Model-oriented naming therapy in semantic dementia: A single-case fMRI study

Abstract

Background: Studies on anomia treatment in semantic dementia demonstrate that re-learning is possible, but maintenance and generalisation of improvements are limited. Changes in cortical activation associated with anomia treatment have already been demonstrated in aphasic patients after stroke. Recovery of brain functions under the impact of deficit-specific treatment in semantic dementia has not been explored yet. Nevertheless, recent activation studies using language tasks in patients with neurodegenerative diseases report altered activation patterns, involving diverse brain regions ipsi- or contralateral to the primarily affected left hemisphere.

Aims: The purpose of the present study was to investigate if phonological and semantic cueing hierarchies established for naming therapy in aphasia were also effective in a patient with semantic dementia. Moreover, we aimed to examine changes of brain activity associated with anomia treatment.

Methods & Procedures: One individual with semantic dementia participated in the present study. Over a period of 4 weeks the participant received an intensive model-oriented treatment with phonological and semantic cueing hierarchies. Two pre-tests and two post-tests (one immediately after training and one 2 months later) were administered. The second pre-test and both follow-ups were registered inside the scanner.

Outcomes & Results: Behaviourally, both treatments resulted in specific training effects, which subsequently decreased over time. Concerning functional magnetic resonance imaging data, improved naming following therapy was mirrored by changes in cortical activity, predominantly located in right superior and inferior temporal gyrus.

Conclusions: Cueing hierarchies were successful, resulting in specific and immediate treatment effects, corroborating previous treatment studies in semantic dementia. Treatment-induced changes in cortical activity were mainly concentrated in right temporal cortex. Since right-sided modulation of cortical activity was associated with training-induced improvements in task performance, it may reflect right hemispheric compensatory mechanisms in this participant.

Keywords:

• Semantic dementia
• Primary progressive aphasia
• Anomia
• Dell's model
• Therapy
• fMRI

Acknowledgments

This work was supported by the Federal Ministry of Education and Research grant (BMBF: 01GW0662) entitled “Mechanisms of brain reorganisation in the language network”.

Notes

¹The following tests were included: BNT: Boston Naming Test (Kaplan, Goodglass, & Weintraub, 1983); BORB: Birmingham Object Recognition Battery (Riddoch & Humphreys, 1993); CERAD-Battery: Consortium to Establish a Registry for Alzheimer's Disease (Morris et al., 1993); MMSE: Mini-Mental State Examination (Folstein, Folstein, & McHugh, 1975); VLMT: German, Verbaler Lern- und Merkfähigkeitstest = Verbal Learning and Retention Test, (Helmstädter & Durwen, 1990).