Model of music cognition and amusia.

INTRODUCTION: The study of the neural networks involved in music processing has received less attention than work researching the brain's language networks. For the last two decades there has been a growing interest in discovering the functional mechanisms of the musical brain and understanding those disorders in which brain regions linked with perception and production of music are damaged. DISCUSSION: Congenital and acquired musical deficits in their various forms (perception, execution, music-memory) are grouped together under the generic term amusia. In this selective review we present the "cutting edge" studies on the cognitive and neural processes implicated in music and the various forms of amusia. CONCLUSIONS: Musical processing requires a large cortico-subcortical network which is distributed throughout both cerebral hemispheres and the cerebellum. The analysis of healthy subjects using functional neuroimaging and examination of selective deficits (e.g., tone, rhythm, timbre, melodic contours) in patients will improve our knowledge of the mechanisms involved in musical processing and the latter's relationship with other cognitive processes.

[Disassociation between agrammatic and anomic patients in their production of verb forms]. / Disociación entre pacientes agramáticos y anómicos en la producción de formas verbales.

INTRODUCTION: Electrophysiological and neuroimaging studies suggest that regular and irregular verbs are differently represented in the brain. Findings from studies of patients seem to agree with this view, but there are discordant data. AIM: To test if there is a dissociation in regular and irregular verb processing between patients with anterior lesions, characterized as Broca's aphasics, and patients with posterior lesions, characterized as anomics. PATIENTS AND METHODS: 10 aphasic patients participated in the study: five presenting evidence of Broca's aphasia and five presenting evidence of anomia. The task required patients to complete 58 sentences with a verb conjugated in the past tense form. 29 sentences required an irregular verb and 29 required a regular verb. RESULTS: Statistical analyses indicate a main effect due to differences between the different types of patients, and an interaction between this effect of patient type and the effect of verb type. The interaction was due to the fact that anomic patients had more difficulty in completing sentences using irregular verbs. CONCLUSIONS: The results of this study support a dual route model, which assumes that regular verbs are processed by application of morphological rules whereas irregular verbs are processed through the addressed recovery of conjugated forms.