[Post-stroke aphasia recovery: what are the predictors?] / Récupération de l'aphasie post-AVC: quels sont les facteurs prédictifs ?

Post-stroke aphasia recovery is multifactorial and results from a complex equation between four types of interrelated factors : a) neurobiological factors, such as lesion size and location, but also to some extent the neural reserve in undamaged brain areas ; b) behavioral factors, mostly related to the initial severity of stroke symptoms ; c) personal factors, such as age and gender, that remain however poorly investigated and debated and d) therapeutic factors, related to medical endovascular interventions and to speech and language therapy. Future studies are crucial to determine more precisely the weight and the interaction of these factors in the recovery process of post-stroke aphasia.

La récupération de l'aphasie post-AVC est multifactorielle et fait l'objet d'une équation complexe entre quatre types de facteurs interreliés : a) des facteurs neurobiologiques, comme la taille et la localisation de la lésion cérébrale, ou encore la réserve neuronale dans les régions non lésées ; b) des facteurs comportementaux, principalement en lien avec la sévérité initiale de la symptomatologie ; c) des facteurs personnels, comme l'âge ou le genre, qui restent toutefois peu explorés et encore débattus à l'heure actuelle et d) des facteurs thérapeutiques, liés aux traitements médicaux endovasculaires et aux traitements logopédiques prodigués. Seuls des travaux de recherche supplémentaires permettront de déterminer plus précisément le poids et l'interaction de ces facteurs dans le processus de récupération de l'aphasie vasculaire.

A common processing system for the concepts of artifacts and actions? Evidence from a case of a disproportionate conceptual impairment for living things.

We report the results of a single-case study carried out with a brain-damaged patient, G.C., whose conceptual knowledge of living things (animals and plants) was significantly more impaired than his knowledge of artifacts and his knowledge of actions, which were similarly impaired. We examined whether this pattern of conceptual impairment could be accounted for by the "sensory/functional" or the "manipulability" account for category-specific conceptual impairments advocated within the feature-based organization theory. To this end, we assessed, first, the patient's knowledge of sensory compared to functional and motor features and, second, his knowledge of nonmanipulable compared to manipulable items. The findings showed that the patient's disproportionate impairment for living things compared to both artifacts and actions was not associated with a disproportionate impairment of sensory compared to functional or motor knowledge or with a relative sparing of manipulable compared to nonmanipulable items. We then discuss how alternative theories of conceptual knowledge organization could account for G.C.'s pattern of category-specific deficit.

The organization of the conceptual system: the case of the "object versus action" dimension.

There are very numerous reports in the neuropsychological literature of patients showing, in naming and/or comprehension tasks, a disproportionate deficit for nouns in comparison with verbs or a disproportionate deficit for verbs in comparison with nouns. A number of authors advanced that, in at least some or even in every of these reported cases, the noun/verb dissociation in fact reflected an underlying conceptual deficit disproportionately affecting either object or action concepts. These patterns thus would put an additional constraint on theories of conceptual knowledge organization, which should be able to explain how brain damage could selectively disrupt the concepts of objects or the concepts of actions. We have reviewed 69 papers (published from 1984 to 2009) that reported a pattern of a noun or a verb disproportionate deficit in a single-case, multiple-case, or group study of brain-damaged patients with various aetiologies. From this review, we concluded that none of these studies provided compelling evidence in favour of the interpretation that the observed noun or verb disproportionate deficit arose at the conceptual processing level and, accordingly, that this level may be organized according to the "object/action" dimension. Furthermore, we argue that investigating conceptual impairments in brain-damaged patients according to the "object/action" dichotomy is not empirically fruitful if the purpose is to inform theories of conceptual knowledge organization. In order to provide evidence relevant to these theories, one needs to consider finer grained distinctions within both the object and the action category when investigating the scope of the patients' conceptual impairment.

Verb comprehension and naming in frontotemporal degeneration: the role of the static depiction of actions.

We report the case study of a patient JB with the frontal variant of frontotemporal dementia (fv-FTD), who was disproportionately impaired in naming and comprehending verbs in comparison with nouns. We examined to what extent the patient's verb disproportionate deficit was dependent on the type of stimuli used to assess verb processing, that is, static depictions of actions, videotaped actions, or verbal stimuli. We found that the verb disproportionate deficit JB presented when her naming or comprehension was assessed from static depictions of actions (i.e., photographs) disappeared when naming or comprehension was assessed from videotaped actions or verbal stimuli. These results indicated that JB did not present disproportionate difficulties with verb processing per se (i.e., with retrieving the lexical and semantic features of verbs). Instead, the seemingly disproportionate verb deficit found in JB -- and possibly also in other previously reported patients with executive resource limitation -- was likely due to the picture stimuli used to probe verb versus noun naming and comprehension not being equal in executive resource demands. The finding of this study thus underscores the need of considering carefully the specific effects of task and type of stimuli in the patients' performance with action pictures before making theoretical claims about the noun versus verb or object versus action lexical and semantic representation in the brain.