An intention manipulation to change lateralization of word production in nonfluent aphasia: current status

Abstract

A review of recent aphasia literature indicates that both the left and right hemispheres participate, under various circumstances, in recovery of language and in treatment response. In chronic aphasias with large lesions and poor recovery of function, the right hemisphere is more likely to demonstrate prominent activity than in cases with small lesions and good recoveries. Extraneous activity during language tasks for aphasia patients may occur in both the left and right hemispheres. Right hemisphere activity during language in aphasia patients is likely to occur in structures homologous to damaged left hemisphere structures. When the left hemisphere is so damaged as to preclude a good recovery, recruitment of right-hemisphere mechanisms in the service of rehabilitation may be desirable. Hence a treatment with an intention manipulation (complex left-hand movement) was developed for nonfluent aphasia to assist in relateralization of language production. A review of existing evidence indicates that the intention manipulation adds value to naming treatments and helps shift lateralization of language production to right frontal structures. However, wholesale transfer of language function to the right hemisphere does not occur, and residual language knowledge in the left hemisphere also seems vital for relearning of word production. Further research is needed to understand fully the contribution of the intention manipulation to treatment response.

Figures

Figure 1

For each treatment phase, change in percent correct responses to probe items from baseline is shown. A significant treatment by phase interaction indicates that patients relearned words more quickly in the intention treatment (red) than the attention treatment (blue). From Crosson, Fabrizio, et al. (2007), Journal of the International Neuropsychological Society, reprinted by permission.

Figure 2

Significant activity for the first patient described in the text is overlaid onto whole brain images divided into three slabs to facilitate viewing of activity. Pre-treatment images are on the left side of the figure; post-treatment images are on the right side of the figure. Since the brains are facing the viewer, the right side of the brain is on the left side of the image. The yellow arrows point to the areas in which activity increased from pre- to post-treatment scans.