Challenging traditions in apraxia

Human Brain Mapping, 2004

The present study aimed to ascertain the neuroanatomical basis of an influential neuropsychological model for upper limb apraxia [Rothi LJ, et al. The Neuropsychology of Action. 1997. Hove, UK: Psychology Press]. Regional cerebral blood flow was measured in healthy volunteers using H 2 15 O PET during performance of four tasks commonly used for testing upper limb apraxia, i.e., pantomime of familiar gestures on verbal command, imitation of familiar gestures, imitation of novel gestures, and an action-semantic task that consisted in matching objects for functional use. We also re-analysed data from a previous PET study in which we investigated the neural basis of the visual analysis of gestures. First, we found that two sets of discrete brain areas are predominantly engaged in the imitation of familiar and novel gestures, respectively. Segregated brain activation for novel gesture imitation concur with neuropsychological reports to support the hypothesis that knowledge about the organization of the human body mediates the transition from visual perception to motor execution when imitating novel gestures [Goldenberg Neuropsychologia 1995;33:63-72]. Second, conjunction analyses revealed distinctive neural bases for most of the gesture-specific cognitive processes proposed in this cognitive model of upper limb apraxia. However, a functional analysis of brain imaging data suggested that one single memory store may be used for "to-be-perceived" and "to-be-produced" gestural representations, departing from Rothi et al.'s proposal. Based on the above considerations, we suggest and discuss a revised model for upper limb apraxia that might best account for both brain imaging findings and neuropsychological dissociations reported in the apraxia literature.

In a prior study it was shown that apraxic patients with posterior infarctions that included the parietal lobe could not discriminate between gestures. In this study these observations were replicated using a nonverbal paradigm in which the subjects did not have to discriminate between gestures, but instead had to comprehend their meaning. Pantomimed acts on videotape were shown to six apraxic-aphasic patients, seven nonapraxic-aphasic patients, and six normal subjects. Four drawings were also shown, one of which matched the pantomime (for example, if the pantomime was of hammering, one drawing was of a nail and three were foils). Subjects responded by pushing a button corresponding to the desired picture. The apraxics made more errors than the aphasics or controls.

Neuropsychologia, 2001

We compared gesture comprehension and imitation in patients with lesions in the left parietal lobe (LPAR, n= 5) and premotor cortex/supplementary motor area (LPMA, n =8) in patients with damage to the right parietal lobe (RPAR, n= 6) and right premotor/supplementary motor area (RPMA, n= 6) and in 16 non-brain damaged control subjects. Three patients with left parietal lobe damage had aphasia. Subjects were shown 136 meaningful pantomimed motor acts on a videoscreen and were asked to identify the movements and to imitate the motor acts from memory with their ipsilesional and contralesional hand or with both hands simultaneously. Motor tasks included gestures without object use (e.g. to salute, to wave) pantomimed imitation of gestures on one's own body (e.g. to comb one's hair) and pantomimed imitation of motor acts which imply tool use to an object in extrapersonal space (e.g. to hammer a nail). Videotaped test performance was analysed by two independent raters; errors were classified as spatial errors, body part as object, parapraxic performance and non-identifiable movements. In addition, action discrimination was tested by evaluating whether a complex motor sequence was correctly performed. Results indicate that LPAR patients were most severely disturbed when imitation performance was assessed. Interestingly, LPAR patients were worse when imitating gestures on their own bodies than imitating movements with reference to an external object use with most pronounced deficits in the spatial domain. In contrast to imitation, comprehension was not or only slightly disturbed and no clear correlation was found between the severity of imitation deficits and gesture comprehension. Moreover, although the three patients with aphasia imitated the movements more poorly than non-aphasic LPAR patients, the severity of comprehension errors did not differ. Whereas unimanual imitating performance and gesture comprehension of PMA patients did not differ significantly from control subjects, bimanual tasks were severely disturbed, in particular when executing different movements simultaneously with the right and left hands.

Brain Communications, 2021

Pantomime has a long tradition in clinical neuropsychology of apraxia. It has been much more used by researchers and clinicians to assess tool-use disorders than real tool use. Nevertheless, it remains incompletely understood and has given rise to controversies, such as the involvement of the left inferior parietal lobe or the nature of the underlying cognitive processes. The present article offers a comprehensive framework, with the aim of specifying the neural and cognitive bases of pantomime. To do so, we conducted a series of meta-analyses of brain-lesion, neuroimaging, and behavioral studies about pantomime and other related tasks (i.e., real tool use, imitation of meaningless postures, and semantic knowledge). The first key finding is that the area PF (Area PF complex) within the left inferior parietal lobe is crucially involved in both pantomime and real tool use as well as in the kinematics component of pantomime. The second key finding is the absence of a well-defined neura...

Neuropsychologia, 1997

In two patients with damage to the inferior portion of the left angular gyrus severely defective imitation of meaningless gestures contrasted with preserved performance of meaningful gestures to verbal command and with preserved imitation of meaningful gestures[ In one patient the imitation de_cit was restricted to the imitation of hand positions while imitation of _nger con_gurations was normal[ In both patients replication of the hand positions on a mannikin was as defective as imitation on themselves[ This pattern of preserved and impaired performances is incompatible with two!stage models of apraxia which posit that defective imitation stems from damage to an executional stage of gesture production[ Interruption of a direct route from perception to execution of action could account for the dissociation between defective imitation of meaningless and preserved performance of meaningful gestures [ We propose that functioning of this route requires the integrity of general knowledge about the structure of the human body[ Þ 0886 Elsevier Science Ltd[ All rights reserved[ Key Words] apraxia^motor control^parietal lobe^imitation[ * ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐ than the pantomime of object use even in controls[ Neuropsychologische Abteilung Krankenhaus Mu à nchenÐ They concluded that only the reverse dissociation was Bogenhausen Englschalkingerstrasse 66 D 70814 Mu à nchen\ FRG^tel[] ¦38!78!8169 1095^fax] ¦38!78!8169 1978[ speci_c for left!brain damage ð3Ł[ Single case studies cast

Current Neurology and Neuroscience Reports, 2016

Since the first studies on limb apraxia carried out by Hugo Liepmann more than a century ago, research interests focused on the way humans process manual gestures by assessing gesture production after patients suffered neurologic deficits. Recent reviews centered their attention on deficits in gesture imitation or processing object-related gestures, namely pantomimes and transitive gestures, thereby neglecting communicative/intransitive gestures. This review will attempt to reconcile limb apraxia in its entirety. To this end, the existing cognitive models of praxis processing that have been designed to account for the complexity of this disorder will be taken into account, with an attempt to integrate in these models the latest findings in the studies of limb apraxia, in particular on meaningful gestures. Finally, this overview questions the very nature of limb apraxia when other cognitive deficits are observed.

Neuroimage, 2001

The clinical test of imitation of meaningless gestures is highly sensitive in revealing limb apraxia after dominant left brain damage. To relate lesion locations in apraxic patients to functional brain activation and to reveal the neuronal network subserving gesture representation, repeated H 2 15 O-PET measurements were made in seven healthy subjects during a gesture discrimination task. Observing paired images of either meaningless hand or meaningless finger gestures, subjects had to indicate whether they were identical or different. As a control condition subjects simply had to indicate whether two portrayed persons were identical or not. Brain activity during the discrimination of hand gestures was strongly lateralized to the left hemisphere, a prominent peak activation being localized within the inferior parietal cortex (BA40). The discrimination of finger gestures induced a more symmetrical activation and rCBF peaks in the right intraparietal sulcus and in medial visual association areas (BA18/19). Two additional foci of prominent rCBF increase were found. One focus was located at the left lateral occipitotemporal junction (BA 19/37) and was related to both tasks; the other in the pre-SMA was particularly related to hand gestures. The pattern of task-dependent activation corresponds closely to the predictions made from the clinical findings, and underlines the left brain dominance for meaningless hand gestures and the critical involvement of the parietal cortex. The lateral visual association areas appear to support first stages of gesture representation, and the parietal cortex is part of the dorsal action stream. Finger gestures may require in addition precise visual analysis and spatial attention enabled by occipital and right intraparietal activity. Pre-SMA activity during the perception of hand gestures may reflect engagement of a network that is intimately related to gesture execution.

Journal of Neurology, Neurosurgery & Psychiatry, 2013

Neuropsychologia, 1995

Imitation of meaningless gestures was examined in patients with left brain damage (LBD), right brain damage (RBD) and controls. In addition to imitation on the own body, patients were asked to replicate the gestures on a life-sized mannikin. Manual dexterity was assessed by manipulation of beads, and general visuospatial abilities by block-design. LBD patients who displayed apraxia when imitating gestures on their own bodies scored dramatically worse than any other group when imitation was assessed on the mannikin. By contrast, on block-design and manipulation of beads patients with RBD were inferior not only to LBD patients without apraxia but also to apractic patients. Analysis of CT scans revealed that apraxia occurred with frontal, parietal and deep lesions, and that the impairment on the manipulation of the mannikin was present regardless of lesion site. The results support the contention that the basic deficit underlying impaired imitation of meaningless gestures in apraxia is to be sought at a conceptual level. Possibly, patients with apraxia are not able to evoke and represent conceptual knowledge about the human body which is necessary for performing the apparently simple task of imitating gestures.

Cognitive Neuropsychology, 2007

An important issue in contemporary cognitive neuroscience concerns the role of motor production processes in perceptual and conceptual analysis. To address this issue, we studied the performance of a large group of unilateral stroke patients across a range of tasks using the same set of common manipulable objects. All patients (n ¼ 37) were tested for their ability to demonstrate the use of the objects, recognize the objects, recognize the corresponding object-associated pantomimes, and imitate those same pantomimes. At the group level we observed reliable correlations between object use and pantomime recognition, object use and object recognition, and pantomime imitation and pantomime recognition. At the single-case level, we document that the ability to recognize actions and objects dissociates from the ability to use those same objects. These data are problematic for the hypothesis that motor processes are constitutively involved in the recognition of actions and objects and frame new questions about the inferences that are merited by recent findings in cognitive neuroscience.