Word-category specific deficits after lesions in the right hemisphere

Abstract

A speeded lexical decision task was used to investigate word-category deficits in patients suffering from lesions in the right hemisphere and in neurological controls without cortical lesion. In all patients from one group (n = 12), the right frontal lobe was affected causing a left-sided hemiparesis. In the second group (n = 6), lesions primarily affected areas in the right inferior temporo-occipital lobes. Patients with motor deficits due to lesions in the spinal cord or in the periphery served as neurological controls (n = 9). Processing of three categories of words was investigated: verbs referring to actions (action verbs (acVs)); nouns with strong visual associations (visually-related nouns (viNs)); and nouns with both strong action and visual associations (bimodal nouns (biNs)). Stimulus categories were matched for word length and normalized lexical frequency. Error scores revealed a significant word category by patient group interaction. Patients with lesions in the right frontal lobe showed most severe deficits in processing action verbs, whereas those with lesions in their right temporo-occipital areas showed most severe deficits in processing visually-related nouns. Neurological controls did not show any differences between word categories. The double dissociation of the processing impairments seen in frontal versus temporo-occipital patients demonstrates that specific word-category deficits can arise from lesions in the right non-dominant hemisphere. An account for these results in terms of distributed neuronal systems representing words is offered.

Meaning and the brain: The neurosemantics of referential, interactive, and combinatorial knowledge

“…Some neuropsychological work reporting category-specific semantic deficits have already been mentioned in previous sections (e.g., Gainotti, 2004;Warrington & McCarthy, 1987). Data from stroke patients with lesions in inferior frontal or temporal lobes indicate a double dissociation between processing action verbs and object-related nouns (A. R. Damasio & Tranel, 1993;Daniele et al, 1994;Fazio et al, 2009;Gainotti, 2004;Miceli, Mazzucchi, Menn, & Goodglass, 1983;Neininger & Pulvermüller, 2003). Action verbs processing is also impaired specifically in patients with degenerative brain diseases affecting the motor system or its direct vicinity, including motor neuron disease (Bak, O'Donovan, Xuereb, Boniface, & Hodges, 2001), Parkinson's disease (Boulenger et al, 2008;Cotelli et al, 2007) and the frontal variant of frontotemporal dementia (Cotelli et al, 2006).…”

Distributed cell assemblies for general lexical and category‐specific semantic processing as revealed by fMRI cluster analysis

“…Especially the double dissociation in the processing of animal and tool knowledge [e.g., Buxbaum and Saffran, 2002] and in processing object-nouns and action verbs [e.g., Neininger and Pulvermü ller, 2003] provide strong evidence that the cortical systems necessary for processing visually based conceptual-perceptual knowledge and action knowledge differ. In addition, recent studies showed that motor cortex degeneration in motor neuron disease leads to a specific impairment of action words and concepts [Bak et al, 2001[Bak et al, , 2006, frontopartietal lesion associated with apraxia degrades object utilization knowledge more strongly than other conceptual aspects of object understanding [Buxbaum and Saffran, 2002], focal lesion in the motor cortex selectively impairs action word processing [e.g., Neininger and Pulvermü ller, 2003], and Parkinson's disease is also accompanied by a specific deficit in processing action verbs [Boulenger et al, 2008]. Although these studies are consistent with the notion of distributed semantic circuits with distinct topographies [for discussion, see Neininger and Pulvermü ller, 2003], they address relatively large semantic and conceptual domains (animal/tool, object/ action, noun/verb), whereas this study focused on more fine-grained distinctions (e.g., action subtypes).…”

“…In addition, recent studies showed that motor cortex degeneration in motor neuron disease leads to a specific impairment of action words and concepts [Bak et al, 2001[Bak et al, , 2006, frontopartietal lesion associated with apraxia degrades object utilization knowledge more strongly than other conceptual aspects of object understanding [Buxbaum and Saffran, 2002], focal lesion in the motor cortex selectively impairs action word processing [e.g., Neininger and Pulvermü ller, 2003], and Parkinson's disease is also accompanied by a specific deficit in processing action verbs [Boulenger et al, 2008]. Although these studies are consistent with the notion of distributed semantic circuits with distinct topographies [for discussion, see Neininger and Pulvermü ller, 2003], they address relatively large semantic and conceptual domains (animal/tool, object/ action, noun/verb), whereas this study focused on more fine-grained distinctions (e.g., action subtypes). However, neuropsychological work also showed that the areas found active for the more fine-grained semantic subcategories play a critical role in their processing.…”

All Talk and No Action: A Transcranial Magnetic Stimulation Study of Motor Cortex Activation during Action Word Production

“…Motor schemata would thus constitute an integral part of semantic knowledge of the word. This hypothesis might lead us to predict that the effects induced by TMS during action word production should be lateralized to the left hemisphere (but see Neininger & Pulvermüller, 2003, for evidence that right hemisphere damage may lead to difficulties in action word production).…”