Word selection processing in Parkinson's disease: When nouns are more difficult than verbs

Selection Processing in Noun and Verb Production in Left- and Right-Sided Parkinson's Disease Patients

“…In the present study we aimed to replicate previous results (Silveri et al, 2018 ) in a new cohort of well-selected PD patients with a clear symptom side predominance (left or right), at a mild to moderate stage of the disease, positive DAT scan and with no decline in cognitive functioning. Indeed, our results confirm that noun and verb production may be differentially impaired when evaluated by a morphological paradigm that allows for keeping under control the number of alternatives among which operate word selection.…”

“…Specifically, in the previous study (Silveri et al, 2018 ) PD patients were impaired not only when they had to select the target from many competitors, but also in the presence of competitors more frequent than the target. An efficient control of the lexical retrieval should inhibit their production, but inhibitory processes are impaired in PD (Castner et al, 2008 ) and competitors more frequent than the target were produced in the place of the target.…”

“…However, in an experimental condition in which it is the noun that must be selected from a larger number of alternatives compared to verb, noun production becomes slower and more prone to errors, thus more difficult. Indeed, in Silveri et al's study ( 2018 ) PD patients were slower and less accurate than healthy controls (HC) when required to produce nouns from verbs in a morphology derivation tasks (e.g., “osservazione” from “osservare”) [“observation” from “to observe”] than verbs from nouns in a morphology generation task, in which the verb must be generated from the noun (e.g., “fallire” from “fallimento”) [“to fail” from “failure”]. In the Italian language morphology, in fact, generation and derivation tasks differ in the number of lexical entries among which the response must be selected (see also Marangolo et al, 2006 ).…”

“…The disproportionate impairment in the production of verbs compared to nouns, frequently documented in patients with Parkinson's disease (PD) (Silveri et al, 2018 ), can be considered an expression of the dysexecutive syndrome, the typical manifestation of PD patient's cognitive decline (Dubois and Pillon, 1996 ; Roussel et al, 2017 ). Deficit for verbs in a pathology typically dominated by disorders of movement has been also attributed to the decay of conceptual representation of the motor components of the action (Boulenger et al, 2008 ; Rodríguez-Ferreiro et al, 2009 ; Cardona et al, 2014 ), according to an embodied view of cognition (Barsalou, 1999 ).…”

Evidence of semantic processing impairments in behavioural variant frontotemporal dementia and Parkinson's disease

“…Indeed, poor verb processing in Parkinson’s disease has been linked to basal ganglia dysfunction and the role of the basal ganglia in inhibition and semantic selection processes during verb processing [25]. Moreover, when semantic selection demands are increased, patients with Parkinson’s disease significantly delayed word generation, regardless of part of speech [68 ▪▪ ]. …”