Brain, Vol. 116, No. 5, 1119-1137, 1993
© 1993 Guarantors of Brain
research-article |
Study of selective reaching and grasping in a patient with unilateral parietal lesion
Dissociated effects of residual spatial neglect
1Institute of Human Physiology Italy 2Institute of Neurology, University of Parma Italy 3Department of Experimental Psychology, University of Oxford UK
Correspondence to:
Correspondence to Dr M Gentilucci, Institute of Human Physiology, University of Parma, via Gramsci 14, 43100 Parma, Italy
SUMMARY
In the present study we investigated the possibility of a dissociation between the visual control of reaching and the visual control of grasping in a prehension task. To this purpose we studied the kinematics of prehension movements in a patient with a right parietal lesion and in six right-handed healthy control subjects. The task we used was one in which the subjects had to reach and grasp target objects in the presence or absence of a simultaneously presented distractor object. All stimuli were presented in the space ipsilateral to the lesion. The distractor could be either of the same or different size to the target object and was presented either to the right or to the left of the target. The following parameters of the prehension ‘transport’ component were analysed: wrist trajectory, transport time, tangential peak velocity, acceleration. Maximal finger aperture, time to maximal finger aperture, peak acceleration and time to peak acceleration of grip aperture were the parameters of the ‘grasping’ component analysed.
The results showed that, although the patient had no misreaching, her hand trajectory deviated abnormally towards the distractor position when the distractor was to the right (ipsilateral) side of the target. In contrast, the grasp kinematics was not affected by the distractors, even when the size of the right distractor was different from the target. It appears, therefore, that the attentional shift towards the ipsilesional side, typical of neglect patients, determines a surprising dissociation in motor control. In the presence of a right distractor, the patient plans and partially executes a reaching movement towards that object and simultaneously performs a grasping movement towards a second object, i.e. the centrally located target. The presentation of distractors had no effects on the prehension kinematics of the control subjects.
Received November 30, 1992. Revised May 18, 1993. Accepted May 21, 1993.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M Rizzo and S P Vecera Psychoanatomical substrates of Balint's syndrome J. Neurol. Neurosurg. Psychiatry, February 1, 2002; 72(2): 162 - 178. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Kurata and E. Hoshi Reacquisition Deficits in Prism Adaptation After Muscimol Microinjection Into the Ventral Premotor Cortex of Monkeys J Neurophysiol, April 1, 1999; 81(4): 1927 - 1938. [Abstract] [Full Text] [PDF]
|
|