scholarly journals Spatial heterogeneity of the restitution portrait in rabbit epicardium

2007 ◽  
Vol 292 (3) ◽  
pp. H1568-H1578 ◽  
Author(s):  
Ann M. Pitruzzello ◽  
Wanda Krassowska ◽  
Salim F. Idriss
Keyword(s):  
Spatial Heterogeneity ◽  
Time Constant ◽  
Short Term Memory ◽  
Zealand White Rabbit ◽  
Electrical Stability ◽  
Short Term ◽  
Term Memory ◽  
Rate Dependent ◽  
Spatial Differences ◽  
Cycle Lengths

Spatial heterogeneity of repolarization can provide a substrate for reentry to occur in myocardium. This heterogeneity may result from spatial differences in action potential duration (APD) restitution. The restitution portrait (RP) measures many aspects of rate-dependent restitution: the dynamic restitution curve (RC), S1-S2 RC, and short-term memory response. We used the RP to characterize epicardial patterns of spatial heterogeneity of restitution that were repeatable across animals. New Zealand White rabbit ventricles were paced from the epicardial apex, midventricle, or base, and optical action potentials were recorded from the same three regions. A perturbed downsweep pacing protocol was applied that measured the RP over a range of cycle lengths from 1,000 to 140 ms. The time constant of short-term memory measured close to the stimulus was dependent on location. In the midventricle the mean time constant was 19.1 ± 1.1 s, but it was 39% longer at the apex ( P < 0.01) and 23% longer at the base ( P = 0.03). The S1-S2 RC slope was dependent on pacing site ( P = 0.015), with steeper slope when pacing from the apex than from the base. There were no significant repeatable spatial patterns in steady-state APD at all cycle lengths or in dynamic RC slope. These results indicate that transient patterns of epicardial heterogeneity of APD may occur after a change in pacing rate. Thus it may affect cardiac electrical stability at the onset of a tachycardia or during a series of ectopic beats. Differences in restitution with respect to pacing site suggest that vulnerability may be affected by the location of reentry or ectopic foci.

The restitution portrait in rabbit epicardium reveals spatial heterogeneity of short-term memory

Heart Rhythm ◽  
2005 ◽  
Vol 2 (5) ◽  
pp. S299
Author(s):  
Ann M. Pitruzzello ◽  
Soma S. Kalb ◽  
Daniel J. Gauthier ◽  
Wanda Krassowska ◽  
Salim F. Idriss
Keyword(s):  
Spatial Heterogeneity ◽  
Short Term Memory ◽  
Short Term ◽  
Term Memory

scholarly journals Formation and decay of auditory short-term memory in the macaque monkey

2019 ◽  
Vol 121 (6) ◽  
pp. 2401-2415 ◽  
Author(s):  
Tobias Teichert ◽  
Kate Gurnsey
Keyword(s):  
Time Constant ◽  
Exponential Decay ◽  
Short Term Memory ◽  
Temporal Dynamics ◽  
Auditory Information ◽  
Short Term ◽  
Term Memory ◽  
Model Based ◽  
Echoic Memory ◽  
Auditory Recognition

Echoic memory (EM) is a short-lived, precategorical, and passive form of auditory short-term memory (STM). A key hallmark of EM is its rapid exponential decay with a time constant between 1 and 2 s. It is not clear whether auditory STM in the rhesus, an important model system, shares this rapid exponential decay. To resolve this shortcoming, two rhesus macaques were trained to perform a delayed frequency discrimination task. Discriminability of delayed tones was measured as a function of retention duration and the number of times the standard had been repeated before the target. Like in the human, our results show a rapid decline of discriminability with retention duration. In addition, the results suggest a gradual strengthening of discriminability with repetition number. Model-based analyses suggest the presence of two components of auditory STM: a short-lived component with a time constant on the order of 550 ms that most likely corresponds to EM and a more stable memory trace with time constants on the order of 10 s that strengthens with repetition and most likely corresponds to auditory recognition memory. NEW & NOTEWORTHY This is the first detailed quantification of the rapid temporal dynamics of auditory short-term memory in the rhesus. Much of the auditory information in short-term memory is lost within the first couple of seconds. Repeated presentations of a tone strengthen its encoding into short-term memory. Model-based analyses suggest two distinct components: an echoic memory homolog that mediates the rapid decay and a more stable but less detail-rich component that mediates strengthening of the trace with repetition.

scholarly journals Short-Long Heart Rate Variation Increases Dispersion of Action Potential Duration in Long QT Type 2 Transgenic Rabbit Model

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tae Yun Kim ◽  
Paul Jeng ◽  
JungMin Hwang ◽  
Zachary Pfeiffer ◽  
Divyang Patel ◽  
...  
Keyword(s):  
Short Term Memory ◽  
Rabbit Model ◽  
Polymorphic Ventricular Tachycardia ◽  
Rate Variation ◽  
Short Term ◽  
Long Qt ◽  
Term Memory ◽  
Transgenic Rabbit ◽  
Cycle Lengths

Abstract The initiation of polymorphic ventricular tachycardia in long QT syndrome type 2 (LQT2) has been associated with a characteristic ECG pattern of short-long RR intervals. We hypothesize that this characteristic pattern increases APD dispersion in LQT2, thereby promoting arrhythmia. We investigated APD dispersion and its dependence on two previous cycle lengths (CLs) in transgenic rabbit models of LQT2, LQT1, and their littermate controls (LMC) using random stimulation protocols. The results show that the short-long RR pattern was associated with a larger APD dispersion in LQT2 but not in LQT1 rabbits. The multivariate analyses of APD as a function of two previous CLs (APDn = C + α1CLn−1 + α2CLn−2) showed that α1 (APD restitution slope) is largest and heterogeneous in LQT2 but uniform in LQT1, enhancing APD dispersion under long CLn−1 in LQT2. The α2 (short-term memory) was negative in LQT2 while positive in LQT1, and the spatial pattern of α1 was inversely correlated to α2 in LQT2, which explains why a short-long combination causes a larger APD dispersion in LQT2 but not in LQT1 rabbits. In conclusion, short-long RR pattern increased APD dispersion only in LQT2 rabbits through heterogeneous APD restitution and the short-term memory, underscoring the genotype-specific triggering of arrhythmias in LQT syndrome.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Working, Declarative, and Procedural Memory in Children With Developmental Language Disorder

2020 ◽  
Vol 63 (12) ◽  
pp. 4162-4178
Author(s):  
Emily Jackson ◽  
Suze Leitão ◽  
Mary Claessen ◽  
Mark Boyes
Keyword(s):  
Working Memory ◽  
Short Term Memory ◽  
Language Disorder ◽  
Declarative Memory ◽  
Memory Systems ◽  
Procedural Memory ◽  
Typically Developing ◽  
Short Term ◽  
Term Memory ◽  
Visual Spatial

Purpose Previous research into the working, declarative, and procedural memory systems in children with developmental language disorder (DLD) has yielded inconsistent results. The purpose of this research was to profile these memory systems in children with DLD and their typically developing peers. Method One hundred four 5- to 8-year-old children participated in the study. Fifty had DLD, and 54 were typically developing. Aspects of the working memory system (verbal short-term memory, verbal working memory, and visual–spatial short-term memory) were assessed using a nonword repetition test and subtests from the Working Memory Test Battery for Children. Verbal and visual–spatial declarative memory were measured using the Children's Memory Scale, and an audiovisual serial reaction time task was used to evaluate procedural memory. Results The children with DLD demonstrated significant impairments in verbal short-term and working memory, visual–spatial short-term memory, verbal declarative memory, and procedural memory. However, verbal declarative memory and procedural memory were no longer impaired after controlling for working memory and nonverbal IQ. Declarative memory for visual–spatial information was unimpaired. Conclusions These findings indicate that children with DLD have deficits in the working memory system. While verbal declarative memory and procedural memory also appear to be impaired, these deficits could largely be accounted for by working memory skills. The results have implications for our understanding of the cognitive processes underlying language impairment in the DLD population; however, further investigation of the relationships between the memory systems is required using tasks that measure learning over long-term intervals. Supplemental Material https://doi.org/10.23641/asha.13250180

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

2020 ◽  
Vol 29 (4) ◽  
pp. 710-727
Author(s):  
Beula M. Magimairaj ◽  
Naveen K. Nagaraj ◽  
Alexander V. Sergeev ◽  
Natalie J. Benafield
Keyword(s):  
Auditory Processing ◽  
Short Term Memory ◽  
Group Differences ◽  
Long Term Memory ◽  
Short Term ◽  
Significant Group ◽  
Term Memory ◽  
Memory And Attention ◽  
Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

The Link Between Verbal Short-Term Memory and Anomia Treatment Gains

2019 ◽  
Vol 28 (3) ◽  
pp. 1039-1052
Author(s):  
Reva M. Zimmerman ◽  
JoAnn P. Silkes ◽  
Diane L. Kendall ◽  
Irene Minkina
Keyword(s):  
Short Term Memory ◽  
Controlled Trial ◽  
Treatment Success ◽  
Linear Regression Models ◽  
Language Performance ◽  
Short Term ◽  
Term Memory ◽  
Treatment Gains ◽  
Post Hoc

Purpose A significant relationship between verbal short-term memory (STM) and language performance in people with aphasia has been found across studies. However, very few studies have examined the predictive value of verbal STM in treatment outcomes. This study aims to determine if verbal STM can be used as a predictor of treatment success. Method Retrospective data from 25 people with aphasia in a larger randomized controlled trial of phonomotor treatment were analyzed. Digit and word spans from immediately pretreatment were run in multiple linear regression models to determine whether they predict magnitude of change from pre- to posttreatment and follow-up naming accuracy. Pretreatment, immediately posttreatment, and 3 months posttreatment digit and word span scores were compared to determine if they changed following a novel treatment approach. Results Verbal STM, as measured by digit and word spans, did not predict magnitude of change in naming accuracy from pre- to posttreatment nor from pretreatment to 3 months posttreatment. Furthermore, digit and word spans did not change from pre- to posttreatment or from pretreatment to 3 months posttreatment in the overall analysis. A post hoc analysis revealed that only the less impaired group showed significant changes in word span scores from pretreatment to 3 months posttreatment. Discussion The results suggest that digit and word spans do not predict treatment gains. In a less severe subsample of participants, digit and word span scores can change following phonomotor treatment; however, the overall results suggest that span scores may not change significantly. The implications of these findings are discussed within the broader purview of theoretical and empirical associations between aphasic language and verbal STM processing.

Symptomvalidierungstests in der neuropsychologischen Diagnostik: eine Analogstudie

2004 ◽  
Vol 15 (2) ◽  
pp. 81-90 ◽  
Author(s):  
Thomas Merten ◽  
Matthias Henry ◽  
Robin Hilsabeck
Keyword(s):  
Short Term Memory ◽  
Memory Test ◽  
Short Term ◽  
Term Memory ◽  
Word Memory Test ◽  
Word Memory ◽  
Complex Figure ◽  
Trail Making ◽  
Figure Test ◽  
Word Completion

Zusammenfassung: In der neuropsychologischen Diagnostik, mehr noch aber in der Begutachtung gewinnen Symptomvalidierungstests (SVT) zur Untersuchung der Leistungsmotivation zunehmend an Bedeutung. In einer Analogstudie wurde die Güte zweier international bekannter Verfahren (Word Memory Test; Amsterdam Short Term Memory Test) sowie einer Neuentwicklung (Word Completion Memory Test) untersucht. Zusätzlich wurden Leistungstests eingesetzt: der Trail Making Test (TMT), der Complex Figure Test sowie die Standard Progressive Matrices (SPM). Eine Gruppe von 10 experimentellen Simulanten wurde spezifisch auf die Vortäuschung von Gedächtnisstörungen vorbereitet, während eine Kontrollgruppe (n = 10) optimale Testanstrengung zeigen sollte. Alle SVT führten im Gegensatz zu den Simulationsmarkern des TMT und der SPM zu einer ausgezeichneten Klassifikationsgüte (95-100 %). Die neuropsychologischen Leistungsmaße wiesen zwar signifikante Gruppenunterschiede aus, zeigten aber auch eine nicht unbedeutende Überlappung der Verteilungen. Mehr Studien sind notwendig, um den SVT in den deutschsprachigen Ländern den Platz zu sichern, den sie international aktuell in der klinisch-neuropsychologischen Forschung und Praxis einnehmen.

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