As such, the model gives insights for managers on the occurrence of interference to enable individual learning support.

Bidirectional decay of auditory memory traces for pitch in speech sounds

Previous studies have shown human listeners have greater detection sensitivity to pitch increment than decrement in successive sounds. Assuming deviance detection is based on the comparison between the memory trace of a recent stimulus and the neural representation of a new stimulus, one hypothesis is that this differential sensitivity between increment and decrement is caused by the downward decay of pitch’s memory trace. Under the same assumption, the present study found bidirectional—as opposed to the predicted unidirectional—decay of memory traces for pitch in speech sounds by measuring listeners' sensitivity to pitch change over varying time intervals with an AX discrimination task. Three properties in the AX task were randomly sampled from preset ranges: (1) f0 of the A token (163:320 Hz), (2) difference between the f0s of A and X (-30:30Hz), and (3) the inter-stimulus interval (ISI; 0:3 s). We found when the stimuli were in the lower portion of the speaker’s pitch range, listeners were less sensitive to pitch increments at larger ISIs. Meanwhile, when the stimuli were in the higher pitch range, listeners were less sensitive to pitch decrements at larger ISIs. These results suggest memory traces for pitch in speech sounds decay toward a center pitch.

Modulation of auditory sensory memory by chronic clinical pain and acute experimental pain: a mismatch negativity study

Pain, especially chronic pain, can lead to cognitive deficits. Mismatch negativity (MMN) is a change-specific component of the auditory event-related brain potential (ERP) that is thought to provide a unique window into sensory memory processes. The present study was designed to determine how chronic and acute pain affects auditory sensory memory. In experiment 1, MMNs elicited by standard and deviant auditory stimuli at short and long inter-stimulus intervals (ISIs) were compared between trigeminal neuralgia (TN) patients and demographically matched healthy controls (HCs). The TN patients were found to have stronger attenuation of the MMN at longer ISIs than HCs. Correlation analysis revealed a significant positive correlation between the sensory subscale of McGill Pain Questionnaire and MMN amplitude reduction across ISI conditions. In experiment 2, MMNs recorded before, during, and after the cold pressor test were compared in healthy subjects. MMN amplitude was significantly reduced during pain exposure and recovered immediately thereafter. These results suggest that both chronic pain and acute pain can interfere with automatic change detection processes in the brain. This study provides the first evidence that chronic pain patients have a faster auditory memory trace decay than HCs.

The Duration of Auditory Sensory Memory for Vowel Processing: Neurophysiological and Behavioral Measures.

Speech perception behavioral research suggests that rates of sensory memory decay are dependent on stimulus properties at more than one level (e.g., acoustic level, phonemic level). The neurophysiology of sensory memory decay rate has rarely been examined in the context of speech processing. In a lexical tone study, we showed that long-term memory representation of lexical tone slows the decay rate of sensory memory for these tones. Here, we tested the hypothesis that long-term memory representation of vowels slows the rate of auditory sensory memory decay in a similar way to that of lexical tone. Event-related potential (ERP) responses were recorded to Mandarin non-words contrasting the vowels /i/ vs. /u/ and /y/ vs. /u/ from first-language (L1) Mandarin and L1 American English participants under short and long interstimulus interval (ISI) conditions (short ISI: an average of 575 ms, long ISI: an average of 2675 ms). Results revealed poorer discrimination of the vowel contrasts for English listeners than Mandarin listeners, but with different patterns for behavioral perception and neural discrimination. As predicted, English listeners showed the poorest discrimination and identification for the vowel contrast /y/ vs. /u/, and poorer performance in the long ISI condition. In contrast to Yu et al. (2017), however, we found no effect of ISI reflected in the neural responses, specifically the mismatch negativity (MMN), P3a and late negativity ERP amplitudes. We did see a language group effect, with Mandarin listeners generally showing larger MMN and English listeners showing larger P3a. The behavioral results revealed that native language experience plays a role in echoic sensory memory trace maintenance, but the failure to find an effect of ISI on the ERP results suggests that vowel and lexical tone memory traces decay at different rates.Highlights:We examined the interaction between auditory sensory memory decay and language experience.We compared MMN, P3a, LN and behavioral responses in short vs. long interstimulus intervals.We found that different from lexical tone contrast, MMN, P3a, and LN changes to vowel contrasts are not influenced by lengthening the ISI to 2.6 s.We also found that the English listeners discriminated the non-native vowel contrast with lower accuracy under the long ISI condition.

Impaired Visuospatial Short-Term Memory in Children with ADHD

ABSTRACTPrevious studies provide clear evidence that visuospatial memory performance in children with attention-deficit/hyperactivity disorder (ADHD) is significantly lower than in typically developing children. In the present study, we investigated a major cause of their low performance using a spatial span test. Possibly, inattention resulting from lack of motivation or interest causes their low performance so that they do not correctly encode targets to be remembered. On the other hand, a deficit in temporary maintenance per se may cause their low performance; that is, their inefficient use of rehearsal during a retention interval may lead to memory traces’ fast decay. Results in this study indicated that children with ADHD could sustain attention during the encoding phase. Furthermore, their performance at delayed recall was significantly lower than immediate recall, but delayed recall did not affect typically developing children's performance. These results provide evidence for the likelihood that a factor causing children with ADHD difficulty in temporarily maintaining visuospatial information is fast decay of memory traces as a result of inefficient use of rehearsal, not inattention in the encoding phase.

On the sources of forgetting in working memory: The test of competing hypotheses.

Whether forgetting from working memory (WM) is only due to interference or is also caused by temporal decay is still a matter of debate. In the present study, this question was examined using complex span tasks in which each memory item was followed by a series of processing episodes, the duration and number of which were varied. It is known that recall performance in these tasks depends on the cognitive load ( CL) of concurrent processing conceived as the ratio between processing time and free time, higher CL resulting in lower spans. The decay-and-refresh hypothesis accounts for this effect by assuming that memory traces decay during processing but are refreshed during free time. This hypothesis predicts lower recall performance with longer processing episodes, but no effect of their number as long as CL remains constant. The interference-only hypothesis supposes that free time is used to alleviate the interference created by processing distractors. This hypothesis is potentially compatible with an effect of the duration of processing episodes through increased interference, but predicts a detrimental effect of their number. In three experiments, the recall pattern fitted the predictions of the decay-and-refresh hypothesis for verbal WM, but that of the interference-only hypothesis for visuospatial WM. Although the entire pattern of data is more easily accommodated by the decay-and-refresh hypothesis than by its interference-only contender, our results suggest that it is unwise to aim at identifying a unique source to a complex phenomenon like WM forgetting.

Lexical decay during online sentence processing in adults with specific language impairment.

Decay of memory traces is an important component of many theories of working memory, but there is conflicting evidence on whether the rate of decay differs for individuals with specific language impairment (SLI) as compared to peers with typical language. The authors tested the hypothesis that adults with SLI have a slower decay rate. Twenty adults with SLI, ages 18-27 years, and 23 age-matched peers identified target words in sentences. Sentences were presented at normal and slow rates. Participants separately judged whether a picture and sentence matched in meaning as a measure of sentence processing efficiency. After controlling for sentence processing efficiency, the group with SLI was slower to detect words in sentences. Response times for the group with SLI increased less in the slow condition as compared to the group with typical language, resulting in a Group × Presentation Rate interaction. The Group × Presentation Rate interaction is consistent with a slower lexical decay rate for adults with SLI, but differences in the ability to manage interference could not be ruled out. The findings suggest that decay rate differences may play a role in the working memory limitations found in individuals with SLI.

Further evidence for temporal decay in working memory: Reply to Lewandowsky and Oberauer (2009).

The sources of forgetting in working memory (WM) are a matter of intense debate: Is there a time-related decay of memory traces, or is forgetting uniquely due to representation-based interference? In a previous study, we claimed to have provided evidence supporting the temporal decay hypothesis (S. Portrat, P. Barrouillet, & V. Camos, 2008). However, reanalyzing our data, S. Lewandowsky and K. Oberauer (2009) demonstrated that they do not provide compelling evidence for temporal decay and suggested a class of alternative models favoring a representation-based interference account. In this article, we develop from the most recent proposals made by Lewandowsky and Oberauer 2 of the most plausible extensions of these alternative models. We show that neither of these extensions can account for recent findings related to between-domain WM performance and that both lead to predictions that are contradicted by new empirical evidence. Finally, we show that recent studies that have been claimed to rule out the temporal decay hypothesis do not resist close scrutiny. We conclude that the time-based resource-sharing model remains the most parsimonious way to account for forgetting and restoration of memory traces in WM.

Modeling working memory: a computational implementation of the Time-Based Resource-Sharing theory

Working memory is a core concept in cognition, predicting about 50% of the variance in IQ and reasoning tasks. A popular test of working memory is the complex span task, in which encoding of memoranda alternates with processing of distractors. A recent model of complex span performance, the Time-Based-Resource-Sharing (TBRS) model of Barrouillet and colleagues, has seemingly accounted for several crucial findings, in particular the intricate trade-off between deterioration and restoration of memory in the complex span task. According to the TBRS, memory traces decay during processing of the distractors, and they are restored by attentional refreshing during brief pauses in between processing steps. However, to date, the theory has been formulated only at a verbal level, which renders it difficult to test and to be certain of its intuited predictions. We present a computational instantiation of the TBRS and show that it can handle most of the findings on which the verbal model was based. We also show that there are potential challenges to the model that await future resolution. This instantiated model, TBRS*, is the first comprehensive computational model of performance in the complex span paradigm. The Matlab model code is available as a supplementary material of this article.

Behavioral effects of agmatine in naive rats are task- and delay-dependent

The present study systematically investigated the effects of agmatine administered i.p. in several commonly used behavioral tasks. In Experiment 1, pre-test treatment of agmatine (1 and 40 mg/kg) appeared to improve animals' performance in the water maze probe test conducted 24 h, but not 120 s, after training, when the effect was evaluated within subjects. In Experiment 2, pre-test agmatine treatment (40 mg/kg) did not affect animals' performance in the open field, and the place navigation, probe tests (1–4 and 6), reversal test and cued navigation in the water maze, but significantly facilitated performance in probe 5 which was conducted 96 h after training. In Experiment 3, rats with pre-test agmatine treatment (40 mg/kg) were less anxious relative to the controls, with no performance changes in the open field. In the water maze task, post-training agmatine treatment (40 mg/kg) did not affect place and cued navigation, but significantly improved animals' performance in the probe test conducted 24 h after training and the reversal test. In the working memory version of the task, agmatine treated rats took significantly less time and generated markedly shorter path length to reach the platform at the 180 s, but not 30 s, delay relative to the controls. In the object recognition task, rats with pre-test agmatine treatment (40 mg/kg) spent significantly more time exploring displaced objects, but not novel object, as compared to the controls. In Experiment 4, pre-test agmatine treatment (40 mg/kg) had no effect on the task acquisition in the delayed non-match to position task in the T-maze, but significantly facilitated performance at the 600 s delay. These results suggest that the behavioral effects of agmatine are task- and delay-dependent, and agmatine facilitates memory particularly when the task difficulty is increased due to memory trace decay and/or greater interference.

The Importance of Temporal Distinctiveness for Forgetting Over the Short Term

Rapidly forgetting information once attention is diverted seems to be a ubiquitous phenomenon. The cause of this rapid decline has been debated for decades; some researchers claim that memory traces decay as a function of time out of the focus of attention, whereas others claim that prior memory traces cause confusability by interfering with the current trace. Here we demonstrate that performance after a long delay can be better than performance after a short delay if the temporal confusability between the current item and previous items is reduced. These results provide strong evidence for the importance of temporal confusability, rather than decay, as the cause of forgetting over the short term.

Impairing Forgetting by Preventing New Learning and Memory.

Two causes of forgetting have been promulgated: memory trace decay and retroactive interference. The authors show that forgetting is an active process requiring both new learning and memory. In the present (1)Lymnaea model system, prevention of new learning of a conflicting association, inhibition of memory consolidation, or Right Pedal Dorsal 1 soma ablation, which blocks LTM formation, are all potent means to prevent forgetting. Thus procedures that alter the ability to learn or form memory of a new conflicting aerial respiratory association prevent forgetting of a learned associative behavior. These results are the 1st demonstration in any model system that forgetting requires the soma of a single neuron.

Spatial memory and choice behavior in the radial arm maze after fornix transection

In the radial arm maze task, it is well established that performance of rats with hippocampal damage is severely impaired on the place version, which relies heavily, if not exclusively, on spatial information. However, very little is known about the effects of hippocampal damage on actual choice behavior. To address this issue, sham-operated (SH) and fornix-transected (FX) rats were trained and tested on the place task in the eight-arm radial maze. The following measures were recorded: the frequency of re-entry errors, the number of choices separating repeated visits to the same arm, the latency to arm re-entry, the distribution and targets of microchoices defined as orientations toward an arm or entries in the proximal portion of an arm [Brown, M.F., 1992. Does a cognitive map guide choices in the radial arm maze? J. Exp. Psychol., Anim. Behav. Processes 18, 56–66]. These measures were used as indexes of performance, within-trial retroactive intrusion, memory trace decay and choice behavior, respectively. As generally observed in the literature, the frequency of errors was higher in rats of the FX group than in rats of the SH group; the impairment persisted even after the training criterion was reached. The analysis of latency to arm re-entry and of the number of choices separating re-entries suggested that this impairment was the result of faster memory decay rather than retroactive interference. Both FX and SH groups exhibited a systematic pattern of microchoices, but the frequency of microchoices was higher in FX lesioned rats than in SH controls. Moreover, in lesioned animals, relatively fewer of the initial microchoices were directed toward the baited arms during training-to-criterion. Some of the results provide support to the working memory theory [Olton, D.S., Becker, J.T., Handelmann, G.E., 1979. Hippocampus, space, and memory. Behav. Brain Sci. 2, 313–365], whereas others look more consistent with the cognitive map view [O'Keefe, J., Nadel, L., 1978. The Hippocampus as a Cognitive Map. Clarendon Press, Oxford]. The discussion suggests that both theories and a distinction between prospective and retrospective memory may be required to account for the function of the hippocampal formation in memory.

The power integration diffusion model for production breaks.

The learning curve during repetitive production and the associated forgetting during production breaks are fundamental issues in the understanding of behavior. A model is suggested that combines 3 basic findings, namely, that single memory traces decay according to a power function of the retention interval, that aggregated memory traces can be combined by integration, and that the time to produce a unit can be described by a diffusion process on the memory trace. This power integration diffusion model is validated with empirical data, and the result fits better than 14 other published forgetting models.

Lexical tone contrast effects related to linguistic experience

Listeners’ auditory discrimination of vowel sounds depends in part on the order in which stimuli are presented (Cowan and Morse, 1986). Such contrast effects have been argued to be language-independent (Polka and Bohn, 1996), and to result from psychophysical (not speech- or language-specific) order-of-presentation effects such as decay of memory traces over time or increased weighting of later-occurring stimuli (Macmillan, Braida, and Goldberg, 1992; Repp and Crowder, 1990). In the present study, native Cantonese speakers’ discrimination of a linguistic tone continuum is shown to exhibit contrast effects similar to those shown for vowels in previous studies. When presented with two syllables differing in F0 by approximately 4 Hz, listeners were significantly more sensitive to this difference when the first syllable was higher in frequency than the second. However, American English-speaking listeners with no experience listening to Cantonese showed no such contrast effect when tested in the same manner using the same stimuli. Neither English nor Cantonese listeners showed any contrast effects in the discrimination of a nonspeech continuum with the same frequency properties. These results suggest that tone contrast effects, unlike vowel effects, may be language-specific and not merely the consequence of general properties of auditory processing.

Sensitivity and specificity of some neuropsychological markers of Alzheimer dementia.

A standardized neuropsychological test battery was administered to 167 patients with different forms of mild-to-moderate dementia: probable Alzheimer dementia (AD: n = 49), multi-infarct dementia (n = 43), idiopathic Parkinson disease with dementia (n = 35), depressive pseudodementia (n = 26), and progressive supranuclear palsy (n = 14). Results obtained were used (a) to analyze the profiles of cognitive impairment shown by the different dementia groups; (b) to assess the incidence of some neuropsychological patterns that we hypothesized to be more characteristic of AD, in the various groups; and hence (c) to evaluate the reliability of these patterns as diagnostic markers of AD. Four of the patterns investigated were derived from a verbal learning task (Rey's Auditory Verbal Learning test): (1) absence of the primacy effect; (2) tendency to produce intrusion errors during free recall of a word list; (3) absolute decay of memory trace; and (4) tendency to produce false alarms during delayed recognition of the same word list. Two additional patterns were derived from visual-spatial tasks (copying drawings and Raven's Coloured Progressive Matrices): (5) occurrence of the closing-in phenomenon in copying drawings; and (6) tendency to choose globalistic or odd responses in Raven's matrices. Though all the six patterns were somewhat useful for identifying AD patients, no pattern met the criteria of being both highly sensitive and highly specific, which should characterize an ideal marker. In fact, intrusions and false alarms were observed in many AD patients, but also in patients affected by other forms of dementia. The absence of the primacy effect, the closing-in phenomenon, and the absolute decay of memory trace were more specific, but could be observed in only one-third of AD patients. We also computed the number of positive patterns shown by each patient and assumed the presence of two or more patterns as a global index suggestive of a dementia of the Alzheimer type. With this cumulative method, a higher level of sensitivity and specificity was achieved in the identification of AD patients.

Arithmetical calculations in monolinguals and bilinguals

A series of 240 arithmetical problems requiring one, two, or three operations of the same kind were presented to 32 German-Swedish bilingual and 14 German dominant subjects in the age range 14–19 years. The results provide evidence that language has an important effect on arithmetical performance, affecting latencies and error rates. Generally the bilingual subjects needed more time to perform the tasks and made more errors than the monolingual subjects. The results are tentatively explained by retrieval interference and decay of memory trace and support an interdependence hypothesis of bilingual organization in memory.

The effects of chlorpromazine on the decay and consolidation of short-term memory traces in mice.

F1 hybrids of two highly inbred strains of mice were trained in a one-trial passive avoidance learning situation. Chlorpromazine, in doses of 0.5, 2.0 and 3.5 mg/kg, was administered at one of four injections times, 10 min before and 0.5, 2 and 10 min after learning. Pre-learning drug administration completely blocked acquisition of a learned avoidance response. Post-learning drug effects were more complex, involving reduced expression of avoidance learning but less rapid extinction of the learned response. The results were related to effects of the drug on short-term memory trace decay and consolidation.

Short-Term Memory Trace Decay in Kinesthetically Monitored Force Reproduction

Abstract The decay of the memory trace for intervals of 1/2 min., 1 1/2 min., and 4 min. between the test stimulus and the reproduction trial was studied for a force reproduction task in which the amount of movement was very small, .13 in. The subject pushed against a handle attached to the top of a steel bar with the preferred hand. Sixty-three women volunteers from college physical education classes performed the experiment. For Part A all subjects first had four trials in which the reproduction was immediate (the control condition). Then they were divided randomly into three subgroups of 21, and each subgroup was assigned to one of the three retention intervals (experimental conditions) for four more trials. In Part B the whole experiment was repeated. For both absolute and algebraic error, analysis of covariance indicated no significant differences at the .05 level among the experimental conditons. Also, no significant differences were found comparing a condition in Part A with its respective conditio...