Neurotransmitter Actions in the Thalamus and Cerebral Cortex

The postsynaptic actions of glutamate, gamma-aminobutyric acid (GABA), acetylcholine, norepinephrine, serotonin, and histamine in the cerebral cortex and thalamus and their relevance to the control of thalamocortical activity are reviewed. Excitatory and inhibitory amino acids (such as glutamate and GABA) are proposed to form the neurotransmitters by which the executative neural networks of the neocortex and thalamus process synaptic information. In contrast, the more slowly acting neurotransmitters, acetylcholine, norepinephrine, serotonin, and histamine, are proposed to control the state of activity and excitability of thalamic and cortical neurons and thereby modulate the state of thalamocortical activity. Specific examples of the involvement of fast and slow transmitter actions in the genesis of epileptic seizures and the determination of sleep-wake cycles are given.