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Bastiaanse and Jonkers (1998) found that in verb-impaired aphasic patients verb retrieval in picture naming tasks and in spontaneous speech do not always correlate. This study aims at (i) further investigating the relationship between verb production in formal tasks and spontaneous speech, (ii) extending this analysis to noun-specific impairments and (iii) using this evidence to clarify the cognitive damage underlying noun-verb dissociation. Seven Italian aphasic patients (three noun-impaired fluent, two verb-impaired fluent and two verb-impaired non-fluent patients) participated in the study. For each patient a three-hundred-word sample of spontaneous speech was analyzed. The number of tokens, types and roots was then calculated for any of these five categories: open-class words, closed-class words, nouns, open-class verbs and closed-class verbs. These variables were analyzed using the modified t-test described by Sokal and Rohlf (1995) and the norms reported in Semenza et al. (1989). Verb-impaired patients split according to the type of aphasia they suffer from; non-fluent patients have a poor verb-type production in spontaneous speech, while fluent patients produce a normal amount of verbs. Also noun-impaired fluent patients have a reduced noun production in spontaneous speech. We argue that this different behaviour depends on the different cognitive damages underlying the dissociations and on the different impact of the frame context characterizing spontaneous speech on noun and verb retrieval. The consequence of these results on the different hypotheses on noun-verb dichotomy mental representation will be also discussed.

Forster et al. (1987) and Meunier et al. (2004) investigated irregular morphological priming with short SOA; they both report equal facilitation when a stem is primed by itself (or a regular inflected word) and by an irregular related word. However, both these studies used only one set of control words, making impossible a perfect prime-control matching in both repetition/regular and irregular conditions. We replicated these lexical decision studies using similar SOA (40ms) and two different control word sets, each of which was matched for length, frequency, number of orthographic neighbours and orthographic overlap with either the repetition or the irregular prime list. The results show that there is a repetition priming effect, there is a borderline irregular priming effect, and this latter is smaller than the repetition effect, contrary to the previous findings. The consequence of these results for the models of complex word recognition will be discussed.

The effect of grammatical class on semantic priming has been poorly investigated so far. In a first experiment we used primes and probes belonging to different grammatical classes (e.g., foodN-eatV) and no facilitation emerged. This result may be explained either semantically (structurally different semantic representations - i.e. functional vs visual, relational vs denotative- do not facilitate each other) or syntactically (i.e., no priming across grammatical classes). In a second experiment, we used strongly related noun-verb pairs in which prime and probe denote very close concepts (ideaN-thinkV): again, no priming emerged, suggesting that the semantic hypothesis is not correct. In a third experiment, we tested noun-noun and verb-verb pairs (dogN-catN; eatV-drinkV): semantic priming emerged with nouns (as usual), but not with verbs . Altogether, the experiments indicate that the mere presence of a verb in a prime-probe pair prevents semantic priming from emerging.

Aphasic patients occasionally manifest a dissociated naming ability between objects and actions: this phenomenon has been interpreted as evidence of a separate organization for nouns and verbs in the mental lexicon. Nevertheless Bird et al. [Bird, H., Howard, D., Franklin, S. (2000). Why is a verb like an inanimate object? Grammatical category and semantic category deficits. Brain and Language, 72, 246-309], suggested that the damage underlying noun-verb dissociation affects the corresponding semantic concepts and not the lexical representation of words; moreover, they claimed that many dissociations reported in literature are caused merely by a strong imageability effect. In fact, most authors used a picture-naming task to assess patients' naming ability, and due to the fact that this test involves the use of pictures to represent actions and objects, nouns were frequently more imageable than verbs [Luzzatti, C., & Chierchia, G. (2002). On the nature of selective deficit involving nouns and verbs. Rivista di Linguistica, 14, 43-71]. In order to overcome this drawback, we devised a new task - nouns and verbs retrieval in a sentence context (NVR-SC) - in which nouns and verbs have the same imageability rate. Patients' performance on this task is compared with that obtained by the same patients on a standard picture-naming task. Of the 16 aphasic patients with a selective verb deficit, as revealed by the picture-naming task, two continued to show dissociation in the NVR-SC task, while 14 did not. The data indicate that at least some patients have an imageability-independent lexical deficit for verbs. The functional locus/i of the damage is also considered, with particular reference to the lemma/lexeme dichotomy suggested by Levelt et al. [Levelt, W.J.M., Roelofs, A., & Meyer, A.S. (1999). A theory of lexical access in speech production. Behavioral and BrainSciences, 22, 1-75]

Introduction Many studies on aphasia have described disproportioned impairment of either verbs or nouns and have broached the issue of mental implementation of the grammatical class distinction. A clear picture has not yet been reached and, while evidence has has been found to indicate the lemma level as the possible locus of this distinction (Crepaldi et al., 2006), some alternative interpretations have been proposed (e.g., Rapp & Caramazza, 2002). These studies have focused almost exclusively on picture naming tasks, and have practically ignored the assessment of the dissociation in spontaneous speech. A remarkable exception is the study by Bastiaanse and Jonkers (1998) in which, however, the authors considered only verb-impaired patients and focused exclusively on the production of verbs. The results of this study indicate that the naming performance resulting from picture naming tasks does not always correlate with lexical retrieval in spontaneous speech. The present study aims at verifying (i) whether the disproportionate verb or noun impairment that emerges from a picture naming task is also present in spontaneous speech, and (ii) whether this occurs irrespective of the type of aphasia. Materials and Methods Seven Italian aphasic patients participated in the study. Their lexical retrieval abilities on nouns and verbs were tested by means of a picture naming task of 40 actions and 30 objects. Nouns and verbs were matched for word frequency, length and age of acquisition (see Luzzatti et al., 2002). Patients were selected according to their performance on this task and their aphasia type in order to represent the major types of noun-verb dissociation observed so far, i.e., noun-impaired fluent (n=3), verb-impaired fluent (n=2) and verb-impaired non-fluent patients (n=2). Spontaneous speech was elicited by asking the patients to describe their job, their family, their hobbies and how their speech disorder started. The spontaneous production was recorded and t

This paper reports the results of several studies on the mechanisms underlying Verb-Noun (V-N) dissociation. The objectives of the studies were to ascertain the location of the lesions causing predominant V or N impairment and to shed light on the different mental representations of these word classes through analyses of the data from neuropsychological patients. With regard to lesion sites, results obtained through an anatomo-correlative study on 15 V-impaired and 5 N-impaired aphasic patients indicate that lesions causing predominant N impairment were mostly located in the middle and inferior left temporal area. Three alternative lesion sites were associated with a V deficit (left posterior temporo-parietal lesions; large left fronto-temporal perisylvian lesions; deep lesions of the insula and/or the basal ganglia). In contrast to the results obtained from several neuropsychological and neuroimaging studies, none of the V-impaired patients had an isolated frontal lesion. The second aim is to discuss grammatical class interaction with semantic factors such as actionality or imageability (said to be the real cause of V-N dissociation). The retrieval of Ns and Vs in a sentence context was tested on 16 V-impaired aphasic patients and the resulting data indicate that imageability interacts with the retrieval of Ns and Vs, but cannot completely account for their dissociation.

We investigated the areas of the brain that are involved in the storage of lexical representations of verbs and nouns by localizing the brain lesions causing disproportionate impairment to the retrieval of these lexical categories in a sample of 20 Italian aphasic patients. In the majority of patients, with disproportionate impairment of nouns, the lesion involved the medial part of the middle and inferior left temporal gyri. In contrast, patients with disproportionate impairment of verbs clustered in two major subsets: either left posterior temporal lobe and inferior parietal lesions, or extensive left fronto-temporal lesions. In a second analysis, an attempt was made to disentangle the effect of imageability from disproportionate verb impairment: in at least two cases, verb damage was found to persist even after the imageability effect was removed. The relationship between imageability and actionality was also investigated: no interaction was found between these variables. A last analysis focused on the mechanisms underlying temporo-parietal damage in verb-impaired patients. Results indicate a critical role of the temporo-parietal area when retrieving verbs, irrespective of their degree of actionality. (c) 2005 Elsevier Ltd. All rights reserved.

INTRODUCTION Several authors described cases of dissociated impairment in naming nouns and verbs. There are four accounts of this dissociation: (i) patients may have purely lexical damage, which selectively affects verbs or nouns at a late stage of the linguistic processing (phonological or orthographic lexicons) (Rapp & Caramazza, 2002); (ii) the damage affects a lexical device, either at an ortographic-phonological modality-specific level (the lexeme; Levelt et al., 1999) or at a unitary lexical-syntactic level (the lemma) (Berndt et al., 1997); (iii) N-V dissociation arises from a semantic damage (Bird, Howard & Franklin, 2000); (iv) N-V dissociation is due to syntactic damage (Friedmann & Grodzinsky, 2000). To disentangle imageability and grammatical class effects, a new task was developed allowing to elicit nouns and verbs with identical imageability ratings in a sentence context. The results obtained will permit to address the following three questions: Does imageability play a role in determining N-V dissociation? If so, is imageability the unique cause of dissociation? If there is additional damage, at which level of linguistic processing does it take place? METHODS Twelve Italian aphasic patients and 11 normal controls participated in the study. Nouns and Verbs Retrieval in a Sentence Context (NVR-SC). Forty-five pairs of sentences denoting the same event, either using a noun or the corresponding verb (e.g. the evasion/to evade) were used. The first sentence was presented in complete form, while a gap was left in the second sentence, to be completed with the target word. For each pair of sentences two different conditions were employed, one triggering a verb and one triggering a noun. E.g. V-N: The prisoner was dreaming to evade The prisoner was dreaming the ......... N-V: The prisoner was dreaming the evasion The prisoner was dreaming to ......... The performance in the NVR-SC task was compared to that obtained on a classic picture naming task

Aphasic patients occasionally suffer from dissociated naming impairment for nouns and verbs. This phenomenon has been interpreted as an evidence of the separated organization of nouns and verbs in the mental lexicon. Nevertheless, Bird, Howard and Franklin (2000) suggested that the damage underlying noun-verb dissociation does not involve the lexical representations, but rather the corresponding semantic knowledge. Moreover, Bird and colleagues claimed that many dissociations reported in literature are merely caused by a strong imageability effect (Bird, Howard & Franklin, 2000; 2003). In fact, most authors used a picture naming task to assess patients’ naming ability and, due to the necessity to represent actions and objects with line drawings, nouns were frequently more imaginable than verbs (Luzzatti at al., 2002). To get around this drawback, we built up a new task which allows to test nouns and verbs with an almost identical imageability rate: the Nouns and Verbs Retrieval in a Sentence Context task (NVR-SC). The patients’ performance in this task has been compared to that obtained by the same patients in a standard picture naming task. We tested 10 aphasic patients with a selective verb deficit in the picture naming task. Two were still dissociated in the NVR-SC task, while 8 were not. The data indicate that imageability interacts with the retrieval of nouns and verbs, but cannot completely account for the noun-verb dissociation. Functional locus of the damage will be also discussed referring in particular to the lemma/lexeme dichotomy suggested by Levelt (Levelt et al., 1999).

Aphasic patients occasionally suffer from dissociated naming impairment for nouns and verbs. This phenomenon has been interpreted as an evidence of the separated organization of nouns and verbs in the mental lexicon. Nevertheless, Bird, Howard and Franklin (2000) suggested that the damage underlying noun-verb dissociation does not involve the lexical representations, but rather the corresponding semantic knowledge. Moreover, Bird and colleagues claimed that many dissociations reported in literature are merely caused by a strong imageability effect (Bird, Howard & Franklin, 2000; 2003). In fact, most authors used a picture naming task to assess patients’ naming ability and, due to the necessity to represent actions and objects with line drawings, nouns were frequently more imaginable than verbs (Luzzatti at al., 2002). To get around this drawback, we built up a new task which allows to test nouns and verbs with an almost identical imageability rate: the Nouns and Verbs Retrieval in a Sentence Context task (NVR-SC). The patients’ performance in this task has been compared to that obtained by the same patients in a standard picture naming task. We tested 10 aphasic patients with a selective verb deficit in the picture naming task. Two were still dissociated in the NVR-SC task, while 8 were not. The data indicate that imageability interacts with the retrieval of nouns and verbs, but cannot completely account for the noun-verb dissociation. Functional locus of the damage will be also discussed referring in particular to the lemma/lexeme dichotomy suggested by Levelt (Levelt et al., 1999).