Cortical Correlates of Gesture Processing: Clues to the Cerebral Mechanisms Underlying Apraxia during the Imitation of Meaningless Gestures

• Published in: NeuroImage (Orlando, Fla.) Vol. 14; no. 1; pp. 149 - 161
• Main Authors: Hermsdörfer, J., Goldenberg, G., Wachsmuth, C., Conrad, B., Ceballos-Baumann, A.O., Bartenstein, P., Schwaiger, M., Boecker, H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-07-2001; Elsevier Limited
• Subjects: Adult; Apraxia; Apraxias - diagnostic imaging; Apraxias - physiopathology; Attention; Brain injury; Cerebral Cortex - diagnostic imaging; Cerebral Cortex - physiopathology; Cognitive ability; Cortex (parietal); Dominance, Cerebral - physiology; Finger; Gestures; Hand; Hemispheric laterality; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Imitative Behavior - physiology; Intraparietal sulcus; Male; meaningless gestures; Middle Aged; neuronal activity; Parietal Lobe - diagnostic imaging; Parietal Lobe - physiopathology; PET; Positron emission tomography; Reference Values; Regional Blood Flow - physiology; Tomography, Emission-Computed; Visual cortex; Visual Cortex - diagnostic imaging; Visual Cortex - physiopathology; Visual discrimination; Visual perception; meaningless gestures; apraxia; neuronal activity; PET
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1006/nimg.2001.0796

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 H152O-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.