A new view of hemineglect based on the response properties of parietal neurones.
Lesion studies of the parietal cortex have led to a wide range of conclusions regarding the coordinate reference frame in which hemineglect is expressed. A model of spatial representation in the parietal cortex has recently been developed in which the position of an object is not encoded in a particular frame of reference, but instead involves neurones computing basis functions of sensory inputs. In this type of representation, a nonlinear sensorimotor transformation of an object is represented in a population of units having the response properties of neurones that are observed in the parietal cortex. A simulated lesion in a basis-function representation was found to replicate three of the most important aspects of hemineglect: (i) the model behaved like parietal patients in line-cancellation and line-bisection experiments; (ii) the deficit affected multiple frames of reference; and (iii) the deficit could be object-centred. These results support the basis-function hypothesis for spatial representations and provide a testable computational theory of hemineglect at the level of single cells.
Pouget
A
A
Institute for Cognitive and Computational Sciences, Georgetown University, Washington, DC 20007-2197, USA.
Sejnowski
T J
TJ
D001072:Apraxias / Q000175:diagnosis*; D001288:Attention; D007839:Functional Laterality; D006801:Humans; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology* / Q000503:physiopathology