Valuations in the BrainThe mind doe

Valuations in the Brain
The mind does not just have concepts and beliefs, but also attaches values to them. How do you feel
about the following kinds of things: babies, dogs, chocolate, beef, basketball, beer, television,
cockroaches, and broccoli? Your mental representations of many of these probably involve definite
emotional attitudes, positive or negative, although you may be indifferent to some of them. Different
facts about these things are also accompanied by emotional attitudes—for example, the positive
thought that chocolate tastes good and the negative thought that it can be fattening. When our brains
represent things using concepts and beliefs, they connect these representations with positive and
negative valuations.
Suppose, as the last two chapters argued, that your concept of chocolate is a pattern of activation in
a population of neurons. These neurons do not need to be confined to brain areas devoted to thinking
with words, but could also include neurons in areas for sensory processes such as sight, smell, and
taste. Hence the look, feel, and taste of chocolate are as much a part of your concept of chocolate as is
the verbal information that it is made out of cocoa beans. The activity of neurons in different regions
of the brain is temporally coordinated through the interactions that take place via synaptic
interconnections, produced by long axons that enable neurons in one part of the brain to excite or
inhibit neurons in other parts. Such multimodal activity makes it possible for you to recognize a
morsel as chocolate because it has the sensory properties, such as taste, smell, and mouth feel, of your
previous experiences of chocolate. For concepts and beliefs, similar kinds of coordination occur with
brain areas important for emotions.
There are many relevant brain areas, but I will focus on just two that are known to affect emotional
processes. First consider the amygdala, a small almond-shaped area located in the lower middle part
of the brain, below the cortex (figure 5.1). Recordings of neuron firings in animals and brain-scanning
experiments in humans show the amygdala is important for emotions, especially fear. For example,
when people are shown a picture of a scary face, brain scans show an increase of blood flow to the
amygdala, indicating that the neurons in it are firing more rapidly and need renourishing. Hence it is
plausible that the experience of being afraid of a gruesome face requires an association between the
firing of neurons that visually represent the face and the firing of neurons in the amygdala. We may
say or think that the face is scary, but this is only a verbal description of the emotional experience of
fear of the face. All mammals have an amygdala, and there are analogous regions in fish and reptiles.
The amygdala has reciprocal connections with many other brain areas, including the prefrontal cortex,
so that neural populations in the amygdala can increase the firing of neurons in the cortex, and vice
versa.
Another brain area important for emotions is the nucleus accumbens, located above the amygdala.
If you like eating chocolate, doing so probably increases activation in this region of your brain, which
has been extensively studied because of its role in addiction to drugs such as alcohol and cocaine.
Both of these drugs increase firing of neurons in the nucleus accumbens and related areas. Feelings of
pleasure and anticipation of desirable outcomes are associated with a circuit of neurons that employ
the neurotransmitter dopamine, running from the ventral tegmental area through the nucleus accumbens
to the prefrontal cortex. Such brain circuits are reciprocal, with many feedback loops. Hence for
people like me, who love chocolate, the pattern of neural firing associated with eating it includes
neurons in the nucleus accumbens as well as parts of the brain involved in verbal, visual, and other
sensory representations
I won't try now to review all the brain regions that contribute to human emotions, a long list that
includes the orbitofrontal cortex (behind the eyes), the ventromedial (bottom middle) prefrontal
cortex, and the insula. More will be said below about how they work together to produce emotions.
The key point is that definite brain areas such as the nucleus accumbens and the amygdala are known
to be associated with positive and negative emotions, and such associations can be accomplished
through coordinated neural firings. The patterns of neural firing that constitute representations such as
concepts include the operations of neural populations in areas known to be involved in emotional
processing. Such associations ensure that when the brain is representing some aspects of the world, it
is simultaneously valuing it.