![]() The subject was requested to make hand postures using the left hand by imitation and by verbal command. ![]() This functional magnetic resonance imaging (fMRI) study was designed to reveal the brain regions that commonly subserve two ideomotor praxis-imitation and movements executed by verbal command-and to find the difference in activated regions between the two types of ideomotor praxis. 6 No evidence is available concerning the different brain mechanisms involved in these two ideomotor praxis. 13 In contrast, in some other cases, performance by verbal command is easier than imitation. Indeed, the performances of patients with ideomotor apraxia in response to verbal command or imitation can be different in some cases, performance by imitation is better than by verbal command. In contrast, imitation requires the subject to recognise and remember what he/she sees, which is not required in movements executed by verbal command. 11, 12 Movements executed by verbal command require the subjects to recall what to do, a cognitive process that is not contained in imitation. 10 Neuroimaging studies have reported that the neural substrate for imitation lies in the left Brodmann area 44, alias Broca’s area. 9 A meta-analysis found that lesions to deep subcortical structures, such as the lenticular nucleus or putamen, with involvement of periventricular or peristriatal white matter, can cause ideomotor apraxia. 8 However, a study of a large sample claimed a crucial role for deep parietofrontal and occipitofrontal fibres in producing ideomotor apraxia, challenging the traditional view. 3– 7 A recent lesion study found maximum overlap of lesions in patients with ideomotor apraxia in the left intraparietal sulcus. Lesion studies have reported defective imitation and movements executed by verbal commands (ideomotor praxis) after left parietal damage. The neural correlates of ideomotor apraxia have been thought to be located in the left parietal lobe, but some studies have claimed other regions. Because most patients with ideomotor apraxia have a deficit both in imitation and in movements executed by verbal command, the brain region activated by both imitation and movements executed by verbal command is thought to contain the neural substrate for ideomotor praxis. 2 For example, individuals with ideomotor apraxia cannot make correct motor responses when the examiner asks them to salute or to wave their hands to express “goodbye”, or when requested to imitate the movements of the examiner. 1 Operationally, ideomotor apraxia is defined as “failure to produce the correct movement in response to verbal command, or failure to imitate correctly a movement performed by the examiner” that cannot be explained by “weakness, incoordination, akinesia, abnormal reflexes, impaired auditory comprehension, or impaired visual perception”. The concept of ideomotor apraxia was proposed by Liepmann. FB/UM, finger bending/unbending movement.fMRI, functional magnetic resonance imaging.BOLD signal differences for movements executed by verbal command against imitation were observed in the superior temporal areas.Ĭonclusions: The depth of the posterior part of the left intraparietal sulcus and bilateral precunei are the neural substrates for IP. The difference in BOLD signal between imitation and verbal command movements was localised in the dorsal and ventral occipital areas. Results: The depth of the posterior part of the left intraparietal sulcus and bilateral precunei were activated during both imitation and verbal command movements. Blood oxygenation level dependent (BOLD) signal increases were compared during two kinds of IP (imitation and verbal command movements) and during finger bending/unbending movements. The finger bending/unbending movement was self paced. Identical postures were instructed verbally for the verbal command condition. Eighteen drawings of left hand postures were presented for the imitation condition. All motor tasks were performed using the left hand. ![]() The experiment comprised three motor conditions (imitation, movements executed by verbal command, and finger bending/unbending) and a rest condition. Functional and anatomical data were acquired. Methods: Twenty two young, right handed, healthy subjects were examined. Brain regions activated by both imitation and verbal command movements were tested against a simple self paced movement. Objectives: To localise the neural substrates for IP using functional magnetic resonance imaging. Lesion studies have identified the left parietal lobe as the neural correlate for ideomotor praxis (IP), although there are opposing views. Background: Ideomotor apraxia is a disorder of both imitation movements and movements executed by verbal command. ![]()
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