Selective impairment of verb processing associated with pathological changes in Brodmann areas 44 and 45 in the motor neurone disease–dementia–aphasia syndrome

Abstract

We report six patients with clinically diagnosed and electrophysiologically confirmed motor neurone disease (MND), in whom communication problems were an early and dominant feature. All patients developed a progressive non-fluent aphasia culminating in some cases in complete mutism. In five cases, formal testing revealed deficits in syntactic comprehension. Comprehension and production of verbs were consistently more affected those that of nouns and this effect remained stable upon subsequent testing, despite overall deterioration. The classical signs of MND, including wasting, fasciculations and severe bulbar symptoms, occurred over the following 6-12 months. The behavioural symptoms ranged from mild anosognosia to personality change implicating frontal-lobe dementia. In three cases, post-mortem examination has confirmed the clinical diagnosis of MND-dementia. In addition to the typical involvement of motor and premotor cortex, particularly pronounced pathological changes were observed in the Brodmann areas 44 (Broca's area) and 45. The finding of a selective impairment of verb/action processing in association with the dementia/aphasia syndrome of MND suggests that the neural substrate underlying verb representation is strongly connected to anterior cortical motor systems.

Word-category specific deficits after lesions in the right hemisphere

“…We found a similar pattern for lesions in the right non-dominant hemisphere. Furthermore, Bak et al [2], Bak and Hodges [3] recently reported that bilateral lesions of frontal areas, as present in motor neuron disease, can also have specific effects on the processing of action verbs. In addition, Cappa et al [10] found most pronounced deficits in fronto-temporal dementia.…”

Mirror neurons and the social nature of language: The neural exploitation hypothesis

“…4 It should be added that several neuropsychological studies testify that frontal lesions, including those of the premotor cortex, produce deficits in the comprehension of action verbs (Bak & Hodges, 2003;Bak, O'Donovan, Xuereb, Boniface, & Hodges, 2001;Bak et al, 2006;Kemmerer & Tranel, 2000. We certainly need more research.…”

Grammatical processing of nouns and verbs in left frontal cortex?

“…1 The third set of stimuli included 48 one-syllable pseudo-words, formally plausible but meaningless syllables like wug, torge and flonk. We used four different kinds of sentence frame, all along the lines of those given above, such that R.C.…”

“…'s specific problems with verb production may stem from damage to part of the left midfrontal gyrus supe-rior to Broca's area, corresponding to Brodmann area 9. Lesions in this region have been linked to verb retrieval deficits in patients with stroke and neurodegenerative diseases [1,8,13], and neuroimaging studies have shown that left prefrontal/premotor cortex is recruited (along with other parts of the brain) more heavily during verb naming than noun naming [36,38]. However, the significance of this association has been controversial.…”