Biomedical subjects

Caterina Ansuini

Publications and source records attributed to Caterina Ansuini.

4 recordsLinked to original sources

PubMed2006

Distractor objects affect fingers' angular distances but not fingers' shaping during grasping.

The aim of the present study was to determine whether and how hand shaping was affected by the presence of a distractor object adjacent to the to-be-grasped object. Twenty subjects were requested to reach towards and grasp a 'convex' or a 'concave' object in the presence or absence of a distractor object either of the same or different shape than the target object. Flexion/extension at the metacarpal-phalangeal (MCP) and proximal interphalangeal joints of all digits, and abduction angle between digits were measured by resistive sensors embedded in a glove. The results indicate robust interference effects at the level of reach duration and the extent of fingers' abduction angles together with changes at the level of a single joint for the thumb. No distractor effects on individual fingers' joints except for the MCP of the middle and little fingers were found. These findings suggest that the presence of distractor object affects hand shaping in terms of fingers' abduction angles, but not at the level of 'shape dependent' fingers' angular excursions. Furthermore, they support the importance of the thumb for the guidance of selective reach-to-grasp movements. We discuss these results in the context of current theories proposed to explain the object selection processes underlying the control of hand action.

Adult↗

PubMed2006

Cross-modal interactions between olfaction and vision when grasping.

This study used kinematics to investigate the integration between vision and olfaction during grasping movements. Participants were requested to smell an odorant and then grasp an object presented in central vision. The results indicate that if the target was small (e.g., a strawberry), the time and amplitude of maximum hand aperture were later and greater, respectively, when the odor evoked a larger object (e.g., an orange) than when the odor evoked an object of a similar size as the target or no odor was presented. Conversely, the time and amplitude of maximum hand aperture were earlier and reduced, respectively, when the target was large (e.g., a peach) and the odor evoked a smaller sized object (e.g., an almond) than when the odor evoked an object of a similar size as the target or no odor was presented. Taken together, these results support the evidence of cross-modal links between olfaction and vision and extend this notion to goal-directed actions.

Adult↗

PubMed2006

Virtual reality applications for the remapping of space in neglect patients.

PURPOSE: The aims of the present article were the following: (i) to provide some evidence of the potential of virtual reality (VR) for the assessment, training and recovery of hemispatial neglect; (ii) to present data from our laboratory which seem to confirm that the clinical manifestation of neglect can be improved by using VR techniques; and (iii) to ascertain the neural bases of this improvement. METHODS: We used a VR device (DataGlove) interfaced with a specially designed computer program which allowed neglect patients to reach and grasp a real object while simultaneously observing the grasping of a virtual object located within a virtual environment by a virtual hand. The virtual hand was commanded in real time by their real hand. RESULTS: After a period of training, hemispatial neglect patients coded the visual stimuli within the neglected space in an identical fashion as those presented within the preserved portions of space. However it was also found that only patients with lesions that spared the inferior parietal/superior temporal regions were able to benefit from the virtual reality training. CONCLUSIONS: It was concluded that using VR it is possible to re-create links between the affected and the nonaffected space in neglect patients. Furthermore, that specific regions may play a crucial role in the recovery of space that underlies the improvement of neglect patients when trained with virtual reality. The implications of these results for determining the neural bases of a higher order attentional and/or spatial representation, and for the treatment of patients with unilateral neglect are discussed.

Aged↗

PubMed2005

Effects of end-goal on hand shaping.

The aim of the present study was to determine whether hand shaping was affected by planning of an action subsequent to object contact. Ten subjects (5 females and 5 males, ages 19-33) were requested to reach toward and grasp a convex object between the thumb and the four fingers of the right hand and to perform one of the following actions: 1) lift up the object; 2) insert the object into a niche of a similar shape and size as the object, or 3) insert the object into a rectangular niche much larger than the object. Flexion/extension at the metacarpal-phalangeal and proximal interphalangeal joints of all digits were measured using resistive sensors embedded in a glove. Although all experimental conditions required grasping the same object, we found different covariation patterns among finger joint angles across conditions. Gradual preshaping of the hand occurred only when planning object lift or when the end-goal required object placement into the tight niche. In contrast, for the larger niche, gradual preshaping was not evident for the ring and the little finger. Further, reaching movements were faster for movements ending with the larger niche than for the other movement conditions. The present results suggest that hand shaping takes into account end-goal in addition to object geometry. We discuss these findings in the context of forward internal models that allow the prediction of the sensorimotor consequences of motor commands in advance to their execution.

Adult↗