190 Self and the Phenomenon of Life
b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity “9x6”in another study that listening to music increases activity of the nucleus
accumbens.^17
In a study regarding romantic love, male and female subjects were
shown photographs of their lovers’ faces. Brain imaging revealed acti-
vation of brain areas related to the nucleus accumbens.^18 Interestingly,
people who experienced rejection in romantic love also showed activa-
tion of the same brain areas, suggesting that the craving/reward system
is active in romantic passion, whether or not it is fulfilled.^19
Recent investigation identified a cerebral nucleus, called the ventral
pallidum (Fig. 9.3), that forms a chemical circuit (involving enkephalin,
an endogenous opium, and anandamide, an endogenous marijuana) with
nucleus accumbens and ventromedial prefrontal cortex. It was reported
that the dopaminergic function of nucleus accumbens alone is respon-
sible for motivation, whereas the combined action of three structures
(nucleus accumbens, ventral pallidum, and ventromedial prefrontal cor-
tex) brings in the experience of reward. (Note that “motivation” is syn-
onymous with drive, craving, and wanting, while “reward” is identical
with enjoyment, pleasure, fulfillment, and satisfaction.)^20
9.5.3 Ventral tegmental area (VTA)
The VTA is a group of neurons in the midbrain that projects dopamin-
ergic fibers to the nucleus accumbens, ventral pallidum, amygdala, ante-
rior cingulate, and the ventromedial prefrontal cortex, collectively called
the “dopaminergic mesolimbic system.” The fibers connecting to the
nucleus accumbens are particularly important for motivation behavior.
9.5.4 Insular cortex
The insula is an “island” of cortex hidden and squeezed between the tem-
poral and fronto-parietal lobes (Fig. 9.2; see also Chapter 10, Fig. 10.1).
Functionally, it can be considered an inward extension of the somatosen-
sory area of the parietal lobe, with the distinction that it is confined to
sensation from the internal organs (following relay in the thalamus), and