The study of inhibitory transmission is limited in the pyramidal neurons and their modulators because the large number of excitatory synapses has overshadowed physiological studies of the inhibitory neurons. The structure of inhibitory synapses on apical dendrites may not be as plastic as the excitatory synapses on these neurons. There is difficulty in differentiating the excitatory and inhibitory synapses using the electrophysiological recordings in many experiments. The excitatory synapses and their patterns are by comparison to the inhibitory system rather uniform in type and properties. The inhibitory system, by contrast, possess several (10) different types of synapses originating from specifically differentiated cells and are much more difficult to track. There is insufficient information to precisely distinguish between excitatory and inhibitory pathways contributing to the alterations in neurotransmitter expression and cell structure changes.