Dissociating neural correlates for nouns and verbs

Abstract

Dissociations in the ability to produce words of different grammatical categories are well established in neuropsychology but have not been corroborated fully with evidence from brain imaging. Here we report on a PET study designed to reveal the anatomical correlates of grammatical processes involving nouns and verbs. German-speaking subjects were asked to produce either plural and singular nouns, or first-person plural and singular verbs. Verbs, relative to nouns, activated a left frontal cortical network, while the opposite contrast (nouns-verbs) showed greater activation in temporal regions bilaterally. Similar patterns emerged when subjects performed the task with pseudowords used as nouns or as verbs. These results converge with findings from lesion studies and suggest that grammatical category is an important dimension of organization for knowledge of language in the brain. D

A place for nouns and a place for verbs? A critical review of neurocognitive data on grammatical-class effects

“…Noun-related activation in the frontal areas was generally obtained with tool nouns (e.g., Martin et al, 1996;Tyler et al, 2003), but this category-specificity was not confirmed in other similar studies; for example, Tyler et al (2003) and Sahin et al (2006) found frontal activation associated with nouns that did not refer to manipulable objects. Furthermore, the FTDH obviously predicts the emergence of frontal activation associated with verbs and temporal activation associated with nouns in direct comparison analyses; however, of the 15 imaging studies reporting verb-noun direct contrasts, only 5 found verb-related activation in frontal areas (Perani et al, 1999;Shapiro et al, 2005;Shapiro et al, 2006;Tyler et al, 2003;Tyler et al, 2004) and only 2 showed noun-related activation in temporal areas (Shapiro et al, 2005;Shapiro et al, 2006). A word of caution should be spent here on the fact that, in this line of reasoning, positive and negative evidence for the FTDH are given the same weight, whereas the common process of statistical inference adopted in neuroimaging studies (and in the whole field of psychology, in fact) is somewhat biased towards positive findings, while negative results may remain not fully assessed.…”

“…In a PET study, Shapiro, Mottaghy, Schiller et al (2005) asked German-speaking subjects to inflect nouns or verbs according to a symbolic cue presented immediately before each trial (* prompted the participants to produce the singular form in noun trials and the first-person-singular form in verb trials, while *** required the subjects to produce the plural form in noun trials and the first-person-plural form in verb trials). Pseudo-word passive viewing and reading constituted the control conditions.…”

Context-dependent interpretation of words: Evidence for interactive neural processes

“…Highly ambiguous words and sentence structures have been shown to elicit a stronger response in LIFG than less ambiguous words and structures, due to competition between alternatives, which requires the inhibition of inappropriate interpretations (Masson et al, 2003;Rodd et al, 2005;Chan et al, 2004). Moreover, the process of settling on an action meaning (e.g., sharpen) also elicits a stronger neural response in LIFG than settling on a noun meaning (e.g., knife; Perani et al, 1999a;Damasio and Tranel, 1993;Shapiro et al, 2005). Verbs involve more complex selection or retrieval processes than nouns because verbs carry additional morphological, syntactic and semantic information (concerning, e.g., the kinds of nouns that occur with them; Tyler et al, 2004;Thompson-Schill et al, 2005).…”

Action verbal fluency in Parkinson’s patients

“…Other studies 12,13 suggest that the processing of verbs is supported by the frontal lobes, requiring a complex network of syntactical and grammatical information coordinated by an executive system. These hypotheses are supported by studies conducted in healthy subjects who showed a selective activation of the left inferior frontal gyrus, during verb production 14 and an activation of the low frontal cortex in tasks requiring syntactical and morphological processing 15 . Cappelletti et al 16 reinforced the idea that the medial anterior portion of the left frontal cortex is critical for verb processing.…”