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Functional Imaging of the Human Brainstem during Somatosensory Input and Autonomic Output.

Henderson LA, Macefield VG - Front Hum Neurosci (2013)

Bottom Line: We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity.More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension.Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Histology, University of Sydney , Sydney, NSW , Australia.

ABSTRACT
Over the past half a century, many investigations in experimental animal have explored the functional roles of specific regions in the brainstem. Despite the accumulation of a considerable body of knowledge in, primarily, anesthetized preparations, relatively few studies have explored brainstem function in awake humans. It is important that human brainstem function is explored given that many neurological conditions, from obstructive sleep apnea, chronic pain, and hypertension, likely involve significant changes in the processing of information within the brainstem. Recent advances in the collection and processing of magnetic resonance images have resulted in the possibility of exploring brainstem activity changes in awake healthy individuals and in those with various clinical conditions. We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity. More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension. Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens.

No MeSH data available.


Related in: MedlinePlus

Functional and anatomical localization of the human rostroventrolateral medulla (RVLM). From left to right: bilateral increase in RVLM functional magnetic resonance imaging (fMRI) signal intensity during a sustained muscle ischemia (Sander et al., 2010), maximal inspiratory breath-hold (Macefield et al., 2006), spontaneous fluctuations in muscle sympathetic nerve activity (MSNA) (Macefield and Henderson, 2010), anatomical identification of the RVLM using the binding of Angiotensin II receptors (reproduced with permission from Allen et al., 1998).
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Figure 6: Functional and anatomical localization of the human rostroventrolateral medulla (RVLM). From left to right: bilateral increase in RVLM functional magnetic resonance imaging (fMRI) signal intensity during a sustained muscle ischemia (Sander et al., 2010), maximal inspiratory breath-hold (Macefield et al., 2006), spontaneous fluctuations in muscle sympathetic nerve activity (MSNA) (Macefield and Henderson, 2010), anatomical identification of the RVLM using the binding of Angiotensin II receptors (reproduced with permission from Allen et al., 1998).

Mentions: Using the protocol described above, we explored the medullary circuits responsible for the baroreflex by measuring regional brainstem activity changes during small, spontaneous changes in MSNA during 10 recording sessions in 8 awake normotensive humans. Using brainstem-specific analysis techniques, we determined which brainstem regions displayed high or low signal intensity during periods of high MSNA. We found that small increases in MSNA were associated with fMRI signal intensity increases in the RVLM and signal decreases within the regions of the CVLM and NTS (Figure 5). That is, significant correlations between regional brainstem signal intensity and MSNA were found to occur in those regions previously described as being responsible for baroreflex functioning in anesthetized experimental animals, the RVLM, CVLM, and NTS (Macefield and Henderson, 2010). The increase in signal intensity within the region of the RVLM coincides with similar activation patterns evoked by maximal inspiratory capacity apneas and sustained hand grip, challenges which are also associated with significant increases in MSNA (refs). Furthermore, these activations lie in the same region defined anatomically as the RVLM by the binding of angiotensin receptors (Allen et al., 1998) (Figure 6).


Functional Imaging of the Human Brainstem during Somatosensory Input and Autonomic Output.

Henderson LA, Macefield VG - Front Hum Neurosci (2013)

Functional and anatomical localization of the human rostroventrolateral medulla (RVLM). From left to right: bilateral increase in RVLM functional magnetic resonance imaging (fMRI) signal intensity during a sustained muscle ischemia (Sander et al., 2010), maximal inspiratory breath-hold (Macefield et al., 2006), spontaneous fluctuations in muscle sympathetic nerve activity (MSNA) (Macefield and Henderson, 2010), anatomical identification of the RVLM using the binding of Angiotensin II receptors (reproduced with permission from Allen et al., 1998).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775150&req=5

Figure 6: Functional and anatomical localization of the human rostroventrolateral medulla (RVLM). From left to right: bilateral increase in RVLM functional magnetic resonance imaging (fMRI) signal intensity during a sustained muscle ischemia (Sander et al., 2010), maximal inspiratory breath-hold (Macefield et al., 2006), spontaneous fluctuations in muscle sympathetic nerve activity (MSNA) (Macefield and Henderson, 2010), anatomical identification of the RVLM using the binding of Angiotensin II receptors (reproduced with permission from Allen et al., 1998).
Mentions: Using the protocol described above, we explored the medullary circuits responsible for the baroreflex by measuring regional brainstem activity changes during small, spontaneous changes in MSNA during 10 recording sessions in 8 awake normotensive humans. Using brainstem-specific analysis techniques, we determined which brainstem regions displayed high or low signal intensity during periods of high MSNA. We found that small increases in MSNA were associated with fMRI signal intensity increases in the RVLM and signal decreases within the regions of the CVLM and NTS (Figure 5). That is, significant correlations between regional brainstem signal intensity and MSNA were found to occur in those regions previously described as being responsible for baroreflex functioning in anesthetized experimental animals, the RVLM, CVLM, and NTS (Macefield and Henderson, 2010). The increase in signal intensity within the region of the RVLM coincides with similar activation patterns evoked by maximal inspiratory capacity apneas and sustained hand grip, challenges which are also associated with significant increases in MSNA (refs). Furthermore, these activations lie in the same region defined anatomically as the RVLM by the binding of angiotensin receptors (Allen et al., 1998) (Figure 6).

Bottom Line: We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity.More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension.Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Histology, University of Sydney , Sydney, NSW , Australia.

ABSTRACT
Over the past half a century, many investigations in experimental animal have explored the functional roles of specific regions in the brainstem. Despite the accumulation of a considerable body of knowledge in, primarily, anesthetized preparations, relatively few studies have explored brainstem function in awake humans. It is important that human brainstem function is explored given that many neurological conditions, from obstructive sleep apnea, chronic pain, and hypertension, likely involve significant changes in the processing of information within the brainstem. Recent advances in the collection and processing of magnetic resonance images have resulted in the possibility of exploring brainstem activity changes in awake healthy individuals and in those with various clinical conditions. We and others have begun to explore changes in brainstem activity in humans during a number of challenges, including cutaneous and muscle pain, as well as during maneuvers that evoke increases in sympathetic nerve activity. More recently we have successfully recorded sympathetic nerve activity concurrently with functional magnetic resonance imaging of the brainstem, which will allow us, for the first time to explore brainstem sites directly responsible for conditions such as hypertension. Since many pathophysiological conditions no doubt involve changes in brainstem function and structure, defining these changes will likely result in a greater ability to develop more effective treatment regimens.

No MeSH data available.


Related in: MedlinePlus