| Abstract: | Conclusions Sex differences exist in the prevalence of dyslexia as well as in overall verbal ability. These sex differences may reflect
sex differences in hemispheric specialization: males show strong left hemisphere specialization for verbal processing and
strong right hemisphere specialization for spatial processing whereas females show greater bihemispheric participation in
both verbal and spatial processing. The greater hemispheric specialization observed in males may have implications including:
(1) lower verbal ability than in females, (2) higher spatial ability than in females, (3) reduced potential for shifting language
to the right hemisphere after early life left hemisphere injury, and (4) diminished capacity to compensate for unfavorable
left-right anatomic asymmetries of the posterior language zone. Lower overall verbal ability as well as an inability to spare
certain language skills effectively in the face of either unfavorable cerebral asymmetries or early life left hemisphere insults
may partially explain the excess of developmental language disorders (and dyslexia in particular) in boys.
Dr. Hier is a neurologist at the Massachusetts Rehabilitation Hospital, an Instructor in Neurology at the Harvard Medical
School, and Clinical and Research Fellow at the Massachusetts General Hospital, Boston. The work reported in this paper was
supported in part by NINCDS Fellowship NS05917-01 and presented at a meeting of the New Branch of The Orton Society in October
1978. |
