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Kinetics of exercise‐induced neural activation; interpretive dilemma of altered cerebral perfusion
Author(s) -
Miyazawa Taiki,
Horiuchi Masahiro,
Ichikawa Daisuke,
Sato Kohei,
Tanaka Naoki,
Bailey Damian M.,
Ogoh Shigehiko
Publication year - 2012
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2011.061978
Subject(s) - dilemma , neuroscience , perfusion , kinetics , medicine , cardiology , physical medicine and rehabilitation , psychology , philosophy , physics , epistemology , quantum mechanics
Neural activation decreases cerebral deoxyhaemoglobin (HHb C ) and increases oxyhaemoglobin concentration (O 2 Hb C ). In contrast, patients who present with restricted cerebral blood flow, such as those suffering from cerebral ischaemia or Alzheimer's disease, and during the course of ageing the converse occurs, in that HHb C increases and O 2 Hb C decreases during neural activation. In the present study, we examined the interpretive implications of altered exercise‐induced cerebral blood flow for cortical oxygenation in healthy subjects. Both O 2 Hb C and HHb C (prefrontal cortex) were determined in 11 healthy men using near‐infrared spectroscopy (NIRS). Middle cerebral artery mean blood velocity (MCA V mean ) was determined via transcranial Doppler ultrasonography. Measurements were performed during contralateral hand‐grip exercise during suprasystolic bilateral thigh‐cuff occlusion (Cuff+) and within 2 s of cuff release (Cuff–) for the acute manipulation of cerebral perfusion. During Cuff+, both MCA V mean and O 2 Hb C increased during exercise, whereas HHb C decreased. In contrast, the opposite occurred during the Cuff– manipulation. These findings highlight the inverse relationship between cerebral blood flow and cerebral oxygenation as determined by NIRS, which has interpretive implications for the kinetics underlying exercise‐induced neural activation.