1. processes in which the transmission of neuronal signals is activated or inhibited by the effects of neurotransmitters on the postsynaptic membrane.

2. antagonistic functions of the nervous system defined by Ivan Pavlov.

3. the stimulation of the cortex and the subsequent facilitation of learning, memory, and action (excitatory processes) versus central nervous system processes that inhibit or interfere with perceptual, cognitive, and motor activities (inhibitory processes). Individuals with a predominance of inhibitory over excitatory processes are theorized to be predisposed to a higher degree of extraversion, whereas individuals with a predominance of excitatory over inhibitory processes are theorized to be predisposed to a higher degree of introversion. Introverted–extraverted behaviors are said to serve the function of modulating these excitation and inhibitory processes: That is, individuals who build up excitatory processes slowly and inhibitory processes quickly need to behave in an extraverted fashion to provide “excitement,” whereas introverts are already excited so they do not need to behave in an extraverted way to increase this excitability but tend instead to shy away from excitatory stimuli. [proposed by Hans Eysenck]