Left-hemisphere specialization for the processing of acoustic transients.
Previous work suggests that speech sounds incorporating short-duration spectral changes (such as the formation transitions of stop consonants) rely on left hemisphere mechanisms for their adequate processing to a greater degree than do speech sounds incorporating spectral changes of a longer duration (such as vowel sounds). Ten normal subjects were scanned using positron emission tomography while discriminating pure tone stimuli incorporating frequency glides of either short or long duration. A comparison of these two conditions yielded significant activation foci in left orbitofrontal cortex, left fusiform gyrus, and right cerebellum. Because non-linguistic stimuli were used, these foci must reflect some basic low level aspect of neural processing that may be relevant to speech but cannot be a consequence of accessing the speech system itself.
Johnsrude
I S
IS
Neuropsychology/Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Canada.
Zatorre
R J
RJ
Milner
B A
BA
Evans
A C
AC
D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000000981:diagnostic imaging / Q000502:physiology*; D002560:Cerebrovascular Circulation; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D014055:Tomography, Emission-Computed