The relation of object naming and other visual speech production tasks:A large scale voxel-based morphometric study

• The shared and unique neural substrates of object naming were examined in 280 stroke patients.
• Clinical CT scans and performance on clinical language tests were analysed using voxel-based morphometry.
• Principal component analysis on the test scores identified a shared language component and a unique naming component.
• The general language component recruits a widespread left-lateralised fronto-temporal network.
• The unique object naming component is linked to the bi-anterior temporal poles and cerebellar areas.

We report a lesion–symptom mapping analysis of visual speech production deficits in a large group (280) of stroke patients at the sub-acute stage (<120 days post-stroke). Performance on object naming was evaluated alongside three other tests of visual speech production, namely sentence production to a picture, sentence reading and nonword reading. A principal component analysis was performed on all these tests' scores and revealed a ‘shared’ component that loaded across all the visual speech production tasks and a ‘unique’ component that isolated object naming from the other three tasks. Regions for the shared component were observed in the left fronto-temporal cortices, fusiform gyrus and bilateral visual cortices. Lesions in these regions linked to both poor object naming and impairment in general visual–speech production. On the other hand, the unique naming component was potentially associated with the bilateral anterior temporal poles, hippocampus and cerebellar areas. This is in line with the models proposing that object naming relies on a left-lateralised language dominant system that interacts with a bilateral anterior temporal network. Neuropsychological deficits in object naming can reflect both the increased demands specific to the task and the more general difficulties in language processing.