Cardiovascular adjustments during anticipated postural changes

Patel, Neesirg M.; Baker, Ethan A G; Wittman, Samuel R; Engstrom, Isaiah C; Bourdages, George; McCall, Andrew A.; Miller, Derek M.; Yates, Bill J.

doi:10.14814/phy2.13554

Cited by 8 publications

(15 citation statements)

References 40 publications

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“…There was no evidence that changes in activity of most units were initiated prior to the onset of rotations, including neurons with robust responses to tilts. These findings extend prior observations that changes in heart rate and cerebral blood flow do not precede 60º head-up tilts signaled by a light cue (46).…”

Section: Page 19supporting

confidence: 89%

“…Cardiovascular responses to a variety of stimuli can be conditioned in animals and humans, such that they are subsequently elicited by cues that are associated with the triggering event (34,41). In a prior study, a light cue preceded 60º head-up rotations of conscious felines that were instrumented to record cerebral blood flow, to ascertain whether brain perfusion or heart rate were modified by a conditioning stimulus paired to the postural alteration (46). This study found no evidence that either heart rate or cerebral blood flow were altered after the cue and prior to the onset of body movement.…”

Section: Pagementioning

confidence: 99%

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Responses of Neurons in the Rostral Ventrolateral Medulla (RVLM) of Conscious Felines to Anticipated and Passive Movements

Miller

Joshi

Kambouroglos

et al. 2019

Preprint

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Considerable evidence demonstrates that the vestibular system contributes to regulating sympathetic nerve activity and blood pressure. Initial studies in decerebrate animals showed that presumed pre-sympathetic neurons in the rostral ventrolateral medulla (RVLM) respond to small-amplitude (<10º) rotations of the body, as in other brain areas that process vestibular signals, despite the fact that such movements do not appreciably affect blood distribution in the body. However, a subsequent experiment in conscious animals showed that few RVLM neurons respond to small-amplitude movements. This study tested the hypothesis that vestibular inputs to RVLM neurons are modulated in conscious animals, such that vestibulosympathetic responses are only elicited when changes in body position are large enough to require changes in sympathetic nerve activity. The activity of approximately a third of RVLM neurons whose firing rate was related to the cardiac cycle, and thus likely received baroreceptor inputs, responded to vestibular inputs elicited by 40º head-up tilts in conscious cats, but not during 10º sinusoidal rotations in the pitch plane that affected the activity of neurons in brain regions providing inputs to the RVLM. These data suggest the existence of brain circuitry that suppresses vestibular influences on the activity of RVLM neurons and the sympathetic nervous system unless these inputs are physiologically warranted. We also determined that RVLM activity is not altered prior to tilts when a light cue is provided signaling the movement. The simplest interpretation of this findings is that feedforward cardiovascular responses are associated with active movement such as occurs during exercise, but not passive movements that require cardiovascular adjustments.

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Section: Page 19supporting

confidence: 89%

Section: Pagementioning

confidence: 99%

Responses of Neurons in the Rostral Ventrolateral Medulla (RVLM) of Conscious Felines to Anticipated and Passive Movements

Miller

Joshi

Kambouroglos

et al. 2019

Preprint

Self Cite

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“…This study employed procedures similar to those used in our prior experiments [7; 8; 9; 28; 30], which entailed acclimating animals for restraint on a computer-controlled tilt table, implanting instrumentation for recording the electrocardiogram (ECG) and single unit neuronal activity from the brainstem, and subsequently collecting data over a period of 112-399 days. Following data collection, animals were euthanized, and unit locations were histologically reconstructed.…”

Section: Methodsmentioning

confidence: 99%

“…It is well-established that feedforward cardiovascular responses are elicited prior to exercise and some other active movements [25; 26; 27]. A study that monitored changes in heart rate and cerebral blood flow in conscious felines before and during 60° head-up tilts preceded by a light cue demonstrated that no preparatory cardiovascular responses occur before such imposed changes in body position [28]. The conclusion of this study was that preparatory cardiovascular responses occur before active movements, but not passive (imposed) movements requiring increases in sympathetic nervous system activity.…”

Section: Introductionmentioning

confidence: 99%

“…However, it is possible that changes in neuronal activity are present upstream in the vestibulo-sympathetic reflex pathway, but suppressed prior to being relayed to the RVLM. Thus, by determining whether the activity of LTF and NTS neurons changes preceding cued head-up tilts, the present study provided an additional test of the hypothesis that feedforward cardiovascular responses occur only before active movements, but are absent prior to expected passive changes in body position [28].…”

Section: Introductionmentioning

confidence: 99%

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Responses of Neurons in the Medullary Lateral Tegmental Field and Nucleus Tractus Solitarius to Vestibular Stimuli in Conscious Felines

Bielanin

Douglas²,

Shulgach³

et al. 2020

Preprint

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Considerable evidence shows that the vestibular system contributes to adjusting sympathetic nervous system activity to maintain adequate blood pressure during movement and changes in posture. However, only a few prior experiments entailed recordings in conscious animals from brainstem neurons presumed to convey baroreceptor and vestibular inputs to neurons in the rostral ventrolateral medulla (RVLM) that provide inputs to sympathetic preganglionic neurons in the spinal cord. In this study, recordings were made in conscious felines from neurons in the medullary lateral tegmental field (LTF) and nucleus tractus solitarius (NTS) identified as regulating sympathetic nervous system activity by exhibiting changes in firing rate related to the cardiac cycle, or cardiac-related activity (CRA). Approximately 38% of LTF and NTS neurons responded to static 40° head up tilts with a change in firing rate of approximately 50%. However, few of these neurons responded to 10° sinusoidal rotations in the pitch plane, in contrast to prior findings in decerebrate animals that the firing rates of both NTS and LTF neurons are modulated by small-amplitude body rotations. Thus, as previously demonstrated for RVLM neurons, in conscious animals NTS and LTF neurons only respond to large rotations that lead to changes in sympathetic nervous system activity. The similar responses to head-up rotations of LTF and NTS neurons with those documented for RVLM neurons suggest that LTF and NTS neurons are components of the vestibulo-sympathetic reflex pathway. However, a difference between NTS/LTF neurons and RVLM was variability in CRA over time. This variability was significantly greater for RVLM neurons, raising the hypothesis that the responsiveness of these neurons to baroreceptor input is adjusted based on the animal's vigilance and alertness.

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Motion Sickness: Our Evolving Understanding and Problems

Lackner¹

2019

Reference Module in Neuroscience and Biobehavioral Psychology

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Cardiovascular adjustments during anticipated postural changes

Cited by 8 publications

References 40 publications

Responses of Neurons in the Rostral Ventrolateral Medulla (RVLM) of Conscious Felines to Anticipated and Passive Movements

Responses of Neurons in the Rostral Ventrolateral Medulla (RVLM) of Conscious Felines to Anticipated and Passive Movements

Responses of Neurons in the Medullary Lateral Tegmental Field and Nucleus Tractus Solitarius to Vestibular Stimuli in Conscious Felines

Motion Sickness: Our Evolving Understanding and Problems

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