While an event is relative in being internally related to other entities
of the same logical
type; which it requires by a
necessity that is «particular and definite,» a species or genus is relative only in that it requires, by a
necessity that is «generic or indefinite,» one or more intentional classes (
of individuals or
of other more
specific kinds), all
of which are only contingently nonempty (1970a, l0l f., 103, 109).
«These experiments with cell
type -
specific pharmacology provide direct evidence for the
necessity of NMDA - Rs in dopamine neurons for the synaptic plasticity observed 3 - 5 hours after exposure to cocaine in vitro, leaving open the molecular explanation for the potentiation AMPA - Rs that occurs after many days
of NMDA - R inactivity in dopamine neurons in vivo.