Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke

Previous studies on left hemisphere (LH) stroke patients reported effector-specific (hand, fingers, bucco-facial) differences in imitation performance. Furthermore, imitation performance differed between meaningless (ML) and meaningful (MF) gestures. Recent work suggests that a gesture’s meaning impacts the body-part specificity of gesture imitation.

We tested the hypothesis that the gesture’s meaning (ML vs MF) affects the lesion correlates of effector-specific imitation deficits (here: bucco-facial vs arm/hand gestures) using behavioural data and support vector regression-based lesion-symptom mapping (SVR-LSM) in a large sample of 194 sub-acute LH stroke patients.

Behavioural data revealed a significant interaction between the effector used for imitation and the meaning of the imitated gesture. SVR-LSM analyses revealed shared lesion correlates for impaired imitation independent of effector or gesture meaning in the left supramarginal (SMG) and superior temporal gyri (STG). Besides, within the territory of the left middle cerebral artery, impaired imitation of bucco-facial gestures was associated with more anterior lesions, while arm/hand imitation deficits were associated with more posterior lesions (Fig. 1). MF gestures were specifically associated with lesions in the left inferior frontal gyrus and the left insular region.

Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke
Fig. 1. Results of the SVR-LSM analyses for bucco-facial and arm/hand gesture imitation. A. Lesion correlates of bucco-facial gesture imitation deficits (red) and arm/hand gesture imitation deficits (green) and their overlap (yellow). B. Lesion correlates specific to bucco-facial gesture imitation deficits. C. Lesion correlates specific to arm/hand gesture imitation deficits. For B./C.: Colours indicate the p-values of the corresponding voxels. For A.-C.: Voxels shown are thresholded at p < 0.05 based on 10,000 permutations; the cluster size threshold is 100 voxels.

Notably, an interaction of effector-specificity and gesture meaning was also present at the lesion level: A more pronounced difference in imitation performance between the effectors for ML (versus MF) gestures was associated with left-hemispheric lesions in the STG, SMG, putamen, precentral gyrus and white matter tracts (Fig. 2).

Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke
Fig. 2. Differential modulation of effector-specific lesion correlates by gesture meaning. Results of the SVR-LSM analysis for the interaction effect of gesture meaning on the effector used for imitation. The depicted lesion correlates were associated with the interaction term (ML bucco-facial gestures − ML arm/hand gestures) − (MF bucco-facial gestures − MF arm/hand gestures). Colours indicate the p-values of the corresponding voxels. Voxels shown are thresholded at p < 0.05 based on 10,000 permutations; the cluster size threshold is 100 voxels.

The current behavioural data show that ML gestures are particularly sensitive in assessing effector-specific imitation deficits in LH stroke patients. Moreover, a gesture’s meaning modulated the effector-specific lesion correlates of bucco-facial and arm/hand gesture imitation. Hence, it is crucial to consider gesture meaning in apraxia assessments.

Publication:

Kleineberg, N. N., Schmidt, C. C., Richter, M. K., Bolte, K., Schloss, N., Fink, G. R., & Weiss, P. H. (2023). Gesture meaning modulates the neural correlates of effector-specific imitation deficits in left hemisphere stroke. NeuroImage: Clinical, 37, 103331. doi: 10.1016/j.nicl.2023.103331

Letzte Änderung: 14.02.2023