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Title: The role of the posterior cerebellar vermis in cardiovascular control
Author: Gallacher, David John
ISNI:       0000 0001 3486 8615
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1995
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The aim of the present study was to ascertain possible roles for the posterior cerebellar vermis in cardiovascular control using the anaesthetised, paralysed and artificially ventilated rabbit. The cortex of lobule IXb was stimulated both electrically and chemically and the effects of removal of lobules VI, VII and IX on the cardiorespiratory responses evoked from defensive behaviour related structures were observed. Arterial blood pressure, heart rate, femoral and renal vascular blood flow, and phrenic and renal nerve activities were routinely measured. Removal of lobule IX resulted in an increase in the sensitivity of the baroreceptor reflex response to a pressor challenge induced by intraluminal balloon inflations in the descending aorta. The increase in baroreflex gain was still evident when the experiments were carried out under β1-receptor blockade, the cell bodies in only lobule IXb were lesioned and whether the gain was calculated using R-R intervals derived from the heart rate or absolute R-R intervals. Stimulation of the HDA or PAG and ACe results in cardiorespiratory responses that are synonymous with those which occur in "fight or flight" and "playing dead" behaviours, respectively. Removal of lobule IX, but not lobules VI and VII, resulted in attenuated HDA, PAG and ACe evoked cardiovascular responses. On the other hand, simultaneous stimulation of lobule IXb with either of these structures resulted in facilitated "cardiovascular defence responses". Indeed, chemical activation of neurons in the HDA, PAG, ACe and lobule IXb identified the structure related nature of these cerebellar-midbrain/forebrain interactions. The cardiovascular effects elicited from the HDA or ACe and lobule IXb were vastly attenuated when cell bodies in the ipsilateral lateral parabrachial nucleus (LPBN) were lesioned with the excitotoxin kainic acid. Neurons in lobule IX demonstrated their ability to receive baroreceptor and hypothalamic inputs upon single or paired-pulse stimulation of the ipsilateral aortic nerve and hypothalamic defence area (HDA). A possible role for lobule IX of the posterior vermis in cardiovascular control is discussed in relation to published physiological and neuroanatomical studies and the results gained in the present study.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Physiology