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PubMed2003

Mirror apraxia affects the peripersonal mirror space. A combined lesion and cerebral activation study.

Mirror apraxia is a condition in which patients with lesions of the posterior parietal cortex have deficits in reaching to objects presented through a mirror. The aim of the present study was to investigate possible mechanisms underlying this disorder. First, we addressed the question of whether mirror apraxia is exhibited to the same extent in peripersonal and in body space. Four patients with lesions of the posterior parietal lobe on either side and with marked mirror apraxia were required to reach for objects that were presented to them through a mirror and located either in body space (i.e. on the body surface) or in peripersonal space (i.e. in the reaching distance). Whereas reaching for objects located in body space was flawless in all patients, the performance deteriorated when the same objects were transferred to the peripersonal space. Although the objects were located only a few centimetres above the body surface, the patients reached towards the virtual object in the mirror. Based on these results we suggest that mirror apraxia may originate from a dissociation between the representations of body schema and peripersonal space and that objects located on the body surface become integrated into the body schema. In the second part of the study, using positron emission tomography study (PET), we studied the cerebral activation pattern during reaching to objects presented through a mirror in the peripersonal space in healthy subjects. The results show that increased neural activity in the anterior part of the intraparietal sulcus and in the dorsal premotor cortex was bound to the transformation of the target position from the mirror space to the real space. In contrast, the activity related to object localization in the mirror occurred at the parieto-occipital junction. Both mirror and arm transformation involved the medial posterior part of the superior parietal lobule, putatively area V6a. The results demonstrate that acting through a mirror is processed in a number of cortical areas of the dorsal stream.

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PubMed1996

Spatio-temporal impairments in limb and body movements during righting in an hemiparkinsonian rat analogue: relevance to axial apraxia in humans.

Humans with Parkinson's disease (PD) often have problems in righting themselves, in that they have difficulty in recruiting their axial musculature to rotate the body to prone. Since this "axial apraxia' is not ameliorated by L-DOPA therapy, it has been concluded that dopamine (DA) does not play a role in recruiting axial rotation of the body [14]. This hypothesis was tested by comparing the righting of rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra (SN) with that of intact rats. Body-on-body righting, where asymmetrical tactile stimulation of the body initiates hindquarter righting, was used to specifically test tactile righting independently of righting triggered or influenced by other sensory systems. In this behavioral test, rats are placed on their sides, their forequarters are held down and their hindquarters released. The DA-depleted rats took longer to begin righting, to complete righting, and used more limb action to right themselves than did control rats. These findings suggest that for this tactile based form of righting, DA-depletion produces axial apraxia. However, frame-by-frame analysis of righting sequences of DA-depleted rats showed that pelvis-led axial rotation could occur, but the spatio-temporal relationship between body and limb movements was disorganized. Therefore, following DA-depletion axial apraxia-like deficits appear to arise from sensorimotor disruption. This raises the issue of whether the axial apraxia in PD patients arises from damage to systems beyond the nigrostriatal DA system, or from interference with sensorimotor integration that is not ameliorated by replacement therapy.

Animals↗
PubMed1986

Disturbed coarticulation in apraxia of speech: acoustic evidence.

The results of a recent perceptual study (W. Ziegler & D. von Cramon, 1985, Anticipatory coarticulation in a patient with apraxia of speech. Brain and Language 26, 117-130) provided evidence for disturbed coarticulation in verbal apraxia. Further support for this finding is now provided by acoustic analyses. Formant frequencies and LP reflection coefficients were chosen to assess anticipatory vowel-to-vowel coarticulation and vowel anticipation in stop consonants, respectively. These parameters revealed a lack of coarticulatory cohesion in the speech of a patient suffering from verbal apraxia, explainable by a consistent delay in the initiation of anticipatory vowel gestures. The findings are discussed with respect to prosodic features and to theoretical and clinical concepts of verbal apraxia.

Adult↗
PubMed1988

Nonspeech and speech processing skills in patients with aphasia and apraxia of speech.

Nonspeech and speech auditory processing skills as well as internal speech processing skills were assessed among four patients with acquired "pure" apraxia of speech, 10 with acquired aphasia, 10 with aphasia plus apraxia of speech, and 11 neurologically normal adults. Fourteen tasks were administered and performances on 68 variables were examined using both nonparametric and parametric analyses controlling for the effects of advancing age and associated hearing loss. In all cases, the "pure" apractic patients performed as normal subjects. Few differences were noted among the performances of the aphasic and aphasic-apractic subjects. Results led to three major conclusions: (1) apraxia of speech is a disorder distinct from aphasia; (2) aphasic individuals, despite locus of lesion, demonstrate disabilities for processing nonspeech and speech materials presented auditorily and for analytically evaluating speech evoked internally; and (3) aphasic individuals demonstrating similar severity levels of language impairment show similar performance patterns for these types of processing tasks, despite locus of lesion or coexistence of apraxia of speech.

Adult↗
PubMed1991

The relationship between buccofacial and limb apraxia.

There are at least two possible models depicting the relationship between buccofacial and limb apraxia. First, apraxia can be viewed as a unitary motor disorder which transcends the output modalities of both buccofacial and limb output. A high degree of similarity between the two types of apraxia would support this model. Alternatively, the relationship between buccofacial and limb apraxia may not include a unitary mechanism. The presence of quantitative and qualitative differences between buccofacial and limb performance would support this nonunitary model. The results of the present study support the nonunitary model.

Adult↗
PubMed2005

Audio-visual matching of speech and non-speech oral gestures in patients with aphasia and apraxia of speech.

BACKGROUND: Audio-visual speech perception mechanisms provide evidence for a supra-modal nature of phonological representations, and a link of these mechanisms to motor representations of speech has been postulated. This leads to the question if aphasic patients and patients with apraxia of speech are able to exploit the visual signal in speech perception and if implicit knowledge of audio-visual relationships is preserved in these patients. Moreover, it is unknown if the audio-visual processing of mouth movements has a specific organisation in the speech as compared to the non-speech domain. METHODS: A discrimination task with speech and non-speech stimuli was applied in four presentation modes: auditory, visual, bimodal and cross-modal. We investigated 14 healthy persons and 14 patients with aphasia and/or apraxia of speech. RESULTS: Patients made substantially more errors than normal subjects on both the speech and the non-speech stimuli, in all presentation modalities. Normal controls made only few errors on the speech stimuli, regardless of the presentation mode, but had a high between-subject variability in the cross-modal matching of non-speech stimuli. The patients' cross-modal processing of non-speech stimuli was mainly predicted by lower face apraxia scores, while their audio-visual matching of syllables was predicted by word repetition abilities and the presence of apraxia of speech. CONCLUSIONS: (1) Impaired speech perception in aphasia is located at a supra-modal representational level. (2) Audio-visual processing is different for speech and non-speech oral gestures. (3) Audio-visual matching abilities in patients with left-hemisphere lesions depend on their speech and non-speech motor abilities.

Adult↗
PubMed1979

Articulatory and phonological aspects of consonant substitutions in apraxia of speech.

The articulatory and distinctive features in 825 consonant substitutions produced by nine subjects with apraxia of speech were analyzed. The articulatory and distinctive features of the target consonants were retained beyond chance levels. The substitution patterns observed were very systematic in that more substitutions were made in the initial word position and stops, alveolars, and voiced consonants were used most often as substitutes for target consonants. The retention and usage of the features in the substitutions were closely related to the phonological markedness of the features, Most of the markedness changes were from marked-to-unmarked. The relationships between distinctive features and their markedness suggest that apraxia of speech is primarily a phonological disorder that is manifested in articulatoriy changes. It appears therefore that speakers with apraxia of speech systematically reduce linguistic complexity and simplify the production of consonants. In addition, the substitutions made in apraxia of speech are similar to those made by children.

Apraxias↗
PubMedDate not supplied

The production of emotional prosody in varying degrees of severity of apraxia of speech.

UNLABELLED: The purpose of this study was to examine the abilities of subjects with varying degrees of apraxia of speech (AOS) to produce emotional prosody. One subject with mild AOS, one subject with moderate AOS and a control subject were asked to produce sentences with happy, sad and neutral emotional intent in a repetition and a reading experiment and naive listeners were asked to identify the intended emotion of the productions based upon the prosodic structures. Acoustic analyses of the subjects' productions revealed that unlike the control subject, the AOS subjects did not produce differences in FO, duration and amplitude cues within their prosodic structures to convey the different emotions. Naive listeners were able to identify the emotional intent of the control subject's productions but were unable to distinguish between the utterances of the experimental subjects. These findings are discussed in conjunction with suggestions for future research in this area. LEARNING OUTCOMES: The reader will (1) be able to define apraxia of speech and identify speech characteristics associated with apraxia of speech; (2) acquire an understanding of prosodic cues used to signal emotional intent; and (3) develop an understanding of the relationship between apraxia of speech and the production of emotional prosody.

Affect↗
PubMedDate not supplied

Use of a content methodology process to enhance feeding abilities threatened by ideational apraxia in people with Alzheimer's-type dementia.

Self-feeding behavior is often the first of a chain of self-maintenance skills to deteriorate in people with Alzheimer's-type dementia and is a major determinant of institutionalization. Moreover, nurses working in geriatric settings report the feeding of patients as a most difficult management problem. Of the various features of Alzheimer's-type dementia that can affect a person's ability to feed him- or herself, ideational apraxia can explain the loss of ability to conceptualize, plan, and execute the complex sequence of motor actions involving the use of tools or objects necessary for feeding. In this article, a systematic process is used to review the research literature to develop substantive content for nurses caring for people with feeding problems related to ideational apraxia. Ideational apraxia is a condition in which an individual is unable to plan movement related to an object because he or she has lost the perception of the object's purpose. The specific abilities necessary for feeding that are threatened by ideational apraxia are identified. A tool to assess these abilities is described, and nursing interventions aimed at enhancing or preserving existing abilities, preventing excess disability, or compensating for lost abilities are presented.

Aged↗
PubMed1975

Respiratory inhibitory apraxia.

Ten patients have been described showing inability to stop breathing on command, spontaneous respiration and voluntary respiratory stimulation being unaffected. This abnormality not previously described in the literature, we feel should be named respiratory inhibitory apraxia (R.I.A.). The anatomical organization of respiration is briefly reviewed. R.I.A. is often associated with other forms of apraxia or motor impersistence. It is thought that the urinary and bowel incontinence present in some of these cases might also represent a form of inhibitory apraxia. Information is presented which supports the view that respiratory inhibitory apraxia is due to a minor hemisphere lesion, usually deepseated. Our one autopsied case showed a lesion in the descending motor pathways in the internal capsule, in middle cerebral artery branch territory, disconnecting the voluntary respiratory inhibitory center in the cortex in anterior and middle cerebral cortical branch territories.

Aged↗
PubMed1983

Spectrographic analysis of vowel and word duration in apraxia of speech.

Most normal speakers of English reduce the duration of the stem word vowel as words increase in length. Theoretically, this durational reduction reflects low-level linguistic knowledge. We posed two questions in this study: First, do speakers with apraxia of speech progressively reduce vowel durations as words increase in length, and second, do these vowel and word durations differ significantly from normal productions? We asked 11 apraxia of speech patients and 11 normal speakers to repeat three sets of three words which progressively increased in length, and we analyzed these productions spectrographically. Our results revealed that both groups reduced vowel duration as words increased in length. Word and vowel duration for apraxia of speech patients, however, were often significantly longer than those for normal speakers. Our results suggest that vowel reduction is a robust phenomenon which resists impairment in apraxia of speech, despite often significant disturbances in motor programming.

Adult↗
PubMed1983

Acoustic patterns of apraxia of speech.

Apraxia of speech (or verbal apraxia) is a controversial disorder, considered by some to be an impairment of the motor programming of speech. Because the disorder is characterized by "higher order" errors such as metathesis and segment addition as well as by errors of apparent dyscoordination of articulation, it seems to reflect a relatively high level of damage to the nervous system. This report presents acoustic descriptions of the speech of seven persons diagnosed as having apraxia of speech but without severe aphasic impairment, especially agrammatism. The acoustic results indicate a variety of segmental and prosodic abnormalities, including slow speaking rate with prolongations of transitions, steady states, and intersyllable pauses; reduced intensity variation across syllables; slow and inaccurate movements of the articulators; incoordination of voicing with other articulations; initiation difficulties; and errors of selection or sequencing of segments. These error patterns are discussed with respect to a theory of motor control based on spatial-temporal schemata. In addition, consideration is given to the controversy about phonologic versus motor programming impairment in apraxia of speech.

Adult↗
PubMed1996

The specific relation between perception and production errors for place of articulation in developmental apraxia of speech.

Developmental apraxia of speech is a disorder of phonological and articulatory output processes. However, it has been suggested that perceptual deficits may contribute to the disorder. Identification and discrimination tasks offer a fine-grained assessment of central auditory and phonetic functions. Seventeen children with developmental apraxia (mean age 8:9, years:months) and 16 control children (mean age 8:0) were administered tests of identification and discrimination of resynthesized and synthesized monosyllabic words differing in place-of-articulation of the initial voiced stop consonants. The resynthetic and synthetic words differed in the intensity of the third formant, a variable potentially enlarging their clinical value. The results of the identification task showed equal slopes for both subject groups, which indicates no phonetic processing deficit in developmental apraxia of speech. The hypothesized effect of the manipulation of the intensity of the third formant of the stimuli was not substantiated. However, the children with apraxia demonstrated poorer discrimination than the control children, which suggests affected auditory processing. Furthermore, analyses of discrimination performance and articulation data per apraxic subject demonstrated a specific relation between the degree to which auditory processing is affected and the frequency of place-of-articulation substitutions in production. This indicates the interdependence of perception and production. The results also suggest that the use of perceptual tasks has significant clinical value.

Apraxias↗
PubMed2001

Intransitive limb gestures and apraxia following unilateral stroke.

Apraxia is the loss of the ability to perform learned, skilled movements correctly, and is frequently attributed to left hemisphere damage (Heilman & Rothi, 1985). Recent work (Dumont, Ska, & Schiavetto, 1999) has shown a dissociation between transitive (tool based; e.g., hammering a nail) and intransitive (expressive/ communicative; e.g., waving goodbye) actions; however, few group studies have specifically addressed apraxia for intransitive gestures. The present investigation examined the frequency and severity of praxis errors related to the production of intransitive gestures in left (LHD) or right hemisphere stroke (RHD) patients in the context of Roy's (1996) model of limb praxis. A total of 119 consecutive stroke patients (LHD = 57, RHD = 62) and 20 healthy age-matched controls performed eight intransitive gestures to pantomime and imitation. Performance was quantified via a multi-dimensional error notation system, providing detail about specific elements of performance (e.g., location), and a composite score reflecting overall gestural accuracy. Analyses of pantomime and imitation performance revealed an equal percentage of apraxic patients in each stroke group, and the severity of apraxia in these groups was also equivalent. Further, analyses of the patterns of apraxia specified by Roy (1996) revealed that patients in each stroke group demonstrated selective impairments in pantomime (LHD = 38%, RHD = 42%), or imitation (LHD = 9%, RHD = 5%) conditions, whereas others demonstrated concurrent impairments (LHD = 30%, RHD = 22%) indicating that stroke to either hemisphere can selectively impair each stage in the production of an intransitive action.

Aged↗
PubMed1981

Intelligence and left hemisphere disease. The role of aphasia, apraxia and size of lesion.

The Raven Progressive Matrices and four subtests of the Wechsler-Bellevue Performance Scale were given to 173 left hemisphere patients subdivided according to presence/absence, type (fluent/non-fluent) and severity (moderate/severe) of aphasia. Constructive and ideomotor apraxia scores and CT scan data of each subject entered the statistical analysis. Factors significant in producing a low score on Progressive Matrices and Wechsler-Bellevue were presence of aphasia and constructive apraxia. Site and size of lesion per se failed to account for the intelligence scores. The relationship between aphasia, apraxia, intelligence test scores, and CT scan data were discussed in an attempt to clarify the meaning of these low intelligence test scores in aphasics and to assess the underlying roles of the brain lesions in this deficit. It appears that there are a number of methodological difficulties complicating interpretation of the intellectual deficit based on the Progressive Matrices and Wechsler-Bellevue scores, since performance on these tests is adversely affected by both aphasia and apraxia.

Aphasia↗
PubMed1983

Callosal apraxia.

A 43-year-old woman suffered a spontaneous corpus callosum disconnection, resulting in apraxia and apraxic agraphia confined to the left hand. She initially had a functionally total callosal disconnection. With time, the splenium of the corpus callosum became functional, and a computerized tomographic scan performed five months after the onset showed infarction of only the body of the corpus callosum. Concomitant with this improvement in callosal function, the apraxia changed from ideational (loss of the concept of skilled movements) to classic ideomotor apraxia. A temporal analysis of this case provided support for Liepmann's (Liepmann, 1900; Liepmann and Maas, 1970) hypothesis that there is a centre for visuokinaesthetic (space-time) engrams in the left hemisphere of right-handed patients that controls skilled motor acts in either hand. This patient's recovery also allowed us a better understanding of the mechanisms underlying various types of apraxia.

Adult↗
PubMed1988

Ideational apraxia.

Ideational apraxia was investigated in 20 left brain-damaged patients with tests requiring the demonstration of how objects are used. On a multiple object use test the most frequent errors were those of omission, misuse and mislocation, while sequence errors were rare. Patients also failed on a single object use test, which showed a correlation of 0.85 with the multiple object use test. Neither of these tests was significantly correlated with an ideomotor apraxia test (imitation of movements). Ideational apraxia was frequently, but not exclusively, associated with damage to the left posterior temporoparietal junction. These findings support the view that ideational apraxia is an autonomous syndrome, linked to left hemisphere damage and pertaining to the area of semantic memory disorders rather than to that of defective motor control.

Apraxias↗
PubMed1992

Conceptual apraxia in Alzheimer's disease.

Theoretical models of praxis have two major components, a praxis conceptual system that includes knowledge of tool use and mechanical knowledge and a praxis production system that includes the information needed to program skilled motor acts. Because patients with Alzheimer's disease may have an impairment of the central conceptual system, we wanted to learn if they had a conceptual apraxia by testing their knowledge of the type of actions associated with tool use, their ability to associate tools with objects that receive their action, their ability to understand the mechanical nature of problems and the mechanical advantages tools may afford. We studied 32 subjects with probable Alzheimer's disease and 32 controls by examining tool-action relationships and tool-object associations. We tested mechanical knowledge by having subjects select alternative tools and solve mechanical puzzles by developing new tools. The Alzheimer's group was subdivided into four groups based on the presence or absence of ideomotor apraxia and a lexical-semantic deficit. Results indicated that each of the four Alzheimer's groups differed from normal controls on at least some measures of conceptual apraxia, suggesting that Alzheimer's patients do have a disturbance of the praxis conceptual system and that impairment of this system is not directly related to language impairment or ideomotor apraxia.

Aged↗