The role of Broca's area in regular past-tense morphology: An event-related potential study

Abstract

It has been suggested that damage to anterior regions of the left hemisphere results in a dissociation in the perception and lexical activation of past-tense forms. Specifically, in a lexicaldecision task in which past-tense primes immediately precede present-tense targets, such patients demonstrate significant priming for irregular verbs (spoke-speak), but, unlike control participants, fail to do so for regular verbs (looked-look). Here, this behavioral dissociation was first confirmed in a group of eleven patients with damage to the pars opercularis (BA 44) and pars triangularis (BA 45) of the left inferior frontal gyrus (i.e., Broca's area). Two conditions containing wordonset orthographic-phonological overlap (bead-bee, barge-bar) demonstrated that the disrupted regular-verb priming was accompanied by, and covaried with, disrupted ortho-phonological priming, regardless of whether prime stimuli contained the regular inflectional rhyme pattern. Further, the dissociation between impaired regular-verb and preserved irregular-verb priming was shown to be continuous rather than categorical; priming for weak-irregular verbs (spent-spend) was intermediate in size between that of regular verbs and strong verbs. Such continuous dissociations grounded in ortho-phonological relationships between present-and past-tense forms are predicted by single-system, connectionist approaches to inflectional morphology and not predicted by current dual-system, rule-based models. Event-related potential data demonstrated that N400 priming effects were intact for both regular and irregular verbs, suggesting that the absence of significant regular-verb priming in the response time data did not result from a disruption of lexical access, and may have stemmed instead from post-lexical events such as covert articulation, segmentation strategies, and/or cognitive control. Keywords aphasia; Broca's area; left inferior frontal gyrus (LIFG); event-related potentials (ERP); inflectional morphology; regular and irregular past tense

An event-related potential study of cross-modal morphological and phonological priming

“…Recent studies of past-tense morphology have begun to explore whether regular-irregular distinctions are better described as categorical or graded (Joanisse & Seidenberg, 2005; Justus et al, 2008; Justus et al, submitted; Kielar et al, 2008; cf. Basnight-Brown et al, 2007).…”

“…The single-system rebuttal to such dissociations is to suggest that they are of a continuous nature, rather than being categorical (Joanisse & Seidenberg, 1999, 2005; Justus, Larsen, de Mornay Davies, & Swick, 2008; Justus, Larsen, Yang, de Mornay Davies, Dronkers, & Swick, submitted; Kielar, Joanisse, & Hare, 2008; McClelland & Patterson, 2002), and as such, they do not necessitate distinct cognitive mechanisms. Joanisse and Seidenberg (1999) developed a connectionist model of the past tense in which phonological units were interconnected with semantic units.…”

“…Justus et al, submitted). The past tense served as the prime and the present tense served as the target in two conditions concerning past-tense morphology, one made up of regular verbs (e.g., looked-look ) and the other of irregular verbs, which in turn were divided into a group of weak irregular verbs (e.g., spent-spend ) and strong verbs ( spoke-speak ).…”

Re-examining Paul Broca’s initial presentation of M. Leborgne: Understanding the impetus for brain and language research

“…Neither of these authors found the evidence for Broca's syndrome convincing. Questions regarding the nature of Broca's area and Broca's aphasia continue to be published to this day (Grodzinsky and Amunts, 2006;Moutier, 1908;Mohr, 1976;Selnes and Hillis, 2000;Fridriksson, Bonilha et al, 2007;Galaburda, 1980;Alexander, Naeser et al, 1990;Justus, Larsen et al, 2011). Nevertheless, most modern textbooks identify both eponyms as scientific facts and attribute priority of discovery to Broca.…”

‘Language of the past’ – Exploring past tense disruption during autobiographical narration in neurodegenerative disorders

“…More specifically, activation in the pars triangularis of the left IFG has been interpreted as reflecting cognitive control processes essential for interference resolution when competing memory representations are present (Badre & Wagner, 2007). The left IFG (pars triangularis and pars opercularis) has been shown to consistently activate in fMRI studies of both regular and irregular past tense production in healthy individuals (Justus et al, 2011), pointing to a form of cognitive control in which detection and conflict resolution between competing representations is required (Justus et al, 2011). Notably, lesions to the left IFG, specifically the ventral pars opercularis (Meteyard, Price, Woollams, & Aydelott, 2013), compromise the production of past tense regular verbs (Tyler et al, 2002;Ullman et al, 2005), potentially via the disruption of a rule-based or grammatical system (Grodzinsky, 2000), or disruption of an articulatory plan based on predictable phonological transformation (Price, 2010).…”