title: Frontotemporal correlates of impulsivity and machine learning in retired professional athletes with a history of multiple concussions.
abstract: The frontotemporal cortical network is associated with behaviours such as impulsivity and aggression. The health of the uncinate fasciculus (UF) that connects the orbitofrontal cortex (OFC) with the anterior temporal lobe (ATL) may be a crucial determinant of behavioural regulation. Behavioural changes can emerge after repeated concussion and thus we used MRI to examine the UF and connected gray matter as it relates to impulsivity and aggression in retired professional football players who had sustained multiple concussions. Behaviourally, athletes had faster reaction times and an increased error rate on a go/no-go task, and increased aggression and mania compared to controls. MRI revealed that the athletes had (1) cortical thinning of the ATL, (2) negative correlations of OFC thickness with aggression and task errors, indicative of impulsivity, (3) negative correlations of UF axial diffusivity with error rates and aggression, and (4) elevated resting-state functional connectivity between the ATL and OFC. Using machine learning, we found that UF diffusion imaging differentiates athletes from healthy controls with significant classifiers based on UF mean and radial diffusivity showing 79-84 % sensitivity and specificity, and 0.8 areas under the ROC curves. The spatial pattern of classifier weights revealed hot spots at the orbitofrontal and temporal ends of the UF. These data implicate the UF system in the pathological outcomes of repeated concussion as they relate to impulsive behaviour. Furthermore, a support vector machine has potential utility in the general assessment and diagnosis of brain abnormalities following concussion.
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room MP14-306, Toronto, ON, M5T 2S8, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Goswami
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Department of Medical Imaging, Toronto Western Hospital and University of Toronto, Toronto, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Dufort
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Canada.|Division of Neurology, Krembil Neuroscience Centre, Toronto, Canada.
authors.forename: M C
authors.initials: MC
authors.lastname: Tartaglia
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Toronto Rehabilitation Institute, University Health Network, Toronto, Canada.
authors.forename: R E
authors.initials: RE
authors.lastname: Green
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room MP14-306, Toronto, ON, M5T 2S8, Canada.|Department of Medical Imaging, Toronto Western Hospital and University of Toronto, Toronto, Canada.|Institute of Medical Science, University of Toronto, Toronto, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Crawley
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room MP14-306, Toronto, ON, M5T 2S8, Canada.|Institute of Medical Science, University of Toronto, Toronto, Canada.|Division of Neurosurgery, Krembil Neuroscience Centre, Toronto Western Hospital, Toronto, Canada.|Department of Surgery, University of Toronto, Toronto, Canada.
authors.forename: C H
authors.initials: CH
authors.lastname: Tator
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Division of Neurology, Krembil Neuroscience Centre, Toronto, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Wennberg
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room MP14-306, Toronto, ON, M5T 2S8, Canada.|Department of Medical Imaging, Toronto Western Hospital and University of Toronto, Toronto, Canada.|Institute of Medical Science, University of Toronto, Toronto, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Mikulis
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada.|Department of Occupational Science and Occupational Therapy, University of Toronto and Holland Bloorview Kids Rehabilitation Hospital, Toronto, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Keightley
authors.affiliation: Canadian Sports Concussion Project, Toronto Western Hospital, Toronto, Canada. kdavis@uhnres.utoronto.ca.|Division of Brain, Imaging and Behaviour-Systems Neuroscience, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Room MP14-306, Toronto, ON, M5T 2S8, Canada. kdavis@uhnres.utoronto.ca.|Institute of Medical Science, University of Toronto, Toronto, Canada. kdavis@uhnres.utoronto.ca.|Department of Surgery, University of Toronto, Toronto, Canada. kdavis@uhnres.utoronto.ca.
authors.forename: Karen D
authors.initials: KD
authors.lastname: Davis
mesh_terms: D000328:Adult; D000368:Aged; D000374:Aggression / Q000502:physiology; D056352:Athletes / Q000523:psychology; D001924:Brain Concussion / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D005538:Football / Q000293:injuries; D005625:Frontal Lobe / Q000473:pathology* / Q000503:physiopathology*; D066128:Gray Matter / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007175:Impulsive Behavior / Q000502:physiology*; D000069550:Machine Learning; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000473:pathology / Q000503:physiopathology; D012680:Sensitivity and Specificity; D013702:Temporal Lobe / Q000473:pathology* / Q000503:physiopathology*
keywords: Concussion; Connectivity; Cortical thickness; Impulsivity; Machine learning; Uncinate fasciculus