Incidental motor sequence learning: Investigations into its cognitive basis and the effects of neurological impairment and treatment

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.To survive in a complex changing environment humans frequently need to adapt their behaviour incidentally from normal interactions in the environment without any specific intention to learn. Whilst there is a considerable body of research into incidental learning of sequential information there is still fundamental debate regarding its cognitive basis, the associated neural mechanisms and the way in which it is affected by neurological disease. These issues were explored, in normal participants and neurological patients, using manipulations of the Serial Reaction Task [SRT] in which participants gradually learn a stimulus sequence (usually screen locations) after responding to each item by pressing corresponding response buttons. The first two experiments (chapter 3) demonstrate that the specific metric used to quantify learning and the occurrence of highly salient repeat locations may inflate estimates of learning in tasks with increased motor demands. The next three experiments (chapter 4) examine whether a secondary (not directly behaviourally relevant) information source during the SRT facilitates chunking in memory and overall learning. In a spatial SRT task (specified by horizontal location), additional spatial information (vertical location) enhanced learning but a secondary perceptual property (colour) produced a cost. However, in a perceptual SRT a secondary perceptual property (colour) had no effect. The next study demonstrates that impairments of incidental learning in Parkinson’s disease are partially reduced by administration of l-Dopa. Implications for models of striatal function and studies suggesting implicit learning is impaired by l-Dopa are discussed. Finally, the impact of Deep Brain Stimulation of the GPi is investigated in a population known to have only limited cognitive deficits relating to their illness (dystonia). Despite previous reports of impaired intentional learning in participants with a high genetic risk of Dystonia, there was no evidence for any impairment before or after stimulation. Implications across studies and future research directions are also discussed

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

Is physical practice necessary for parallel development of implicit and explicit sequence knowledge? Evidence from observational learning

The present experiment evaluated Willingham & Goedert-EschmannÂs proposal (1999) that physical practice is required to support the parallel activation of explicit and implicit systems during practice of an SRT task. Individuals either physically executed or observed an individual producing a repeating 12-element sequence. Models and observers were provided with explicit information regarding the sequence or were uninformed. Congruent with previous findings, providing explicit instructions resulted in a significant decrease in response times to sequenced stimuli during acquisition. Individuals who physically performed the sequences during practice exhibited performance during direct and indirect tests consistent with parallel activation of both the explicit and implicit systems. Unexpectedly, performance on the indirect test for the observers that revealed explicit learning was similar to that reported for the model, indicating parallel activation also occurred during observation. This finding addresses some of the predictions made by WillinghamÂs COBALT (1998). Furthermore, a subset of observers revealed no explicit knowledge of the 12-element sequence but performed well on the indirect test. Learning via the implicit system during observation is congruent with recent behavioral data of Bird and colleagues (2005)

Self-Selected Strategies of L2 Learners: Effects on Immediate- and Delayed Word Retention in Intentional and Incidental Vocabulary Acquisition, With Eye-Tracking Implementation

This study establishes the preferences for vocabulary learning strategies (VLSs) in different contexts, by examining two groups of learners of Arabic (one with L1 English and the other with L1 Chinese) as an L2. The first and second experiments were designed to identify the selection and use of VLSs in intentional and incidental modes of vocabulary learning, and to examine the effects of VLSs on immediate and delayed word retention. The third experiment (eye-tracking) explored these strategies in depth, alongside the behaviours utilised for incidental vocabulary acquisition, also assessing the factors influencing be VLS use, using the eye tracking technique to aid stimulated verbal recall. A mixed methods design was used, based on triangulating the findings from quantitative (vocabulary tests and retrospective reporting of strategies) and qualitative (interviews and stimulated recall interviews using eye-tracking) data collection instruments. The study identified a list of VLSs that were used in both modes, and these were then systematically classified into four vocabulary learning categories. The quantitative data revealed a number of strategies were vulnerable to the significant effects from predictor variables; i.e., group, mode of learning, and test time. The quantitative data also showed a significant relationship between the VLSs used and the uptake of vocabulary type (noun/verb) and subtypes (concrete/abstract noun & action/state verb) in post and delayed post-test tasks. The qualitative data highlighted different ways of implementing VLS, especially with strategies identified in the incidental mode, such as guessing strategies, and repeated reading. The findings showed further interesting variations in the vocabulary gained, confirming that VLSs are conscious and essential in both modes of learning (intentional/incidental). The implications of these findings as they effect learning and teaching in the intentional and incidental context are presented and discussed

Neuromuscular modularity and behavioral correlates of motor control

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2006.Includes bibliographical references (p. 259-276).I studied organizational principles that may subserve the control and learning of forelimb movements. Among these principles, I focused on muscular coordination patterns, motor cortical excitability, and sensorimotor interactions. I found that muscle activity in grasping and reaching behaviors could be reconstructed by linear combinations of a small number of time-varying muscle synergies, each fit with coefficients unique to the behavior. However, the generalization of these synergies between behavioral conditions was limited, in part by the sensitivity of the extraction algorithm to stereotyped muscular relations within contrasted conditions. In reaching studies designed to assist or resist different movement directions, I found a gradual change in the structure, as well as recruitment, of synergies. When a perturbation was targeted to the activity within a single muscle, I found a transient, relative suppression of this muscle in response to descending motor commands. In other motor cortical microstimulation experiments, I confirmed that long-train microstimulation is able to evoke complex, convergent movements. Even during highly-trained reaching movements, I found that there was relatively little invariance of the muscular patterns in relation to kinematic variables coding for the hand's displacement and velocity.(cont.) In two studies examining the kinematic consequences of modulating cortical excitability, I either infused tissue plasminogen activator into monkey cortex or applied transcranial magnetic stimulation to human cortex, either while or before each adapted to a clockwise force field. In both cases basal motor performance was spared, but each manipulation appeared to be associated with disruptions of subjects' ability to retain, improve, or recall recent adaptations. Among other human studies, I investigated the interaction of dynamic adaptation and sequence learning, and found that simultaneous acquisition of a force field and a sequence does not impair performance on either but may have enabled subjects to tune in to, and chunk, their movements. I found that motor consolidation may be dependent on the more effortful learning enabled by catch-trial interruptions of practice on a novel condition. Finally, I used functional imaging and manual cutaneous stimulation to show that the hemodynamic response was biased according to receptor density but generally non-somatotopic and distributed throughout sensorimotor cortex.by Simon Alexander Overduin.Ph.D

Neoliterate adult dyslexia and literacy policies : a neurocognitive research review of a curious unexplored phenomenon

There are about 750 million adult illiterates who in principle could learn fluent reading. However, adult literacy programs have performed poorly. Various social and operational reasons may be responsible. This paper explores the role of some neurocognitive reasons in adult performance. Automatic readers of a script detect letters and words effortlessly and involuntarily. Adults learning new scripts find it hard to attain this performance. Whether illiterate or educated, adults learning a new script detect letters slowly, may make mistakes, understand little, soon abandon the task, and may also forget what they learned. When neoliterates glance at a text, they often see a jumble of letters and may process only a few of their features. They must activate reading consciously andsound out each letter. The difficulties are perceptual, and interviews suggest that perceptual distortions may continue for decades. This phenomenon called “neoliterateadult dyslexia” (NAD) has escaped attention, possibly because few educated adults need to learn new scripts, and because the adult literacy failures are often attributed to social reasons. The phenomenon also may have been missed because researchers of perceptual learning use simpler stimuli. Automaticity in reading musical notation and air traffic control may reflect similar age-related learning difficulties. In the brain, the problem may originate at the early stages of the parietal cortex at the dorsal reading path, which constricts short-term visual memory. The visual areas V1 and perhaps V4 may also be involved. Deficits affect the ventral path that provides parallel processing and direct ‘print-to-meaning’ reading. Some neuronal groups may have a sensitive period that affects the capacity to collect frequency data and to integrate the appropriate features of letters and words. Then adults do not learn to perceive letter shapes and words as easily as most children do. A lack of data and research makes it difficult to design effective interventions.The adults’ difficulties are not linguistic. Dysfluent readers simply cannot decipher the symbols in sufficient time to get to the meaning of texts, or they do so after considerable conscious visual effort. Therefore language competence seems to have little relationship to the visuospatial tasks described in this document. Language knowledge does help predict likely words when judgements must be made on the basis of just a few letter features, but the relative ease of linguistic identification may lead to reading errors. The readers’ symptoms resonate with descriptions of severe and unremitting developmental dyslexia. Certain perceptual deficits may arise during adolescence and become more severe in adulthood. Some adults may become better readers than others. But learning a script at increasingly later ages seems related to worse outcomes, though no data exist to map this trajectory. To explore this curious phenomenon, this review brings together a range of insights from of neurocognitive research, notably studies on (a) perceptual learning, including studies on feature integration and face recognition; (b) neurocognitive studies aimed at dyslexic children, (c) studies of adults suffering from brain damage that causes alexia, and (d) performance of adult literacy programs. Implications and potential remedies are also presented. The author posits the hypothesis that perhaps all people become dyslexics for new alphabets at about age 19, and thatability to read new alphabets fluently decreases with age. Neoliterate adult dyslexia (NAD) may partly account for the difficulties of adult literacy programs. Thus it seems to impact about 750 million adult illiterates. For this reason, the paper calls for urgent research into this phenomenon

Interactive effects of orthography and semantics in Chinese picture naming

Posters - Language Production/Writing: abstract no. 4035Picture-naming performance in English and Dutch is enhanced by presentation of a word that is similar in form to the picture name. However, it is unclear whether facilitation has an orthographic or a phonological locus. We investigated the loci of the facilitation effect in Cantonese Chinese speakers by manipulating—at three SOAs (2100, 0, and 1100 msec)—semantic, orthographic, and phonological similarity. We identified an effect of orthographic facilitation that was independent of and larger than phonological facilitation across all SOAs. Semantic interference was also found at SOAs of 2100 and 0 msec. Critically, an interaction of semantics and orthography was observed at an SOA of 1100 msec. This interaction suggests that independent effects of orthographic facilitation on picture naming are located either at the level of semantic processing or at the lemma level and are not due to the activation of picture name segments at the level of phonological retrieval.postprin

Kinematic changes following robotic-assisted upper extremity rehabilitation in children with hemiplegia : dosage effects on movement time

Indiana University-Purdue University Indianapolis (IUPUI)Background: Rehabilitation Robotics (RR) has become a more widely used and better understood treatment intervention and research tool in the last 15 years. Traditional research involves pre and post-test outcomes, making it difficult to analyze changes in behavior during the treatment process. Harnessing kinematics captured throughout each treatment allows motor learning to be quantified and questions of application and dosing to be answered. Objective: The aims of this secondary analysis were: (i) to investigate the impact of treatment presentation during RR on upper extremity movement time (mt) in children with hemiplegic cerebral palsy (CP) and (ii) to investigate the impact of training structure (dose and intensity) on mt in children with CP participating in RR. Methods: Subjects completed 16 intervention sessions of RR (2 x week; 8 weeks) with a total of 1,024 repetitions of movement per session and three assessments: pre, post and 6 month f/u. During each assessment and intervention, subjects completed “one-way record” assessments tracking performance on a planar task without robotic assistance. Kinematics from these records were extracted to assess subject performance over the course of and within sessions. Results: For all participants, a significant decrease in mt was found at post-test and follow-up. No significant differences were found in mt for age, severity or group placement. A significant interaction was found between treatment day, block and group (p = .033). Significant mt differences were found between the three blocks of intervention within individual days (p = .001). Specifically, significant differences were found over the last block of treatment (p = .032) and between successive treatment days (p = .001). Conclusion: The results indicate that for children with CP participating in RR, the number of repetitions per session is important. We hypothesized that children’s performance would plateau during a treatment day as attention waned, the opposite proved to be true. Despite the high-number of repetitions and associated cognitive demand, subjects’ performance actually trended upwards throughout the 1,024 repetitions suggesting that children were able to tolerate and learn from a high volume of repetitions

The role of phonology in visual word recognition: evidence from Chinese

Posters - Letter/Word Processing V: abstract no. 5024The hypothesis of bidirectional coupling of orthography and phonology predicts that phonology plays a role in visual word recognition, as observed in the effects of feedforward and feedback spelling to sound consistency on lexical decision. However, because orthography and phonology are closely related in alphabetic languages (homophones in alphabetic languages are usually orthographically similar), it is difficult to exclude an influence of orthography on phonological effects in visual word recognition. Chinese languages contain many written homophones that are orthographically dissimilar, allowing a test of the claim that phonological effects can be independent of orthographic similarity. We report a study of visual word recognition in Chinese based on a mega-analysis of lexical decision performance with 500 characters. The results from multiple regression analyses, after controlling for orthographic frequency, stroke number, and radical frequency, showed main effects of feedforward and feedback consistency, as well as interactions between these variables and phonological frequency and number of homophones. Implications of these results for resonance models of visual word recognition are discussed.postprin