Failure to activate the left temporoparietal cortex in dyslexia. An oxygen 15 positron emission tomographic study.
To test the hypothesis of left temporoparietal dysfunction in dyslexia, suggested by neuropsychological and neuropathologic data, cerebral blood flow was measured with positron emission tomography in 14 right-handed men with severe developmental dyslexia (mean [SD] age, 27 [5] years; median reading level, fifth grade) and 14 matched controls at rest and during an auditory phonologic task (rhyme detection) and an auditory attention task involving the detection of target tones. As expected, normal readers activated left temporoparietal cortex during rhyme detection but not during the nonphonologic attentional task. Dyslexic men failed to activate those left temporoparietal regions activated in controls during rhyme detection but did not differ from controls in these regions during rest or attentional testing. Thus, the expected left temporoparietal dysfunction was demonstrated only when specific probes for these regions were employed.
Rumsey
J M
JM
Child Psychiatry Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892.
Andreason
P
P
Zametkin
A J
AJ
Aquino
T
T
King
A C
AC
Hamburger
S D
SD
Pikus
A
A
Rapoport
J L
JL
Cohen
R M
RM
D000328:Adult; D002560:Cerebrovascular Circulation; D004292:Dominance, Cerebral; D004410:Dyslexia / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010104:Oxygen Radioisotopes; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011932:Reading; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014055:Tomography, Emission-Computed
D010104:Oxygen Radioisotopes