Knowledge about gestural behavior is theoretically relevant for understanding cognitive, emotional, and interactive processes, but it also has far-reaching practical implications for diagnostics and therapy in the clinical context, for learning processes, and for obtaining communicative competencies. Thus, research on gestural behavior is conducted in several academic disciplines, including neuroscience, medicine, psychology, linguistics, anthropology, and social sciences. Especially because of the shift in recent decades toward transferring information through visual media, a thorough knowledge of how gesture reflects and affects the gesturer's thinking and feeling, as well as of how it influences the recipient's cognitive and emotional processes, is becoming increasingly important.Despite many examinations carried through in various disciplines, the state of knowledge about the neuropsychology of gestural behavior has not developed far beyond the popular level (i.e., "body language"). This situation is partly due to methodological deficiencies in the analysis of gestural behavior. In many studies, gesture units and gesture types are not clearly defined, and interrater agreement is rarely examined. Furthermore, the assumptions behind the diverse gesture classifications applied in the studies are not made transparent, and sometimes there is an implicit claim that the particular coding system suits all research questions. In addition, different forms of presenting data (e.g., in terms of total numbers [n] of gesturesn/min, n/5 min, n/100 words, n/time speaking, n/time of interview, or logarithms-or of handedness-right vs. left hands only; right, left, or both hands; no differentiation of hand laterality; or handedness indices) are an obstacle for comparing the results of different studies and for gradually building up a corpus of knowledge on gestural behavior. By way of example, the apparent contradictions between study results on the relationship between aphasia (loss of the ability to produce and/or comprehend language) and gesture production/comprehension-that is, between an equally distributed deficit and a compensatory use of gestures (see, e.g., Lott, 1999)-are mainly due to a lack of scrutiny during development of the study methods.A similar situation exists in the area of media annotation, even when only the digital era is considered. A variety of tools are available to the public, each designed for a certain group of users with a specific task or a particular platform (operating system) in mind. The data produced by these tools are stored in various ways and in different formats. This is another obstacle to interoperability and comparison, in addition to those mentioned above.The XML (Extensible Markup Language) data produced by the majority of contemporary tools are a significant improvement on the old-time proprietary formats. XML data are relatively easy to transform, but nevertheless the conversion is rarely lossless. In an attempt to improve interoperability between tools from multiple modalities, ...
Investigations of left hand praxis in imitation and object use in patients with callosal disconnection have yielded divergent results, inducing a debate between two theoretical positions. Whereas Liepmann suggested that the left hemisphere is motor dominant, others maintain that both hemispheres have equal motor competences and propose that left hand apraxia in patients with callosal disconnection is secondary to left hemispheric specialization for language or other task modalities. The present study aims to gain further insight into the motor competence of the right hemisphere by investigating pantomime of object use in split-brain patients. Three patients with complete callosotomy and, as control groups, five patients with partial callosotomy and nine healthy subjects were examined for their ability to pantomime object use to visual object presentation and demonstrate object manipulation. In each condition, 11 objects were presented to the subjects who pantomimed or demonstrated the object use with either hand. In addition, six object pairs were presented to test bimanual coordination. Two independent raters evaluated the videotaped movement demonstrations. While object use demonstrations were perfect in all three groups, the split-brain patients displayed apraxic errors only with their left hands in the pantomime condition. The movement analysis of concept and execution errors included the examination of ipsilateral versus contralateral motor control. As the right hand/left hemisphere performances demonstrated retrieval of the correct movement concepts, concept errors by the left hand were taken as evidence for right hemisphere control. Several types of execution errors reflected a lack of distal motor control indicating the use of ipsilateral pathways. While one split-brain patient controlled his left hand predominantly by ipsilateral pathways in the pantomime condition, the error profile in the other two split-brain patients suggested that the right hemisphere controlled their left hands. In the object use condition, in all three split-brain patients fine-graded distal movements in the left hand indicated right hemispheric control. Our data show left hand apraxia in split-brain patients is not limited to verbal commands, but also occurs in pantomime to visual presentation of objects. As the demonstration with object in hand was unimpaired in either hand, both hemispheres must contain movement concepts for object use. However, the disconnected right hemisphere is impaired in retrieving the movement concept in response to visual object presentation, presumably because of a deficit in associating perceptual object representation with the movement concepts.
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