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Willem B. Verwey - One of the best experts on this subject based on the ideXlab platform.
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the simon effect in a Discrete Sequence production task key specific stimuli cannot be ignored due to attentional capture
Acta Psychologica, 2020Co-Authors: Willem B. Verwey, David L. Wright, Robert Henricus Johannes Van Der LubbeAbstract:Two experiments examined whether practicing Discrete key pressing Sequences eventually leads to a disregard of the key-specific stimuli, as suggested by Sequence learning models, or whether these stimuli continue to be relied upon because the associated luminance increase attracts visuospatial attention. Participants practiced two Sequences by reacting to two fixed series of seven letter stimuli, each displayed at a location that did or did not correspond with the required response location. Stimulus use was indicated by a Simon effect in that key presses were slowed when stimulus and key locations did not correspond. Experiment 1 demonstrated that letter stimuli continued to be used as the Simon effect occurred with each Sequence element, and this remained quite stable across practice and did not differ for familiar and unfamiliar Sequences. Experiment 2 showed that the Simon effect remained present even with meaningless stimuli that were often even harmful. These findings suggest that even in motor Sequences that can be executed without element-specific stimuli attention attraction enforces stimulus use. The data further supported the assumptions that S-R translation and sequencing systems are racing to trigger individual responses, and that explicit Sequence representations include spatial and verbal knowledge.
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multi session transcranial direct current stimulation concurrent with Discrete Sequence production task in young and older adults
Geriatrics Center Research Symposium 2016, 2016Co-Authors: Brian Greeley, Willem B. Verwey, J S Barnhoorn, Rachael D SeidlerAbstract:The Discrete Sequence production (DSP) task is an explicit motor Sequence learning task that can be used to measure chunking, or a grouping together of once Discrete individual elements. The DSP task used here involves two, 6-item Sequences presented at one time. Over many trials, participants learn the two, 6-item Sequences and execute the Sequences as 2 or more segments, or chunks. Right and left dorsolateral prefrontal cortex (DLPFC) have been demonstrated to be involved in early explicit Sequence learning as well as early adaptation. Primary motor cortex (M1) has been shown to be involved in explicit Sequence learning and retention. Further, pre-SMA has been shown to be involved in chunk loading in Sequence learning. Here, we use transcranial direct current stimulation (tDCS), a non-invasive form of brain stimulation, in an effort to facilitate chunking in young and older adults in a modified version of the DSP task. Forty young (range 18-28 years) and 16 older (range 65-85 years), right-handed, adults completed a modified version of the DSP task while receiving anodal or sham tDCS to either right DLPFC, left DLPFC, M1, or pre-SMA over two sessions. Using a model developed by Acuna et al. (2014) to quantify chunking, preliminary results suggest that tDCS stimulation to pre-SMA facilitates at least one component of chunking in both young and older adults, whereas tDCS stimulation to m1 is more beneficial to only young adults. Specifically, the pause at the beginning of a chunk was significantly faster for young and older adults in the pre-SMA group relative to the sham group ( p = .037) providing further support for the notion that this region plays a role in chunk loading. There were no significant differences between m1, right, and left DLPFC groups relative to sham.
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A framework for explaining serial processing and Sequence execution strategies
2016Co-Authors: Willem B. Verwey, Charlie Shea, David L. WrightAbstract:Behavioral research produced many task-specific cognitive models that do not say much about the underlying information processing architecture. Such an architecture is badly needed to understand better how cognitive neuroscience can benefit from existing cognitive models. This problem is especially pertinent in the domain of sequential behavior where behavioral research suggests a diversity of cognitive processes, processing modes and representations. Inspired by decades of reaction time (RT) research with the Additive Factors Method, the Psychological Refractory Period paradigm, and the Discrete Sequence Production task, we propose the Cognitive framework for Sequential Motor Behavior (C-SMB). We argue that C-SMB accounts for cognitive models developed for a range of sequential motor tasks (like those proposed by Keele et al., 2003; Rosenbaum et al., 1983, 1986, 1995; Schmidt, 1975; Sternberg et al., 1978, 1988). C-SMB postulates that Sequence execution is controlled by a central processor using central-symbolic representations, and a motor processor using Sequence-specific motor representations. On the basis of this framework we present a classification of the strategies to produce movement Sequences. We complete this presentation by proposing the neural underpinnings of this framework.
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modifying the Discrete Sequence production task for a multiday tdcs study in young and older adults
45th Society for Neuroscience Annual Meeting 2015: Society for Neuroscience Annual Meeting, 2015Co-Authors: Brian Greeley, Willem B. Verwey, J S Barnhoorn, Rachael D SeidlerAbstract:The Discrete Sequence production (DSP) task is an explicit motor learning Sequence task where two 6-item Sequences are presented one item at a time. Over many repetitions, participants eventually execute a 6-item Sequence as 2 or more segments, an indication of distinct motor chunks. Previous work has demonstrated that older adults exhibit a reduction in chunk length and have an impaired explicit memory, relative to young adults. Right and left dorsolateral prefrontal cortex (DLPFC) have been demonstrated to be involved in early explicit Sequence learning as well as early adaptation. Primary motor cortex (M1) has been shown to be involved in explicit Sequence learning and retention. Further, premotor cortex has been shown to be involved in memory consolidation in Sequence learning. Here, we use transcranial direct current stimulation (tDCS), a non-invasive form of brain stimulation, to facilitate early learning and chunking in both younger and older adults in a truncated version of the traditional DSP task. Participants attend three sessions over the course of a week, and are randomized into one of five tDCS conditions (right DLPFC, left DLPFC, M1, premotor, or sham). Over the three sessions, participants complete a battery of cognitive and motor tasks that correlate with motor learning ability and executive functioning in order to characterize the participant, use later as covariates in analysis, and understand how these cognitive and motor tasks might change from baseline as a function of the tDCS condition. Participants also practice the DSP task while receiving tDCS for up to 25 minutes during sessions 1 and 2. During session three, participants are tested on their ability to remember the Sequence of the DSP task without stimulation. We hypothesize that tDCS to right DLPFC will facilitate early learning in both older and younger adults, with older adults receiving the most benefit from the tDCS stimulation. We also predict that tDCS over premotor cortex will help facilitate chunking in older adults, relative to older adults in the sham group. We expect that stimulation to M1, left DLPFC, and premotor in younger adults will change the rate of motor learning relative to young adults in the sham tDCS group. Our preliminary results suggest that younger adults without tDCS are still able to chunk with fewer trials in the DSP task over three sessions.
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A cognitive framework for explaining serial processing and Sequence execution strategies
Psychonomic bulletin & review, 2014Co-Authors: Willem B. Verwey, Charles H. Shea, David L. WrightAbstract:Behavioral research produced many task-specific cognitive models that do not say much about the underlying information processing architecture. Such an architecture is badly needed to understand better how cognitive neuroscience can benefit from existing cognitive models. This problem is especially pertinent in the domain of sequential behavior where behavioral research suggests a diversity of cognitive processes, processing modes and representations. Inspired by decades of reaction time (RT) research with the Additive Factors Method, the Psychological Refractory Period paradigm, and the Discrete Sequence Production task, we propose the Cognitive framework for Sequential Motor Behavior (C-SMB). We argue that C-SMB accounts for cognitive models developed for a range of sequential motor tasks (like those proposed by Keele et al., 2003; Rosenbaum et al., 1983, 1986, 1995; Schmidt, 1975; Sternberg et al., 1978, 1988). C-SMB postulates that Sequence execution can be controlled by a central processor using central-symbolic representations, and also by a motor processor using Sequence-specific motor representations. On the basis of this framework we present a classification of the Sequence execution strategies that helps researchers to understand better the cognitive and neural underpinnings of serial movement behavior
David L. Wright - One of the best experts on this subject based on the ideXlab platform.
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the simon effect in a Discrete Sequence production task key specific stimuli cannot be ignored due to attentional capture
Acta Psychologica, 2020Co-Authors: Willem B. Verwey, David L. Wright, Robert Henricus Johannes Van Der LubbeAbstract:Two experiments examined whether practicing Discrete key pressing Sequences eventually leads to a disregard of the key-specific stimuli, as suggested by Sequence learning models, or whether these stimuli continue to be relied upon because the associated luminance increase attracts visuospatial attention. Participants practiced two Sequences by reacting to two fixed series of seven letter stimuli, each displayed at a location that did or did not correspond with the required response location. Stimulus use was indicated by a Simon effect in that key presses were slowed when stimulus and key locations did not correspond. Experiment 1 demonstrated that letter stimuli continued to be used as the Simon effect occurred with each Sequence element, and this remained quite stable across practice and did not differ for familiar and unfamiliar Sequences. Experiment 2 showed that the Simon effect remained present even with meaningless stimuli that were often even harmful. These findings suggest that even in motor Sequences that can be executed without element-specific stimuli attention attraction enforces stimulus use. The data further supported the assumptions that S-R translation and sequencing systems are racing to trigger individual responses, and that explicit Sequence representations include spatial and verbal knowledge.
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A framework for explaining serial processing and Sequence execution strategies
2016Co-Authors: Willem B. Verwey, Charlie Shea, David L. WrightAbstract:Behavioral research produced many task-specific cognitive models that do not say much about the underlying information processing architecture. Such an architecture is badly needed to understand better how cognitive neuroscience can benefit from existing cognitive models. This problem is especially pertinent in the domain of sequential behavior where behavioral research suggests a diversity of cognitive processes, processing modes and representations. Inspired by decades of reaction time (RT) research with the Additive Factors Method, the Psychological Refractory Period paradigm, and the Discrete Sequence Production task, we propose the Cognitive framework for Sequential Motor Behavior (C-SMB). We argue that C-SMB accounts for cognitive models developed for a range of sequential motor tasks (like those proposed by Keele et al., 2003; Rosenbaum et al., 1983, 1986, 1995; Schmidt, 1975; Sternberg et al., 1978, 1988). C-SMB postulates that Sequence execution is controlled by a central processor using central-symbolic representations, and a motor processor using Sequence-specific motor representations. On the basis of this framework we present a classification of the strategies to produce movement Sequences. We complete this presentation by proposing the neural underpinnings of this framework.
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A cognitive framework for explaining serial processing and Sequence execution strategies
Psychonomic bulletin & review, 2014Co-Authors: Willem B. Verwey, Charles H. Shea, David L. WrightAbstract:Behavioral research produced many task-specific cognitive models that do not say much about the underlying information processing architecture. Such an architecture is badly needed to understand better how cognitive neuroscience can benefit from existing cognitive models. This problem is especially pertinent in the domain of sequential behavior where behavioral research suggests a diversity of cognitive processes, processing modes and representations. Inspired by decades of reaction time (RT) research with the Additive Factors Method, the Psychological Refractory Period paradigm, and the Discrete Sequence Production task, we propose the Cognitive framework for Sequential Motor Behavior (C-SMB). We argue that C-SMB accounts for cognitive models developed for a range of sequential motor tasks (like those proposed by Keele et al., 2003; Rosenbaum et al., 1983, 1986, 1995; Schmidt, 1975; Sternberg et al., 1978, 1988). C-SMB postulates that Sequence execution can be controlled by a central processor using central-symbolic representations, and also by a motor processor using Sequence-specific motor representations. On the basis of this framework we present a classification of the Sequence execution strategies that helps researchers to understand better the cognitive and neural underpinnings of serial movement behavior
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Effector-independent and effector-dependent learning in the Discrete Sequence production task.
Psychological research, 2003Co-Authors: Willem B. Verwey, David L. WrightAbstract:This study examined whether skill in the Discrete Sequence production task involves, apart from the typical effector-independent component, an effector-dependent component. To that end, 12 participants practiced two 5-key Sequences, each for 1,060 trials. One group practiced with three fingers of one hand, the other group with three fingers of two hands. In a subsequent test phase, participants in both groups executed the same Sequences and two new Sequences with the hand configuration they had used during practice, and with the hand configuration of the other group. The results provide support for an effector-dependent component in that both groups performed the practiced Sequences faster with the hand configuration they had used during practice than with the hand configuration that was new to them. In addition, the unpracticed hand configuration performed the practiced Sequences faster than the new Sequence, which demonstrated the effector-independent component.
Mark S Mooseker - One of the best experts on this subject based on the ideXlab platform.
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an in vitro model for the analysis of intestinal brush border assembly ii changes in expression and localization of brush border proteins during cell contact induced brush border assembly in caco 2bbe cells
Journal of Cell Science, 1993Co-Authors: Michelle D Peterson, William M Bement, Mark S MoosekerAbstract:In the companion paper (M. D. Peterson and M. S. Mooseker (1993). J. Cell Sci. 105, 445–460) we describe a method for modeling brush border assembly in the Caco-2BBe clones. In this study we have examined the molecular changes accompanying cell contact-induced brush border assembly. A subset of brush border proteins was tracked throughout brush border assembly by immunoblotting and by immunofluorescent localization using laser scanning confocal microscopy. Actin, fodrin, villin and presumptive unconventional myosin immunogens were distributed at the periphery of depolarized cells. All proteins partitioned primarily with the membrane fraction upon differential sedimentation of depolarized cell lysates; the fractionation patterns were comparable to those of confluent cells. After a monolayer had formed, each protein showed a redistribution to the apical domain in a Discrete Sequence. Actin and villin began to shift apically at 2 d, while fodrin and the unconventional myosin immunogens did not redistribute until 3 d. Enterocyte-like localization was observed by 5 d for all proteins. Sucrase-isomaltase was not reliably detectable until 9 d by immunofluorescence, after brush border assembly was complete. Quantitative immunoblot analysis of total cell extracts demonstrated an average 10-fold increase in villin levels, while fodrin levels appeared to remain unchanged. Three putative unconventional myosin immunogens of 140 kDa, 130 kDa, and 110 kDa have been detected previously in the C2BBe cells with a head-specific monoclonal antibody to avian brush border myosin I (M. D. Peterson and M. S. Mooseker (1992) J. Cell Sci. 102, 581–600). Each of these immunogens displayed distinct expression patterns during brush border assembly. The 140 kDa species decreased by half, while the 130 kDa immunogen(s) did not change in any consistent fashion. The 110 kDa protein, presumed to be human brush border myosin I, rose on average 8-fold. A ribonuclease protection assay was also performed using a probe for human brush border myosin I. Equal amounts of total RNA from depolarized and confluent cells were assayed; the level of protected product was approximately 9-fold greater in the confluent cells. The expression patterns of the brush border proteins, coupled with the correlation to the ultrastructural features during brush border assembly in C2BBe cells, show that differentiation of the C2BBe cells closely resembles the changes that occur during human fetal intestinal differentiation.
J P W Young - One of the best experts on this subject based on the ideXlab platform.
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Molecular diversity of arbuscular mycorrhizal fungi colonising Hyacinthoides non-scripta (bluebell) in a seminatural woodland
Molecular Ecology, 1999Co-Authors: Thorunn Helgason, Alastair H. Fitter, J P W YoungAbstract:Arbuscular mycorrhizal (AM) fungi form symbiotic associations with plant roots. Around 150 species have been described and it is becoming clear that many of these species have different functional properties. The species diversity of AM fungi actively growing in roots is therefore an important component of ecosystem diversity. However, it is difficult to identify AM fungi below the genus level from morphology in planta, as they possess few informative characters. We present here a molecular method for identifying infrageneric Sequence types that estimate the taxonomic diversity of AM fungi present in actively growing roots. Bluebell roots were sampled from beneath two different canopy types, oak and sycamore, and DNA Sequences were amplified from roots by the polymerase chain reaction with fungal-specific primers for part of the small subunit ribosomal RNA gene. Restriction fragment length polymorphism among 141 clones was assessed and 62 clones were Sequenced. When aligned, Discrete Sequence groups emerged that cluster into the three families of AM fungi: Acaulosporaceae, Gigasporaceae and Glomaceae. The Sequence variation is consistent with rRNA secondary structure. The same Sequence types were found at both sampling times. Frequencies of Scutellospora increased in December, and Acaulospora increased in abundance in July. Sites with a sycamore canopy show a reduced abundance of Acaulospora, and those with oak showed a reduced abundance of Glomus. These distribution patterns are consistent with previous morphological studies carried out in this woodland. The molecular method provides an alternative method of estimating the distribution and abundance of AM fungi, and has the potential to provide greater resolution at the infrageneric level.
Michelle D Peterson - One of the best experts on this subject based on the ideXlab platform.
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an in vitro model for the analysis of intestinal brush border assembly ii changes in expression and localization of brush border proteins during cell contact induced brush border assembly in caco 2bbe cells
Journal of Cell Science, 1993Co-Authors: Michelle D Peterson, William M Bement, Mark S MoosekerAbstract:In the companion paper (M. D. Peterson and M. S. Mooseker (1993). J. Cell Sci. 105, 445–460) we describe a method for modeling brush border assembly in the Caco-2BBe clones. In this study we have examined the molecular changes accompanying cell contact-induced brush border assembly. A subset of brush border proteins was tracked throughout brush border assembly by immunoblotting and by immunofluorescent localization using laser scanning confocal microscopy. Actin, fodrin, villin and presumptive unconventional myosin immunogens were distributed at the periphery of depolarized cells. All proteins partitioned primarily with the membrane fraction upon differential sedimentation of depolarized cell lysates; the fractionation patterns were comparable to those of confluent cells. After a monolayer had formed, each protein showed a redistribution to the apical domain in a Discrete Sequence. Actin and villin began to shift apically at 2 d, while fodrin and the unconventional myosin immunogens did not redistribute until 3 d. Enterocyte-like localization was observed by 5 d for all proteins. Sucrase-isomaltase was not reliably detectable until 9 d by immunofluorescence, after brush border assembly was complete. Quantitative immunoblot analysis of total cell extracts demonstrated an average 10-fold increase in villin levels, while fodrin levels appeared to remain unchanged. Three putative unconventional myosin immunogens of 140 kDa, 130 kDa, and 110 kDa have been detected previously in the C2BBe cells with a head-specific monoclonal antibody to avian brush border myosin I (M. D. Peterson and M. S. Mooseker (1992) J. Cell Sci. 102, 581–600). Each of these immunogens displayed distinct expression patterns during brush border assembly. The 140 kDa species decreased by half, while the 130 kDa immunogen(s) did not change in any consistent fashion. The 110 kDa protein, presumed to be human brush border myosin I, rose on average 8-fold. A ribonuclease protection assay was also performed using a probe for human brush border myosin I. Equal amounts of total RNA from depolarized and confluent cells were assayed; the level of protected product was approximately 9-fold greater in the confluent cells. The expression patterns of the brush border proteins, coupled with the correlation to the ultrastructural features during brush border assembly in C2BBe cells, show that differentiation of the C2BBe cells closely resembles the changes that occur during human fetal intestinal differentiation.