title: Right-, left-dominance and ambidexterity in grasp reflex in human newborn: importance of left brain in cerebral lateralization.
abstract: The grasp reflex was studied in human newborn without familial sinistrality. Of 60 females, 26 (43.3%) were right-handed and 34 (56.7%) ambidextrous. Of 62 males, 20 (32.3%) were right-handed, 39 (62.9%) ambidextrous, and 3 (4.8%) left-handed. There was a nonsignificant preponderance of right-dominance in females and a significant preponderance of nonright-handedness in males. In right-handers, the mean right minus left (R-L) grasp-reflex showed a positive linear correlation with the grasp-reflex from the right and left hands, with a higher correlation for the right hand. In ambidexters, the R-L grasp reflex did not show any significant correlation with the grasp reflex from the right and left hands. The mean grasp-reflex from right and left were found to be significantly smaller in ambidextrous males and females then right-handed males and females, with a much higher significance for the right hand. It was concluded that females tended to have a more pronounced reflex lateralization than males. The results also indicated that the left brain may be more important than the right brain for the development of a spinocerebral motor lateralization in humans.
authors.affiliation: Atatürk University, Medical Faculty, Department of Physiology, Erzurum, Turkey.
authors.forename: U
authors.initials: U
authors.lastname: Tan
authors.forename: R
authors.initials: R
authors.lastname: Ors
authors.forename: M
authors.initials: M
authors.lastname: Kürkçüoglu
authors.forename: N
authors.initials: N
authors.lastname: Kutlu
authors.forename: A
authors.initials: A
authors.lastname: Cankaya
mesh_terms: D001921:Brain / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008297:Male; D009048:Motor Skills / Q000502:physiology; D009119:Muscle Contraction; D012018:Reflex / Q000502:physiology*