Functional lateralization of the chicken forebrain revealed by use of intracranial glutamate

By injecting monosodium L-glutamate into either one of the forebrain hemispheres of the developing chicken brain and examining the behavioural effects which ensue, it has been possible to demonstrate that there is functional lateralization for control of a number of behaviours. Glutamate treatment of the left hemisphere retards visual discrimination learning and auditory habituation, as does glutamate treatment of both hemispheres, but treatment of the right hemisphere is without effect on these behaviours. An imbalance generated by administering glutamate to the left hemisphere causes a marked increase in aggressive and sexual behaviour, which does not occur either after treatment of both hemispheres or treatment of the right hemisphere. A preliminary study on the distribution of radioactive glutamate is also reported.