title: Cerebral lateralization for motor tasks in simulated microgravity a transcranial Doppler technique for astronauts.
abstract: In Space, central cognitive operations are unaffected but humans are slower in perceptual-motor performance. Transcranial Doppler ultrasonography was used to monitor blood flow velocity in both middle cerebral arteries during unilateral and bilateral fingers' movements before, during and after -6 degrees 24 hours of head-down tilt (HDT) in 14 (8 males and 6 females) subjects. Physiologic hemisphere dominance was assessed by breath-holding test. There was a significant main effect of motor task, F(4, 328) = 16.05, p<0.00000001, MSe = 48.2. There was a gender vs head-position interaction F(3,246) = 4.90 p<0.002) MSe = 120. At pre-HDT females were right lateralized and males were left lateralized. A left shift in lateralization pattern was seen during 24hrs-HDT for both genders. There was a significant main effect of breath-holding test and a breath-holding test vs head position vs motor task interaction. HDT alters cerebral lateralization for motor control and this may be responsible for slowing in perceptual-motor performance in Space. TCD monitoring may be required for motor performance tasks in Space.
authors.affiliation: Non-invsive Neurocybernetic Flow Laboratory, International Institutes of Advanced Research and Training, Chidicon Medical Center. Owerri, Imo State, Nigeria. chidicon@yahoo.com
authors.forename: Philip C
authors.initials: PC
authors.lastname: Njemanze