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In the present paper we report the performance on object use and on semantic tasks of two patients, D.L. with probable semantic dementia, and A.M. with an atypical onset of dementia of Alzheimer, assessed twice two years apart. In particular, we investigated whether the patients' ability to use objects degraded as a function of their semantic knowledge about those objects. Results from the two assessments...
An influential theory suggests that the dorsal (occipito-parietal) visual stream computes representations of objects for purposes of guiding actions (determining ‘how’) independently of ventral (occipito-temporal) stream processes supporting object recognition and semantic processing (determining ‘what’). Yet, the ability of the dorsal stream alone to account for one of the most common forms of human...
The nesting-cup task has been used to assess cognitive capability in humans as well as non-human primates. Previous studies have attempted to highlight interesting aspects of behavior by constructing and assessing various categories of manipulation. The present study introduces a new notation system for describing manipulation in nesting-cup tasks in the form of sequential codes. Following this notation,...
When humans manipulate a control device under operational rules, with the goal of indirectly controlling a remote tool to achieve a desired outcome, they may rely on the power of internal representation to organize individual moves of the controller and tool into a set of sequences by mapping the motor space among hand, controller and tool. We recently used functional brain imaging (PET) to investigate...
We present two studies aimed at elucidating why patients with dysexecutive syndrome encounter difficulties with the use of tools and technical devices. Two different groups of patients with dysexecutive syndrome took part in them. Their results were compared with those of two groups of normal controls and in the first study also with those of patients with posterior left or right brain lesions. The...
In a first experiment we studied, through a line bisection task, (a) the frequency of the selective disruption of far or near space representations in a group of 28 right brain-damaged patients and (b) the effect of tool use on line bisection error in far and near space in order to clarify whether the kind of action performed by the subject influences the extension of space representation, as suggested...
The active and skilful use of tools has been claimed to lead to the “extension” of the visual receptive fields of single neurons representing peripersonal space - the visual space immediately surrounding one's body parts. While this hypothesis provides an attractive and potentially powerful explanation for one neural basis of tool-use behaviours in human and nonhuman primates, a number of competing...
Studies of categories of objects, including tools, have spurred the development of the sensory-motor model of object concept representation. According to this model, information about objects is represented in the same neural subsystems that are active when we perceive and use them. In turn, this model has provided insight into the brain mechanisms of tool use. For tools, three types of information...
The impact of ideomotor apraxia (IMA) on functional ability has been a relatively neglected topic in research. This has been due to the continued focus on performance on gesture imitation and pantomime of tool-use, together with widespread acceptance of anecdotal evidence that IMA has no effect when directly manipulating objects. An increasing number of studies have shown that IMA does in fact result...
In human and non human primates, evidence has been reported supporting the idea that near peripersonal space is represented through integrated multisensory processing. In humans, the interaction between near peripersonal space representation and action execution can be revealed in brain damaged patients through the use of tools that, by extending the reachable space, modify the strength of visual-tactile...
Patients with ideomotor apraxia (IM) are frequently more impaired in the production and imitation of object-related (transitive) than non-object-related, symbolic (intransitive) gestures, but reasons for this dissociation, and its anatomical underpinnings, remain unclear. Our theoretical model of praxis (Buxbaum, 2001) postulates that left inferior parietal lobe (IPL) gesture representations store...
Internal models are neural mechanisms that can mimic the input-output properties of controlled objects. Our studies have shown that: 1) an internal model for a novel tool is acquired in the cerebellum (Imamizu et al., 2000); 2) internal models are modularly organized in the cerebellum (Imamizu et al., 2003); 3) their outputs are sent to the premotor regions after learning (Tamada et al., 1999); and...
The purpose of this study is to identify the functional brain networks activated in relation to actual tool-use in humans. Although previous studies have identified brain activity related to tool-use gestures (Moll et al., 2000), they did not investigate the brain activity involved in such tool-use. We investigated brain activity using functional magnetic resonance imaging (fMRI) while human subjects...
State estimation of self-movement, based on both motor commands and sensory feedback, has been suggested as essential to human movement control to compensate for inherent feedback delays in sensorimotor loops. The present study investigated the neural basis for state estimation of human movement using event-related functional magnetic resonance imaging (fMRI). Participants traced visually presented...
The behaviour of ideational apraxic patients on simple tasks involving multiple objects is typically marked by a variety of errors. While some of these errors concern the sequential organisation of action through time, many relate to the misuse of, or failure to use, necessary or appropriate tools. In this paper we apply the computational model of Cooper and Shallice (2000) to five standard multiple...
We examined neural basis underlying tool-use behavior to discuss whether or not the usage of a well-learned tool has a specific route. Regional cerebral blood flow was measured in healthy Japanese subjects using functional magnetic resonance imaging (fMRI) during object pick-up using chopsticks, object pick-up using the hand, pantomiming the use of chopsticks, imagining the use of chopsticks, and...
Object manipulation with the hand is a complex task. The task has redundancies at many levels, allowing many possibilities for the selection of grasp points, the orientation and posture of the hand, the forces to be applied at each fingertip and the impedance properties of the hand. Despite this inherent complexity, humans perform object manipulation nearly effortlessly. This article presents experimental...
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