The modulation of hippocampal theta rhythm by the vestibular system

Abstract

The vestibular system is a sensory system that has evolved over millions of years to detect acceleration of the head, both rotational and translational, in three dimensions. One of its most important functions is to stabilize gaze during unexpected head movement; however, it is also important in the control of posture and autonomic reflexes. Theta rhythm is a 3- to 12-Hz oscillating EEG signal that is intimately linked to self-motion and is also known to be important in learning and memory. Many studies over the last two decades have shown that selective activation of the vestibular system, using either natural rotational or translational stimulation, or electrical stimulation of the peripheral vestibular system, can induce and modulate theta activity. Furthermore, inactivation of the vestibular system has been shown to significantly reduce theta in freely moving animals, which may be linked to its impairment of place cell function as well as spatial learning and memory. The pathways through which vestibular information modulate theta rhythm remain debatable. However, vestibular responses have been found in the pedunculopontine tegmental nucleus (PPTg) and activation of the vestibular system causes an increase in acetylcholine release into the hippocampus, probably from the medial septum. Therefore, a pathway from the vestibular nucleus complex and/or cerebellum to the PPTg, supramammillary nucleus, posterior hypothalamic nucleus, and septum to the hippocampus is likely. The modulation of theta by the vestibular system may have implications for vestibular effects on cognitive function and the contribution of vestibular impairment to the risk of dementia.

EEG dynamics and neural generators of psychological flow during one tightrope performance

“…This corroborates a 2016 report by Hülsdünker et al 42 , showing increased theta power in the frontal, central, and parietal regions when a balance task became more challenging. This finding is also compatible with evidence that the vestibular system can modulate theta oscillation 43 .…”

Vestibular function and cortical and sub-cortical alterations in an aging population

“…Moreover, several studies have shown that vestibular lesions result in loss of location-specific firing of place cells, which largely reside in CA1 [ 71 , 72 ]. Further, theta rhythm, an EEG rhythm important for the coordination of place cells, has also been shown to be disrupted in CA1 and the ERC after bilateral vestibular deactivation or lesions in rats [ 73 , 74 , 75 , 76 , 77 ]. In addition, the ERC projects strongly to CA3 and CA1 of the hippocampus [ 78 ].…”

Slouched Posture, Sleep Deprivation, and Mood Disorders: Interconnection and Modulation by Theta Brain Waves

“…It has been suggested that hippocampal theta is actually linked to attention and arousal (Jacobs, Lega, & Watrous, 2017). This type of theta has been linked to sensorimotor functions (Bland & Oddie, 2001;Burgess, Barry, & O'Keefe, 2007;Ekstrom et al, 2005;Hoffman et al, 2013;Jacobs et al, 2017;Lopour, Tavassoli, Fried, & Ringach, 2013;Mormann et al, 2005;Watrous, Fried, & Ekstrom, 2011), spatial navigation (Aitken, Zheng, & Smith, 2018;Ekstrom et al, 2005;Jacobs et al, 2017;Kahana, Sekuler, Caplan, Kirschen, & Madsen, 1999;Vass et al, 2016;Watrous et al, 2011), episodic memory coding (Jacobs et al, 2017), and, of particular interest, head position all through its connection to the vestibular system (Aitken et al, 2018).…”

“…One of the functions of the vestibular system, specifically that of the vestibular organs within the inner ear, is to allow people to sense head acceleration; from this, the head position can then be calculated (Aitken et al, 2018). While there is currently very little research on how EEG brain waves change as head position shifts, Spironelli, Busenello, and Angrilli (2016) found that lying in a supine position correlated with decreased cortical activity and increased alpha and delta wave amplitude compared to seated position.…”