Functional asymmetry for auditory processing in human primary auditory cortex.
Structural asymmetries in the supratemporal plane of the human brain are often cited as the anatomical basis for the lateralization of language predominantly to the left hemisphere. However, similar asymmetries are found for structures mediating earlier events in the auditory processing stream, suggesting that functional lateralization may occur even at the level of primary auditory cortex. We tested this hypothesis using functional magnetic resonance imaging to evaluate human auditory cortex responses to monaurally presented tones. Relative to silence, tones presented separately to either ear produced greater activation in left than right Heschl's gyrus, the location of primary auditory cortex. This functional lateralization for primary auditory cortex is distinct from the contralateral dominance reported for other mammals, including nonhuman primates, and may have contributed to the evolution of a unique role for the left hemisphere in language processing.
Devlin
Joseph T
JT
Centre for Functional Magnetic Resonance Imaging of the Brain, Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom. devlin@fmrib.ox.ac.uk
Raley
Josephine
J
Tunbridge
Elizabeth
E
Lanary
Katherine
K
Floyer-Lea
Anna
A
Narain
Charvy
C
Cohen
Ian
I
Behrens
Timothy
T
Jezzard
Peter
P
Matthews
Paul M
PM
Moore
David R
DR
D000328:Adult; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D001307:Auditory Perception; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male