Theta Oscillations and Human Navigation: A Magnetoencephalography Study

Abstract

Magnetoencephalography (MEG) was used to study alpha and theta activity while subjects navigated through a computer-generated virtual reality town. The subjects were first allowed to explore the environment freely. They then had to navigate from a starting point to a destination, knowing that an obstruction would appear at one of several possible locations along the main route and force them to take a detour. Spatiotemporal analysis of the theta and alpha bands were performed (1) prior to the start of navigation, (2) from the start of navigation until the obstruction was encountered, (3) during the time subjects were contemplating a detour and were not navigating, and (4) from the resumption of navigation until the destination was reached. In all subjects, theta power was strongest during the two periods of navigation. The peak frequency of the oscillations was approximately 3.7 Hz. Control studies consisted of a motor task similar to that required for navigation, passive viewing of a tour through the same virtual reality town, and a mental concentration task. No consistent increases in theta power were seen in the MEG during any of the control tasks. The results suggest an association between theta rhythm and the performance of navigational tasks in humans.

Brain Oscillatory Activity during Spatial Navigation: Theta and Gamma Activity Link Medial Temporal and Parietal Regions

“…Gamma and theta oscillations have been linked with numerous aspects of human spatial navigation using iEEG (Caplan et al, 2001;Ekstrom et al, 2005;Jacobs et al, 2009) and MEG (Cornwell et al, 2008;de Araújo et al, 2002). Our findings replicate observed theta and gamma oscillations within parietal and medial temporal regions during spatial navigation.…”

“…Hartley et al, 2003;Iaria et al, 2007), EEG studies have reported theta and gamma activity associated with a number of behaviours associated with virtual movement Jacobs et al, 2009), suggesting a line-following control is inappropriate in such studies. de Araújo et al (2002) explored an appropriate control condition in an MEG study of human navigation, focussing on theta activity. These researchers excluded frontal midline theta, the motor demands of the task, and passive viewing of the visual environment as factors explaining enhanced theta in virtual town navigation, albeit using MEG sensors largely distributed over temporal regions.…”

“…Elevated theta power associated with VR navigation has been demonstrated using MEG (Cornwell et al, 2008;de Araújo et al, 2002). Using a VR town navigation task, a strong increase in theta power during periods of navigation was localized to temporal and parietal regions using a single current dipole model; the authors concluding that more sophisticated source modelling could provide more definitive evidence of medial temporal involvement (de Araújo et al, 2002).…”

“…Using a VR town navigation task, a strong increase in theta power during periods of navigation was localized to temporal and parietal regions using a single current dipole model; the authors concluding that more sophisticated source modelling could provide more definitive evidence of medial temporal involvement (de Araújo et al, 2002). Using a beamformer spatial filtering technique, elevated theta activity during navigation using a modified VR Morris water maze was observed in left hippocampal and parahippocampal regions (Cornwell et al, 2008).…”

Increased mesiotemporal delta activity characterizes virtual navigation in humans

“…This is an important issue since in the human literature there is abundant data on theta that was found during virtual navigation (Kahana et al, 1999;de Araújo et al, 2002;Bischof & Boulanger, 2003;Ekstrom et al, 2005) working memory tasks (Tesche & Karhu, 2000;Raghavachari et al, 2001;Schauseng et al, 2004) and REM sleep (Cantero et al, 2003 ). These studies report theta appearing in short and phasic bursts instead of continuous activity typically seen in animals.…”