Biomedical Engineering Reference
In-Depth Information
The subcortical gray matter and paralimbic cortices that assess re-
ward/aversion information as part of a theoretical iBM (Figures 2 and 3) also
appear to be integrated into other processes for: (1) selection of objectives for
fitness and (2) behavior. Perceptual inputs from multiple channels are processed
through successive stages in unimodal association regions of the frontal, tempo-
ral and parietal cortices. This processing achieves more complex discrimination
of features relevant for organizing behavior (Figure 3). Channel-specific infor-
mation is conveyed to multimodal areas for intermodal integration in the neocor-
tical heteromodal association areas. In turn, information relayed to paralimbic
and limbic structures such as the cingulate gyrus, the insula, the orbitofrontal,
frontomedial, parahippocampal and temporopolar cortices, as well as the amyg-
dala, sublenticular extended amygdala, and hippocampus, is used for feature
extraction and encoding. Feature extraction and integration for probability de-
termination further involves the orbitofrontal cortex, amygdala, and cingulate
gyrus, with the ventral tegmentum and nucleus accumbens septi. Contingent
probability assessments require extensive working memory and attentional re-
sources, and thus will be integrated with activity in limbic brain stem structures,
and heteromodal frontal, parietal, and limbic cortices in a modality- and domain-
specific way. These probability assessments are necessary for making predic-
tions about future homeostatic needs or potential deficit states, and, accordingly,
will be involved in selecting objectives for fitness over time (Figures 2-4). They
can also be important for prediction of effects of social interactions on homeo-
static needs, and for focusing the majority of behavioral output on social func-
tions. Valuation and probability computations around possible goal-objects and
events, their combination as outcomes, and subsequent counterfactual compari-
sons are further integrated with information regarding the costs of changing
body position in space, potential risks to action and inaction, and discounted
benefits of other consummatory opportunities. Subcortical gray matter and para-
limbic cortices function in concert with multiple corticothalamic circuits for
determination of physical plans and actual behavior. For instance, the cingulate
gyrus has extensive involvement with the alteration of attention for motivational
state. Other paralimbic cortices and ventral striatal regions interact with the sup-
plementary motor and premotor frontal areas in preparation for executive behav-
ior and directed action appropriate to environmental and internal factors
(173,180,184,195).
The circuits that process reward/aversion information as an iBM, and inter-
act with other brain regions to produce behavior and to determine objectives
optimizing fitness, are fundamental for normal emotion function, as well as its
malfunction. The systems biology of reward/aversion assessment, in line with
the systems biology of other subprocesses such as attention or memory, repre-
sents an interface across which the genome, epigenome, and environment inter-
act. The interaction of the genome, epigenome, and environment across this
interface (see Figure 14) determines the set of all possible behaviors. This inter-
