Biomedical Engineering Reference
In-Depth Information
Extrapolating from observation of facial expression, he theorized that the ex-
pression of emotion communicates internal motivational states between organ-
isms. Experimental evidence supporting such a thesis of internal sources for
emotion was produced by Cannon (50) and others (49,73,144,147). An alterna-
tive theory on emotion from James and Lange (129,145) posited that sensory
inputs regarding bodily function were central to emotional experience. The
James-Lange thesis has also been supported by experimental data (65). These
perspectives on emotional function are both represented by processes within the
general schema for motivation in Figure 4. By this view, emotion represents an
interaction between processes for (1) evaluation of potential deficit states, (2)
prediction of future needs, (3) processing of sensory input about the condition of
the body and others' bodies, (4) assessment of the presence of potential goal-
objects or aversive events that might alter particular deficit states, and (5) re-
trieval and updating of memories regarding (a) the outcome of prior deficit
states, (b) social interactions plus conversations, and (c) contexts with particular
goal-objects or aversive events. A view of this sort potentially allows for the
intrapsychic complexity of human psychology (177). It conceptualizes emotion
within the schema of motivation, potentially permitting linkage to processes that
have been a strong focus of cognitive neuroscience research, and synthesizing
the original perspectives of Darwin and James.
In Figure 4, processes shown in solid blue are supported by behavioral and
neuroscience data. Processes determining input and output to the organism ap-
pear to be readily observed via experimentation. In contrast, the processes
shown in light green are supported by emerging behavioral data, although much
remains to be known about their systems biology. Relatively recently, the proc-
esses indicated with purple dashes (also see subprocesses at the bottom of Figure
3) have been associated with neural activity in a distributed set of deep brain
regions, suggesting that they are part of an informational backbone for motiva-
tion processing rewarding and aversive events.
4.
NEUROIMAGING OF THE GENERAL REWARD
/
AVERSION
SYSTEM UNDERLYING MOTIVATED BEHAVIOR
Animal studies implicate the many projection fields of the VT dopamine
neurons—such as the nucleus accumbens (NAc), hypothalamus, amygdala,
sublenticular extended amygdala (SLEA) of the basal forebrain, and multiple
fields in the paralimbic girdle (117,154,174,263) (Figure 5)—as components of
the neural system that selects rewarding goal-objects and avoids their obverse.
Over the last 8 years, functional neuroimaging studies of humans have identified
homologous systems to be processing reward/aversion information, and have
begun to dissect their contributions to motivated behavior.
