Brain Rhythms: Higher-Frequency Theta Oscillations Make Sense in Moving Humans

Abstract

The hippocampal theta rhythm is critical for learning and memory. New research demonstrates that theta oscillations in freely moving humans are similar in frequency and function to those observed in rodents and are modulated by movement speed and exploratory behavior.

Functionally distinct high and low theta oscillations in the human hippocampus

“…Two recent studies measured human hippocampal oscillations from people walking in the physical world and reported high-theta oscillations (Bohbot et al, 2017; Aghajan et al, 2016; but see Meisenhelter et al, 2018). These results were interpreted to suggest that virtual navigation relies on a fundamentally different, lower-frequency oscillatory network state compared to real-world navigation (Yassa, 2018); however, it should be noted that at least one of the studies that previously showed high-theta oscillations in real-world navigation showed examples of these patterns at relatively posterior locations (Bohbot et al, 2017). By demonstrating that humans can show high theta during virtual-reality, our results suggest a different view.…”

“…Some studies in humans show hippocampal oscillations at 1–5 Hz that have similar functional properties as the theta oscillations seen in rodents (e.g., Arnolds et al, 1980; Jacobs et al, 2007; Vass et al, 2016; Watrous et al, 2011; Watrous, Lee, et al, 2013; Jacobs, 2014). There is also evidence that human movement-related hippocampal theta oscillations vary substantially in frequency according to whether a subject is in a physical or virtual environment (Aghajan et al, 2016; Bohbot et al, 2017; Yassa, 2018). Together, these studies have been interpreted to suggest that the human hippocampus does show a signal analogous to theta oscillations observed in rodents but that this oscillation is more variable and slower in frequency (Jacobs, 2014).…”

Perspective: Assessing the Flexible Acquisition, Integration, and Deployment of Human Spatial Representations and Information

“…Similarly, low-frequency, movement-related theta oscillations in the hippocampus, semi-periodic fluctuations in the local field potential that manifest during navigation, are present during desktop VR ( Watrous et al, 2011 , 2013 ; Bohbot et al, 2017 ), retrieval of spatial information ( Ekstrom et al, 2007 ), encoding and retrieval of verbal associations ( Sederberg et al, 2003 ; Yaffe et al, 2014 ), and during real-world navigation ( Aghajan et al, 2017 ; Bohbot et al, 2017 ). One possibility is that the frequency of theta oscillations during real-world navigation in humans might be higher than VR, similar to higher frequency theta oscillations in rodents ( Yassa, 2018 ). This in turn might seem to bolster the argument that VR and real-world navigation alter underlying neural representations ( Aghajan et al, 2017 ).…”

Retrieving Against the Flow: Incoherence Between Optic Flow and Movement Direction Has Little Effect on Memory for Order

“…In the human realm, there is empirical evidence suggesting that the entorhinal cortex is implicated in spatial processing, as shown by fMRI data reported by Nau et al ( 2018 ), and the relation between the theta rhythm and movement has also been demonstrated (Yassa, 2018 ). For example, on the basis of intracranial electroencephalographic activity in the medial temporal lobe, Aghajan et al ( 2017 ) were able to observe that theta power was significantly higher when participants moved in a real-world controlled environment than when they were stationary.…”