Central command-related increases in blood velocity of anterior cerebral artery and prefrontal oxygenation at the onset of voluntary tapping

The anterior cerebral artery (ACA) supplies blood predominantly to the frontal lobe including the prefrontal cortex. Our laboratory reported that prefrontal oxygenated-hemoglobin concentration (Oxy-Hb) increases prior to and at exercise onset, as long as exercise is arbitrarily started. Moreover, the increased prefrontal oxygenation seems independent of both exercise intensity and muscle mass. If so, mean blood velocity of the ACA (ACABV) should increase with "very light motor effort", concomitantly with the pre-exercise and initial increase in prefrontal Oxy-Hb. This study aimed to examine the responses in ACABV and vascular conductance index (ACAVCI) of the ACA as well as prefrontal Oxy-Hb during arbitrary or cued finger-tapping in 12 subjects, an activity with a Borg scale perceived exertion rating of 7 (median). With arbitrary start, ACABV increased at tapping onset (14 ± 9%) via an elevation in ACAVCI. Likewise, prefrontal Oxy-Hb increased at the onset of tapping with a time course resembling that of ACABV. A positive cross-correlation between the initial changes in ACABV and prefrontal Oxy-Hb was found significant in 67% of subjects, having a time lag of 2 s, while a positive linear regression between them was significant in 75% of subjects. When tapping was forced to start by cue, the initial increases in ACABV, ACAVCI, and prefrontal Oxy-Hb were delayed and blunted as compared to an arbitrary start. Thus active vasodilatation of the ACA vascular bed occurs at tapping onset, as long as tapping is arbitrarily started, and contributes to immediate increases in blood flow and prefrontal oxygenation.

Download Full-text

Cerebral oxygenation changes in response to motor stimulation

Journal of Applied Physiology ◽

10.1152/jappl.1996.81.3.1174 ◽

1996 ◽

Vol 81 (3) ◽

pp. 1174-1183 ◽

Cited By ~ 165

Author(s):

H. Obrig ◽

C. Hirth ◽

J. G. Junge-Hulsing ◽

C. Doge ◽

T. Wolf ◽

...

Keyword(s):

Time Course ◽

Near Infrared ◽

Cerebral Oxygenation ◽

Motor Task ◽

Hemoglobin Concentration ◽

Hemodynamic Response ◽

Blood Oxygenation ◽

Initial Increase ◽

Cerebral Hemodynamic ◽

Course Changes

We studied cerebral hemodynamic response to a sequential motor task in 56 subjects to investigate the time course and distribution of blood oxygenation changes as monitored by near-infrared spectroscopy (NIRS). To address whether response is modulated by different performance velocities, a group of subjects (n = 12) was examined while performing the motor task at 1, 2, and 3 Hz. The results demonstrate that 1) the NIRS response reflects localized changes in cerebral hemodynamics, 2) the response, consisting of an increase in oxygenated hemoglobin concentration [oxy-Hb] and a decrease in deoxygenated hemoglobin concentration ([deoxy-Hb]), is lateralized and increases in amplitude with higher performance rates, and 3) changes in [oxy-Hb] and [deoxy-Hb] differ in time course. Changes in [oxy-Hb] are biphasic, with a fast initial increase and a pronounced poststimulus undershoot. The stimulus-associated decrease in [deoxy-Hb] is monophasic, and response latency is greater. We conclude that NIRS is able to detect even small changes in cerebral hemodynamic response to functional stimulation.

Download Full-text

Contribution of muscle afferent activation to the anterior cerebral artery blood velocity response to calf exercise in humans

The FASEB Journal ◽

10.1096/fasebj.23.1_supplement.787.10 ◽

2009 ◽

Vol 23 (S1) ◽

Author(s):

Lauro C Vianna ◽

James P Fisher

Keyword(s):

Cerebral Artery ◽

Anterior Cerebral Artery ◽

Blood Velocity ◽

Afferent Activation ◽

Velocity Response ◽

Muscle Afferent ◽

Calf Exercise ◽

Exercise In Humans

Download Full-text

Simultaneous determination of the kinetics of cardiac output, systemic O2 delivery, and lung O2 uptake at exercise onset in men

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00366.2005 ◽

2006 ◽

Vol 290 (4) ◽

pp. R1071-R1079 ◽

Cited By ~ 45

Author(s):

Frédéric Lador ◽

Marcel Azabji Kenfack ◽

Christian Moia ◽

Michela Cautero ◽

Denis R. Morel ◽

...

Keyword(s):

Cardiac Output ◽

Steady State ◽

Phase I ◽

Time Course ◽

Hemoglobin Concentration ◽

Two Phase ◽

Rapid Phase ◽

Steady State Method ◽

Exercise Onset ◽

Kinetics Of

We tested whether the kinetics of systemic O2 delivery (Q̇aO2) at exercise start was faster than that of lung O2 uptake (V̇o2), being dictated by that of cardiac output (Q̇), and whether changes in Q̇ would explain the postulated rapid phase of the V̇o2 increase. Simultaneous determinations of beat-by-beat (BBB) Q̇ and Q̇aO2, and breath-by-breath V̇o2 at the onset of constant load exercises at 50 and 100 W were obtained on six men (age 24.2 ± 3.2 years, maximal aerobic power 333 ± 61 W). V̇o2 was determined using Grønlund's algorithm. Q̇ was computed from BBB stroke volume (Qst, from arterial pulse pressure profiles) and heart rate ( fh, electrocardiograpy) and calibrated against a steady-state method. This, along with the time course of hemoglobin concentration and arterial O2 saturation (infrared oximetry) allowed computation of BBB Q̇aO2. The Q̇, Q̇aO2 and V̇o2 kinetics were analyzed with single and double exponential models. fh, Qst, Q̇, and V̇o2 increased upon exercise onset to reach a new steady state. The kinetics of Q̇aO2 had the same time constants as that of Q̇. The latter was twofold faster than that of V̇o2. The V̇o2 kinetics were faster than previously reported for muscle phosphocreatine decrease. Within a two-phase model, because of the Fick equation, the amplitude of phase I Q̇ changes fully explained the phase I of V̇o2 increase. We suggest that in unsteady states, lung V̇o2 is dissociated from muscle O2 consumption. The two components of Q̇ and Q̇aO2 kinetics may reflect vagal withdrawal and sympathetic activation.

Download Full-text

The prefrontal oxygenation and ventilatory responses at start of one-legged cycling exercise have relation to central command

Journal of Applied Physiology ◽

10.1152/japplphysiol.00401.2016 ◽

2016 ◽

Vol 121 (5) ◽

pp. 1115-1126 ◽

Cited By ~ 10

Author(s):

Ryota Asahara ◽

Kanji Matsukawa ◽

Kei Ishii ◽

Nan Liang ◽

Kana Endo

Keyword(s):

Time Course ◽

Perceived Exertion ◽

Ventilatory Response ◽

Minute Ventilation ◽

Hemoglobin Concentration ◽

Carbon Dioxide Tension ◽

Rating Of Perceived Exertion ◽

Subjective Rating ◽

Central Command ◽

Cycling Exercise

When performing exercise arbitrarily, activation of central command should start before the onset of exercise, but when exercise is forced to start with cue, activation of central command should be delayed. We examined whether the in-advance activation of central command influenced the ventilatory response and reflected in the prefrontal oxygenation, by comparing the responses during exercise with arbitrary and cued start. The breath-by-breath respiratory variables and the prefrontal oxygenated-hemoglobin concentration (Oxy-Hb) were measured during one-legged cycling. Minute ventilation (V̇e) at the onset of arbitrary one-legged cycling was augmented to a greater extent than cued cycling, while end-tidal carbon dioxide tension (ETco2) decreased irrespective of arbitrary or cued start. Symmetric increase in the bilateral prefrontal Oxy-Hb occurred before and at the onset of arbitrary one-legged cycling, whereas such an increase was absent with cued start. The time course and magnitude of the increased prefrontal oxygenation were not influenced by the extent of subjective rating of perceived exertion and were the same as those of the prefrontal oxygenation during two-legged cycling previously reported. Mental imagery or passive performance of the one-legged cycling increased V̇e and decreased ETco2. Neither intervention, however, augmented the prefrontal Oxy-Hb. The changes in ETco2 could not explain the prefrontal oxygenation response during voluntary or passive one-legged cycling. Taken together, it is likely that the in-advance activation of central command influenced the ventilatory response by enhancing minute ventilation at the onset of one-legged cycling exercise and reflected in the preexercise increase in the prefrontal oxygenation.

Download Full-text