Apraxia, pantomime and the parietal cortex

Abstract

Apraxia, a disorder of higher motor cognition, is a frequent and outcome-relevant sequel of left hemispheric stroke. Deficient pantomiming of object use constitutes a key symptom of apraxia and is assessed when testing for apraxia. To date the neural basis of pantomime remains controversial. We here review the literature and perform a meta-analysis of the relevant structural and functional imaging (fMRI/PET) studies.Based on a systematic literature search, 10 structural and 12 functional imaging studies were selected.Structural lesion studies associated pantomiming deficits with left frontal, parietal and temporal lesions. In contrast, functional imaging studies associate pantomimes with left parietal activations, with or without concurrent frontal or temporal activations. Functional imaging studies that selectively activated parietal cortex adopted the most stringent controls.In contrast to previous suggestions, current analyses show that both lesion and functional studies support the notion of a left-hemispheric fronto-(temporal)-parietal network underlying pantomiming object use. Furthermore, our review demonstrates that the left parietal cortex plays a key role in pantomime-related processes. More specifically, stringently controlled fMRI-studies suggest that in addition to storing motor schemas, left parietal cortex is also involved in activating these motor schemas in the context of pantomiming object use. In addition to inherent differences between structural and functional imaging studies and consistent with the dedifferentiation hypothesis, the age difference between young healthy subjects (typically included in functional imaging studies) and elderly neurological patients (typically included in structural lesion studies) may well contribute to the finding of a more distributed representation of pantomiming within the motor-dominant left hemisphere in the elderly.

Specialization of the left supramarginal gyrus for hand-independent praxis representation is not related to hand dominance

“…Consistent with more recent neuropsychological findings pointing to a wider network of areas that are critical for praxis skills (e.g., Goldenberg, 2003b; including the middle frontal gyrus, MFg, e.g., Haaland, Harrington, & Knight, 2000, and left inferior frontal gyrus, with adjacent insular and ventral premotor cortices, Goldenberg, Hermsdorfer, Glindemann, Rorden, & Karnath, 2007), neuroimaging studies also report increased hand-independent activity in various regions that lie beyond the left posterior parietal cortex (for a recent neuroimaging meta-analysis see Niessen, Fink, & Weiss, 2014). These areas include the left MFg, supplementary motor (SMA) area, premotor, and/or the prefrontal cortices (Choi et al, 2001; Hermsdorfer, Terlinden, Muhlau, Goldenberg, & Wohlschlager, 2007; Johnson-Frey et al, 2005; Kroliczak & Frey, 2009; Moll et al, 2000; Ohgami et al, 2004; Rumiati et al, 2004).…”

Functional connectivity associated with hand shape generation: Imitating novel hand postures and pantomiming tool grips challenge different nodes of a shared neural network

“…In addition, the connectivity schema would predict that left frontal damage is also likely to impair tool pantomiming, a repeated observation that has been hotly debated in the past Haaland et al, 2000]. The finding that given their strategic relations, inferior parietal and frontal areas may disrupt tool pantomiming is in agreement with the conclusions of a recent meta-analysis of structural and functional neuroimaging studies on pantomime [Niessen et al, 2014].…”

Using subjective expectations to model the neural underpinnings of proactive inhibition

“…Kühn and colleagues suggest that this region plays a role in inhibitory processes when voluntary suppression of a response requires more selection effort or attention. Other research has linked the right inferior parietal cortex (rIPC) to the storage of acquired motor skills (Niessen, Fink, & Weiss, 2014), as lesions to this region disrupt the ability to perform previously learned actions (Halsband, Schmitt, Weyers, & Binkofski, 2001), and has demonstrated its involvement in response selection processes (Dippel & Beste, 2015). Together with our findings, this suggests that the rIPC could be involved in the decision for an alternative motor response when the probability or expectation of having to change the response, e.g., on encountering a stop-signal, is high.…”