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.  _( June 2015  ) _

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See also:  Reward system 

Some researchers believe that the use of somatic markers (i.e.,  afferent
feedback  ) would be a very
inefficient method of influencing behavior. Damasio's notion of the _as-if_
experience dependent feedback route,  [1]  [20]  whereby bodily responses are
re-represented utilizing the somatosensory cortex (  postcentral gyrus
 ), also proposes an inefficient
method of affecting explicit behavior.  [21]  Rolls (1999) stated that; "it
would be very inefficient and noisy to place in the execution route a
peripheral response, and transducers to attempt to measure that peripheral
response, itself a notoriously difficult procedure" (p. 73).  [21]
Reinforcement association located in the orbitofrontal cortex and amygdala,
where the incentive value of stimuli is decoded, is sufficient to elicit
emotion-based learning and to affect behavior via, for example, the 
orbitofrontal-striatal pathway  .  [21]  [22]  This process can occur via implicit or explicit
processes.  [21]

The somatic marker hypothesis represents a model of how feedback from the body
may contribute to both advantageous and disadvantageous decision-making in
situations of complexity and uncertainty. Much of its supporting data comes
from data taken from the Iowa gambling task.  [23]  While the Iowa gambling
task has proven to be an ecologically valid measure of decision-making
impairment, there exist three assumptions that need to hold true.

First, the claim that it assesses implicit learning as the reward/punishment
design is inconsistent with data showing accurate knowledge of the task
possibilities  [24]  and that mechanisms such as working-memory appear to have
a strong influence. Second, the claim that this knowledge occurs through
preventive marker signals is not supported by competing explanations of the
psychophysiology generated profile.  [25]  Lastly, the claim that the
impairment is due to a 'myopia for the future' is undermined by more plausible
psychological mechanisms explaining deficits on the tasks such as reversal
learning, risk-taking, and working-memory deficits. There may also be more
variability in control performance than previously thought, thus complicating
the interpretation of the findings.

Furthermore, although the somatic marker hypothesis has accurately identified
many of the brain regions involved in decision-making, emotion, and body-state
representation, it has failed to clearly demonstrate how these processes
interact at a psychological and evolutionary level. There are many experiments
that could be implemented to further test the somatic marker hypothesis. One
way would be to develop variants of the Iowa gambling task that control some
of the methodological issues and interpretation ambiguities generated. It may
be a good idea to include removing the reversal learning confound, which would
make the task more difficult to consciously comprehend. Additionally, causal
tests of the somatic marker hypothesis could be practiced more insistently in
a greater range of populations with altered peripheral feedback, like on
patients with facial paralysis.

In conclusion, the somatic marker hypothesis needs to be tested in more
experiments. Until a wider range of empirical approaches are employed in order
to test the somatic marker hypothesis, it appears that the framework is simply
an intriguing idea that is in need of some better supporting evidence. Despite
these issues, the somatic marker hypothesis and the Iowa gambling task
reestablish the notion that emotion has the potential to be a benefit as well
as a problem during the decision-making process in humans.  [26]