Research Reports - Decision-making deficits after traumatic brain injury
Brain Cogn. 2014 Feb;84(1):63-8
Yasuno F(1), Matsuoka K(2), Kitamura S(2), Kiuchi K(2), Kosaka J(2), Okada K(2), Tanaka S(2), Shinkai T(3), Taoka T(4), Kishimoto T(2)
Patients with traumatic brain injury (TBI) were reported to have difficulty
making advantageous decisions, but the underlying deficits of the network of
brain areas involved in this process were not directly examined. We report a
patient with TBI who demonstrated problematic behavior in situations of risk and
complexity after cerebral injury from a traffic accident. The Iowa gambling task
(IGT) was used to reveal his deficits in the decision-making process. To examine
underlying deficits of the network of brain areas, we examined T1-weighted
structural MRI, diffusion tensor imaging (DTI) and Tc-ECD SPECT in this patient.
The patient showed abnormality in IGT. DTI-MRI results showed a significant
decrease in fractional anisotropy (FA) in the fasciculus between the brain stem
and cortical regions via the thalamus. He showed significant decrease in gray
matter volumes in the bilateral insular cortex, hypothalamus, and posterior
cingulate cortex, possibly reflecting Wallerian degeneration secondary to the
fasciculus abnormalities. SPECT showed significant blood flow decrease in the
broad cortical areas including the ventromedial prefrontal cortex (VM). Our study
showed that the patient had dysfunctional decision-making process.
Microstructural abnormality in the fasciculus, likely from the traffic accident,
caused reduced afferent feedback to the brain, resulting in less efficient
decision-making. Our findings support the somatic-marker hypothesis (SMH), where
somatic feedback to the brain influences the decision-making process.