Who Needs Emotions? The Brain Meets the Robot

organization of motivational–emotional systems 65
Figure 3.8. Receptors that selectively bind opiates and cannabinoids are
present in the mammalian brain, perhaps indicating a coevolutionary relationship
between humans and plant alkyloids, as discused in the text. (A)
Strong expression of cannabinoid receptors in the basolateral nucleus of the
amygdala in rat brain, an area involved in emotion regulation. On the left is a
low-power view and on the right is a high-power view of sections stained for
cannabinoid receptor immunoreactivity. BLA, Basolateral amygdala; Ce,
central nucleus; ic, internal capsule. (From Katona et al., 2001, with permission.)
(B) Localization of opiate receptor binding in the striatum of rat brain,
utilizing 3H-naloxone autoradiography. Light staining against dark field
indicates dense, patchy distribution of mu opiate receptor distribution in the
dorsal and ventral striatum, areas important for learning and reinforcement
processes. Small arrow in cortex indicates mu binding in layer k of cortex;
larger arrow indicates intense binding in the subcallosal streak and patchy
areas called “striosomes.” (From Delfs et al., 1994, with permission.)
neurotransmitters (the monoamines and acetylcholine). This could bring a clear
benefit in times of privation and resource scarcity. Behavioral, nutritional, and
energetic advantages have been ascribed to ethanol consumption, present in
low levels in ripe and fermenting fruit, which have been consumed by frugivore
primates for 40 million years (Dudley, 2002).
Whatever the ultimate explanation for drug-seeking behavior, it is clear
that there is a close evolutionary relationship between certain plant alkaloids