Is navigation in virtual reality with FMRI really navigation?

Abstract

Identifying the neural mechanisms underlying spatial orientation and navigation has long posed a challenge for researchers. Multiple approaches incorporating a variety of techniques and animal models have been used to address this issue. More recently, virtual navigation has become a popular tool for understanding navigational processes. Although combining this technique with functional imaging can provide important information on many aspects of spatial navigation, it is important to recognize some of the limitations these techniques have for gaining a complete understanding of the neural mechanisms of navigation. Foremost among these is that, when participants perform a virtual navigation task in a scanner, they are lying motionless in a supine position while viewing a video monitor. Here, we provide evidence that spatial orientation and navigation rely to a large extent on locomotion and its accompanying activation of motor, vestibular, and proprioceptive systems. Researchers should therefore consider the impact on the absence of these motion-based systems when interpreting virtual navigation/functional imaging experiments to achieve a more accurate understanding of the mechanisms underlying navigation.

Figure 1.

Conceptual framework for spatial orientation and navigation. Two major component processes are depicted. Within the gray ellipse on the right, idiothetic cues, which use an egocentric reference frame, are primarily processed by subcortical structures and are used in the path integration system. Within the green ellipse on the left, allothetic cues shown in teal, such as visual, auditory, and tactile information, are combined to provide spatial information about landmarks. Landmark information along with spatial memories concerning context are integrated with the path integration system to yield spatial cells that provide information about the participantʼs spatial orientation with respect to the environment using an allocentric reference frame. This landmark navigational system involves higher level cognitive processes and takes place within limbic and cortical brain areas.