AMINO-ACIDS AS THE SOURCE OF CONSIDERABLE EXCITATION IN CEREBRAL-CORTEX

A number of different factors contributed to the rationale for providi ng a critical review of the field of excitatory amino acids in the cer ebral cortex at this time. In addition to the recent growing realisati on by clinicians that the excitatory amino acids are linked critically to a number of neurological conditions, including neurodegenerative s yndromes such as Alzheimer's disease, cortical damage due to stroke an d cerebral ischemia, epilepsy, amyotropic lateral sclerosis, and schiz ophrenia, the recent cloning and membrane reconstitution of specific r eceptors known as AMPA, NMDA, kainate, and metabotropic receptors and their known subunits have prompted a surge of renewed interest in this important family of synaptic transmitter molecules. Moreover, recent advances in our understanding of the molecular events involved in grow th promotion in the early stages of the development of the cortex have shown that both NMDA and non-NMDA receptor subtypes perform important roles in certain aspects of target selection and neurite outgrowth, i n cone stimulation and guidance, and in spine formation and morphologi cal alterations. A recent explosive growth in interest in the possible roles of nitric oxide and related short-lived radicals in plasticity, disease, and synaptic transmission also is related closely with the a ctions of excitatory amino acids. All these relatively new advances ha ve transpired in parallel with ongoing work that has extended our appr eciation for the roles of excitatory amino acids in the areas of synap tic plasticity (long-term potentiation, long-term depression, receptiv e field reorganisation following drug-induced or peripheral sensory di sturbances, such as denervation or amputation), in processes of normal transmission at functionally and electrophysiologically identified ne urones of the cerebral cortex, and in distinct proposed roles for cort ical glia. A greater appreciation of the diverse types and properties of the burgeoning family of receptors for the metabotropic receptor al so contributed to our desire to feature that aspect of the field in th e context of glia and neurones of the cerebral cortex. That part of th e field of neuroscience concerned with the functions of excitatory ami no acids has grown so large over the past 10 years or so, that a revie w paper focusing on the contributions to a specialized meeting devoted solely to cerebral cortex could easily be supported by material compr ising a sufficient body of communications from top-quality research la boratories. The present account endeavours to summarize and discuss th e biochemical characteristics, physiological roles, pharmacological pr operties, clinical relevance, developmental involvements, and anatomic al-morphological aspects pertaining to the excitatory amino acid trans mitters in cerebral cortex.