Who Needs Emotions? The Brain Meets the Robot

asic principles for emotional processing 103
mating underlies bond formation in females. Similarly, if a drug that blocks
vasopressin is put in the ventricles of a male prairie vole before mating, the
male mates but does not bond. The drug blocks attachment but not sexual
responses. Thus, blocking oxytocin in female and vasopressin in male prairie
voles makes them act like montane voles. Oxytocin affects bonding only
in female brains and vasopressin in male brains.
Oxytocin and vasopressin are also present in the brains of humans and
are released during sexual behavior. These hormones have not yet been
proven to underlie attachment in humans. Regardless of whether the vole
findings on oxytocin and vasopressin end up being completely applicable to
the human brain, this work illustrates important principles that will surely
guide research for some time.
Areas of the amygdala are included in both the fear and sex circuits.
However, the circuits are otherwise quite different. Even within the amygdala
different areas are involved in sex (medial and posterior nuclei) and fear (lateral
and central nuclei). This emphasizes the importance of mapping the
circuit for different kinds of emotional system rather than assuming that there
is a universal circuitry for all emotions. At the same time, different emotion
circuits, like the fear and sex circuits, sometimes interact with one another.
For example, the medial nucleus sends connections to the central nucleus
(Canteras, Simerly, & Swanson, 1995), where oxytocin receptors are present
(Veinante & Freund-Mercier, 1997). This may be related to the ability of
both oxytocin and positive social interactions to reduce fear and stress.
Pair bonding in animals has given researchers a behavioral paradigm for
studying a phenomenon akin to love without analyzing subjectivity, but what
about the feelings of love? Although there is little research to draw upon at
this point, we can use our more detailed understanding of cognitive–
emotional interactions in fear to speculate about how our brain feels love.
Suppose you unexpectedly see a person you care about and feel the love
you have for that person. Let us follow the flow of information from the
visual system through the brain to the point of the feeling of love as best we
can. First, the stimulus will flow from the visual system to the prefrontal
cortex (putting an image of the loved one in working memory). The stimulus
also reaches the explicit memory system of the temporal lobe and activates
memories about that person. Working memory then retrieves relevant
memories and integrates them with the image of the person. Simultaneous
with these processes, the subcortical areas presumed to be involved in attachment
will be activated. Activation of attachment circuits then impacts
on working memory in several ways. One involves direct connections from
the attachment areas to the prefrontal cortex (as with fear, it is the medial
prefrontal region that is connected with subcortical attachment areas). Activation
of attachment circuits also leads to activation of brain-stem arousal