TY - UNPB

T1 - Pedunculopontine-stimulation obstructs hippocampal theta rhythm and halts movement

AU - Berg, Rune W.

AU - Komi, Salif Axel

AU - Dmytriyeva, Oksana

AU - Houser, Grace Anne

AU - Bonfils, Madelaine C A

AU - Kaur, Jaspreet

PY - 2024

Y1 - 2024

N2 - It is known that movement arrest can be induced by optogenetic stimulation of a brainstem nucleus, the pedunculopontine nucleus (PPN)1–6. This evoked arrest appears conspicuously similar to the freezing behavior often seen as a fear response. Nevertheless, the behavior could also represent a global halting mechanism for movement. This introduces two possible roles of this nucleus: A hub for orchestrating fear-related responses or an omnipotent halting mechanism devoid of emotional components that could, in principle, encompass brain activities other than movement per se. We seek to understand this phenomenon better by engaging the distinct electrical brain activity, the hippocampal theta rhythm7,8. It is prominent during locomotor activity in rodents9–13 and immobile yet vigilant states like freezing14–18. We recorded the hippocampal brain rhythm before and during movement arrest induced by optogenetic stimulation of the PPN in rats. The motor arrest was associated with a clear obstruction of the ongoing theta activity. The timescale of movement arrest was less than 200 ms, similar to the obstruction of the theta rhythm. Since anxiety, fear, and behavioral freezing are associated with hippocampal theta rhythm, which we did not see during PPN stimulation, we suggest that induced motor arrest occurs without an associated emotional component.

AB - It is known that movement arrest can be induced by optogenetic stimulation of a brainstem nucleus, the pedunculopontine nucleus (PPN)1–6. This evoked arrest appears conspicuously similar to the freezing behavior often seen as a fear response. Nevertheless, the behavior could also represent a global halting mechanism for movement. This introduces two possible roles of this nucleus: A hub for orchestrating fear-related responses or an omnipotent halting mechanism devoid of emotional components that could, in principle, encompass brain activities other than movement per se. We seek to understand this phenomenon better by engaging the distinct electrical brain activity, the hippocampal theta rhythm7,8. It is prominent during locomotor activity in rodents9–13 and immobile yet vigilant states like freezing14–18. We recorded the hippocampal brain rhythm before and during movement arrest induced by optogenetic stimulation of the PPN in rats. The motor arrest was associated with a clear obstruction of the ongoing theta activity. The timescale of movement arrest was less than 200 ms, similar to the obstruction of the theta rhythm. Since anxiety, fear, and behavioral freezing are associated with hippocampal theta rhythm, which we did not see during PPN stimulation, we suggest that induced motor arrest occurs without an associated emotional component.

KW - Faculty of Health and Medical Sciences

U2 - 10.21203/rs.3.rs-3876253/v1

DO - 10.21203/rs.3.rs-3876253/v1

M3 - Preprint

SP - 1

EP - 14

BT - Pedunculopontine-stimulation obstructs hippocampal theta rhythm and halts movement

PB - Research Square

ER -