Biomedical Engineering Reference
In-Depth Information
Figure 11
. The bottom row of images indicates the anatomy of subcortical gray matter regions and paralimbic
cortex. The top row of images consolidates reports of significant signal change for a number of distinct cate-
gories of rewarding stimuli in these regions. The colored symbols on the brain slices in the top row consoli-
date activation surveyed from 26 studies of reward function in healthy controls. These include four studies
focused on appetitive reward with fruit juice, chocolate, or pleasant tastes. Ten studies utilized monetary
reward (five with a guessing paradigm determining compensation, four with a performance task determining
compensation, and one with a prospect theory based game of chance). Five studies focused on some aspect of
social reward (two with beautiful faces, one with passive viewing of a loved face, and two with music stim-
uli). Five studies involved amphetamine or procaine reward, and two studies focused on a probabilistic para-
digm. The gray tone structural images in the bottom row are coronal slices taken (left to right) +18, +6, -6,
and -21 mm relative to the anterior commissure. In this diagram, subcortical gray matter implicated in the
processing of reward and aversion input include the NAc (nucleus accumbens), Put (putamen), Cau (caudate),
SCC (subcallosal cortex), Amyg (amygdala), SLEA (sublenticular extended amygdala), Hypo (hypothala-
mus), GP (globus pallidus), Thal (thalamus), Hipp (hippocampus), VT (ventral tegmentum). Components of
the paralimbic girdle include: sgaCG (subgenual anterior cingulate gyrus), GOb (orbitofrontal cortex), aCG
(anterior cingulate gyrus), pCG (posterior cingulate gyrus), INS (insula), pHip (parahippocampus), and TP
(temporal pole). Abbreviations for anatomy follow the schema adapted from the Massachusetts General
Hospital Center for Morphometric Analysis (37,38,158,175). Figure adapted with permission from Breiter and
Gasic (32).
evaluated relative preferences with multiple categories of beautiful and average
faces. At issue is the question of how to gauge the relative reward value of stim-
uli. Another issue is that all of the drugs infused into healthy controls have
known global effects along with purported regional effects, making the associa-
tion of regional activation to subjective reports of euphoria less certain. Lastly,
most studies compiled in Figure 11 involved monetary reward, which is theo-
rized to substitute for most other categories of reward (47,172). Despite the sali-
ency of expectancy effects, most of these reports did not control for expectancy,
and thus the results reflect a combination of expectancy and outcome effects
(Figures 3 and 7). With these considerations in mind, there appears to be strong
convergence between animal and human studies on the neural basis for re-
ward/aversion (3,19,38,132).
