title: Decision-making deficit of a patient with axonal damage after traumatic brain injury.
abstract: 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.
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan. Electronic address: ejm86rp@yahoo.co.jp.
authors: Fumihiko
authors: F
authors: Yasuno
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Kiwamu
authors: K
authors: Matsuoka
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Soichiro
authors: S
authors: Kitamura
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Kuniaki
authors: K
authors: Kiuchi
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Jun
authors: J
authors: Kosaka
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Koji
authors: K
authors: Okada
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Syohei
authors: S
authors: Tanaka
authors: Department of Radiation Oncology, Nara Medical University, Kashihara, Japan.
authors: Takayuki
authors: T
authors: Shinkai
authors: Department of Radiology, Nara Medical University, Kashihara, Japan.
authors: Toshiaki
authors: T
authors: Taoka
authors: Department of Psychiatry, Nara Medical University, Kashihara, Japan.
authors: Toshifumi
authors: T
authors: Kishimoto
mesh_terms: D000328:Adult; D001369:Axons / Q000473:pathology*; D001930:Brain Injuries / Q000473:pathology*; D003657:Decision Making / Q000502:physiology*; D056324:Diffusion Tensor Imaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012306:Risk; D015899:Tomography, Emission-Computed, Single-Photon
keywords: Decision-maiking process; Diffusion tensor imaging (DTI); Somatic-marker hypothesis; Traumatic Brain Injury (TBI); Voxel-based morphometry (VBM)