Acquisition and generalization of visuomotor transformations by nonhuman primates

Rony Paz*, Chen Nathan, Thomas Boraud, Hagai Bergman, Eilon Vaadia

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The kinematics of straight reaching movements can be specified vectorially by the direction of the movement and its extent. To explore the representation in the brain of these two properties, psychophysical studies have examined learning of visuomotor transformations of either rotation or gain and their generalization. However, the neuronal substrates of such complex learning are only beginning to be addressed. As an initial step in ensuring the validity of such investigations, it must be shown that monkeys indeed learn and generalize visuomotor transformations in the same manner as humans. Here, we analyze trajectories and velocities of movements as monkeys adapt to either rotational or gain transformations. We used rotations with different signs and magnitudes, and gains with different signs, and analyzed transfer of learning to untrained movements. The results show that monkeys can adapt to both types of transformation with a time course that resembles human learning. Analysis of the aftereffects reveals that rotation is learned locally and generalizes poorly to untrained directions, whereas gain is learned more globally and can be transferred to other amplitudes. The results lend additional support to the hypothesis that reaching movements are learned locally but can be easily rescaled to other magnitudes by scaling the peak velocity. The findings also indicate that reaching movements in monkeys are planned and executed very similarly to those in humans. This validates the underlying presumption that neuronal recordings in primates can help elucidate the mechanisms of motor learning in particular and motor planning in general.

Original languageAmerican English
Pages (from-to)209-219
Number of pages11
JournalExperimental Brain Research
Issue number2
StatePublished - Feb 2005

Bibliographical note

Funding Information:
Acknowledgements This study was supported in part by a Center for Excellence grant (8006/00) administered by the ISF, by BMBF-DIP, by grant 2001073 administered by the BSF, and by a special contribution from the Golden Charitable Trust. R.P. was supported by a Constantiner fellowship.


  • Internal model
  • Motor learning
  • Psychophysics
  • Reaching movements
  • Sensorimotor adaptation


Dive into the research topics of 'Acquisition and generalization of visuomotor transformations by nonhuman primates'. Together they form a unique fingerprint.

Cite this