Brain activation of actual but not simulated car-driving using PET and [18F]FDG

Background and Aims: Car-driving is a combination of complex neural tasks such as attention, perception, integration of visual and somatosensory inputs, generation of motor outputs and action controls. Though the car-driving is not a difficult task for many experienced drivers, all drivers might sometimes encounter potentially-dangerous situations induced by cognitive and psychomotor deficits due to aging, neurological disorders, sedative drugs and mobile phone use. Therefore, elucidation of the brain mechanism during car-driving is important and might lead to development of an effective system to prevent accidents. The present study aims at identifying the brain activation during actual car-driving on the road, and at comparing the result to those of previous studies on simulated car-driving. Methods: Thirty normal volunteers, aged 20 to 56 years, were divided into three subgroups, active driving, passive driving and control groups, for examination by positron emission tomography (PET) and [18F]2-deoxy-2-fluoro-D-glucose (FDG). The active driving subjects (n=10) drove for 30 minutes on quiet normal roads with a few traffic signals. The passive driving subjects (n=10) participated as passengers on the front seat. The control subjects (n=10) remained to be seated in a lit room with their eyes open. Voxel-based t-statistics were applied using SPM2 to search of brain activation among the subgroups mentioned above. Results: Significant brain activation was detected during active driving in the primary and secondary visual cortices, primary sensorimotor areas, premotor area, the parietal association area, the cingulate gyrus, the parahippocampal gyrus as well as in the thalamus and cerebellum. The passive driving manifested a similar-looking activation pattern, lacking activations in the premotor area, the cingulate and parahippocampal gyri and in the thalamus. Direct comparison of the active and passive driving conditions revealed activation in the cerebellum. Conclusions: So far, several activation studies during simulated car-driving have been conducted using functional MRI and PET with [15O]H2O. The result of actual driving seemed to be similar to that of simulated driving, suggesting that visual perception and visuomotor coordination were the main brain functions while driving. In terms of attention and autonomic arousal, however, it seems there was a significant difference between simulated and actual driving possibly due to risk of accidents. Autonomic and emotional aspects of driving should be studied using actual driving study-design. Functional neuroimaging using actual and simulated car-driving task will be a useful tool in the filed of transportation medicine.