Rapid topographical plasticity of the visuomotor spatial transformation.
Information about the world is often encoded in the brain as topographic maps. These internal representations are not always static but can have a dynamic nature, allowing for constant adjustments that depend on factors like experience or injury. Recently, it has been shown that areas involved in visuomotor transformations also show topographical organization. These findings suggest that it could be possible to observe plastic modifications in specific parts of the representation in response to a local perturbation that affects only a part of the space that is represented. Here, we tested this hypothesis using an adaptation paradigm with hemiprisms. Our results suggest that, initially, the system tries to modify the visuomotor transformation in the whole spatial representation; however, if feedback is available from both hemifields, the system can perform specific regional topographical realignments. The results also suggest that access to the rearranged visuomotor transformation is independent of eye position, in contrast with previous studies that found a kind of conditional learning. Also, whereas prism adaptation experiments using ballistic movements do not show intermanual transfer of learning, the topographical modification found here is available to both hands. These results provide strong evidence for rapid topographical plasticity that can modify space transformations between two different modalities.
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México D.F., Mexico. jfr@servidor.unam.mx
Juan
J
Fernandez-Ruiz
Rosalinda
R
Diaz
Pablo
P
Moreno-Briseño
Aurelio
A
Campos-Romo
Rafael
R
Ojeda
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D009473:Neuronal Plasticity / Q000502:physiology*; D012016:Reference Values; D012149:Restraint, Physical; D013028:Space Perception / Q000502:physiology*; D014794:Visual Fields; D014796:Visual Perception