Activation of left intraparietal sulcus using a fMRI conceptual praxis paradigm

Abstract

-The present paper reports the results of a fMRI subtraction study of the pattern of cortical activation induced by an ideational praxis paradigm in six normal right-handed subjects. The control task consisted of a sequence of complex meaningless hand movements. A complete study was done for each hand in each subject. The left intraparietal sulcus was the only structure activated in all subjects regardless of the hand used in the task. These findings, albeit preliminary, suggest that the organization of actions involving the mediation of tools and utensils are strongly lateralized to the left hemisphere and that damage to the dominant intraparietal sulcus may be critical for the development of the clinical syndrome of conceptual apraxia.KEY WORDS: conceptual apraxia, intraparietal sulcus, cerebral asymmetry, functional magnetic resonance imaging. Ativação do sulco intraparietal esquerdo utilizando RMf e um paradigma de praxis conceitualRESUMO -No presente artigo, reportamos os resultados de RMf da ativação cortical induzida por um paradigma de praxis de uso de ferramentas em seis pessoas dextras normais. A tarefa-controle consistiu de uma sequência de movimentos unimanuais complexos, mas desprovidos de significado. Um estudo completo de pantomima e controle foi feito para cada mão. O sulco intraparietal esquerdo foi a única estrutura ativada em todos os indivíduos, independentemente da mão utilizada. Esses achados, embora preliminares, indicam que a organização de ações mediadas por ferramentas e utensílios são fortemente lateralizadas para o hemisfério esquerdo nas pessoas normais, e sugerem que lesões na região do sulco intraparietal do hemisfério dominante são críticas para o aparecimento de apraxia conceitual. PALAVRAS-CHAVE: apraxia conceitual, sulco intraparietal, assimetria cerebral, ressonância magnética funcional.

Evidence for a distributed hierarchy of action representation in the brain

“…More contemporary lesion studies confirm this localization, but also show action retrieval deficits in posterior left middle frontal gyrus (MFG) (Haaland, Harrington, & Knight, 2000). (Moll, De Oliveira-Souza, De Souza-Lima, & Andreiuolo, 1998). Using go, no-go paradigms, we have used functional imaging of normal participants during retrieval of common actions (such as a demonstration of how to use a hammer).…”

Ideomotor apraxia: A review

“…This is the "disconnection" hypothesis [8], which emphasizes cortico-cortical projections as the main culprit. Evidence suggests that the left parietal cortex (specifically, the inferior parietal lobule) stores motor representations, or "engrams," that, if damaged, would affect not only performance, but also recognition of pantomimes [39][40][41][42][43][44]. Damage to these engrams was initially thought to explain the deficit [45].…”

Upper Limb Apraxia

“…Further, a loss of movement representation should impair action-motor imagery, and Ochipa and colleagues 21 demonstrated that ideomotor apraxia can be associated with deficits in movement imagery. Further evidence supporting the hypothesis that the dominant parietal lobe stores action-movement representations (praxicons) comes from functional imaging studies of healthy subjects 22 …”