title: Brain Regions Influencing Implicit Violent Attitudes: A Lesion-Mapping Study.
abstract: Increased aggression is common after traumatic brain injuries and may persist after cognitive recovery. Maladaptive aggression and violence are associated with dysfunction in the prefrontal and temporal cortex, but such dysfunctional behaviors are typically measured by explicit scales and history. However, it is well known that answers on explicit scales on sensitive topics--such as aggressive thoughts and behaviors--may not reveal true tendencies. Here, we investigated the neural basis of implicit attitudes toward aggression in humans using a modified version of the Implicit Association Task (IAT) with a unique sample of 112 Vietnam War veterans who suffered penetrating brain injury and 33 healthy controls who also served in combat in Vietnam but had no history of brain injury. We hypothesized that dorsolateral prefrontal cortex (dlPFC) lesions, due to the crucial role of the dlPFC in response inhibition, could influence performance on the IAT. In addition, we investigated the causal contribution of specific brain areas to implicit attitudes toward violence. We found a more positive implicit attitude toward aggression among individuals with lesions to the dlPFC and inferior posterior temporal cortex (ipTC). Furthermore, executive functions were critically involved in regulating implicit attitudes toward violence and aggression. Our findings complement existing evidence on the neural basis of explicit aggression centered on the ventromedial prefrontal cortex. These findings highlight that dlPFC and ipTC play a causal role in modulating implicit attitudes about violence and are crucially involved in the pathogenesis of aggressive behavior.
  
  
  CONCLUSIONS
  Maladaptive aggression and violence can lead to interpersonal conflict and criminal behavior. Surprisingly little is known about implicit attitudes toward violence and aggression. Here, we used a range of techniques, including voxel-based lesion-symptom mapping, to examine the causal role of brain structures underpinning implicit attitudes toward aggression in a unique sample of combat veterans with traumatic brain injury. We found that damage to the dorsolateral prefrontal cortex (dlPFC) led to a more positive implicit attitude toward violence that under most normal situations would be considered inappropriate. These results suggest that treatments aimed at increasing cognitive control using cognitive behavioral therapies dependent on the intact dlPFC could treat aggressive and violent behavior.
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611, Department of Physical Medicine and Rehabilitation and jgrafman@northwestern.edu irene.cristofori@gmail.com.
authors.forename: Irene
authors.identifier: http://orcid.org/0000-0003-2339-1457
authors.initials: I
authors.lastname: Cristofori
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611, Department of Physical Medicine and Rehabilitation and.
authors.forename: Wanting
authors.identifier: http://orcid.org/0000-0002-6025-1739
authors.initials: W
authors.lastname: Zhong
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611.
authors.forename: Valerie
authors.identifier: http://orcid.org/0000-0001-9164-4378
authors.initials: V
authors.lastname: Mandoske
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611.
authors.forename: Aileen
authors.initials: A
authors.lastname: Chau
authors.affiliation: Molecular Neuroscience Department and Department of Psychology, George Mason University, Fairfax, Virginia 22030.
authors.forename: Frank
authors.identifier: http://orcid.org/0000-0003-3420-2463
authors.initials: F
authors.lastname: Krueger
authors.affiliation: Department of Psychology, George Mason University, Fairfax, Virginia 22030.
authors.forename: Maren
authors.initials: M
authors.lastname: Strenziok
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611, Department of Physical Medicine and Rehabilitation and Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, and jgrafman@northwestern.edu irene.cristofori@gmail.com.
authors.forename: Jordan
authors.identifier: http://orcid.org/0000-0001-8645-4457
authors.initials: J
authors.lastname: Grafman
mesh_terms: D000368:Aged; D000374:Aggression; D001290:Attitude; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D001931:Brain Mapping; D003072:Cognition Disorders / Q000209:etiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D015898:Tomography Scanners, X-Ray Computed; D014728:Veterans; D047829:Vietnam Conflict
keywords: aggression; implicit attitudes; traumatic brain injury