The same parts of the human brain
that are involved in positive
reinforcement of behaviour are also involved in the sensation of pleasure.
The radical behaviourists’ explanation of positive reinforcement
ignored the concept of pleasure.
But these two ideas can be applied almost
synonymously to human beings, who when asked why they engage in reinforced behaviours,
will usually spontaneously cite the subjective experience of pleasure that these
The expression "pleasure centres of the brain", introduced
by Olds in a 1956 article, is still a good way to describe the neuronal substrates
of rewards for behaviour. As researchers have discovered new neural pathways involved
in pleasure and rewards, however, the term “centre”
which suggests a single locus, has gradually been replaced by the word “system,”
which stresses the involvement of multiple groups of neurons.