Inter-hemispheric wave propagation failures in traumatic brain injury are indicative of callosal damage.
Approximately 3.2-5.3 million Americans live with the consequences of a traumatic brain injury (TBI), making TBI one of the most common causes of disability in the world. Visual deficits often accompany TBI but physiological and anatomical evidence for injury in mild TBI is lacking. Axons traversing the corpus callosum are particularly vulnerable to TBI. Hemifield representations of early visual areas are linked by bundles of fibers that together cross the corpus callosum while maintaining their topographic relations. Given the increased vulnerability of the long visual axons traversing the corpus callosum, we hypothesized that inter-hemispheric transmission for vision will be impaired following mild TBI. Using the travelling wave paradigm (Wilson, Blake, & Lee 2001), we measured inter-hemispheric transmission in terms of both speed and propagation failures in 14 mild TBI patients and 14 age-matched controls. We found that relative to intra-hemispheric waves, inter-hemispheric waves were faster and that the inter-hemispheric propagation failures were more common in TBI patients. Furthermore, the transmission failures were topographically distributed, with a bias towards greater failures for transmission across the upper visual field. We discuss the results in terms of increased local inhibition and topographically-selective axonal injury in mild TBI.
Traumatic Brain Injury Program, The Research Institute of the McGill University Health Center, Montréal, Canada; McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montréal, Canada. Electronic address: daniel.spiegel@mcgill.ca.
Daniel P
DP
Spiegel
Traumatic Brain Injury Program, The Research Institute of the McGill University Health Center, Montréal, Canada; Department of Neurology and Neurosurgery, McGill University, Montréal, Canada.
Maude
M
Laguë-Beauvais
McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montréal, Canada.
Gaurav
G
Sharma
Traumatic Brain Injury Program, The Research Institute of the McGill University Health Center, Montréal, Canada; McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montréal, Canada. Electronic address: reza.farivar@mcgill.ca.
Reza
R
Farivar
D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology*; D003337:Corpus Callosum / Q000293:injuries*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009435:Synaptic Transmission / Q000502:physiology*; D014786:Vision Disorders / Q000209:etiology / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult
Binocular rivalry; Corpus callosum; Intra-hemispheric; Traumatic brain injury; Vision; Visual deficit