A new look at the potential of the brain to change as a result of early experience: The possible role of glutamate in early learning and retardation

Lateralized brain function was originally thought to be unique to humans, but it has now been demonstrated to occur in many animal species, including primates, rats, dogs, and birds. Memory consolidation and retrieval in chicks is lateralized in neuroanatomical areas used and also in the times these areas are active. As the general patterns of memory encoding, elucidated in chicks, might also occur in humans, chicks are used as a model system for studying learning and memory. In addition, the detailed neurochemical investigation of imprinting has shown that the neurotransmitter glutamate plays an important role in the consolidation of early learning. Glutamate is also known to be important in neural plasticity, and a close link is now seen between early memory formation and the neural plastic events of early brain development. Behavioural testing using chicks has shown that glutamate intake can cause retardation of visual discrimination learning. This is of some concern given the common use of glutamate as a food additive. Clearly the role and indeed the presence of glutamate in the brain are finely balanced. This information is leading us to a greater understanding of the brain and its dynamic interaction with its environment. It also reinforces the increasing concerns regarding neural interactions with environmental roxins.