Letter imagery deficits in a case of pure apraxic agraphia

Pure apraxic agraphia is a condition in which motor writing is impaired but limb praxis and nonmotor writing (typing, anagram letters) are preserved. This condition is believed to result from disruption of a parietal lobe graphemic area which generates grapheme representations used to program motor-writing patterns. We report a single case of pure apraxic agraphia in which defective letter imagery was evident. Results of writing and imagery evaluations suggest that the graphemic area may be responsible for generating letter images. In this respect, clinical evaluation of letter imagery abilities in cases of apraxic agraphia may be useful in identifying subtypes of the disorder resulting in a better understanding of the neuropsychological process involved in writing.     

Cerebellar-induced apraxic agraphia: a review and three new cases

Apraxic agraphia is a writing disorder due to a loss or lack of access to motor engrams that program the movements necessary to produce letters. Clinical and functional neuroimaging studies have demonstrated that the neural network responsible for writing includes the superior parietal region and the dorsolateral and medial premotor cortex. Recent studies of two cases with atypical lesion localisations in the left thalamus and the right cerebellum support the hypothesis that the written language network is larger than previously assumed. The aim of this study is twofold: (1) to provide a survey of cases of apraxic agraphia published between 1973 and June 2010, and (2) to provide further evidence for a role of the cerebellum in writing via three additional cases who presented with apraxic agraphia after ischemic damage in the cerebellum. Functional neuroimaging studies by means of brain perfusion SPECT showed perfusional deficits in the anatomoclinically suspected supratentorial areas, subserving language dynamics, syntax, naming, writing and executive functioning.     

Apractic agraphia in a patient with normal praxis

Most right-handed crossed aphasics are not apractic. They usually have agraphia characterized by misspellings but retain the ability to write well-formed graphemes. We describe a right-handed patient with a right parietal lesion who was aphasic and not apractic. He was unable to write any formed graphemes despite a relatively preserved ability to spell aloud. We postulate that praxis and writing are dissociated in this patient because the motor engrams for praxis were located in his left hemisphere and the engrams for writing were in his right hemisphere. In addition, he comprehended commands for limb motor activities (praxis) far better than he comprehended other speech. This suggests that in this patient the areas used to comprehend limb motor commands may be anatomically distinct from areas important in comprehending other aspects of speech.     

Scaling a motor skill through observation and practice

The authors examined the proposal that a motor skill is scaled through physical practice and not through observation of a model. In 4 groups, participants (N = 32) did or did not imitate a model bowling a ball to a target 8 m away. In an assessment phase, those groups did or did not observe the same model bowling a ball to a target 4 m away. Participants who viewed a model in the assessment phase were more accurate and consistent in terms of bowling accuracy than were those who did not. Their shoulder and wrist velocity profiles were more similar to those of the 4-m model than were those of the no-model group. Participants who had previous practice and viewed a demonstration were more accurate at scaling the wrist of the bowling arm. Observing a demonstration facilitates the acquisition of control-related features of a movement. Furthermore, early acquisition of coordination aids the use of velocity information for scaling the endpoint of the primary effector.     

Intention in motor learning through observation

The purpose of this experiment was to assess whether learning an action through observation is enhanced by the intention to reproduce the observed behaviour. Two groups of participants observed a model practise a timing task and performed a 24-hour delayed retention test. Participants in the first group of observers were explicitly instructed that they would be required to execute the timing task that they had observed as accurately as possible during the delayed retention test. Observers in the second group were instructed that they would be required to describe as accurately as possible the behaviour that they had observed. A control group of participants, who did not observe the model, was also administered the delayed retention test. The results of the retention test indicated that absolute timing (parameterization) was learned by the observers to the same extent with or without intention to reproduce the task. Indeed, on the retention test absolute timing for the two groups of observers was as effective as that for the models. However, observing with an intention to reproduce the task was beneficial for learning the movement's relative timing structure. Results are discussed with respect to a potential mechanism by which intention enhances observation.     

Intention in motor learning through observation

The purpose of this experiment was to assess whether learning an action through observation is enhanced by the intention to reproduce the observed behaviour. Two groups of participants observed a model practise a timing task and performed a 24-hour delayed retention test. Participants in the first group of observers were explicitly instructed that they would be required to execute the timing task that they had observed as accurately as possible during the delayed retention test. Observers in the second group were instructed that they would be required to describe as accurately as possible the behaviour that they had observed. A control group of participants, who did not observe the model, was also administered the delayed retention test. The results of the retention test indicated that absolute timing (parameterization) was learned by the observers to the same extent with or without intention to reproduce the task. Indeed, on the retention test absolute timing for the two groups of observers was as effective as that for the models. However, observing with an intention to reproduce the task was beneficial for learning the movement's relative timing structure. Results are discussed with respect to a potential mechanism by which intention enhances observation.     

A different form of agraphia: Syntactic writing errors in patients with motor speech and movement disorders

Three patients are described who displayed syntactic writing errors in combination with a motor speech disturbance and impaired motor limb function. Two of the patients had bulbar amyotrophic lateral sclerosis (ALS). Agraphia appeared when verbal communication was no longer possible. Autopsy in one patient disclosed only lesions consistent with ALS. The third patient had palilalia and chorea and, although not aphasic, his written language showed persistent syntactic errors. We hypothesize that the agraphia in these patients occurred because of the combination of disordered feedback from the motor speech apparatus and limbs.     

Response-specific effects of pain observation on motor behavior

How does seeing a painful event happening to someone else influence the observer's own motor system? To address this question, we measured simple reaction times following videos showing noxious or innocuous implements contacting corporeal or noncorporeal objects. Key releases in a go/nogo task were speeded, and key presses slowed, after subjects saw a video of a needle pricking a fingertip. No such effect was seen when the observed hand was replaced by a sponge, nor when the needle was replaced by a cotton bud. These findings demonstrate that pain observation modulates the motor system by speeding withdrawal movements and slowing approach movements of the finger. This illustrates a basic mechanism by which visual information about pain is used to facilitate appropriate behavioral responses.     

Residual reading capability in a patient with alexia without agraphia

A case of pure alexia due to an ischemic lesion of the occipital temporal region is described. Written words could be matched but not read. Immediate memory span for graphemes was defective. The reading defect probably depends on the inability to modify the written word “globally”; the phonological process was intact, but the memory disturbance impeded reading. The dissociation is explained by the preservation of word forms, which are linked to the semantic stage. Nonwritten stimuli trigger a “meaning” which evokes the word form and so the written word is recognized even though it cannot be read.     

Progressive agraphia can be a harbinger of degenerative dementia

By investigating three patients with progressive agraphia, we explored the possibility that this entity is an early sign of degenerative dementia. Initially, these patients complained primarily of difficulties writing Kanji (Japanese morphograms) while other language and cognitive impairments were relatively milder. Impairments in writing Kana (Japanese syllabograms), verbal language, executive function, visuo- and visuospatial cognition and memory were identified by neuropsychological testing. The agraphia was compatible with a peripheral type, based on deficits at the interface between the central letter selection and the graphemic motor execution (Patient 1) or at the stage of central letter selection as well (Patients 2 and 3). Agraphia was generally more prominent, although not exclusive, for Kanji probably because of later acquisition and larger total number of Kanji letters leading to lower frequency of use and familiarity per letter. Concurrent or subsequent emergence of non-fluent aphasia, ideomotor apraxia, executive dysfunction and asymmetric akinetic-rigid syndrome in two patients suggested degenerative processes involving the parietal-occipital-temporal regions, basal ganglia and striato-frontal projections. We propose that progressive agraphia may be one of the early symptoms of degenerative dementia such as corticobasal degeneration.     

Action observation produces motor resonance in Parkinson's disease

Observation of movement activates the observer's own motor system, influencing the performance of actions and facilitating social interaction. This motor resonance is demonstrated behaviourally through visuomotor priming, whereby response latencies are influenced by the compatibility between an intended action and an observed (task‐irrelevant) action. The impact of movement disorders such as Parkinson's disease (PD) on motor resonance is unclear, as previous studies of visuomotor priming have not separated imitative compatibility (specific to human movement) from general stimulus‐response compatibility effects. We examined visuomotor priming in 23 participants with mild‐to‐moderate PD and 24 healthy older adults, using a task that pitted imitative compatibility against general stimulus‐response compatibility. Participants made a key press after observing a task‐irrelevant moving human finger or rectangle that was either compatible or incompatible with their response. Imitative compatibility effects, rather than general stimulus‐response compatibility effects, were found specifically for the human finger. Moreover, imitative compatibility effects did not differ between groups, indicating intact motor resonance in the PD group. These findings constitute the first unambiguous demonstration of imitative priming in both PD and healthy ageing, and have implications for therapeutic techniques to facilitate action, as well as the understanding of social cognition in PD.     

Use of video observation and motor imagery on jumping performance in national rhythmic gymnastics athletes

The aim of this study was to evaluate whether a mental training protocol could improve gymnastic jumping performance. Seventy-two rhythmic gymnasts were randomly divided into an experimental and control group. At baseline, experimental group completed the Movement Imagery Questionnaire Revised (MIQ-R) to assess the gymnast ability to generate movement imagery. A repeated measures design was used to compare two different types of training aimed at improving jumping performance: (a) video observation and PETTLEP mental training associated with physical practice, for the experimental group, and (b) physical practice alone for the control group. Before and after six weeks of training, their jumping performance was measured using the Hopping Test (HT), Drop Jump (DJ), and Counter Movement Jump (CMJ). Results revealed differences between jumping parameters F(1, 71) = 11.957; p < .01, and between groups F(1, 71) = 10.620; p < .01. In the experimental group there were significant correlations between imagery ability and the post-training Flight Time of the HT, r(34) = −.295, p < .05 and the DJ, r(34) = −.297, p < .05. The application of the protocol described herein was shown to improve jumping performance, thereby preserving the elite athlete’s energy for other tasks.     

Motor imagery combined with action observation training optimized for individual motor skills further improves motor skills close to a plateau

The acquisition of high-level motor skills beyond a “plateau” is important in sports training and rehabilitation. We aimed to investigate whether motor skills close to a plateau state can be improved further by performing motor imagery (MI) training while observing movements with difficulty levels optimized for individual motor skills. The subjects were divided randomly into four groups (n = 10 per group): the control group and three groups of MI combined with action observation (MI + AO) training with varying difficulty levels. The task was to rotate the two cork balls 20 times counterclockwise using the left hand. The subjects performed 30 and 10 successful trials of this task before and after MI + AO training, respectively. In the three training groups, MI training was performed while observing videos showing ball rotation movements adjusted to the same level, a moderately higher level, or a remarkably higher level of difficulty than that achieved by the individual subjects. The improvement rate of the ball rotation time after MI + AO training was significantly higher in the moderate-difficulty than in the control group and remarkably higher level of difficulty group. The other two MI + AO training groups did not differ significantly compared with the control group. The vividness of the MI during MI + AO training was significantly greater in the moderate-difficulty vs. the remarkably-high-difficulty group. These results suggest that performing MI training while observing movement at a level that is moderately higher than an individual's ability can promote improvements in motor skills (close to a plateau state) in rehabilitation and sports training. The vividness of MI may be an important index for determining the difficulty level of the movement to be observed during MI + AO training.     

Iconic reading in a case of alexia without agraphia caused by a brain tumor: a tachistoscopic study

The lack of nonverbal reading comprehension in the clinical disconnection syndrome, alexia without agraphia, has been contradictory to the relative reading comprehension of the right hemisphere in split brains. We report a 39-year-old patient with verbal alexia without agraphia caused by brain tumor. On rapid tachistoscopic presentation of object names, he denied seeing anything but showed nonverbal reading comprehension by pointing to the corresponding objects. He lost this ability when he recovered ability to name individual letters of the object names. Our results suggest that even partial verbal reading such as the naming of single letters makes demonstration of iconic reading impossible and that total functional disconnection from verbalization, as initially noted in this case or in split brain studies, is necessary to show nonverbal reading comprehension.     

Assessing a new response-microswitch combination with a boy with minimal motor behavior

This study assessed whether a boy with profound multiple disabilities and minimal motor behavior could learn to use a new response-microswitch combination to control environmental stimulation. The response selected was a chin movement; a mechanical microswitch was set up for this response. The boy learned to use the microswitch, increasing the frequency of the chin response and the level of pleasant stimulation following such response. The performance was retained at a 2-mo. post-intervention check.