Abstract
Hand gestures are an integral part of social interactions and communication. Several imaging studies in healthy subjects and lesion studies in patients with apraxia suggest the praxis network for gesture production, involving mainly left inferior frontal, posterior parietal and temporal regions. However, little is known about the structural connectivity underlying gesture production. We recruited 41 healthy participants and 39 patients with schizophrenia. All participants performed a gesture production test, the Test of Upper Limb Apraxia, and underwent diffusion tensor imaging. We hypothesized that gesture production is associated with structural network connectivity as well as with tract integrity. We defined the praxis network as an undirected graph comprised of 13 bilateral regions of interest and derived measures of local and global structural connectivity and tract integrity from Finsler geometry. We found an association of gesture deficit with reduced global and local efficiency of the praxis network. Furthermore, reduced tract integrity, for example in the superior longitudinal fascicle, arcuate fascicle or corpus callosum were related to gesture deficits. Our findings contribute to the understanding of structural correlates of gesture production as they first present diffusion tensor imaging data in a combined sample of healthy subjects and a patient cohort with gestural deficits.
Highlights
Gestures play an important role in language and communication
The connectivity between the left and right inferior frontal gyrus (IFG), the bilateral uncinate fascicle (UF) and left arcuate fascicle (AF) differed between groups (p < .05, false discovery rate (FDR) corrected), indicating that patients displayed lower connectivity values than controls
We aimed to investigate whether structural network organization and structural integrity of connections predict gesture production in healthy subjects and schizophrenia patients
Summary
Gestures play an important role in language and communication They support language production and comprehension, and are critically involved in nonverbal communication as they transmit information independent from language (GoldinMeadow & Alibali, 2013). While the ventro-dorsal stream, termed the use system, is responsible for the long-term storage of skilled tool use actions (Binkofski & Buxbaum, 2013). Tool use involves several temporal and parietal regions including the middle temporal gyrus (MTG), which stores semantic and conceptual information of tools, the posterior supramarginal gyrus (SMG) and angular gyrus (AG), which store representations of invariant features of meaningful gestures, and the anterior SMG, which is important for the planning of gestures and generation of a motor plan (Ramayya et al, 2010). The ventral premotor cortex and the inferior frontal gyrus (IFG), which store motor programs for grasping and manipulation of objects are involved (Ramayya et al, 2010)
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