Document Detail


Cortical and brain stem changes in neural activity during static handgrip and postexercise ischemia in humans.
MedLine Citation:
PMID:  20185626     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Static isometric exercise increases muscle sympathetic nerve activity (MSNA) and mean arterial pressure, both of which can be maintained at the conclusion of the exercise by occlusion of the arterial supply [postexercise ischemia (PEI)]. To identify the cortical and subcortical sites involved, and to differentiate between central command and reflex inputs, we used blood oxygen level-dependent (BOLD) functional MRI (fMRI) of the whole brain (3 T). Subjects performed submaximal static handgrip exercise for 2 min followed by 6 min of PEI; MSNA was recorded on a separate day. During the contraction phase, parallel increases in BOLD signal intensity occurred in the contralateral primary motor cortex and cerebellar nuclei and cortex; these matched the effort profile and ceased at the conclusion of the contraction. Progressive increases in the contralateral insula and primary and secondary somatosensory cortices, with progressive decreases in the perigenual anterior cingulate and midcingulate cortices, were sustained during the period of PEI and thus did not depend on central command. Discrete bilateral activation of the medial and lateral dorsal medulla was also observed during the contraction and PEI; we believe that these represent the nucleus tracts solitarius (NTS) and rostral ventrolateral medulla (RVLM), respectively. Given that metaboreceptor afferents are known to project to the NTS and that the RVLM is the primary output nucleus for MSNA, our data support that the metaboreflex is mediated by the medulla, whereas the somatosensory, insular, and anterior cingulate cortices are involved in the sensory and affective components of the maneuver.
Authors:
Mikael Sander; Vaughan G Macefield; Luke A Henderson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-02-25
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  108     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-06-03     Completed Date:  2010-10-08     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1691-700     Citation Subset:  IM    
Affiliation:
Aviation Medicine and Copenhagen Muscle Research Centre, Department of Cardiology, National Hospital, Blegdamsvej 9, Copenhagen DK-2100, Denmark. mikael.sander@gmail.com
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MeSH Terms
Descriptor/Qualifier:
Action Potentials*
Adaptation, Physiological
Adult
Brain Ischemia / physiopathology*
Cerebral Cortex / physiopathology*
Female
Hand Strength*
Humans
Male
Middle Aged
Muscle Contraction*
Muscle, Skeletal
Physical Exertion*
Young Adult

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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