Toyota R&D study finds drivers show significantly more gray matter in brain regions than non-drivers
A brain study by researchers from Toyota Central R&D Laboratories, along with a colleague from Japan’s National Institute of Physiological Sciences, has found that drivers show significantly greater gray matter (GM) volume in the left cerebellar hemisphere—which has been associated with cognitive rather than motor functioning—than non-drivers. An open access paper on their work is published in the journal Scientific Reports.
Previous neuroimaging studies have found multiple brain areas associated with distinct aspects of car driving in simulated traffic environments. Few studies, however, have examined brain morphology associated with everyday car-driving experience in real traffic, the researchers said. Their goal was to identify gray matter volume differences between drivers and non-drivers.
Driving is a complex everyday activity that requires multiple types of sensory processing, cost-weighted decision making, precise motor control, and other abilities. Even on an empty road, drivers must continuously operate the steering wheel and pedals in consideration of complicated vehicle dynamics. Driving is also a vigilance task, which is often undertaken for prolonged periods of time, and carries a constant risk of injury or death resulting from collisions. Despite this, driving is commonly thought to provide pleasure, at least, in certain circumstances or among car enthusiasts. Each of these features shapes the peculiarities of car driving in everyday life experiences.
It is widely accepted that experience can alter the structure of the brain. … it is highly likely that everyday car-driving experience modulates the structure of specific brain regions associated with the demands of driving a car in real traffic. However, few studies have investigated brain morphology associated with car-driving experience.—Sakai et al.
The team recruited university students with either a few years’ or no driving experience and collected structural brain images for a whole-brain voxel-based morphometry (VBM) analysis to examine between-group differences in regional gray matter volume.
The whole-brain VBM analysis found brain regions showing greater GM volume (adjusted for age) in drivers compared to non-drivers; no brain areas showed a significantly larger GM volume in non-drivers compared with drivers.
Within the limitations of cross-sectional investigation, the current results demonstrate that a few years of car-driving experience in real traffic is associated with greater GM volume in the left cerebellar hemisphere. However, it is not possible to completely rule out hidden factors confounded with car-driving experience. Any activities and experiences concomitant with the selection of the primary transportation mode (i.e., to use or not use a car) are potential confounding factors between drivers and non-drivers. In that respect, the most obvious limitation of this study is that transportation modes in non-drivers were not fully assessed.
Accordingly, given the results of the present study, we cannot specify which aspects of car driving are associated with left cerebellar GM increase. In addition, larger cerebellar GM volume might foster more interest in car driving, rather than be a consequence of car-driving experience. To overcome these limitations, it is desirable to conduct a larger sample, randomized longitudinal study that collects detailed information regarding not only frequency and type of usage of cars in drivers but also transportation modes in non-drivers, as well as the concomitant activities and experiences in both groups.—Sakai et al.
Toyota Central R&D Laboratories funded the study.
Hiroyuki Sakai, Takafumi Ando, Norihiro Sadato & Yuji Uchiyama (2017) “Greater cerebellar gray matter volume in car drivers: an exploratory voxel-based morphometry study” Scientific Reports 7, Article number: 46526 doi: 10.1038/srep46526