Neural correlates of transitive and intransitive action imitation: an investigation using voxel-based morphometry

Abstract

The ability to reproduce visually presented actions has been studied through neuropsychological observations of patients with ideomotor apraxia. These studies include attempts to understand the neural basis of action reproduction based on lesion-symptom mapping in different patient groups. While there is a convergence of evidence that areas in the parietal and frontal lobes within the left hemisphere are involved in the imitation of a variety of actions, questions remain about whether the results generalize beyond the imitation of tool use and whether the presence of a strong grasp component of the action is critical. Here we used voxel-based lesion-symptom mapping to assess the neural substrates of imitating meaningful (familiar, MF) and meaningless (unfamiliar, ML) tool-related (transitive) and non-tool related (intransitive) actions. The analysis showed that the left parietal cortex was involved in the imitation of transitive gestures, regardless of whether they were meaningful or not. In addition there was poor reproduction of meaningless actions (both transitive and intransitive) following damage of the right frontal cortex. These findings suggest a role of right frontal regions in processing of unfamiliar actions.

Keywords: Action imitation; Ideomotor apraxia; Intransitive gestures; Transitive gestures; Voxel-based morphometry.

Fig. 1

This figure shows the accuracy in imitation for patients and controls. The data for transitive and intransitive MF and ML actions are based on proportions as the total maximum scores varied across stimuli. Abbreviations: P-TR-MF, patients' mean proportional accuracy with MF transitive actions; P-TR-ML, patients' mean proportional accuracy with ML transitive actions; P-INT-MF, patients' mean proportional accuracy with MF intransitive actions; P-INT-ML, patients' mean proportional accuracy with ML intransitive actions; C-TR-MF, controls' mean proportional accuracy with MF transitive actions; C-TR-ML, controls' mean proportional accuracy with ML transitive actions; C-INT-MF, controls' mean proportional accuracy with MF intransitive actions; C-INT-ML, patients' mean proportional accuracy with ML intransitive actions.

Fig. 2

Grey matter substrates of the imitation of transitive and intransitive MF and ML gestures (results based on the model with all covariates).Abbreviations: l_PCUN, left precuneus; l_CUN, left cuneus; l_SMA, left supplementary motor area; MF TR, meaningful transitive actions; ML TR, meaningless transitive actions; MF INT, meaningful intransitive actions; ML INT, meaningless transitive actions.

Fig. 3

Grey matter substrates of the imitation of transitive and intransitive MF and ML gestures (results from models with single covariate of interest).Abbreviations: l_PCUN, left precuneus; l_MidOCC, left middle occipital cortex; r_SFC, right superior frontal cortex; r_Mid_CC, right middle cingulum; l_PCC, left posterior cingulum; l_SMA, left supplementary motor area; r_SMA, right supplementary motor area; l_SPC, left superior parietal cortex. Blobs colours: green = transitive ML; red = transitive MF; blue = intransitive ML.

Fig. 4

White matter substrates for transitive ML. Results indicate that deficits in transitive ML gestures were linked to damage within the left corticospinal tract, left corpus callosum and white matter within the left superior temporal gyrus.