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Behavioural Neurology
Volume 7 (1994), Issue 2, Pages 43-48

Is Disturbed Transfer of Learning in Callosal Agenesis due to a Disconnection Syndrome?

T. Imamura,1,5 A. Yamadori,2 Y. Shiga,1 M. Sahara,3 and H. Abiko4

1Department of Neurology, Institute of Brain Diseases, Tohoku University School of Medicine, Sendai, Japan
2Hyogo Institute for Aging Brain and Cognitive Disorders, Himeji, Japan
3Department of Neurology, Kohnan Hospital, Sendai, Japan
4Department of Neurosurgery, National Sendai Hospital, Sendai, Japan
5Division of Behavioral Neurology, Department of Clinical Neurosciences, Hyogo Institute for Aging Brain and Cognitive Disorders, 520, Saisho-Ko, Himeji 670, Japan

Copyright © 1994 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Disturbed intermanual transfer of tactile learning in callosal agenesis has been interpreted as a sign of disconnection syndrome. We observed this sign in one of four acallosal patients with a conventional form-board task, and tried to elucidate the nature of the deficit. The form-board performance of the patient with disturbed transfer of learning totally depended on motor skill, while the other acallosals and normal controls executed the task based on spatial and somesthetic information. All acallosals and normals, however, failed to show transfer of learning with another tactile task which needed motor skill but not spatial-somesthetic information. These findings suggest that the task-performing strategies in form-board learning change the state of interhemispheric transfer. Unimanual learning effect is transferred if spatial-somesthetic information is acquired in the process of learning, but is not transferred if motor skill is the exclusive content of learning. We conclude that disturbed “transfer” of learning in some acallosals is not a true disconnection sign. It should be attributed to a lack of appropriate strategy, as a result of ineffective problem solving in tactile tasks.