title: Reconsidering the 90 degrees head-rotation paradigm used in neuropsychological research: are there reflexive rather than hemispatial effects?
abstract: The 90 degrees head-rotation paradigm has often been used in neuropsychological studies to manipulate external hemispace (circumcorporeal space) relative to the head. Under the 90 degrees head-rotation paradigm, the performance of limb and hand movements carried out within the left or right hemispace as defined by head positions relative to the body is likely to be affected by the reflexive effect due to the neck and vestibular afferent inputs elicited by the head rotations, as well as by the hemispatial effect. Using the H-reflex technique, the present study examined whether the reflexive effect on the spinal motoneuron excitability occurred with head rotations under the 90 degrees head-rotation paradigm. The results showed that the amplitudes of H-reflexes evoked on both the thumb flexor and soleus muscles were not affected by head rotations, indicating no reflexive change in the spinal motoneuron excitability for both the thumb and soleus muscles. This finding suggests that the reflexive effect due to neck and vestibular afferent inputs can be ruled out from possible causal factors influencing the motor performance of limb and hand movements performed within the left or right hemispace as manipulated by the 90 degrees head-rotation paradigm.
authors.affiliation: Department of Health and Physical Education, Faculty of Liberal Arts, Nagasaki University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Imanaka
authors.forename: K
authors.initials: K
authors.lastname: Funase
authors.forename: Y
authors.initials: Y
authors.lastname: Nishihira
mesh_terms: D000293:Adolescent; D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D000842:Ankle / Q000294:innervation; D001288:Attention / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D004576:Electromyography; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D009132:Muscles / Q000294:innervation; D009334:Neck Muscles / Q000294:innervation*; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012016:Reference Values; D013116:Spinal Cord / Q000502:physiology; D013933:Thumb / Q000294:innervation; D014725:Vestibular Nerve / Q000502:physiology*